FIELD OF THE INVENTION;
The present invention relates to functionally graded composite materials (FGCMs) and a process for preparation thereof.
BACKGROUND OF THE INVENTION:
Functionally gradient materials (FGMs) are nonhomogeneous materials in which the material composition is varied spatially to optimize the performance of the material for a specific application. In ceramic and metal based systems, lots of processing methods that developed earlier with slight modifications, are available like thermal spraying, powder metallurgy, coating process, melt processing, etc with certain disadvantages of each technique [B. Kieback, A. Neubrand and H. Riedel, "Processing techniques for functionally graded materials", Materials Science and Engineering, A362, (2003) pp 81-105], Compared to the metal or ceramic based systems, the knowledge on processing methods for polymeric FGMs is limited.
In polymers, compositional and microstructural gradients are intended to allow an optimum combination of component properties, like surface hardness, wear resistance, impact resistance and toughness. Graded polymers that have been processed so far include graded porosity in polyurethane [H. Piechota, H. Rphr, Integralschaumstoffe, Hanser, Wien, 1975], graded fiber composites [Q. Wang, Z. Huang and S. Ramakrishna, in K. Trumble, K. Bowman, I. Reimanis, and S. Sampath (Eds), Functionally graded materials 2000, Proceedings of the 6th International Symposium on Functionally Graded Materials 2000, Ceramic Transactions 114, American Ceramic Society, Westerville, OH, 2001, pp 89-96.], graded interpenetrating polymer networks [Y.S. Lipatov and L.V. Karabanova, J. Materials Science, 30, (1995) pp 2475-2484], graded biodegradable polyesters [C. Schiller, M. Siedler, F. Peters and M. Epple, Functionally graded materials 2000, Ceramic Transactions 114, American Ceramic Society, Westerville, OH, 2001, pp 97-107], graded index polymer fibers and microlenses [S. Sato, T. Nose, S. Masuda, S. Yanase, in W.A. Kaysser (Ed.), Functionally graded materials 1998, Proceedings of the 5th International Symposium on Functionally Graded Materials 1998, Trans Tech Publications, Switzerland, (1999), pp 567-572], polymer alloys [Y. Kano, K. Ishikura, S. Kawahara and S. Akiyama, "Analysis of surface segregation in blends of acrylate copolymer with fluoro copolymer", Polymer Journal, (1992), 24(2), 135-144], graded crystalline phase on the properties of semicrystalline polymers [Y. Agari,
"Development of functionally graded polymer materials", Kagaku Kogyo (1999), 50(8), 630-639] and graded SiC reinforcement in polymer matrix using centrifuging prior to polymerization [N.J. Lee, J. Jang, M. Park, C.R. Choe, J. Materials Science, 32 (1997) pp 2013-2020].
On the other hand, rubber/elastomeric materials in the industrial field are composites comprising of three dimensional network structures and fillers. Again one of the major drawbacks associated with the experimental studies is the preparation of FGMs having large scale gradation and also availability of matrix material in the solid form.
OBJECTS OF THE INVENTION;
An object of the present invention is to develop functionally graded elastomer nanocomposites (FGENCs) for the high tech application having various shapes and types of gradation through the use of nanoparticles and elastomer matrix.
Another object of the present invention is to characterize the newly developed FGENCs through hardness, specific gravity, and mechanical properties, i.e., modulus, tensile strength, elongation at break, strain energy, hysteresis loss, hysteresis loss ratio, tear strength and dynamic mechanical properties i.e., storage modulus, loss modulus, complex modulus, damping, etc.
Still another object of the present invention is to propose a functionally graded elastomer nanocomposite materials (FGCMs) and a process for preparation thereof, which facilitates the controlled variation of density/specific gravity/modulus/tensile strength/elongation at break/strain energy/hysteresis loss/hysteresis loss ratio/tear strength/storage modulus/loss modulus/complex modulus/damping, etc along with particle size in FGENCs.
Yet further object of the present invention is to propose a functionally graded elastomer nanocomposite materials (FGCMs) and a process for preparation thereof, which facilitates the controlled variation of density/specific gravity/modulus/tensile strength/elongation at break/strain energy/hysteresis loss/hysteresis loss ratio/tear strength/storage modulus/loss modulus/complex modulus/damping, etc along with particle size in FGENCs along the three directions for three dimensional product.
Further object of the present invention is to propose a functionally graded elastomer nanocomposite materials (FGCMs) and a process for preparation thereof, which facilitates the controlled variation of density/specific gravity/modulus/tensile strength/elongation at break/strain energy/hysteresis loss/hysteresis loss ratio/tear strength/storage modulus/loss modulus/complex modulus/damping, etc along with particle size in FGENCs along the three directions both from inner surface to the outer surface and from outer surface to the inner surface.
Further object of the present invention is to propose a functionally graded elastomer nanocomposite materials (FGCMs) and a process for preparation thereof, which facilitates the controlled variation of density/specific gravity/modulus/tensile strength/elongation at break/strain energy/hysteresis loss/hysteresis loss ratio/tear strength/storage modulus/loss modulus/complex modulus/damping, etc along with particle size either increasing or decreasing order in FGENCs along the three directions both from inner surface to the outer surface and from outer surface to the inner surface.
The inventive features of the present invention are depicted in the independent claims and the advantageous features are indicated in the dependent claims.
STATEMENT OF INVENTION
According to this invention there is provided a functionally graded elastomer nanocomposites (FGENCs) comprising an elastomer matrix, and nanomaterials, and rubber chemicals i.e., antioxidant, accelerator, accelerator activator, processing oil and curing agent.
Further according to this invention there is provided a process for preparation of a FGENCs comprising the steps of:
- Mixing of 1 to 70% (by volume) of nanoparticles in rubber chemicals which is
embedded in the elastomer matrix at the semisolid state (i.e., above the glass
transition temperature but below the melting point of rubber) by the conventional
two roll mixing mill
-preparation of a layer -0.1 mm from the nanoparticles imbedded elastomer matrix by two roll mill and hydraulic press at the semisolid state
- coating of the nanoparticles imbedded elastomer matrix on both sides with
coating agent (i.e., silicone spray, soap solution, silicone emulsion solution,
stearic acid, polytetrafluoro ethylene, polyvinyl alcohol, etc)
- cutting of the coated/uncoated nanoparticles imbedded elastomer matrix into
the required size using template
- lamination of the cut piece either in increasing or decreasing order as per
requirement (shown in Figs 1 to 9) to get green functionally graded elastomer
nanocomposites
- moulding of the green graded sheet in the coated mould (coating of the mould is
done by any one of these silicone spray, soap solution, silicone emulsion solution,
stearic acid, polytetrafluoro ethylene, polyvinyl alcohol)
- curing of the mould with green graded sheet for a certain period of time at a
specified temperature and pressure to obtain a cured FGENCs (temperature is
applied from one or both sides that depends on the type of FGENCs as shown in Pigs 1 to 9)
- removal of the cured FGENCs from the mould after curing followed by cooling in room temperature.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS AND TABLES;
Further, objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings and wherein:
Figure 1 shows: Schematic diagram of rectangular functionally graded elastomer nanocomposite, where the concentration of nanoparticles increases from one surface to the opposite surface.
Figure 2 shows: Schematic diagram of rectangular functionally graded elastomer nanocomposite, where the concentration of nanoparticles increases from inner surface to the outer surface.
Figure 3 shows: Schematic diagram of cylindrical functionally graded elastomer nanocomposite, where the concentration of nanoparticles increases from inner surface to the outer surface.
Figure 4 shows: Schematic diagram of rectangular functionally graded elastomer nanocomposite, where the concentration of nanoparticles decreases from inner surface to the outer surface.
Figure 5 shows: Schematic diagram of cylindrical functionally graded elastomer nanocomposite, where the concentration of nanoparticles decreases from inner surface to the outer surface.
Figure 6 shows: Schematic diagram of rectangular hollow functionally graded elastomer nanocomposite, where the concentration of nanoparticles increases from inner surface to the outer surface.
Figure 7 shows: Schematic diagram of rectangular hollow functionally graded elastomer nanocomposite, where the concentration of nanoparticles decreases from inner surface to the outer surface.
Figure 8 shows: Schematic diagram of cylindrical hollow functionally graded elastomer nanocomposite, where the concentration of nanoparticles increases from inner surface to the outer surface.
Figure 9 shows: Schematic diagram of cylindrical hollow functionally graded elastomer nanocomposite, where the concentration of nanoparticles decreases from inner surface to the outer surface.
Figure 10 shows: (a) Hardness (ES) and specific gravity profile () of type 1 FGENCs (as shown in Fig 1) made of natural rubber (polyisoprene) matrix and carbon nanoparticles having a particle size in the range of 20 to 30 nm (average -25 nm), (b) Change in hardness () and specific gravity () of same type 1 FGENCs (as shown in Fig 1) with distance. The thickness of the FGENCs along the gradient direction is 3.5 mm.
Figure 11 shows: (a) Hardness (E3) and specific gravity profile () of type 1 FGENCs (as shown in Fig 1) with volume fraction of nanomaterials in the natural rubber (polyisoprene) matrix and carbon nanoparticles having a particle size in the range of 20 to 30 nm (average -25 nm), (b) Change in hardness () and specific gravity () of same type 1 FGENCs (as shown in Fig 1) with change in volume fraction of nanomaterials (particle size in the range of 20 to 30 nm, but average -25 nm) in the natural rubber (polyisoprene) matrix.
Figure 12 shows: (a) Stress-elongation and (b) strain energy-elongation behaviour of type 1 FGENCs (as shown in Fig 1) made of natural rubber (polyisoprene) matrix and carbon nanoparticles having a particle size in the range of 20 to 30 nm (average -25 nm). Experimental results were reproducible within + 5% error. The thickness of the FGENCs along the gradient direction is 3.5 mm.
Figure 13 shows: (a) Tensile strength () and elongation at breaking point profile () of type 1 FGENCs (as shown in Fig 1) made of a natural rubber (polyisoprene) matrix and carbon nanoparticles having a particle size in the range of 20 to 30 nm (average -25 nm), (b) Change in tensile strength (E9) and elongation () of same type 1 FGENCs (as shown in Fig 1) with distance for a natural rubber (polyisoprene) matrix and carbon nanoparticles having a particle size in the range of 20 to 30 nm (average -25 nm). The thickness of the FGENCs along the gradient direction is 3.5 mm.
