Description:FORM 2
THE PATENT ACT, 1970
(39 of 1970)
COMPLETE SPECIFICATION
(See section 10, rule 13)

TITLE
CHLOROBUTYL RUBBER NANOCOMPOSITE INCORPORATING MELAMINE EXFOLIATED BORON NITRIDE AND METHOD OF PRODUCTION THEREOF

APPLICANT
AMRITA VISHWA VIDYAPEETHAM
Amritapuri Campus, Engineering College,
Amritapuri, Clappana PO
Kollam 690 525, Kerala, India

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

CHLOROBUTYL RUBBER NANOCOMPOSITE INCORPORATING MELAMINE EXFOLIATED BORON NITRIDE AND METHOD OF PRODUCTION THEREOF
CROSS-REFERENCES TO RELATED APPLICATIONS
None.
FIELD OF THE INVENTION
The invention generally relates to a nanocomposite, and in particular to a nanocomposite for oil water separation, for use as acid resistant material, to impart flame retardancy and for use as self-healing materialand its method of fabrication.
DESCRIPTION OF THE RELATED ART
Chlorine isobutylene isoprene rubber or chlorobutyl rubber (CIIR) belongs to the class of compounds called halogenated butyl rubber and owns excellent moisture impermeability, good resistance to weathering and ageing, inherent chemical resistance, acid resistance, ozone resistance and better resealing. Owing to the inherent characteristics, CIIR finds application in the field of tire inner liners, pharmaceutical closures, seals, conveyer belts and so on. In addition, CIIR have good miscibility with other polymers and exhibits enhanced speed of vulcanization.
Hexagonal boron nitride (h-BN) or “white graphene” is a refractory compound of boron and nitrogen, holds superior thermal conductivity, better thermal stability, excellent mechanical strength, low dielectric constant as well as inherent hydrophobic nature. In addition, its interaction with polymer matrix is effectual in comparison to carbon fillers owing to the polarized character of B-N bond.Among different methods adopted for exfoliating h-BN, exfoliating agent assisted liquid exfoliation can help in the introduction of new functional moieties onto the surface of exfoliated layers in addition to the enhancement in filler dispersion. However, tuning of the properties of CIIR nanocomposites using exfoliating agent in order to develop a material with multi-functional application is still in the stage of infancy.
The white crystalline organic compound melamine (MA) is a trimer of cyanamide having a 1,3,5-triazine skeleton. The rich amount of nitrogen present in the structure provides exceptional properties to melamine including superior flame retardancy and good chemical resistance. In addition, it possesses excellent acoustic characteristics and electrical insulating properties.The ability of melamine to make π-π interaction and hydrogen bonding with various molecules owing to the presence of benzene ring and amino group helps to boost the characteristics of melamine.Moreover, melamine plays the role of an excellent exfoliating agent. However, research works which reported the exfoliation of h-BN using melamine were rare. Wang et al. reported the exfoliation of h-BN using melamine borate via ball-milling process. The material obtained by incorporating the exfoliated filler in epoxy matrix showed excellent thermal and electrical performance along with flame retardancy. In another work by Yoo et al., a similar ball milling technique was used to exfoliate and functionalize h-BN using melamine and incorporated in the epoxy matrix. They noticed the excellent mechanical performance displayed by the material and proposed dental applications.
A nanocomposite showing improved mechanical, hydrophobic, oleophilic, acid resistance, flame retardancy properties and self-healing ability is disclosed.
SUMMARY OF THE INVENTION
In variousembodiments, a nanocomposite (100) for oil water separation, for use as acid resistant material, to impart flame retardancy orfor use as self-healing material is disclosed. The nanocomposite (100), comprises melamine (MA) (102) exfoliated hexagonal-boron nitride (h-BN) (103) nanofiller (h-BN:MA) (104), incorporated into a chlorine isobutylene isoprene rubber (CIIR) (101) matrix.The ratio of h-BN:MA is 1:3 and the nanofiller (104) is present in an amount of 0.88%- 5.88%of the matrix (101), wherein the matrix comprises 0.84%-0.88% stearic acid, 4.2%-4.4% zinc oxide, 2.5-2.6% tetramethylthiuram disulfide (TMTD), 0.42-0.44% magnesium sulphate and 2.1-2.2% sulphur.
In one embodiment, the XRD analysis gives peaks at 14.8°, 12.2°, 31.9◦, 34.6°, 36.4°, and 56.7° and a peak at 26.9°, indicating intercalation of exfoliated boron nitride with melamine in the CIIR nanocomposite.
According to some embodiments, the optimum weight loading of h-BN:MA nanofiller in CIIR is 4.27%.The nanocomposite (100) comprising 4.27% h-BN:MA nanofiller in CIIR nanocomposite shows at least one of 17.5% increase in glass transition temperature, 368% increase in tensile strength, 69 % decrease in loss on ignition or 69% increase in char yield,177.6% increase in absorption capacity and98% increase in potential load bearing than bare CIIR.
In one embodiment, the contact angle value of the h-BN:MA/ CIIR nanocomposite lies in the range of 88-96 degrees, thereby exhibiting hydrophobicity.
In another embodiment, a media for oil-water separation comprising the nanocomposite (100) is disclosed. The media is fabricated into sheet, pellet or granular form and has absorption capacity of 3.302 g or more of oil/g of the nanocomposite.
In some embodiments, an acid resistant article comprising the nanocomposite (100) is disclosed. The article is one of, a seal, a gasket, a hose a fabric or a sheet.
In one embodiment, a flame retardant article comprising the nanocomposite (100)is disclosed. The article has a percentage loss on ignition of 20.75% or less and a char yield of 79.25% or more.
In one embodiment, a self-healing material comprising the nanocomposite (100)is disclosed. The material is fabricated into nanosheets or films, and has a potential load bearing ranging from –to ---g after healing or a glass transition temperature of -41.72o C.
According to one embodiment, a method of (200) fabrication of hexagonal-Boron Nitride: melamine/ chlorine isobutylene isoprene rubber (h-BN:MA/CIIR) nanocomposite is disclosed. The method (200) comprising milling (201) predetermined ratio of hexagonal-Boron Nitride (h-BN) and melamine(MA) in a ball mill at 300 rpm to obtain h-BN:MA nanofillers, obtaining (203) uniform CIIR dispersion of 20 g rubber swollen in hexane by probe sonication, dispersing (204) a predetermined quantity of h-BN:MA nanofiller in hexane to obtained CIIR dispersion by probe sonication, casting (205) on a petri dish at room temperature to obtain a thin film and drying in vacuum oven at 60°C, mixing (206) cast film with 80 g CIIR on a two-roll mill, compounding (207) using stearic acid, zinc oxide,tetramethylthiuram disulfide (TMTD), magnesium oxide, and sulphur; and compression moulding (208) at ---°C to obtain h-BN:MA/CIIR nanocomposite.
In some embodiments, the h-BN is exfoliated using melamine and the predetermined ratio of h-BN: MA is 1: 3 in the nanocomposite and the loading of h-BN:MA nanofiller in CIIR is in the range of 0.88%-5.88%.
This and other aspects are described herein.

