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

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

INVENTORS
ASOK Aparna, Citizen of India
PILLAI A Saritha, Citizen of India
Department of Chemistry,
Amrita Vishwa Vidyapeetham
Amritapuri Campus, Amritapuri, Clappana PO
Kollam – 690525, Kerala, India

APPLICANT
AMRITA VISHWA VIDYAPEETHAM
Amrita School of Physical Sciences,
Amritapuri Campus,
Amritapuri, Clappana P O,
Kollam – 690525, Kerala, India

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

CHLOROBUTYL RUBBER NANOCOMPOSITE INCORPORATING BORON NITRIDE AND METHOD OF PRODUCTION THEREOF
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] None.
FIELD OF THE INVENTION
[0002] The invention generally relates to a nanocomposite, and in particular to a bio based exfoliating agent based nanocomposite for reusable protective clothing, for oil water separation and water purification and its method of fabrication.
DESCRIPTION OF THE RELATED ART
[0003] Chlorobutyl rubber or chlorine isobutylene isoprene rubber, owing to the low gas and moisture permeability, good vibration damping, low glass transition temperature, excellent resistance to ageing and weathering, scientific community pays attention to the development of CIIR materials with enhanced properties. Compared to other butyl rubbers, they showed fast curing with less amount of curatives owing to the reactive chlorinated sites and offers high temperature performance with low permeability. The incorporation of various nanofillers in CIIR matrix should effectively reduce the gas permeability and improve thermal stability. Because of their excellent weather and ozone resistance, and enhanced chemical resistance, CIIR is an excellent choice for rubber articles needing good resistance to chemicals, weathering and ozone such as tank linings, special purpose conveyor belts and protective clothing. Even though CIIR nanocomposites finds unending applications in the field of aerospace, aircraft, automotive and high vacuum systems, they do not meet the complete requirements to be used in chemical protective clothing, medical fields and environmental protection. The role of CIIR in the development of a clean environment is not studied yet.
[0004] Hexagonal boron nitride or “white graphene” is an emerging two dimensional nanomaterial which possess attractive characteristics such as increased aspect ratio, better compatibility with polymer materials, improved gas barrier performance, and enhanced mechanical properties. Molecular dynamics (MD) simulation studies carried out by numerous researchers concluded that the interaction of h-BN with polymers could be more efficient in comparison with carbon fillers owing to their B–N bond with polarized nature. Moreover, increased bonding potential of boron and nitrogen atoms in addition to the Vander Waals and coulomb attraction of h-BN with polymers leads to the increased interaction of h- BN in polymer matrix. Hence the incorporation of h-BN into CIIR matrix will improve the mechanical and barrier properties.
[0005] Tannic acid has bio-functional properties including anti-enzymatic, antioxidant, antimutagenic, antiviral, anticarcinogenic properties, antibacterial activities against many bacterial species, including Staphylococcus aureus, Escherichia coli, and Helicobacter pylori due to the occurrence of phenolic hydroxyl group. Jing et al. discloses the antibacterial properties of three-dimensional graphene microstructure (TA-GH) prepared with the help of tannic acid in which TA induced the self-assembly of reduced graphene oxide into graphene hydrogel. Tannic acid’s presence in the 3D graphene skeleton act as a bio functional component significantly contributes to the improved antibacterial properties of TA-GH. Numerous works are reported regarding the antibacterial properties of TA. The exfoliation and functionalization of boron nitride using TA was mostly reported for the thermal management applications. Zhao et al. described the simultaneous exfoliation and functionalization of boron nitride using TA and the incorporation of as-mentioned filler into poly vinyl alcoholwhich induced excellent in-plane thermal conductivity to the material owing to the horizontal alignment of boron nitride nanosheets (BNNS) and improved hydrogen bond of TA with PVA. The improved thermal conductivity of epoxy nanocomposite incorporated with TA exfoliated BNNS was reported by Wu et al. Fabrication of membranes using TA exfoliated BNNS for wastewater treatment was reported by Lere Keshebo et al.The nanofiltration performance of thin-film nanocomposite membranes fabricated using TA exfoliated BNNS was detailed by Zheng et al.
[0006] Even though the enhancement of hydrophilicity with the help of TA is reported, the hydrophobicity and oleophilicity attained by the nanocomposite after the incorporation of TA exfoliated nanofiller was never reported. Though the use of fillers like layered silicates , CNT, TiO2, graphene oxide etc. in CIIR has been reported, the use of boron nitride in the bare form or modified form has not yet been reported in CIIR. A nanocomposite showing improved mechanical, antibacterial, hydrophobic and oleophilic properties is disclosed.
SUMMARY OF THE INVENTION
[0007] The present subject matter discloses a nanocomposite for use as reusable protective clothing and for oil water separation.
[0008] According to one embodiment of the present subject matter, the nanocomposite comprises tannic acid (TA) exfoliated hexagonal-boron nitride (h-BN) as nanofiller (h-BN:TA), incorporated into a chlorine isobutylene isoprene rubber (CIIR) matrix. The ratio of h-BN:TA varies from 1:1 to 1:4 and the nanofiller is present in an amount at 1-7 % of the matrix. The FT-IR analysis of the composite gives peaks at 2940, 1636, 1237, 964 cm?1 along with an intensified peak at 1223 cm?1due to C-O-C linkage and a less intense peak at 796 cm-1. The XRD analysis gives peaks at 14.8°, 12.2°, 31.9?, 34.6°, 36.4°, and 56.7° and a peak at 23.4° indicating the exfoliation of boron nitride with tannic acid in the CIIR nanocomposite.
[0009] According to some embodiments, the tannic acid exfoliated boron nitride/CIIR nanocomposite shows a tensile strength of 2.64 MPa and above. The nanocomposite having h-BN and TA in the ratio 1:3, 1:3 h-BN:TA/CIIR exhibits a degradation temperature of 248°C or more. The nanocomposite exhibits antimicrobial activity by the introduction of tannic acid exfoliated boron nitride and shows enhanced resistance against S. aureus bacteria with an increase in TA loading. The exfoliation using tannic acid increases the thermal decontamination efficiency of the composite and increases with increase in tannic acid. The nanocomposite exhibits a thermal decontamination efficiency value upto 99.79 %. According to one embodiment,a waterproof protective clothing comprising the nanocomposite is disclosed. The clothing has a thickness ranging from 1 mm to 2 mm The contact angle value of the nanocomposite lies in the range of 91° to 93°.
[0010] According to one embodiment of the invention, a method of fabrication of hexagonal-Boron Nitride : Tannic acid / chlorine isobutylene isoprene rubber (h-BN:TA/CIIR) nanocomposite is disclosed. The method includes dispersing tannic acid (TA) in water and adding h-BN at a predetermined ratio. The predetermined ratio of h-BN : TA varies from 1: 1 to 1:4 in the nanocomposite. The method includes obtaining uniform dispersion by bath ultrasonication for one hour and oven drying for 24 hours at a temperature of 75°C to obtain h-BN:TA nanofillers. A predetermined quantity of h-BN:TA nanofiller in hexane is dispersed and mixed with 20 g rubber swollen in hexane by probe sonication. The method includes casting on a petri dish at room temperature to obtain a thin film and drying in vacuum oven at 60°C. The cast film is mixed with 80g CIIR on a two-roll mill and compounded using stearic acid, zinc oxide, TMTD (tetramethylthiuram disulphide), magnesium oxide, and sulphur. The method includes compression moulding at 150°C to obtain h-BN:TA/CIIR nanocomposite. The h-BN is exfoliated using tannic acid.
[0011] According to one embodiment of the invention, a media for oil-water separation is disclosed. The media comprises tannic acid (TA) exfoliated hexagonal-boron nitride (h-BN) as nanofiller (h-BN:TA), incorporated into a chlorine isobutylene isoprene rubber (CIIR) matrix, wherein the ratio of h-BN:TA is in a ratio 1:4 and the nanofiller is present in an amount at 1-7 % of the matrix. The media is fabricated into sheet, pellet or granular form. The thickness of the sheet or diameter of the pellet or granular form is in the range 1 mm to 2 mm.
[0012] According to another embodiment of the invention, a method of removing oil from water using the nanocomposite is disclosed. The method comprises introducing the h-BN:TA/CIIR nanocomposite media in an oil-water mixture to obtain a swelled media containing adsorbed oil, and separating the water from the media with the adsorbed oil. The method further comprises recovering the adsorbed oil by solvent extraction using isopropyl alcohol.
[0013] This and other aspects are described herein.