Figure 14 shows: (a) Tensile strength () and elongation at breaking point profile () of type 1 FGENCs (as shown in Fig 1) with volume fraction of nanomaterials (particle size in the range of 20 to 30 nm but average -25 nm) in natural rubber (polyisoprene) matrix, (b) Change in tensile strength () and elongation at breaking point profile () of same type 1 FGENCs (as shown in Fig 1) with change in volume fraction of nanomaterials in natural rubber (polyisoprene) matrix.
Figure 15 shows: (a) Moduli at 100% () and 200% () strain of FGENCs (type 1, shown in Fig 1) made of natural rubber (polyisoprene) matrix, (b) Change in moduli at 100% () and 200% () strain of same FGENCs (type 1, shown in Fig 1) with distance for a natural rubber (polyisoprene) matrix and carbon nanoparticles having a particle size in the range of 20 to 30 nm (average -25 nm). The thickness of the FGENCs along the gradient direction is 3.5 mm.
Figure 16 shows: (a) Moduli at 100% () and 200% () strain of type 1 FGENCs (as shown in Fig 1) with volume fraction of nanomaterials (particle size in the range of 20 to 30nm, but average -25 nm) in natural rubber (polyisoprene) matrix, (b)
Change in moduli at 100% () and 200% () strain of same type 1 FGENCs (as shown in Pig 1) with change in volume fraction of nanomaterials in natural rubber (polyisoprene) matrix.
Figure 17 shows: Tear strength () and change in tear strength () with (a) distance and (b) volume fraction of nanomaterials having particle size within the range of 20 to 30 nm (average -25 nm) in type 1 FGENCs (as shown in Pig 1) made of natural rubber (polyisoprene) matrix. The thickness of the FGENCs along the gradient direction is 3.5 mm.
Figure 18 shows: (a) Hysteresis loss and (b) hysteresis loss ratio of FGENCs (type 1, shown in Fig 1) made of natural rubber (polyisoprene) matrix and carbon nanoparticles having a particle size within the range of 20 to 30 nm (average -25 nm) at a temperature of 25°C, strain of 50%, and crosshead speed of 500 mm/min under tensile mode. Experimental results were reproducible within + 5% error. The thickness of the FGENCs along the gradient direction is 3.5 mm.
Figure 19 shows: (a) Hardness () and specific gravity profile (), (b) change in hardness (E) and specific gravity profile () of type 2 FGENCs (as shown in Fig 2) made of natural rubber (polyisoprene) matrix and carbon nanoparticles having a particle size within the range of 20 to 30 nm (average -25 nm). The thickness of the FGENCs along the gradient direction is 3.5 mm.
Figure 20 shows: (a) Tensile strength () and elongation at breaking point profile (), (b) change in tensile strength (E3) and elongation at breaking point () of type 2 FGENCs (as shown in Fig 2) made of natural rubber (polyisoprene) matrix and carbon nanoparticles having a particle size within the range of 20 to 30 nm (average -25 nm). The thickness of the FGENCs along the gradient direction is 3.5 mm.
Figure 21 shows: (a) Hardness () and specific gravity profile (), (b) change in hardness () and specific gravity profile () of type 4 FGENCs (as shown in Fig 4) made of natural rubber (polyisoprene) matrix and carbon nanoparticles having a particle size within the range of 20 to 30 nm (average -25 nm). The thickness of the FGENCs along the gradient direction is 3.5 mm.
Figure 22 shows: (a) Tensile strength () and elongation at breaking point profile (), (b) change in tensile strength () and elongation at breaking point () of type 4 FGENCs (as shown in Fig 4) made of natural rubber (polyisoprene) matrix and carbon nanoparticles having a particle size within the range of 20 to 30 nm (average -25 nm). The thickness of the FGENCs along the gradient direction is 3.5 mm.
Figure 23 shows: (a) Storage modulus (b) loss modulus vs temperature profile at different distance (E3: 0.5 mm, Hi: 1.00 mm, p: 1.5 mm; : 2.0 mm; : 2.5 mm; and : 3.00 mm) of type 1 FGENCs (as shown in Fig 1) made of natural rubber (polyisoprene) matrix and carbon nanoparticles having a particle size within the range of 20 to 30 nm (average -25 nm). Experimental results were reproducible
within ±4% error. The thickness of the FGENCs along the gradient direction is 3.5 mm.
Figure 24 shows: tan delta vs temperature profile at different distance (Jx[: 0.5 mm, : 1.00 mm, p: 1.5 mm; : 2.0 mm; and E3: 3.00 mm) of type 1 FGENCs (as shown in Fig 1} made of natural rubber (polyisoprene) matrix and carbon nanoparticles having a particle size within the range of 20 to 30 nm (average -25 nm). Experimental results were reproducible within +4% error. The thickness of the FGENCs along the gradient direction is 3.5 mm.
Figure 25 shows: (a) Hardness () and specific gravity profile () of type 2 FGENCs (as shown in Fig 2) made of styrene butadiene rubber matrix and carbon nanoparticles having a particle size within the range of 20 to 30 nm (average ~25 nm), (b) Change in hardness () and specific gravity () of same type 2 FGENCs. The thickness of the FGENCs along the gradient direction is 3.5 mm.
Figure 26 shows: (a) Hardness () and specific gravity profile () of type 2 FGENCs (as shown in Fig 2) with volume fraction of nanomaterials (average size -25 nm) in styrene butadiene rubber matrix, (b) Change in hardness () and specific gravity () of same type 2 FGENCs with change in volume fraction of nanomaterials in styrene butadiene rubber matrix. The thickness of the FGENCs along the gradient direction is 3.5 mm.
Figure 27 shows: (a) Stress-strain and (b) strain energy-elongation behaviour of type 1 FGENCs (as shown in Fig 1) made of styrene butadiene rubber matrix and carbon nanoparticles having a particle size within the range of 20 to 30 nm (average -25 nm). Experimental results were reproducible within ±4% error. The thickness of the FGENCs along the gradient direction is 3.5 mm.
Figure 28 shows: (a) Tensile strength () and elongation at breaking point profile () of type 2 FGENCs (as shown in Fig 2) made of styrene butadiene rubber matrix and carbon nanoparticles having a particle size within the range of 20 to 30 nm (average -25 nm), (b) Change in tensile strength () and elongation at breaking point () of same type 2 FGENCs with distance. The thickness of the FGENCs along the gradient direction is 3.5 mm.
Figure 29 shows: (a) Tensile strength () and elongation at breaking point profile () of type 2 FGENCs (as shown in Fig 2) with volume fraction of nanomaterials (average size -25 nm) in styrene butadiene rubber matrix, (b) Change in tensile strength () and elongation at breaking point profile () of same type 2 FGENCs.
Figure 30 shows: Moduli at 25% () and 50% () strain of type 2 FGENCs (as shown in Fig 2) with (a) distance and (b) volume fraction of nanomaterials (average size -25 nm) for a styrene butadiene rubber matrix. The thickness of the FGENCs along the gradient direction is 3.5 mm.
Figure 31 shows: Tear strength () and change in tear strength () with (a) distance and (b) volume fraction of nanomaterials in type 2 FGENCs (as shown in
Fig 2} made of styrene butadiene rubber matrix and carbon nanoparticles having
particle size within the range of 20 to 30 nm (average -25 nm). The thickness of the
FGENCs along the gradient direction is 3.5 mm. I
Figure 32 shows: (a) Hardness () and specific gravity profile () of type 1 FGENCs
(as shown in Fig 1) made of butyl rubber matrix and carbon nanoparticles having;a
particle size within the range of 20 to 30 nm (average ~25 nm), (b) Change in
hardness () and specific gravity () of same type 1 FGENCs. The thickness of the
FGENCs along the gradient direction is 3.5 mm. |
Figure 33 shows: (a) Tensile strength () and elongation at breaking point profile
(*) of type 1 FGENCs (as shown in Fig 1) made of butyl rubber matrix and carbon
nanoparticles having a particle size within the range of 20 to 30 nm (average ~?5
nm) (b) Change in tensile strength () and elongation () of same type 1 FGENCs.
The thickness of the FGENCs along the gradient direction is 3.5 mm. |
Figure 34 shows: (a) Moduli and (b) change in moduli at 100% () and 200% () strains of type 1 FGENCs (as shown in Fig 1) made of butyl rubber matrix ajid carbon nanoparticles having a particle size within the range of 20 to 30 nm (average -25 nm). The thickness of the FGENCs along the gradient direction is 3.5 mm. i
Figure 35 shows: Tear strength () and change in tear strength () with i(a) distance and (b) volume fraction of nanomaterials in type 1 FGENCs (as shown in Fig 1) made of butyl rubber and carbon nanoparticles having a particle size within the range of 20 to 30 nm (average -25 nm}. The thickness of the FGENCs along the gradient direction is 3.5 mm.
Figure 36 shows: (a) Storage modulus (E') and (b) loss modulus (E") vs temperature profile (: average volume fraction of nanoparticles throughout the matrix 15% (not a functional graded material); p: average volume fraction of nanoparticles throughout the matrix 15% (It is a functional graded material, force is applied on the surface having lower volume percentage of nanoparticles); and O: average volume fraction of nanoparticles throughout the matrix 15% (It is a functional graded material, force is applied on the surface having higher volume percentage; of nanoparticles) for a butyl rubber matrix and carbon nanoparticles having a particle size within the range of 20 to 30 nm (average -25 nm). Experimental results were reproducible within ±4% error. The thickness of the FGENCs along the gradient direction is 3.5 mm.
Table-1 shows: Formulation of mixes.
Table-2 shows: Moduli at a temperature of 25°C for FGENCs (carbon j as nanomaterial having a particle size within the range of 20 to 30 nm (average 1-25 nm) and natural rubber as matrix)
Table-3 shows: Tear strength at a temperature of 25°C for FGENCs having average 20 volume% of carbon nanomaterials having a particle size within the range of 20 to 30 nm (but average -25 nm) in the matrix of natural rubber.
Table-4 shows: Strain energy density, work removed and hysteresis loss during deformation of first and fourth cycles, at a strain of 50%, and temperature of 25°C for FGENCs having average 16 and 20 volume% of carbon nanomaterials having particle size within the range of 20 to 30 nm (but average -25 nm) in the matrix of natural rubber.
DETAILED DESCRIPTION OF THE PRESENT INVENTION;
Conditioning of Materials
Nanomaterials are kept in an oven at a temperature of 125°C for an hour to remove moisture. Conditioned nanomaterials are stored in a closed moisture-proof container until cool and then used for weighing and mixing.