BRIEF DESCRIPTION OF THE DRAWINGS
The invention has other advantages and features, which will be more readily apparent from the following detailed description of the invention and the appended claims, when taken in conjunction with the accompanying drawings, in which:
FIG. 1: showsa schematic representation of theh-BN:MA/CIIR nanocomposite.
FIG. 2: shows the steps involved in the method of fabrication of hexagonal-Boron Nitride : Melamine / chlorine isobutylene isoprene rubber (h-BN:MA/CIIR) nanocomposite.
FIG.3: gives the FT-IR spectrum of h-BN, MA and h-BN-MA.
FIG. 4: gives the X-ray diffraction peaks obtained for different samples of the h-BN:MA/CIIR nanocomposite in various proportions.
FIG. 5: shows SEM images of A) Bare CIIR B) 1h-BN-MA/CIIR C) 3h-BN-MA/CIIR D) 5h-BN-MA/CIIR E) 7h-BN-MA/CIIR in 100 µm, D1) 5h-BN-MA/CIIR E1) 7h-BN-MA/CIIR in 10 µm and E2) 7h-BN-MA/CIIR in 5 µm.
FIG. 6: gives a DSC thermograms of CIIR and h-BN-MA/CIIR nanocomposites.
FIG. 7: gives a bar diagram of tensile strength of CIIR, h-BN-MA/CIIR samples.
FIG. 8: shows an images of droplets placed on A) Bare CIIR B) 1h-BN-MA/CIIR C) 3h-BN-MA/CIIR D) 5h-BN-MA/CIIR and E) 7h-BN-MA/CIIR.
FIG. 9: shows an images of acid resistance exhibited by bare CIIR and various proportions of h-BN-MA/CIIR nanocomposites.
FIG. 10A: shows an image of the self-healed portion of CIIR and h-BN-MA/CIIR nanocomposites.
FIG. 10B: gives a graphical representation of potential weight loading of CIIR and h-BN-MA/CIIR nanocomposites.
DETAILED DESCRIPTION OF THE EMBODIMENTS
While the invention has been disclosed with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material to the teachings of the invention without departing from its scope.
Throughout the specification and claims, the following terms take the meanings explicitly associated herein unless the context clearly dictates otherwise. The meaning of "a", "an", and "the" include plural references. The meaning of "in" includes "in" and "on." Referring to the drawings, like numbers indicate like parts throughout the views. Additionally, a reference to the singular includes a reference to the plural unless otherwise stated or inconsistent with the disclosure herein.
The present subject matter describes a nanocomposite for oil water separation, for use as acid resistant material, to impart flame retardancy or for use as self-healing materialand method of fabrication of the nanocomposite.
The invention in various embodiments discloses a nanocomposite 100for oil-water separation, for use as acid resistant material, to impart flame retardancy orfor use as self-healing material. A schematic representation of the nanocomposite is as shown in FIG. 1A and FIG 1B. The nanocomposite comprises melamine (MA) 102 exfoliated hexagonal-boron nitride (h-BN) 103as nanofiller (h-BN:MA) 104, incorporated into a chlorine isobutylene isoprene rubber (CIIR) or chlorobutyl rubber101 matrix. The ratio of h-BN:MAis 1:3 and the nanofiller is present in an amount 0.88%- 5.88%of the matrix 101. The matrix comprises 0.84%-0.88% stearic acid, 4.2%-4.4% zinc oxide, 2.5-2.6%TMTD, 0.42-0.44% magnesium sulphate and 2.1-2.2% sulphur.The nanocomposites are loaded with 1g h-BN-MA, 3g h-BN-MA, 5g h-BN-MA and 7g h-BN-MA in the ratio of 1:3 was introduced into CIIR matrix 101. The nanocomposites may be represented as 1g h-BN-MA/CIIR, 3g h-BN-MA/CIIR, 5g h-BN-MA/CIIR and 7g h-BN-MA/CIIR.