Antioxidant is in pellet form so it is converted into powder form with the help of mortar and pestle. The rubber and nanomaterials are weighed within a tolerance of ±lg. All other chemicals are weighed within a tolerance of ±0. Ig accuracy.
Mixing
Mixing of nanomaterials and rubber chemicals in elastomer matrix is carried out using two-roll mill at a temperature of 50 to 125°C depending on the type of rubber. The speed of front roll is in between 10 to 34 rpm and friction ratio between front and rear roll is 1:1.1 to 1: 1.5. The clearance between rolls is adjustable from 0.1 to 12 mm. The formulation of the various mixes is given in Table 1. In these formulations the loading of metal oxide/s, acid/s, antioxidant/s, processing oil/s, accelerator/s and curing agent/s are in the range of 1 to 10 phr. During mixing, at first rubber is fed into the nip gap of two roll to get a thin sheet. Then antioxidant in powder form is added slowly followed by acid. The batch is cut % of the distance across the roll with the help of a knife, and held the knife at this position until the bank just disappears. This process is continued for 10 minutes. Then carbon nanomaterials are added evenly across the mill at a uniform rate. Processing oil is added with carbon nanomaterials to get a good distribution of nanomaterials into the matrix. The materials falling through the nip is collected carefully from the tray and returned back to the mix. The mixing cycle is concluded by passing the rolled batch endwise through the mill six to eight times with an opening of 0.2 mm to improve the dispersion. Finally the mixed compound is passed four times through the mill at a setting of 0.1 mm, folding it back on itself each time. The batch is removed and kept on the glass sheet, in a closed container to prevent absorption of moisture from the air for 24 hours. After 24 hours accelerator followed by curing agent is added according to the procedure mentioned above.
A thin uncured layer -0.1 mm (even less than 0.1 mm) of the mix is prepared by pressing in between two teflon sheets in the hydraulic press (for few seconds). The inner surfaces of the teflon sheets are coated with coating agent for easy removal of the layer. The volume (thickness) of all the layers of different mixes is made equal by taking different amount of mixes according to the specific gravity of the chemicals. All these layers of different mixes are stacked sequentially with increasing/decreasing amount of nanomaterials in each layer to form a green FGENCs
Curing
Curing is carried out in the hydraulic press. The press comprises a temperature controller of for example 400°C. It is capable of exerting a pressure in between 1 to 20 MPa on the cross sectional area of the cavities of the mold. The green FGENCs are cut into pieces according to the dimension of the mold cavity using template. Before putting the green FGENCs in the mould cavity the molding surfaces is polished and cleaned with distilled water and again coated with mould releasing agent.
The mold is kept at a curing temperature of 100 to 200°C depending on the type of base rubber in the closed press, held at this temperature for at least 20 min before the green FGENCs are inserted. The temperature of the mold is controlled by means of the temperature controller attached with the press. The press is opened, inserted the green FGENCs into the mold, and closed the press in the minimum time possible to prevent the excessive cooling of the mold by contact with cool metal surfaces or by exposure to air drafts. A pressure of 1 to 15 MPa is applied and three bumping is given to remove the air bubbles present, if any, for equal time of 15 sec. Finally a desired pressure is applied and held the mold for 10 minutes to 8 hours in the press. As soon as the press is opened the cure FGENCs from the mold is removed and cooled in water for 10 to 15 min. The cured FGENCs are conditioned at a temperature of 23±2°C for at least 16 hours before preparing the samples and testing.
The elastomer matrix is selected from the group comprising of natural rubber, polyisoprene rubber, styrene-butadiene rubber, polybutadiene rubber, ethylene-propylene rubber, ethylene-propylene diene-monomer rubber, butyl rubber, halobutyl rubber, nitrile rubber, hydrogenated nitrile rubber, polysulfide rubber, polyacrylic rubber, neoprene rubber, hypalon rubber, silicone rubber, fluorocarbon rubber, polyurethane rubber, thermoplastic elastomer, and mixture thereof.
The elastomer matrix natural rubber is selected from the group comprising of standard malaysian rubber (SMR) L, SMR CV, SMR WF, SMR GP, SMR LV, SMR 5, SMR 10, SMR 20, SMR 50, technically specified rubbers (TSR) 5, TSR 10, TSR 20, TSR 50, technically classified rubber, oil extended natural rubber, deproteinized natural rubber, peptized natural rubber, skim natural rubber, superior processing natural rubber, heveaplus MG rubber, epoxidized natural rubber, thermoplastic natural rubber, and mixture thereof; the elastomer matrix styrene-butadiene rubber

is selected from the group comprising of solution styrene-butadiene rubber i.e., SBR 2305, SBR 2304, emulsion styrene-butadiene rubber i.e., cold SBR 1500, cold SBR 1502, hot SBR 100, and mixture thereof; the elastomer matrix polybutadiene rubber is selected from the group comprising of cisamer-01, cisamerl220, BR 9000, BR 9004A, BR 9004B, low molecular weight 1, 3 polybutadiene, and mixture thereof; the elastomer matrix butyl rubber is selected from the group comprising of IIR-1751, IIR-1751F, IIR-745, Exxon butyl 007, Exxon butyl 065, Exxon butyl 068, Exxon butyl 165, Exxon butyl 268, Exxon butyl 269, Exxon butyl 365, polysar butyl 100, polysar butyl 101, polysar butyl 101-3, polysar butyl 301, polysar butyl 402, and mixture thereof; the elastomer matrix ethylene-propylene rubber is selected from the group comprising of dutral-CO-034, dutral-CO-038, dutral-CO-043, dutral-CO-054, dutral-CO-058, dutral-CO-059, dutral-CO-055, and mixture thereof; the elastomer matrix ethylene-propylene-diene-monomer rubber is selected from the group comprising of ethylene-propylene-dicyclopentadiene rubber, ethylene-propylene-ethylidenenorbornene rubber, ethylene-propylene-1, 4 hexadiene rubber, and mixture thereof; the elastomer matrix halobutyl rubber is selected from the group comprising of Exxon chlorobutyl 1065, Exxon chlorobutyl 1066, Exxon chlorobuityl 1068, Polysar chlorobutyl 1240, Polysar chlorobutyl 1255, Exxon bromobutyl 2222, Exxon bromobutyl 2233, Exxon bromobutyl 2244, Exxon bromobutyl 2255, Polysar bromobutyl X2, Polysar bromobutyl 2030, and mixture thereof; the elastomer matrix nitrile rubber is selected from the group comprising of Krynac-2750, Nipol-1053, Nipol-1032, Paracril-C, Chemigum-N-3, Krynac-5075, and mixture thereof; the elastomer matrix hydrogenated nitrile rubber is selected from the group comprising of zetpol-1010, zetpol-1020, zetpol-2010, zetpol-2020, therban, and mixture thereof; the elastomer matrix polyacrylic rubber is selected from the group comprising of hycar-4051, hycar-4052, hycar-4054, vamac-B-124, and mixture thereof; the elastomer matrix neoprene rubber is selected from the group comprising of neoprene-AC, neoprene-AD, neoprene-ADG, neoprene-AF, neoprene-AG, neoprene-FB, neoprene-GN, neoprene-GNA, neoprene-GRT, neoprene-GS, neoprene-GW, neoprene-W, neoprene-W-MI, neoprene-WB, neoprene-WD, neoprene-WHV, neoprene-WHY-100, neoprene-WHV-200, neoprene-WHV-A, neoprene-WK, neoprene-WRT, neoprene-WX, neoprene-TW, neoprene-TW-100, neoprene-TRT, and mixture thereof; the elastomer matrix hypalon rubber is selected from the group comprising of hypalon-20, hypalon-30, hypalon-LD-999, hypalon-40S, hypalon-40, hypalon-4085, hypalon-623, hypalon-45, hypalon-48S, hypalon-48, and mixture thereof; the elastomer matrix silicone rubber is selected from the group comprising of silicone MQ, silicone MPQ, silicone MPVQ, silicone FVQ, and mixture thereof; the elastomer matrix fluorocarbon rubber is selected from the group comprising of viton-LM, viton-C-10, viton-A-35, viton-A, viton-A-HF, viton-E-45, viton-E-60, viton-E-60C, viton-E403, viton-B-50, viton-B, viton-B-70, viton-910, viton-GLT, viton-GF, viton-VTR-4730, DAI-EL-G-101, DAI-EL-701, DAI-EL-751, DAI-EL-702, H)AI-EL-704, DAI-EL-755, DAI-EL-201, DAI-EL-501, DAI-EL-801, DAI-EL-901, DAI^EL-902, tecnoflon-FOR-LHF, tecnoflon-NMLB, tecnoflon-NML, tecnoflon-NMB, tecnoflon-NM, tecnoflon-NH, tecnoflon-FOR-45-45BI,
tecnoflon-FOR-70-70BI, tecnoflon-FOR-45-C-CI, tecnoflon-FOR-60K-KI, tecnoflon-FOR-50E, tecnoflon-TH, tecnoflon-TN-50, tecnoflon-TN, tecnoflon-FOR-THF, tecnoflon-FOR-TF-50, tecnoflon-FOR-TF, fluorel-2145, fluorel-FC-2175, fiuorel-FC-2230, fluorel-FC-2178, fluorel-FC-2170, fluorel-FC-2173, fiuorel-FC-2174, fiuorel-FC-2177, fluorel-FC-2176, fluorel-FC-2180, fluorel-FC-81, fiuorel-FC-79, fluorel-2152, fluorel-FC-2182, fluorel-FC-2460, fluorel-FC-2690, fluorel-FC-2480, and mixture thereof, the elastomer matrix polyurethane rubber (polyether and polyester type) is selected from the group comprising of FMSC-1035, FMSC-1035T, FMSCp-1040, FMSC-1050, FMSC-1060, FMSC-1066, FMSC-1070, FMSC-1075, FMSC-1080-SLOW, FMSC-1080-FAST, FMSC-1085, FMSC-1090-FAST, FMSC-1090-SLOW, and mixture thereof; the elastomer matrix thermoplastic elastomer (polyurethane, polyester, polyamide, styrene-butadiene-styrene, blends, etc) is selected from the group comprising of SBS 1401, SBS 4402, SBS 4452, SBS 1301, SBS 1401-1, SBS 4303, estane-55103, hytrel-40xy, hytrel-63xy, hytrel-72xy, gaflex-547, pebax-2533, pebax-6333, TPR-1600, TPR-1900, TPR-2800, TELCAR-340, SOMEL-301, SOMEL-601, santoprene, cariflex-TR, solprene-400, stereon, and mixture thereof; the elastomer matrix polysulfide elastomer is selected from the group comprising of thiakol-A, thiakol-B, thiakol-FA, thiakol-ST, and mixture thereof;