According to one embodiment of the invention, the XRD analysis of the nanocomposite gives peaks at 14.8°, 12.2°, 31.9◦, 34.6°, 36.4°, and 56.7°. A peak seen at 26.9° is due to the exfoliation of boron nitride with melamine.Both h-BN-MA 104 and CIIR101 peaks are present in the h-BN-MA/CIIR 100 composite spectrum which confirms the successful incorporation of h-BN-MA in the CIIR matrix.

In various embodiments, the optimum weight loading of h-BN:MA nanofiller104 in CIIR 100is 4.27%.i.e., 5g h-BN: MA in the ratio of 1:3 is introduced into CIIR matrix 101.

In another embodiment, 5g h-BN:MA or 4.27%h-BN:MA nanofiller loaded nanocomposite shows 17.5% increase in glass transition temperature, 368% increase in tensile strength, 69 % decrease in loss on ignition or 69% increase in char yield,177.6% increase in absorption capacity and98% increase in potential load bearing than bare CIIR.

In one embodiment, the nanocomposite 100exhibits excellent hydrophobicity by combining the inherent barrier properties of CIIR 100and, superior moisture resistance and waterproof nature of melamine 102.The contact angle values of the nanocomposite lies in the range of 88° to 96°. Contact angle increases with up to 5g filler loading and then decreases.

In another embodiment, a media for oil-water separation comprising the nanocomposite 100is disclosed. The media is fabricated into sheet, pellet or granular form and has absorption capacity of 3.302 g or more of oil/g of the nanocomposite.

In one embodiment, an acid resistant article comprising the nanocomposite 100 is disclosed. The article is fabricated into a seal, a gasket,a hose a fabric or a sheet.

In one embodiment, a flame retardant article comprising the nanocomposite 100is disclosed. The article has a percentage loss on ignition of 20.75% or less and a char yield of 79.25% or more.

In another embodiment, a self-healing material comprising the nanocomposite 100is disclosed. The material is fabricated into nanosheets or films, ------- and has a potential load bearing ranging from –to ---g after healing or a glass transition temperature of -41.72o C.

According to one embodiment of the invention, a method of 200 fabrication of hexagonal-Boron Nitride: melamine/ chlorine isobutylene isoprene rubber (h-BN:MA/CIIR) nanocomposite is disclosed. FIG. 2 shows the steps involved in the method of fabrication. The method includes milling 201 predetermined ratio of hexagonal-Boron Nitride (h-BN) and melamine (MA) in a ball mill at 300 rpm to obtain h-BN:MA nanofillers. The next step 202 includes soaking CIIR in hexane for one day to swell. The step 203 includes obtaining uniform CIIR dispersion of 20 g rubber swollen in hexane by probe sonication. The next step 204 include dispersing a predetermined quantity of h-BN:MA nanofiller obtained in step 201andCIIR dispersion by probe sonication. The predetermined ratio of h-BN:MA nanofiller is 1:3and the loading of h-BN:MA nanofiller in CIIR is in the range of 0.88%-5.88%. The obtained product is cast on a petri dish at room temperature to obtain a thin film and dried in vacuum oven at 60°C at 205. The method next includes mixing cast film with 80g chlorine isobutylene isoprene rubber (CIIR) on a two-roll mill at 206. The method includes compoundingusing stearic acid, zinc oxide, TMTD (Tetramethylthiuram disulphide), magnesium oxide, and sulphur at 207. The method next includes compression moulding at1---°C to obtain h-BN:MA/CIIR nanocomposite 208. According to one embodiment of the invention, the h-BN is exfoliated using melamine.

The invention in its various embodiments discloses a melamine exfoliated boron nitride reinforced chlorobutyl rubber (CIIR) or chlorine isobutylene isoprene rubber nanocomposite. Melamine act as exfoliating agent and improves the properties of the rubber nanocomposite. The usage of h-BN in the exfoliated form imparts excellent properties to the CIIR matrix including enhanced mechanical strength, improved glass transition temperature (Tg), and excellent hydrophobicity. In addition, the nanocomposite exhibited good acid resistance, exceptional flame retardancy, good self-healing ability and exceptional oil-water separation capability.
EXAMPLES
Example 1: Exfoliation of boron nitride using melamine and fabrication of h-BN:MA/nanocomposites:
Melamine assisted exfoliation of boron nitride: Exfoliation of h-BN using melamine was carried out via ball milling process. Briefly, the mixture of h-BN and melamine in the ratio of 1:3 were fed into the cylinder of planetary ball mill and about 60 balls were introduced into the same. After closing the lid, the rotating speed of the machine was fixed to 300 rpm.The modified filler was collected from the cylinder after two hours of continuous milling.
Fabrication of h-BN:MA/CIIR nanocomposites: The fabrication of h-BN:MA/CIIR nanocomposite were performed via solution intercalation method.20 g of CIIR were swelled on hexane and kept it for one day. The partially swollen chlorobutyl rubber was mixed well using a probe sonication to obtain a uniform dispersion.1 g h-BN:MA filler was mixed with hexane via bath sonication and added to the CIIR dispersion. Probe sonication was continued until the modified filler was uniformly mixed with CIIR. The process was repeated with 3g, 5g, and 7g filler loading. The nanocomposite mixture obtained were solvent caste don a petri dish and allowed to evaporate the solvent under room temperature. The film obtained was dried in a vacuum oven at 60°C till there was no alteration in weight. The control film of bare CIIR was prepared. This process of solution mixing was followed by the addition of a sulphur cure package on a two-roll mill and compounded for a period of 15 min by precisely controlling the nip gap and temperature. The recipe for the compounding of CIIR is displayed in TABLE 1. The samples of nanocomposites prepared were loaded with 1g h-BN-MA, 3g h-BN-MA,5g h-BN-MA and 7g h-BN-MAin the ratio of 1:3 was introduced into CIIR matrix for the fabrication of h-BN-MA/CIIR nanocomposites.
TABLE 1: Materials used for Compounding of CIIR
Sl. No. Materials Quantity (g)
1 Rubber 100
2 Stearic acid 1
3 Zinc oxide 5
4 TMTD(Tetramethylthiuram disulfide) 3
5 Magnesium oxide 0.5
6 Sulphur 2.5
7 Filler 1-7

Example 2: Characterization of h-BN:MA/CIIR nanocomposite
h-BN:MA dispersions and h-BN:MA/CIIR nanocomposites were characterized through various microscopic and spectroscopic techniques.
Different spectroscopic and microscopic analysis were performed to evaluate the extent of exfoliation in MA exfoliated h-BN nanofiller and to identify the dispersion of h-BN-MA nanofiller in the CIIR matrix. The property improvement in h-BN-MA/CIIR nanocomposite is greatly related to the extent of exfoliation.
A) FT-IR analysis:
Fourier transform infrared (FT-IR) analysis was accomplished using PerkinElmer IR spectrometer, Spectrum 2 through KBr/ATR (Recording range from 400 cm⁻¹ to 4000 cm⁻¹).FTIR spectroscopy analysis was performed to identify the nature of exfoliation occurred in the h-BN filler by MA incorporation.
Two strong peaks at 1361 and 765 cm-1 is observed in the FTIR spectrum of h-BN, as shown in FIG.3, due to the in-plane BN stretching and out plane BN bending. FTIR spectra of melamine showed absorption peaks at 3469, 3415, 3340 and 3132 cm-1 owing to the -NH2 stretching vibration. The peaks at 1654, 1533 and 808 cm-1 corresponds to the triazine ring of melamine. The as-mentioned absorption peaks of melamine in the range of 2000 to 4000 cm-1and 1600 cm-1 to 750 cm-1are observed in the FTIR spectrum of h-BN-MAalong with the peaks of h-BN suggesting the successful non-covalent functionalization of melamine to h-BN.Absence of new peak formation and the reduction in intensity due to the combined effect of h-BN and MA,strengthens the above observation.
B) XRD analysis:
X-ray diffraction (XRD) studies using Brucker D8 Advance with Cu Kα radiation at wavelength 1.54 Å with a spectral recording range from 0 to 90º was conducted to identify the nature of h-BN-MA arrangement in CIIR nanocomposites.
XRD analysis of h-BN:MA/CIIR nanocomposites was performed to evaluate the nature of dispersion of MA exfoliated h-BN filler in CIIR matrix and the X-ray diffraction spectrum is shown in FIG. 4. All the melamine peaks were observed in the h-BN-MA spectrum with a reduction in intensity compared to the individual XRD spectrum of h-BN and MA. The peak of h-BN at 26.8° and peak of MA at 26.9° were found to be merged with a reduction in intensity in the h-BN-MA spectrum give a guarantee of good exfoliation provided by MA. In addition, the widened peaks of h-BN-MA confirmed the better exfoliation and incorporation of MA between h-BN layers. The reduction in peak intensity confirms the enhancement in interlayer spacing owing to the intercalation of MA between h-BN layers.
Morphology analysis: The morphology of h-BN:MA in CIIR matrix and the extent of exfoliation was analyzed by SEM images.In order to notice the morphology of h-BN-MA/CIIR nanocomposites, Scanning Electron Microscopy (SEM) analysis was performed using NovaNano SEM 450, United states.
SEM analysis was performed to analyse the morphology of h-BN-MA/CIIR nanocomposites and the nature of filler distribution in the CIIR matrix. FIG.5 depicts the SEM images of h-BN-MA/CIIR nanocomposites at 100, 10 and 5 µm. In FIG.5A, the surface of CIIR matrix is less disturbed. However, the presence of compounding ingredients was visible. After the addition of 1g h-BN-MA filler into the CIIR matrix, the filler was uniformly distributed without any agglomeration as displayed in FIG. 5B. The uniform distribution of h-BN-MA in the CIIR matrix after the incorporation of 3g and 5g was confirmed from FIG. 5C and 5D.However, the deep scanning of the sample incorporated with 5g at 10 µm displayed the beginning of polymer intercalation as shown in FIG. 5D1. CIIR starts to intercalate between the filler layers when the amount of h-BN-MA in the CIIR matrix was increased which causes the generation of crystallinity in the CIIR matrix. The extent of polymer intercalation was increased after the addition of 7g h-BN-MA into the CIIR matrix. FIG. 5E depicts the SEM image of 7h-BN-MA/CIIR nanocomposite which showed the uniform distribution of filler. However, in the deep scanning of sample at 10 µm indicated the enhanced polymer intercalation and a close look at 5 µm displayed the small agglomeration of h-BN-MA in the CIIR matrix (highlighted in a yellow circle) as shown in FIG.5 E1 and FIG. 5 E2 respectively. Hence, the h-BN-MA/CIIR nanocomposite showed a uniform distribution of filler up to 5g h-BN-MA addition and started to agglomerate in case of 7g h-BN-MA addition which may cause the reduction of properties.