The elastomer matrix natural rubber is cured by vulcanizing agent selected from the group comprising of sulphur, hydrogen peroxide, dicumyl peroxide, benzoyl peroxide, diurethane, and mixture thereof which is in the range of 0.5 to 12 parts per hundred rubber (phr); the elastomer matrix styrene-butadiene rubber is cured by vulcanizing agent selected from the group comprising of sulphur, hydrogen peroxide, dicumyl peroxide, benzoyl peroxide, diurethane, and mixture thereof which is in the range of 0.5 to 12 parts per hundred rubber (phr); the elastomer matrix polybutadiene rubber is cured by vulcanizing agent selected from the group comprising of sulphur, hydrogen peroxide, dicumyl peroxide, benzoyl peroxide, diurethane, and mixture thereof which is in the range of 0.5 to 12 parts per hundred rubber (phr); the elastomer matrix butyl rubber is cured by vulcanizing agent selected from the group comprising of sulphur, hydrogen peroxide, dicumyl peroxide, benzoyl peroxide, diurethane, p-quinone dioxime, p-quinone dioxime dibenzoate, phenol-formaldehyde resin, and mixture thereof which is in the range of 0.5 to 12 parts per hundred rubber (phr); the elastomer matrix ethylene-propylene rubber is cured by vulcanizing agent selected from the group comprising of hydrogen peroxide, dicumyl peroxide, benzoyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis (t-butyl peroxy) hexane, bis(2,4-dichloro-benzoyl) peroxide, and mixture thereof which is in the range of 0.5 to 12 parts per hundred rubber (phr); the elastomer matrix ethylene-propylene-diene-monomer rubber is cured by vulcanizing agent selected from the group comprising of sulphur, hydrogen peroxide, dicumyl peroxide, benzoyl peroxide, diurethane, and mixture thereof which is in the range of 0.5 to 12 parts per hundred rubber (phr); the elastomer matrix halobutyl rubber is cured by vulcanizing agent selected from the group comprising of sulphur, hydrogen peroxide, dicumyl peroxide, benzoyl peroxide, zinc oxide, p-quinone dioxime, p-quinone dioxime dibenzoate, phenol-formaldehyde resin, amine, and mixture thereof which is
in the range of 0.5 to 12 parts per hundred rubber (phr); the elastomer matrix nitrile rubber is cured by vulcanizing agent selected from the group comprising of sulphur, hydrogen peroxide, dicumyl peroxide, benzoyl peroxide, and mixture thereof which is in the range of 0.5 to 12 parts per hundred rubber (phr); the elastomer matrix hydrogenated nitrile rubber is cured by vulcanizing agent selected from the group comprising of sulphur, hydrogen peroxide, dicumyl peroxide, benzoyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis (t-butyl peroxy) hexane, bis(2,4-dichloro-benzoyl) peroxide, tertiary butyl perbenzoate, and mixture thereof which is in the range of 0.5 to 12 parts per hundred rubber (phr); the elastomer matrix polyacrylic rubber is cured by vulcanizing agent selected from the group comprising of amine, diamine, activated thiol, sulphur, thiourea, trithiocyanuric acid, hydrogen peroxide, dicumyl peroxide, benzoyl peroxide, and mixture thereof which is in the range of 0.5 to 12 parts per hundred rubber (phr); the elastomer matrix neoprene rubber is cured by vulcanizing agent selected from the group comprising of magnesium oxide, zinc oxide, lead oxide, iron oxide, titanium oxide, amine, phenol, sulfenamide, thiazoles, thiuram, thiourea, guanidine, and mixture thereof which is in the range of 0.5 to 12 parts per hundred rubber (phr); the elastomer matrix hypalon rubber is cured by vulcanizing agent selected from the group comprising of magnesium oxide, zinc oxide, lead oxide, iron oxide, titanium oxide, sulphur, hydrogen peroxide, dicumyl peroxide, benzoyl peroxide, N,N'-m-phenylenedimaleimide, amine, phenol, sulfenamide, thiazoles, thiuram, thiourea, guanidine, and mixture thereof which is in the range of 0.5 to 12 parts per hundred rubber (phr); the elastomer matrix silicone rubber is cured by vulcanizing agent selected from the group comprising of hydrogen peroxide, dicumyl peroxide, benzoyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis (t-butyl peroxy) hexane, bis(2,4-dichloro-benzoyl) peroxide, tertiary butyl perbenzoate, and mixture thereof which is in the range of 0.5 to 12 parts per hundred rubber (phr); the elastomer matrix fluorocarbon rubber is cured by vulcanizing agent selected from the group comprising of hydrogen peroxide, dicumyl peroxide, benzoyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis (t-butyl peroxy) hexane, bis(2,4-dichloro-benzoyl) peroxide, tertiary butyl perbenzoate, hexamethylenediamine carbamate, bis(cinnamylidene) hexamethylenediarnine, hydroquinone, 4-4'-isopropylidene bisphenol or mixture thereof which is in the range of 0.5 to 12 parts per hundred rubber (phr); the elastomer matrix polyurethane rubber (polyether and polyester type) is cured by vulcanizing agent selected from the group comprising of 1,4-butanediol, 1,4-cyclohexanedimethanol, l,4-bis(2-hydroxyethoxy) benzene, 4,4'methylene-bis(2-chloroaniline), and mixture thereof which is in the range of 0.5 to 12 parts per hundred rubber (phr); the elastomer matrix thermoplastic elastomer (polyurethane, polyester, polyamide, styrene-butadiene-styrene, blends, etc) is cured by vulcanizing agent selected from the group comprising of lead oxide, cadmium oxide, zinchydroxide, hydrogen peroxide, dicumyl peroxide, benzoyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis (t-butyl peroxy) hexane, bis(2,4-dichloro-benzoyl) peroxide, tertiary butyl perbenzoate, and mixture thereof which is in the range of 0.5 to 12 parts per hundred rubber (phr); and the elastomer matrix polysulfide elastomer is cured by vulcanizing agent selected from the group comprising of lead oxide, cadmium oxide, zinchydroxide, hydrogen
peroxide, dicumyl peroxide, benzoyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-
bis (t-butyl peroxy) hexane, bis(2,4-dichloro-benzoyl) peroxide, tertiary butyl
perbenzoate, hexamethylenediamine carbamate, bis(cinnamylidene)
hexamethylenediamine, hydroquinone, 4-4'-isopropylidene bisphenol, and mixture thereof which is in the range of 0.5 to 12 parts per hundred rubber (phr)
The elastomer matrix comprising of either natural rubber, polyisoprene rubber, styrene-butadiene rubber, polybutadiene rubber, ethylene-propylene rubber, ethylene-propylene diene monomer rubber, butyl rubber, halobutyl rubber, nitrile rubber, hydrogenated nitrile rubber, polysulfide elastomer, polyacrylic rubber, neoprene rubber, hypalon rubber, silicone rubber, fluorocarbon rubber, polyurethane rubber, thermoplastic elastomer and/or mixture thereof is graded by carbon nanoparticles selected from the group comprising of N-l 10, N-l 15, N-120, N-121, N-125, N-134, N-135, N-212, N-220, N-231, N-234, N-293, N-299, N-315, N-326, N-330, N-335, N-339, N-343, N-347, N-351, N-356, N-358, N-375, N-539, N-550, N-582, N-630, N-642, N-650, N-660, N-683, N-754, N-762, N-765, N-772, N-774, N-787, N-907, N-908, N-990, N-991, and mixture thereof which is in the range of 0 to 70 volume percentage
The elastomer matrix comprising of either natural rubber, polyisoprene rubber, styrene-butadiene rubber, polybutadiene rubber, ethylene-propylene rubber, ethylene-propylene diene monomer rubber, butyl rubber, halobutyl rubber, nitrile rubber, hydrogenated nitrile rubber, polysulfide elastomer, polyacrylic rubber, neoprene rubber, hypalon rubber, silicone rubber, fluorocarbon rubber, polyurethane rubber, thermoplastic elastomer and/or mixture thereof is further graded by various silica nanoparticles i.e., precipitated silica (i.e., HS-200, HS-500, HS-700, etc), fumed silica and mixture thereof which is in the range of 0 to 70 volume percentage.
The elastomer matrix comprising of either natural rubber, polyisoprene rubber, styrene-butadiene rubber, polybutadiene rubber, ethylene-propylene rubber, ethylene-propylene diene monomer rubber, butyl rubber, halobutyl rubber, nitrile rubber, hydrogenated nitrile rubber, polysulfide elastomer, polyacrylic rubber, neoprene rubber, hypalon rubber, silicone rubber, fluorocarbon rubber, polyurethane rubber, thermoplastic elastomer and/or mixture thereof is further graded by clay nanoparticles which is in the range of 0 to 70 volume percentage.
The elastomer matrix comprising of either natural rubber, polyisoprene rubber, styrene-butadiene rubber, polybutadiene rubber, ethylene-propylene rubber, ethylene-propylene diene monomer rubber, butyl rubber, halobutyl rubber, nitrile rubber, hydrogenated nitrile rubber, polysulfide elastomer, polyacrylic rubber, neoprene rubber, hypalon rubber, silicone rubber, fluorocarbon rubber, polyurethane rubber, thermoplastic elastomer and/or mixture thereof is further graded by mixed carbon nanoparticles, nanosilica and nanoclay in a volume ratio of 5:2:1 to 1:2:5 selected from the group comprising of N-l 10, N-l 15, N-120, N-121, N-125, N-134, N-135, N-212, N-220, N-231, N-234, N-293, N-299, N-315, N-326, N-
330, N-335, N-339, N-343, N-347, N-351, N-356, N-358, N-375, N-539, N-550, N-582, N-630, N-642, N-650, N-660, N-683, N-754, N-762, N-765, N-772, N-774, N-787, N-907, N-908, N-990, N-991, precipitated silica (i.e., HS-200, HS-500, HS-700, etc), fumed silica, clay and mixture thereof.