 
Example 3: Thermal and mechanical analysis of the composite
Thermal stability of h-BN:MA/CIIR nanocomposites was evaluated via TGA analysis. Thermogravimetric analysis (TGA) was carried out via TGA-DTA Hitachi STA7000, Japan from 32 ºC to 760 ºC at a heating rate of 10 ºC/min under nitrogen atmosphere to evaluate the thermal stability of the h-BN-MA/CIIR nanocomposites.In addition, Differential scanning colorimetry was carried out using DSC Netzsch DSC 204 F1 Heat flux DSC, Germany.
The influence of h-BN-MA filler in the glass transition temperature of CIIR were evaluated using differential scanning calorimetry. FIG. 6 represents the DSC thermograms of bare CIIR and h-BN-MA/CIIR nanocomposites. As displayed in figure, glass transition temperature of -50.55 °C was observed for bare CIIR. An enhancement in the glass transition temperature was noticed with an increase in h-BN-MA loading. After the incorporation of 1, 3, and 5g of h-BN-MA, the Tg value got increased into -46.34, -44.38 and -41.72 °C respectively owing to the development of good interaction between the h-BN-MA filler and CIIR matrix, When 5g h-BN-MA was incorporated into the CIIR matrix, the polymer starts to intercalate between the layers of h-BN-MA which generates superior interaction between the matrix and filler.The possibility of hydrogen bonding interaction between electronegative atoms of h-BN and MA moieties, Vander Waals force of attraction between h-BN, excess MA and active chlorine atoms of CIIR were responsible for the interaction between matrix and filler. This was reflected in the enhanced Tg value of 5h-BN-MA/CIIR nanocomposites. The good interaction between matrix and filler produces excellent network structure which causes the robustness of 5h-BN-MA/CIIR nanocomposites and thereby an increased Tg value of -41.72 °C. However, the Tg value of 7h-BN-MA/CIIR nanocomposite was reduced to -45.12 °C due to the agglomeration of filler occurred in the CIIR matrix. Hence, a better thermal conduction path was generated by h-BN-MA/CIIR nanocomposite incorporated with 5g h-BN-MA owing to the exceptional polymer-filler network.
The mechanical properties of CIIR rubber after the incorporation of h-BN and MA exfoliated h-BN was evaluated. Mechanical testing was performed using Dak System Inc, Universal testing machine (UTM) with a crosshead speed of 500 mm/min. Dumbbell shaped specimens based on ASTM standards D 412 was followed for mechanical testing and the values obtained for five samples were taken to calculate an average value.
The results of mechanical analysis are displayed in FIG. 7. Block A shows the tensile strength of CIIR without any fillers in FIG. 7A. The obtained value of 1.94 MPa is increased to 2.91 MPa in Block B, when the CIIR matrix is incorporated with 1 g of h- BN-MA. A continuous enhancement in tensile strength was observed after the incorporation of 3g and 5g h-BN-MA into the CIIR system with a value of 7.47 and 9.03 MPa, in block C and D respectively. The excellent mechanical properties shown by 5h-BN-MA/CIIR nanocomposite was due to the good network structure created in the sample owing to the better interaction created by h-BN and MA. The highly cross-linked network structure of h-BN-MA/CIIR nanocomposites reduces the tendency to break and can withstand appreciable strain given to the material. After the incorporation of 7g h-BN-MA (Block E) into the CIIR matrix, the tensile strength was slightly reduced to 8.92 MPa owing to the agglomeration of filler in the CIIR system as evident from the SEM images.
The details of mechanical properties and percentage improvement are summarized in Table 2.
TABLE 2: Mechanical Properties of CIIR and h-BN-MA/CIIR Nanocomposites
Sample Tensile modulus (MPa) Elongation at break (%) Tensile Strength (MPa) % improvement
CIIR 0.41 453.6 1.93 0
1h-BN-MA/CIIR 0.45 577.3 2.91 50.77
3h-BN-MA/CIIR 0.58 744.7 7.47 287.04
5h-BN-MA/CIIR 0.65 827.3 9.03 367.87
7h-BN-MA/CIIR 0.59 834.9 8.92 362.17

 
Example 4: Evaluation of contact angle in h-BN:MA/CIIR nanocomposite:
Hydrophobicity of bare CIIR and h-BN-MA/CIIR nanocomposites were evaluated by contact angle measurement as shown in FIG.8. The contact angle data were summarized in TABLE 3. Contact angle analysis of the nanocomposite was performed using Labdsa to identify the hydrophobic nature of nanocomposites. The contact angle value less than 90° represents the hydrophilic nature and contact angle greater than 90° indicates the hydrophobic nature.
Bare CIIR showed a contact angle of 81.7° which is in the hydrophilic range. Although, the contact angle value got a change from hydrophilic region to hydrophobic region after the incorporation of h-BN-MA into the CIIR matrix. The contact angle value was increased to 83.5° for 1h-BN-MA/CIIR nanocomposite. Further enhancement in the contact angle was observed for 3h-BN-MA/CIIR nanocomposite with a value of 88.7° which is in the nearly hydrophobic region. Nevertheless, the material incorporated with 5 g h-BN-MA displayed a higher contact angle value of 96.1° which indicated the excellent hydrophobic nature. The better hydrophobicity possessed by h-BN, excellent inherent barrier properties of CIIR and, superior moisture resistance and waterproof nature of melamine synergistically act to develop the 5h-BN-MA/CIIR nanocomposite with excellent hydrophobicity. But the contact angle showed a reduction in case of the material incorporated with 7 g h-BN-MA with a value of 90.7° owing to the agglomeration of filler particles.
TABLE 3: Contact Angle Data of CIIR and h-BN-MA/CIIR Nanocomposites

Sample Code Sample Contact angle (°)
A CIIR 81.7
B 1h-BN-MA/CIIR 83.5
C 3h-BN-MA/CIIR 88.7
D 5h-BN-MA/CIIR 96.1
E 7h-BN-MA/CIIR 90.7

 
Example 5: Evaluation of Acid resistance of the nanocomposite.
Acid resistance of CIIR nanocomposite incorporated with various h-BN-MA loadings were evaluated by dipping square pieces of nanocomposite with a dimension of 10×10×2 mm in concentrated nitric acid for one hour.The changes observed for each h-BN-MA/CIIR nanocomposite was captured as shown inFIG. 9. Bare CIIR sample was completely attacked by conc. HNO3, and the colour was changed from mid cream colour to dark brown after one hour. However, the addition of h-BN-MA into the CIIR matrix reduced the acid attack with increase in filler loading. After the incorporation of 1g filler, the intensity of acid attack was reduced which was confirmed from the light brown shade of 1h-BN-MA/CIIR nanocomposite. The trend was again reduced after the addition of 3g h-BN-MA into the CIIR system. However, the CIIR matrix incorporated with 5g h-BN-MA showed excellent acid resistance as evident from the untouched sample shown in red circle. The resistance to acid attack was increased with an increase in filler loading owing to the appreciable acid resistance characteristics possessed by h-BN and CIIR matrix. The property reduced after the addition of 7 g h-BN-MA due to the agglomeration generated in the material. Owing to the filler agglomeration, some parts of the 7h-BN-MA/CIIR nanocomposite did not have the presence of filler particles which causes the initiation of acid attack.
Example 6: Evaluation of Flame retardancy of the nanocomposite.
Flame retardancy behaviour of h-BN-MA/CIIR nanocomposite was assessed via ignition test. Weight of the sample before ignition and weight of the char obtained after ignition was noticed to calculate char yield and percentage loss on ignition (LOI). Loss on ignition represents the amount of sample lost when the material is subjected to high temperature on ignition. The percentage loss on ignition was calculated using the Equation (1).
%LOI= (W_(2 )- W_3)/(W_2 -W_1 ) ×100 ……………. (1)
W2 – Weight of the crucible + dry sample
W3 – Weight of the crucible + dry sample after ignition
W1 – Weight of the crucible
The flame-retardant nature of h-BN-MA/CIIR nanocomposite was determined via ignition test and the data were summarized in Table 4. Char yield and percentage loss on ignition were calculated to evaluate the extend of retardancy possessed by the nanocomposites. In case of bare CIIR, the sample caught fire easily and 89.81% of the material was burnt and lost on ignition. Only 10.19% of the CIIR had remained after the completion of ignition which indicates the poor flame retardancy nature of bare rubber. However, the addition of h-BN-MA into the CIIR matrix enhanced the flame retarding efficiency of rubber. Even after the incorporation of 1 g h-BN-MA, the percentage loss on ignition was drastically reduced to 58.92% and the corresponding char yield was increased to 41.08%. The same trend was observed after the incorporation of 3 g h-BN-MA into the CIIR matrix in which the percentage loss on ignition was reduced to 40.75% and char yield was enhanced to 59.25%. Only less than half of the material was lost on ignition, and more than half of the sample was retained in case of 3h-BN-MA/CIIR nanocomposites. Excitingly, the CIIR matrix incorporated with 5 g h-BN-MA showed an excellent flame-retardant property with a percentage loss on ignition of 20.75% and char yield of 79.25%.
The enhancement in flame retardancy was due to the enhancement in the loading of h-BN-MA, more specifically due to the enhancement in the amount of melamine exfoliating agent. Melamine possesses excellent flame-retardant properties which was evident from the previous reports .Upon ignition, melamine started to degrade, initiating the formation of char on the surface of h-BN which act as a protective layer above the h-BN surface to reduce heat transfer. In addition, the ignition of melamine leads to the production of nitrogen gas which causes the generation of an inert atmosphere. This leads to the dilution of oxygen in the surroundings and reduces the chances of further ignition. The CIIR matrix incorporated with 7 g h-BN-MA showed a reduced char yield and enhanced percentage loss on ignition owing to the agglomeration of h-BN-MA in the matrix. Some parts of the 7h-BN-MA/CIIR nanocomposites caught fire easily due to agglomeration which resulted in property reduction.
 