The elastomer matrix comprising of either natural rubber, polyisoprene rubber, styrene-butadiene rubber, polybutadiene rubber, ethylene-propylene rubber, ethylene-propylene diene monomer rubber, butyl rubber, halobutyl rubber, nitrile rubber, hydrogenated nitrile rubber, polysulfide elastomer, polyacrylic rubber, neoprene rubber, hypalon rubber, silicone rubber, fluorocarbon rubber, polyurethane rubber, thermoplastic elastomer and/or mixture thereof is further graded by mixed carbon nanoparticles having same concentration gradient but different particle size i.e 5 to 85 nm and selected from the group comprising of N-110, N-115, N-120, N-121, N-125, N-134, N-135, N-212, N-220, N-231, N-234, N-293, N-299, N-315, N-326, N-330, N-335, N-339, N-343, N-347, N-351, N-356, N-358, N-375, N-539, N-550, N-582, N-630, N-642, N-650, N-660, N-683, N-754, N-762, N-765, N-772, N-774, N-787, N-907, N-908, N-990, N-991
The curing of elastomer matrix comprising of either natural rubber,
polyisoprene rubber, styrene-butadiene rubber, polybutadiene rubber, ethylene-
propylene rubber, ethylene-propylene diene monomer rubber, butyl rubber,
halobutyl rubber, nitrile rubber, hydrogenated nitrile rubber, polysulfide elastomer,
polyacrylic rubber, neoprene rubber, hypalon rubber, silicone rubber, fluorocarbon
rubber, polyurethane rubber, thermoplastic elastomer and/or mixture thereof is
further accelerated by accelerator selected from the group comprising of tert-
buttylbenzthiazyl sulphonamide, benzthiazyl 2-sulphenmorpholide, dicyclohexyl
benzthiazyl sulphonamide, N-cyclohexyl-2-benzothiazole sulfenamide, 2-
mercaptobenzothiazole, 2,2'dibenzothiazyl disulfide, tetramethylthiuram disulfide,
zinc dimethyldithiocarbamate, zinc dibutyldithiocarbamate, 4,4'dithiodimorpholine,
tellurium diethyldithiocarbamate, dipentamethylene thiuramhexasulfide,
tetramethylthiuram monosulfide, ferricdimethyldithiocarbamate, zinc
mercaptobenzthiazole, zinc 0,0 dibutylphosphorodithioate, zinc
diethyldithiocarbamate, 4-4'dithio dimorpholine, which is in
the range of 0.1 to 10 parts per hundred rubber (phr) and , and mixture thereof in a ratio of 1 : 99 to 99:1 (by weight)
The curing of elastomer matrix comprising of either natural rubber, polyisoprene rubber, styrene-butadiene rubber, polybutadiene rubber, ethylene-propylene rubber, ethylene-propylene diene monomer rubber, butyl rubber, halobutyl rubber, nitrile rubber, hydrogenated nitrile rubber, polysulfide elastomer, polyacrylic rubber, neoprene rubber, hypalon rubber, silicone rubber, fluorocarbon rubber, polyurethane rubber, thermoplastic elastomer and/or mixture thereof is further accelerated by accelerator activator selected from the group comprising of metal oxide and acid which is in the range of 10:1 to 1:10 parts per hundred rubber (phr).
The metal oxide used in accelerator activator is selected from the group comprising of zinc oxide, lead oxide, calcium oxide, magnesium oxide, lead oxide, etc which is in the range of 1 to 10 parts per hundred rubber (phr)
The acid used in accelerator activator is selected from the group comprising of stearic acid, palmitic acid, oleic acid, etc which is in the range of 1 to 10 parts per hundred rubber (phr).
The FGENCs further comprises an antioxidant selected from the group comprising of condensation product of acetone and diphenyl-amine, phenyl-beta-napthylamine, blends of diphenyl-p-phenylene diamine and selected arylamine derivatives, blend of arylamines, polymerized 1,2 dihydro 2,2,4-trimethyl quinoline, N-(l,3-dimethylbutyl)-N'-phenyl-p-phenylene-diamine, diaryl para phenylene diamines, 2 mercaptobenzimidazole, and mixture thereof which is in the range of 10:1 to 1:10 parts per hundred rubber (phr)
The FGENCs further comprises a process oil selected from the group comprising of paraffinic oil, naphthenic oil, aromatic oil, vegetable oil, and mixture thereof which is in the range of 10:1 to 1:10 parts per hundred rubber (phr).
The nanoparticles and other rubber chemicals imbedded elastomer matrix is prepared by mixing the rubber and other compounding ingredients by conventional methods such as open roll mixing using two roll mill and internal mixing kneader, intermix and banbary mixer.
The green graded nanocomposites is prepared by laminating of thin elastomer layer to produce a rectangular sheet having a thickness within the range of 2 to 1000 mm or unlimited in higher side, or cylindrical shape having a diameter within the range of 10 to 100 mm or unlimited in higher side.
The volume fraction of nanomaterials is varied within the range of 1 to 70% from the inner surface to outer surface (Figs 2, 3, 6 and 8) or from outer surface to inner surface (Pigs 4, 5, 7 and 9) or from outer surface to outer surface i.e., opposite surface (Fig 1)
The orifice both regular and irregular, i.e., complex geometry including its dimension (as shown in Figs 6, 7, 8, and 9) were made from one surface to the opposite surface using template; and the concentration of nanomaterials at the inner surface could be varied from 0 to 70% by volume (maximum) depending on the requirement; and the dimension of orifice could be varied using template.
VARIOUS EMBODIMENTS OF THE PRESENT INVENTION COMPRISE THE FOLLOWINGS:-
Fabrication of functionally graded elastomer nanocomposites having variou& shape (Figs 1 to 9) and gradation using elastomer matrix, nanoparticles, antioxidant, accelerator, accelerator activator, processing oil and curing agent.
Various carbon nanoparticles (act as reinforcing materials) i.e., N-110, N-115, N-120, N-121, N-125, N-134, N-135, N-212, N-220, N-231, N-234, N-293, N-299, N-315, N-326, N-330, N-335, N-339, N-343, N-347, N-351, N-356, N-358, N-375, ti-539, N-550, N-582, N-630, N-642, N-650, N-660, N-683, N-754, N-762, N-765, N-
772, N-774, N-787, N-907, N-908, N-990, N-991, etc are tested to make a novel functionally graded elastomer nanocomposite wherein the concentration of nanoparticles decreases or increases based on the requirement, but the particle size remains constant in each FGENCs.
Various carbon nanoparticles i.e., N-110, N-115, N-120, N-121, N-125, N-134, N-135, N-212, N-220, N-231, N-234, N-293, N-299, N-315, N-326, N-330, N-335, N-339, N-343, N-347, N-351, N-356, N-358, N-375, N-539, N-550, N-582, N-630, N-642, N-650, N-660, N-683, N-754, N-762, N-765, N-772, N-774, N-787, N-907, N-908, N-990, N-991, etc are also tested to make FGENCs wherein the total volume fraction of carbon nanoparticles in FGENCs is constant but the particle size of nanoparticles decreases or increases from one surface to the opposite surface.
Various mixed carbon nanoparticles i.e., combination of any two or more following carbons, i.e., N-110, N-115, N-120, N-121, N-125, N-134, N-135, N-212, N-220, N-231, N-234, N-293, N-299, N-315, N-326, N-330, N-335, N-339, N-343, N-347, N-351, N-356, N-358, N-375, N-539, N-550, N-582, N-630, N-642, N-650, N-660, N-683, N-754, N-762, N-765, N-772, N-774, N-787, N-907, N-908, N-990, N-991, etc are also tested to make FGENCs wherein both concentration and particle size of nanoparticles decreases or increases at a time.
Various silica nanoparticles i.e., precipitated silica (i.e., HS-200, HS-500, HS-700, etc) and fumed silica are tested to make a novel FGENCs.
Nanoclay is tested to make a novel FGENCs.
Various mixed nanoparticles i.e., combination of any one of the following carbons, i.e., N-110, N-115, N-120, N-121, N-125, N-134, N-135, N-212, N-220, N-231, N-234, N-293, N-299, N-315, N-326, N-330, N-335, N-339, N-343, N-347, N-351, N-356, N-358, N-375, N-539, N-550, N-582, N-630, N-642, N-650, N-660, N-683, N-754, N-762, N-765, N-772, N-774, N-787, N-907, N-908, N-990, N-991, etc, and silica (precipitated and fumed) or clay are also tested to make FGENCs.
Various polymer (elastomer) matrix i.e., natural rubber, styrene-butadiene rubber, polybutadiene rubber, polyisoprene rubber, ethylene propylene rubber, butyl rubber, halobutyl rubber, nitrile rubber, polyacrylic rubber, neoprene rubber, hypalone rubber, silicone rubber, fluorocarbon rubber, polyurethane rubber, etc are tested to make a novel FGENCs.
Various mixed polymer (elastomer) matrix i.e., combination of any two or more of the following rubbers, i.e., natural rubber, styrene-butadiene rubber, polybutadiene rubber, polyisoprene rubber, ethylene propylene rubber, butyl rubber, halobutyl rubber, nitrile rubber, polyacrylic rubber, neoprene rubber, hypalone rubber, silicone rubber, fluorocarbon rubber, polyurethane rubber, etc are tested to make a novel FGENCs.
Various geometries i.e., rectangular, cylindrical, etc are tested to make a novel FGENCs using template.
Various hollow geometries i.e., rectangular, cylindrical including complex irregular geometry are tested to make a novel FGENCs using template.
The gradient in properties i.e., modulus, hardness, tensile strength, elongation at breaking point, tear strength, strain energy density, hysteresis loss, work released during retraction, storage modulus, loss modulus, damping, complex modulus, storage compliance, loss compliance, complex compliance, etc are made in both directions as shown in Figs 10 to 36.
Study in performance between functionally graded elastomer nanocomposite, and conventional nanocomposite where the distributions of nanoparticles are uniform through out the matrix.
Study in performance between functionally graded elastomer nanocomposites where the percentage of nanomaterials is same, geometry is also same, but the concentration gradient is not same.
Specimen preparation
The specimen is cut with the help of sample cutter. Before cutting the specimen, the edges of the die (Type-2, and angle tear) are lubricated with water to facilitate cutting. Thickness of the specimen is measured by means of thickness gauge. Three readings are taken within the gauge length of the specimen, and finally average of the readings is calculated. Width of the specimens is also measured as the distance between the cutting edges of the blades of the die.
Specific gravity
Specific gravity of FGENCs is measured by the specific gravity balance.
Volume fraction of nanomaterials
The volume fraction of nanomaterials in the cured FGENCs is determined by the thermogravimetric analyzer using Perkin Elmer Diamond TGA in oxygen atmosphere at a heating rate of 10°C/minute.
Hardness
Shore A type durometer is used to measure the hardness of FGENCs. The instrument uses a calibrated spring to provide indenting force. The load imposed by spring varies with indentation. Reading is taken after 30 sec. The method adopted is the same as that of ASTM D2240-81.
Modulus, Tensile Strength and Elongation at Break
Modulus, tensile Strength and elongation at break are determined according to the ASTM D412-80 test method using dumbbell shaped specimens. Samples are punched along the mill grain direction from the cure sheet using ASTM type
dumbbell cutting die. The thickness of the narrow portion of the specimen is measured using a bench thickness guage. The tests are carried out in Zwick Universal Testing Machine (UTM) interfaced with a computer. All tests are carried out at 500 nim/min. cross head speed. The tests at elevated temperatures are done using a temperature cabinet equipped with a temperature controller. The modulus and tensile strength are reported in MPa and the elongation break in percentage.
Tear Strength
Tear strength is measured in Zwick (UTM) using unnotched 90° angled tear test specimen (die C) as per ASTM D 624-73. The samples are punched out from the molded sheet of FGENCs. The speed of crosshead is adjusted to 500 mm/min.
Hysteresis
Hysteresis loss of materials defines as the amount of energy dissipated during cyclic deformation is determined form the area under work done during extension (Wi) and work done during retraction (W2) when the specimen are stretched to varying extent and rate of elongation and then allow to retract at the same rate to the unstretched state.
Hy = (W1-W2) ...(1)
Work done during extension (W1) or strain energy is the area under the force deflection curve upto a fixed deflection and is expressed in joule. When it is divided by the volume of the test piece, it is known as the strain energy density, which is expressed in J/m3.
Hysteresis loss ratio is another parameter, which plays important role in the study of mechanical properties of materials. It is defined, as the energy dissipated relative to the energy supplied on stretching, is determined from the following expression.
W1 –W2
(Hy)r = W1 100% ...(2)
Dynamic mechanical properties:
Owing to the viscoelastic nature of rubbers, the sinusoidal strain lags the stress by an angle when the stress is applied to the sample. Accordingly the stress can be resolved into two components: one in phase with the strain and the other 90° out of phase. Mathematically these quantities can be handled most conveniently by complex variables and functions, and for a rubbery material the input and steady state response are described as
where (t), o, (t), 0,  and t represent stress at time (t), stress amplitude, strain at time (t), strain amplitude, frequency, and time respectively. The complex modulus (G*) is given by
G*=(t)/ (t)
= (0 / 0)ei
=(0 / 0)(cos + I sin ) ….(4)
=G’ +iG”
where G' and G" are known as storage modulus and loss modulus respectively. The loss tangent is represented by
tan  = G” / G’ ...(5)
For an applied deformation, the instrument measures the load and the phase difference, and converts them to G", G' and tan 8 through software.
The complex modulus, storage modulus, loss modulus, and tan 6 are measured in bending mode over a range of frequency (0.01 to 100 Hz), temperature (+25 to 100°C) and a peak to peak displacement 4x64 microns with a heating rate of 5°C per minute. Owing to the small dimensions of the specimens, the wave effect is absent, i.e., the phase of deformation of the entire specimen is same at any moment of time. In the case of multifrequency measurement, the changeover from one frequency to another is automatic. These data are analyzed for FGENCs.
In functionally graded elastomer nanocomposites (FGENCs) properly designed property gradients in materials science and engineering lead to a better performance, which cannot be achieved with a homogeneous material of the same kind or by the joining of two different materials through chemical and mechanical bonding. This gradient is defined as an additional material design parameter. It can be adopted and optimized to meet the requirements for a particular high tech application. Again this lead to the unusual situation, where the peWormance of the material is strongly influenced by the geometric factors such as shape of materials and the extent of deformation and profile of property gradient required for a specific application. Keeping this in mind various types of FGENCs (Figs 1 to 9) are designed using a formulation given in Table 1 with a variation of geometrical factors, concentration gradients of nanoparticles, size of nanomaterials, type of nanomaterials, matrix materials, etc and its performance is evaluated through the mechanical properties.
Hardness of FGENCs (type 1, as shown in Pig 1) made of natural rubber as a matrix is measured along the thickness direction to understand its performance and shown in Fig lO(a). In these FGENCs, the gradation is carried out by the carbon nanoparticles having a particle size within the range of 20 to 30 nm (average size -25 nm). The concentration of these carbon nanoparticles is zero at one surface and maximum at the opposite surface. Fig 10(a) demonstrates that the hardness increases with increasing distance from one end to the opposite end. Its magnitude varies from 35 to 92 shore A. The increased hardness is attributed to the presence of more
amounts of carbon nanoparticles. As there is more amounts of carbon nanoparticles along the thickness direction, so the specific gravity should increase along the thickness direction. To understand the effect of carbon nanoparticles on hardness, specific gravity is also measured along the thickness direction. It varies from 0.97 to 1.25 and shown in the same Pig 10(a). The increased specific gravity is due to the difference of specific gravity of matrix and carbon nanoparticles. The matrix has a specific gravity of -0.92 and carbon nanoparticles of -1.8. Now to know the rate of increments of these properties i.e., hardness, specific gravity, etc with respect to the thickness, change in material properties is calculated from Eqn. (6) using the data of Pig 10(a) and plotted in Pig 10(b) against change in thickness/distance.
P -P
Change in properties (%) = ——- ... 6)
Po
where, Px and Po are the average properties at a distance where the change in properties is to be measured and properties at the reference point where the concentration of carbon nanoparticles is minimum or any other reference point. The nature of these plots shown in Fig 10(b) is same as Fig. 10(a), i.e., the change in hardness increases with an increase of change in distance from one end to the opposite end. The variation of hardness is - 160% from one end to the opposite end. Similar trend shown in Fig. 10(b) is also observed for specific gravity. The increment of specific gravity is -30%.
As the hardness and specific gravity both depend on the volume fraction of the carbon nanoparticles content, the amount of carbon nanoparticles present in this FGENCs with respect to the distance is measured by the thermogravimetric analysis in oxygen atmosphere. Hardness and specific gravity are plotted against the volume fraction of carbon nanoparticles and shown in Pig 11 (a). With increasing the volume fraction of carbon nanoparticles, both hardness and specific gravity increase. Hardness and specific gravity go up from 35 to 92 shore A and from 0.97 to 1.24 respectively with increasing the volume fraction of carbon nanoparticles from 0 to 0.32. The specific gravity of carbon nanoparticles is more than matrix material (approximately 2 times, specific gravity of carbon nanoparticles -1.8 and matrix -0.92). Similarly the change in hardness and specific gravity is also calculated using the data of Pig 11 (a) and plotted in Fig ll(b). Same trend as in Fig 11 (a) is also observed here. The increase in hardness and specific gravity (Fig. 11 (b)) of the FGENCs is 160 and 27 respectively. Now to understand the effect of sample thickness on these properties, few more
FGENCs are made, where the concentration of carbon nanoparticles is same at the both sides, but it has different thickness. The nature of these plots, i.e., hardness and specific gravity versus distance and volume fraction of carbon nanoparticles, and change of these properties with respect to the distance and volume fraction of carbon nanoparticles is same (Figs, are not shown here). However the magnitude is a function of concentration gradient, i.e., thickness of FGENCs.
Now it is necessary to determine the variation of mechanical properties i.e., stresses and strain energy at various deformations/elongations, tensile strength, elongation at breaking point, tear strength, hysteresis loss, hysteresis loss ratio, strain energy during deformation, strain energy during retraction, etc in FGENCs for evaluation of these novel materials in high tech applications. All these properties are measured along the thickness direction with respect to the distance and volume
fraction of carbon nanoparticles. With variation of the carbon nanoparticles content along the thickness direction, all these mechanical properties vary. One can see the stress-strain/elongation and strain energy-elongation profiles of FGENCs (type 1, as shown in Fig 1) at different distance from one end to the opposite end and shown in Figs 12 (a) and (b). The layer at a distance of 0.5 mm extends by more than 1000 % with a stress value of 20 MPa, which is much more than the opposite layer at a distance of 3.0 mm. This attributes to the strain induced crystallization in the vulcanizates. With increasing amount of carbon nanoparticles content along the thickness direction of the graded nanocomposite, the strain induced crystallization mitigates and the tensile strength and % elongation drops down. The opposite layer comprising of maximum carbon nanoparticles (volume fraction 0.32) shows the least value of tensile stress and % elongation of 9 MPa and 133 respectively. Similar trends as shown in Fig 12(b) are also observed when the strain energy is plotted against the deformation/elongation. The strain energy of the layer at a distance of 0.5 mm is one decade higher than that of the opposite layer at a distance of 3.0 mm. The values of the strain energy at 0.5 and at 2.5 mm along thickness direction are 3.15 x 106 and 5 x 105 J/m2 respectively.
Now the tensile strength and elongation at breaking point are calculated from Fig 12(a) to characterize these FGENCs from the corner of mechanical properties. Both parameters i.e., tensile strength and elongation at breaking point vary along the thickness as the carbon nanoparticle content varies. The variation of tensile strength and elongation at breaking point along the thickness in FGENCs (as type 1, shown in Fig 1) is shown in Fig 13 (a). The tensile strength and elongation at breaking point are continuously decreasing along the thickness from 20 to 9 MPa and from 1090 to 130 respectively within the span of 3 mm. The percentage changes in tensile strength and % elongation with respect to the change of distance are shown in Fig 13 (b). The tensile strength and elongation at breaking point decrease continuously from 0 to 55 % and from 0 to 90 % respectively within the span of 3 mm. The decreased tensile strength and elongation at breaking point is attributed to the presence of more amounts of carbon nanoparticles in the elastomer matrix, which ultimately reduces the Vander wall forces of attraction between the elastomer chains and more stress concentration along the surface of nanoparticle region. As a result crack starts to propagate from these highly stress concentrated region. Now to understand the effect of carbon nanoparticles on tensile strength and elongation at breaking point, these parameters are plotted against the volume fraction of nanoparticles along the thickness direction. The tensile strength and % elongation vary with the volume fraction of the carbon nanoparticle content. The variation of these properties with the volume fraction of the carbon nanoparticles in FGENCs (type 1, as shown in Fig 1) is shown in Fig 14 (a). The tensile strength and % elongation at break are continuously decreasing with increasing the volume fraction of carbon nanoparticles. By increasing the volume fraction of carbon nanoparticles from 0 to 0.32, tensile strength decreases from 20 to 9 MPa and % elongation decreases from 1080 to 135 respectively. The percentage change of these properties against the change in volume fraction of carbon nanoparticles is shown in Fig 14 (b). The tensile strength ami % elongation at break decrease continuously from 0 to
55% and from 0 to 90% respectively after increasing the volume fraction of carbon nanoparticles by 32%.