TABLE 4: Char Yield and Percentage Loss on Ignition of Bare CIIR and h-BN-MA/CIIR Nanocomposites
Sample Weight (g) Char weight (g) Char yield (%) %LOI
CIIR 0.3531 0.036 10.19 89.81
1h-BN-MA/CIIR 0.4982 0.2047 41.08 58.92
3h-BN-MA/CIIR 0.5186 0.3073 59.25 40.75
5h-BN-MA/CIIR 0.4883 0.387 79.25 20.75
7h-BN-MA/CIIR 0.4924 0.212 43.05 56.95

Example 6: Evaluation of oil-water separation efficiency of the nanocomposite.
Oil-water separation efficiency of CIIR, h-BN:MA/CIIRnanocomposites was analyzed. Oleophilic nature was assessed by introducing samples into oil-water mixture containing 20 vol% of oil. The weight of samples was checked after 20, 40, 60 and 180 minute to calculate the absorption capacity of samples. The Equation 2 was used to calculate the absorption capacity in g/g.
Absorptioncapacity = (W_(1 )- W_0)/W_0 g/g …………. (2)
The possibility of using h-BN-MA/CIIR nanocomposites for oil-water separation was confirmed by introducing samples into water containing 20 vol% of oil. Absorption capacity of each sample was calculated using equation 2, and the values were outlined in Table 5. Bare rubber with a weight of 0.2428 g displayed an absorption capacity of 1.526 g/g. However, a gradual enhancement in the absorption capacity was observed after the incorporation of h-BN-MA into the CIIR matrix. The introduction of 1 g h-BN-MA bring about an enhancement in absorption capacity with a value of 2.129 g/g. The absorption capacity was further increased to 2.823 g/g after the addition of 3 g h-BN-MA which was literally higher compared to the previous reported works based on nanocomposite sheet fabricated using synthetic rubber incorporated with nanomaterials. Excitingly, the incorporation of 5 g h-BN-MA resulted in the improvement of absorption capacity to 3.302 g/g. We observed the introduction of melamine as an exfoliating agent enhanced the absorption capacity of h-BN/CIIR system which shows the inimitable role of melamine in h-BN-MA/CIIR nanocomposites. Melamine has magnificent oil absorption capability owing to the presence of numerous nitrogen atoms in the structure. However, it has the potential to absorb oil and water simultaneously. Hence, exploiting the potential hydrophobic nature of h-BN and oleophilic characteristics of melamine together generates a material with superior hydrophobic and oleophilic nature which was evident from the highest absorption capacity value displayed by h-BN-MA/CIIR nanocomposites. The absorption capacity was reduced to 1.921 g/g in the case of 7 g h-BN-MA incorporated sample owing to the agglomeration of filler in the CIIR matrix.
Table 5: Details of the Absorption Capacity of CIIR and h-BN-MA/CIIR Nanocomposites
Sample W0 (g) W20min (g) W40min (g) W60min (g) W180min (g) Absorption capacity (g/g) Absorption capacity (%)
CIIR 0.2428 0.2798 0.4153 0.5427 0.6135 1.526 152.6
1h-BN-MA/CIIR 0.2743 0.3691 0.5782 0.7147 0.8584 2.129 212.9
3h-BN-MA/CIIR 0.2393 0.4299 0.6892 0.8154 0.9149 2.823 282.3
5h-BN-MA/CIIR 0.2194 0.4865 0.7032 0.8249 0.9439 3.302 330.2
7h-BN-MA/CIIR 0.2458 0.368 0.5923 0.6376 0.7182 1.921 192.1