With increasing the volume fraction of carbon nanoparticles, tensile strength and elongation at breaking point both decrease, but the slope of the curve increases at each and every point. Again tensile strength and elongation at breaking point are failure parameters. Generally designers are least interested about these two parameters. They have defined another parameter known as modulus from the design point of view especially in structural application. In this context modulus at 50% (amount of stress required to get a deformation of 50%), 100% (similarly the required stress at 100% strain) and 200% (similarly the required stress at 200% strain) elongations are measured for these FGENCs. Moduli at 100 and 200 % elongations increase with thickness in type 1 FGENCs (as shown in Fig 1) and shown in Pig 15(a). The enhancement in modulus is attributed to the increase in carbon nanomaterial content along the thickness direction and explained as follows. Researchers suggested that occluded elastomer, bound elastomer and immobilized elastomer shell around the carbon nanoparticle surface overlap each other and can form a complicated interlinked three dimensional structure. This adsorbed hard immobilized elastomer fraction increases with the carbon nanoparticles loading. Since the hard portion increases with an increasing nanoparticle loading, as a result modulus increases. The increased modulus may also be attributed to the superposition of different relaxation processes, hydrodynamic effect of the cartion nanoparticles imbedded in the elastomer continuum, stronger elastomer-carbon nanoparticles interaction and tightening of the network associated with a shell of hindered elastomer at the carbon nanoparticle surface which increases viscoelastic response of the elastomer. Thus the elastomer matrix in carbon nanoparticle filled vulcariizates deform to a larger degree than the macroscopic strain applied to the samples. The values of moduli at 100 and 200% elongations are increasing from 0.90 to 7.7 and 1.2 to 11 MPa respectively. The increment in the modulus is steep in the first half along the thickness and then increases rapidly in the next half. The percentage changes of moduli at 100 and 200% elongations are shown in Pig 15 (b). The modulus at 100% elongation increases by 600% in the span of 2.5 mm while the modulus at 200% lifts up by 800% in the span of same 2.5 mm. Where as modulus at 100% elongation increases by 800% in the span of 3 mm while modulus at 200% lifts up same 800% in the span of 2.5 mm. The top/opposite layer having a volume fraction of carbon nanoparticles in the range of 0.3 doesn't extend to 200%. Few more FGENCs (as type 1, shown in Fig 1) are made with different thickness but same volume fraction of carbon nanoparticles at both sides. The properties i.e., tensile strength, modulus at breaking point and modulus at various deformation vary in the same fashion. However in few cases the improvement of modulus at 50% elongation is ~ 800%.
Now to verify the statement given above to explain the enhancement of modulus along thickness direction, moduli at 100 and 200% elongations are plotted against the volume fraction of carbon nanoparticles and shown in Fig 16(a). Similarly the moduli at 100 and 200% elongations increase with increasing the
volume fraction of the carbon nanoparticles in FGENCs as observed in Pig 15(a). The values of moduli at 100 and 200% elongation are increasing from 0.9 to 7.7 and 1.2 to 11 MPa respectively when the volume fraction of the carbon nanoparticles is increased from 0 to 0.32. The percentage changes of moduli at 100 and 200 % elongations with the change of volume fraction of carbon nanoparticles along the thickness directions are shown in Pig 16 (b). The modulus at 100% elongation increases by 800% with increasing the volume of nanomaterials by 32%. While modulus at 200% lifts up by 650% with increasing the volume of nanomaterials by 28% as the matrix with further increment in the volume fraction of the nanomaterials doesn't extend to 200% deformation.
The FGENCs are characterized by another mechanical properties i.e., tear strength (the amount of stress required to break the specimen having a pre imbedded crack as per ASTM standard) and shown in Pig 17(a). The variation of tear strength along the thickness direction is not linear as of tensile strength, elongation and moduli curves. The tear strength increases from 65 to 135 kN/m till the mid-thickness of -1.5 mm and drops down to -60 kN/m at the end. The change in tear strength with respect to the distance is also plotted in same Fig 17(a). The increase in tear strength is 120% halfway along the thickness and again decreases by 10% of the value at a distance of 0.5 mm, where the concentration of carbon nanoparticles is - zero. In a similar way, by increasing the volume fraction of the carbon nanoparticles from 0 to 0.15, the tear strength increases from 65 to 135 kN/m as shown in Fig 17(b), where the material properties are plotted against the volume fraction of carbon nanoparticles. Again with further increment of the volume fraction of the carbon nanoparticles from 0.15 to 0.32, tear strength decreases to 60 kN/m from 135 kN/m.
Few more FGENCs are made where the concentration of carbon nanoparticles is 50 (by weight) with respect to the matrix material of 100. The tear strength of these FGENCs are compared with the materials where the concentration of carbon nanoparticles is same through out the matrix, i.e., homogeneous distribution of carbon nanoparticles, i.e., homogeneous composites and given in Table 3. The tear strength of few graded nanocomposites shows higher values than their corresponding homogeneous nanocomposites. It is observed from Table 3 that various forms of FGENCs show the tear strength values of 100, and 90 kN/m that are much higher than the corresponding homogeneous composites value of 70 kN/m.
Hysteresis loss, hysteresis loss ratio, strain energy during deformation and strain energy during retraction were measured for type 1 FGENCs (as shown in Fig 1) over a number of cycle (uptolO111 cycle) to understand their behaviour in target application. As shown in Fig 18(a), the hysteresis loss at a distance of 0.5 mm of FGENCs decreases drastically in the second cycle and attains a plateau value at the forth cycle. The change is insignificant after this. The decreased hysteresis loss is attributed to the session or rearrangement of molecular chains, the fracture of week entanglements and the structure change of carbon nanoparticle aggregates. A similar trend is also observed for the hysteresis loss ratio (Pig 18(b)). Strain energy during deformation and strain energy during retraction (Figs are not shown here)

follow same trend as hysteresis loss ratio. As it is observed in the last few Figs that the concentration of carbon nanoparticles increases with moving from one surface to the opposite surface along the thickness direction so hysteresis loss, hysteresis loss ratio, strain energy during deformation and strain energy during retraction should depend on the distance, where all these properties are measured. Now to understand the effect of carbon nanoparticles on all these properties, experiments were carried out on FGENCs at different distance and plotted in same Fig 18(a). All properties display similar behaviour. With the increased loading of carbon nanoparticles all these properties increase. The values of hysteresis loss at a distance of 0.5 and 3.0 mm are 2.3 x 103 and 2.2 x 105 J/m2 respectively. The remarkable change ;in hysteresis loss is explained by the same way as described in the moduli values. Similarly here researchers suggested that the occluded elastomer, bound elastomer and immobilized elastomer shell around the carbon nanoparticle surface overljap each other and can form a complicated interlinked three dimensional structure. This adsorbed hard immobilized elastomer fraction increases with the carbon nanoparticles loading. Since the hard portion increases with an increasing | of nanoparticle loading, as a result modulus increases. The increased hysteresis Ibss may also be attributed to the superposition of different relaxation processes, hydrodynamic effect of the carbon nanoparticles imbedded in the elastomer continuum, stronger elastomer-carbon nanoparticles interaction and tightening of the network associated with a shell of hindered elastomer at the carbon nanoparticle surface which increases viscoelastic response of the elastomer. Thus the elastonier matrix in carbon nanoparticle filled vulcanizates deform to a larger degree than the macroscopic strain applied to the samples.
As it is mentioned earlier that the performance of the FGENCs is strongly influenced by the geometric factors, now to understand its effect another type of FGENCs using natural rubber matrix are made (as shown in Fig 2). Hardness and specific gravity were measured for this type 2 FGENCs and plotted in Fig 19(a) against distance. Fig 19(a) shows that the hardness and specific gravity both decrease in the first half along the thickness as the carbon nanoparticles loading decreases and again increases in the next half with the increasing volume fraction of nanomaterial. Hardness decreases from 92 to 35 shore A along the thickness direction from outer surface to the inner surface at a distance of 1.5 mm. The concentration of carbon nanoparticles is minimum at a distance of 1.5 mm. Specific gravity also drops down from 1.24 to 0.97 in the first half along the thickness and then both properties lift up to their original values, as the concentration of carbon nanoparticles is same in the outer surface. The change of these properties is plotted against the thickness as shown in Fig 19 (b). Hardness decreases by 160% in the first half along the distance and then lifts up by the same amount. Similarly, the specific gravity also decreases by 30% and again goes to its original value.
Now with changing the geometric factor, the plots of tensile strength and elongation at break also change with the loading of carbon nanoparticles. the variation of tensile strength and elongation at breaking point along the thickness direction at different distance is shown in Fig 20 (a). The tensile strength goes up from 9 to 20 MPa in the first halfway along the thickness as the loading of the

carbon nanoparticles decreases. In the same way, elongation at break also increases from 130 to 1075 in the first half and then in the next halfway along the thickness, both properties drop down to their original values. The percentage change in tensile strength and elongation at break with respect to the inner layer, where the concentration of carbon nanoparticles is less, is affected due to the change in gradation of carbon nanoparticles and shown in Pig 20 (b). In the first half along the thickness, tensile strength and elongation at break both increases by 55 and 50% respectively. In the next half, both the properties again come down by the same amount.
Few more FGENCs (type 1 to 9, as shown in Figs 1 to 9) were made using natural rubber and other carbon nanoparticles, i.e., N-110, N-115, N-120, N-121, JN-125, N-134, N-135, N-212, N-220, N-231, N-234, N-293, N-299, N-315, N-326, N-330, N-335, N-339, N-343, N-347, N-351, N-356, N-358, N-375, N-539, N-550, :N-582, N-630, N-642, N-650, N-660, N-683, N-754, N-762, N-765, N-772, N-774, JN-787, N-907, N-908, N-990, N-991, etc to understand the effect of particle sizej of nanomaterials on the performance of FGENCs in structural applications. Here tjhe particle size varies from ~ 5 to 85 nm through out the matrix. But the total volume fraction of nanomaterials is same in the FGENCs. The graded composites are characterized by hardness, specific gravity, moduli, tensile strength, elongation at breaking point, strain energy, hysteresis loss, hysteresis loss ratio, tear strength, storage modulus, loss modulus, complex modulus, loss tangent, etc over a range of frequency and temperature of 25 to 100°C. These properties are plotted against j;he distance and volume fraction of carbon nanoparticles in the graded composites. The nature of these plots are same (not shown here), but the magnitude of these properties increases with increasing the particle size of carbon nanoparticles in the order of 5-10 (average 7 nm) > 11-20 (average 15 nm) > 21-30 (average 25 nm) > 31-40 (average 35 nm) > 41-49 (average 45nm) > 50-59 (average 55 nm) > 60-69 (average 65 nm) > 70-79 (average 75 nm) > 80-89 (average 85 nm) (Figs are not shown here). Here the gradient with respect to the concentration is same, but the size of nanomaterials is different. It implies that, within the FGENCs the concentration gradient of nanomaterials is same.
To understand the effect of mixed particle size in the range of 5 to 90 nm, again few more FGENCs (type 1 to type 9, as shown in Figs 1 to 9) were made using natural rubber matrix. Here carbon nanoparticles i.e., N-110, N-115, N-120, N-121, N-125, N-134, N-135, N-212, N-220, N-231, N-234, N-293, N-299, N-315, N-326, N-330, N-335, N-339, N-343, N-347, N-351, N-356, N-358, N-375, N-539, N-550, N-582, N-630, N-642, N-650, N-660, N-683, N-754, N-762, N-765, N-772, N-774, N-787, N-907, N-908, N-990, N-991, etc were mixed together and used in FGENCs. Here the average particle size is -45 nm. The total volume fraction of nanomaterials is varied from 0 to 60 nm. The natures of these plots are similar to the FGENCs having the particle size within the range of 20 to 30 nm (average size -25 nm). But the magnitude of mechanical properties and hardness of these FGENCs where the average particle size is -45 nm is less than that of FGENCs where the average particle size is -25 nm.
Mechanical properties depend on the size of the carbon nanoparticles used in
composites material as observed in the last section. To understand the effect of
particle size gradation, few more FGENCs (type 1 to 9, as shown in Figs 1 to 9) were
made using natural rubber matrix. In these FGENCs particle size
increases/decreases either from one surface to the opposite surface or from inner to
outer or outer to inner. The gradation of particle size within this FGENCs is as 5-
10-5, 11-20-15, 21-30-25, 31-40-35, 41-49-45, 50-59-55, 60-69-65, 70-79475,
80-89-85 nm. The natures of these plots are similar to the previous figures but the
magnitude decreases with increasing particle size. j
Few more FGENCs (type 1 to 9, as shown in Pigs 1 to 9) were made using natural rubber and other nanomaterials i.e., silica (precipitated and fumed) and clay. The variations of mechanical properties are similar to the carbon nanomaterials. But the magnitu decreases from carbon nanomaterials to silica to clay. This is attributed to the lesser elastomer silica and/or clay interaction.
Another type of FGENCs was made using natural rubber matrix, where the minimum concentration of carbon nanoparticles is on the outer surface and maximum at the inner surface and shown in Pig 4. Hardness and specific gravity are measured for these FGENCs at different distance along the thickness direction and shown in Pig 21(a). Here, the hardness and specific gravity curves follow the reverse fashion as the concentration of carbon nanoparticles is perfectly opposite to the type 2. Hardness goes up from 35 to 95 shore A and specific gravity also lifts up from 0.95 to 1.25 in the first half along the thickness as the loading of the carbon nanoparticles increases from the outer surface to the inner surface and then both properties go down to their original values. It can be observed that, the percentage changes in hardness and specific gravity along the distance in Fig 21 (b). Hardness and specific gravity of the graded nanocomposite increase by 160 and 30% respectively at a distance of 1.5 mm from the outer surface along thickness direction and in the next half, both the properties go down by the same amount.
The variation of tensile strength and elongation at break in type 4 FGENCs also follow the reverse fashion with respect to type 2 FGENCs and shown in Fig 22 (a). The magnitude of tensile strength and elongation at breaking point is same as the maximum and minimum concentrations of nanoparticles is same in both cases. Here (type 4 FGENCs), the tensile strength decreases at a distance of 1.5 mm along the thickness direction from 20 to 9 MPa and then come to their original values in the next halfway as shown in Fig 22 (a). The percentage change in tensile strength and elongation,at breaking point with respect to the layer, where the concentration of carbon nanoparticle is minimum, is calculated and shown in Fig 22 (b). Similar trend is also observed here. The magnitude is same as previous type 2 FGENCs.
Now the FGENCs are characterized under dynamic conditions to understand its performance under repeated number of deformations. Storage modulus, loss modulus,

WE CLAIM;
1. A functionally graded elastomer nanocomposites (FGENCs) comprising an
elastomer matrix, nanomaterials, and rubber chemicals such as herein described.
2. A process for preparation of a FGENCs comprising the steps of:
Mixing of elastomer matrix with nanomaterials and rubber chemicals at 50 to 125°C for 10 to 150 minutes in a roll mixing mill followed by preparation of a layer such as herein described;
Lamination of the sheet obtained above to obtain green functionally graded elastomer nanocomposites followed by curing such as herein described.
3. A nanocomposite and a process thereof as claimed in Claim 1 or 2 wherein the
elastomer matrix is selected from the group comprising of natural rubber,
polyisoprene rubber, styrene-butadiene rubber, polybutadiene rubber, ethylene-
propylene rubber, ethylene-propylene diene-monomer rubber, butyl rubber,
halobutyl rubber, nitrile rubber, hydrogenated nitrile rubber, polysulfide rubber,
polyacrylic rubber, neoprene rubber, hypalon rubber, silicone rubber,
fluorocarbon rubber, polyurethane rubber, thermoplastic elastomer, and mixture
thereof.
4. A nanocomposite and a process thereof as claimed in any of the preceding claims
wherein the elastomer matrix is graded by carbon nanoparticles or various silica
nanoparticles or clay nanoparticles, which is in the range of 0 to 70 volume
percentage or the elastomer matrix is graded by mixed carbon nanoparticles,
nanosilica and nanoclay in a volume ratio of 5:2:1 to 1:2:5 or the matrix is graded
by mixed carbon nanoparticles having same concentration gradient with different
particles size ranging from 5 to 85 nm.
5. A nanocomposite and a process thereof as claimed in any of the preceding claims
wherein the curing of elastomer matrix comprising of either natural rubber,
polyisoprene rubber, styrene-butadiene rubber, polybutadiene rubber, ethylene-
propylene rubber, ethylene-propylene diene monomer rubber, butyl rubber,
halobutyl rubber, nitrile rubber,hydrogenated nitrile rubber, polysulfide
elastomer, polyacrylic rubber, neoprene rubber, hypalon rubber, silicone rubber,
fluorocarbon rubber, polyurethane rubber, thermoplastic elastomer and/or
mixture thereof is further accelerated by accelerator selected from the group
comprising of tert-buttylbenzthiazyl sulphonamide, benzthiazyl 2-
sulphenmorpholide, dicyclohexyl benzthiazyl sulphonamide, Ncyclohexyl-2-
benzothiazole sulfenamide, 2-mercaptobenzothiazole, 2,2'dibenzothiazyl disulfide,
tetramethylthiuram disulfide, zinc dimethyldithiocarbamate, zinc
dibutyldithiocarbamate, 4,4'dithiodimorpholine, tellurium
diethyldithiocarbamate, dipentamethylene thiuramhexasulfide,
tetramethylthiuram monosulfide, ferricdimethyldithiocarbamate, zinc
mercaptobenzthiazole, zinc 0,0 dibutylphosphorodithioate, zinc
diethyldithiocarbamate, 4-4'dithio dimorpholine, which is in the range of 0.1 to
10 parts per hundred rubber (phr) and , and mixture thereof in a ratio of 1 : 99 to 99:1 (by weight)
6. A nanocomposite and a process thereof as claimed in any of the preceding claims
wherein the curing of elastomer matrix comprising of either natural rubber,
polyisoprene rubber, styrene-butadiene rubber, polybutadiene rubber, ethylene-
propylene rubber, ethylene-propylene diene monomer rubber, butyl rubber,
halobutyl rubber, nitrile rubber, hydrogenated nitrile rubber, polysulfide
elastomer, polyacrylic rubber, neoprene rubber, hypalon rubber, silicone rubber,
fluorocarbon rubber, polyurethane rubber, thermoplastic elastomer and/or
mixture thereof is further accelerated by accelerator activator selected from the
group comprising of metal oxide and acid which is in the range of 10:1 to 1:10
parts per hundred rubber (phr)
7. A nanocomposite and a process thereof as claimed in any of the preceding claims
wherein the metal oxide used in accelerator activator is selected from the group
comprising of zinc oxide, lead oxide, calcium oxide, magnesium oxide, lead oxide,
etc which is in the range of 1 to 10 parts per hundred rubber (phr); and the acid
used in accelerator activator is selected from the group comprising of stearic aqid,
palmitic acid, oleic acid, etc which is in the range of 1 to 10 parts per hundred
rubber (phr).
8. A nanocomposite and a process thereof as claimed in any of the preceding claims
wherein the FGENCs further comprises an antioxidant selected from the group
comprising of condensation product of acetone and diphenyl-amine, phenyl-beta-
napthylamine, blends of diphenyl-p-phenylene diamine and selected arylamine
derivatives, blend of arylamines, polymerized 1,2 dihydro 2,2,4-trimethyl
quinoline, N-(l,3-dimethylbutyl)-N'-phenyl-p-phenylene-diamine, diaryl para
phenylene diamines, 2 mercaptobenzimidazole, and mixture thereof which is in
the range of 10:1 to 1:10 parts per hundred rubber (phr); and a process oil
selected from the group comprising of paraffinic oil, naphthenic oil, aromatic oil,
vegetable oil, and mixture thereof which is in the range of 10:1 to 1:10 parts per
hundred rubber (phr)
9. A nanocomposite and a process thereof as claimed in any of the preceding claims
wherein the elastomer layer is uncoated or coated by one or more coating agent
selected from the group comprising of polytetrafluoro ethylene, polyvinyl alcohol,
silicone emulsion and detergent/soap solution.
10. A functionally graded composite materials (FGCMs) and a process for
preparation thereof substantially as herein described and illustrated with
reference to accompanying examples and drawings.