Example 6: Evaluation of self-healing ability of the nanocomposite.
Self-healing ability represents the materials’ ability to correct any disturbances or issues brought into them and thereby recovering into its original nature. h-BN-MA/CIIR nanocomposites pieces with known weight were cut into two separate pieces and placed together in oven for one hour at 150 °C to evaluate the self-healing ability. The nature of joints after self-healing was captured and the images were shown inFIG.10A . The uncomplete healing of bare CIIR was confirmed from the unconnected portions observed for bare CIIR. In case of CIIR incorporated with 1 g h-BN-MA, the two separated pieces were connected in all portions and was healed to an optimum extend. After the addition of 3 g h-BN-MA into CIIR, the two pieces were mostly connected and healed. However, a small scratch-like portion was visible in the image. Interestingly, after the incorporation of 5 g h-BN-MA into CIIR matrix, the two separate pieces were completely healed without leaving any mark on the connected portion which indicates the excellent self-healing ability of the sample. The ability was reduced in the case of 7h-BN-MA/CIIR nanocomposite owing to the agglomeration.
Moreover, in addition to the above-mentioned visible changes, the samples retained excellent strength after self-healing. The mechanical strength possessed by each sample after self-healing was checked by providing load gradually on a hanging scale. The details are summarized in Table 6 and FIG.10B. Bare CIIR held 300 g of weight after self-healing. However, after the addition of h-BN-MA into CIIR matrix, an enhancement in the load bearing capacity was observed with an increase in h-BN-MA loading. h-BN-MA/CIIR nanocomposites held 400 and 500 g of load after the incorporation of 1 and 3 g of h-BN-MA. 5 g addition of h-BN-MA into the CIIR matrix enhanced the holding capacity such that a piece of 5h-BN-MA/CIIR nanocomposite with 0.5288 g weight was able to hold a load of 600 g after self-healing which indicated the magnificent strength of material. Although, the CIIR matrix added with 7 g nanofiller showed a reduction in the holding capacity since agglomeration of h-BN-MA occurred in the fabricated composite.
While the invention has been disclosed with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material the teachings of the invention without departing from its scope, which should be as defined by the claims appended herewith.
, Claims:We claim:

1. A nanocomposite (100) for oil water separation, for use as acid resistant material, to impart flame retardancy and for use as self-healing material, comprising:
melamine (MA) (102) exfoliated hexagonal-boron nitride (h-BN) (103) nanofiller (h-BN:MA) (104), incorporated into a chlorine isobutylene isoprene rubber (CIIR) (101) matrix, wherein the ratio of h-BN:MA is 1:3 and the nanofiller (104) is present in an amount of 0.88%- 5.88%of the matrix (101), wherein the matrix comprises 0.84%-0.88% stearic acid, 4.2%-4.4% zinc oxide, 2.5-2.6% tetramethylthiuram disulfide(TMTD), 0.42-0.44% magnesium sulphate and 2.1-2.2% sulphur.

2. The nanocomposite (100) as claimed in claim 1, wherein the XRD analysis gives peaks at 14.8°, 12.2°, 31.9◦, 34.6°, 36.4°, and 56.7° and a peak at 26.9° indicating intercalation of exfoliated boron nitride with melamine in the CIIR nanocomposite.

3. Thenanocomposite (100) as claimed in claim 1, wherein the optimum weight loading of h-BN:MA nanofiller in CIIR is 4.27%.

4. The nanocomposite (100) as claimed in claim 1, wherein 4.27% h-BN:MA nanofiller in CIIR nanocomposite shows at least one of
17.5% increase in glass transition temperature,
368% increase in tensile strength,
69 % decrease in loss on ignition or 69% increase in char yield,
177.6% increase in absorption capacity and
98% increase in potential load bearing than bare CIIR.

5. Thenanocomposite (100) as claimed in claim 1, wherein the contact angle value of the h-BN:MA/ CIIR nanocomposite lies in the range of 88-96 degrees, thereby exhibiting hydrophobicity.

6. A media for oil-water separation comprising the nanocomposite (100) as claimed in claim 1, wherein the media is fabricated into sheet, pellet or granular form and has absorption capacity of 3.302 g or more of oil/g of the nanocomposite.

7. An acid resistant article comprising the nanocomposite (100) as claimed in claim 1, wherein the article is one of, a seal, a gasket, a hose a fabric or a sheet.

8. A flame retardant article comprising the nanocomposite (100) as claimed in claim 1, wherein the article has a percentage loss on ignition of 20.75% or less and a char yield of 79.25% or more.

9. A self-healing material comprising the nanocomposite (100) as claimed in claim 1, wherein the material is fabricated into nanosheets or films, and has a potential load bearing ranging from –to ---g after healing or a glass transition temperature of -41.72o C.

10. A method of (200) fabrication of hexagonal-Boron Nitride: melamine/ chlorine isobutylene isoprene rubber (h-BN:MA/CIIR) nanocomposite, comprising:
milling (201) predetermined ratio of hexagonal-Boron Nitride (h-BN) and melamine(MA) in a ball mill at 300 rpm to obtain h-BN:MA nanofillers;
obtaining (203) uniform CIIR dispersion of 20 g rubber swollen in hexane by probe sonication;
dispersing (204) a predetermined quantity of h-BN:MA nanofiller in hexane to obtained CIIR dispersion by probe sonication;
casting (205) on a petri dish at room temperature to obtain a thin film and drying in vacuum oven at 60°C;
mixing (206) cast film with 80 g CIIR on a two-roll mill;
compounding (207) using stearic acid, zinc oxide,tetramethylthiuram disulfide(TMTD), magnesium oxide, and sulphur; and
compression moulding (208) at ---°C to obtain h-BN:MA/CIIR nanocomposite.

11. The method as claimed in claim 10, wherein the h-BN is exfoliated using melamine.

12. The method as claimed in claim 10, wherein the predetermined ratio of h-BN: MA is 1: 3 in the nanocomposite.

13. The method as claimed in claim 10, wherein the loading of h-BN:MA nanofiller in CIIR is in the range of 0.88%-5.88%.

Dr V. SHANKAR IN/PA-1733
For and on behalf of the Applicants