BRIEF DESCRIPTION OF THE DRAWINGS
[0014] 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:
[0015] FIG. 1 shows a schematic representation of the h-BN:TA/CIIR nanocomposite.
[0016] FIG. 2 shows the steps involved in the method of fabrication of hexagonal-Boron Nitride : Tannic acid / chlorine isobutylene isoprene rubber (h-BN:TA/CIIR) nanocomposite.
[0017] FIG. 3 the FTIR analysis of the h-BN:TA/CIIR nanocomposite.
[0018] FIG. 4 gives the X-ray diffraction peaks obtained for different samples of the h-BN:TA/CIIR nanocomposite in various proportions.
[0019] FIG. 5 gives a graphical representation of tensile strength, elongation at break and tensile modulus of CIIR, h-BN/CIIR and h-BN:TA/CIIR samples

DETAILED DESCRIPTION OF THE EMBODIMENTS
[0020] 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.
[0021] 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.
[0022] The present subject matter describes a nanocomposite for use as reusable protective clothing and for oil water separation and method of fabrication of the nanocomposite.
[0023] The invention in various embodiments discloses a nanocomposite 100 for use as reusable protective clothing and for oil water separation. A schematic representation of the nanocomposite is as shown in FIG. 1A and FIG 1B. The nanocomposite comprises tannic acid (TA) 102 exfoliated hexagonal-boron nitride (h-BN)104 as nanofiller (h-BN:TA) 106, incorporated into a chlorine isobutylene isoprene rubber (CIIR) or chlorobutyl rubber101matrix. The ratio of h-BN:TA varies from 1:1 to 1:4 and the nanofiller is present in an amount at 1-7% of the matrix. The nanocomposites may be represented as 1:1 h-BN:TA/CIIR, 1:2 h-BN:TA/CIIR, 1:3 h-BN:TA/CIIR,1:4 h-BN:TA/CIIR. Tannic acid acts a reinforcing agent in addition to an exfoliated agent. According to one embodiment of the invention, the characterisation of the nanocomposite by FT-IR analysis gives peaks at 2940, 1636, 1237, 964 cm?1 along with an intensified peak at 1223 cm?1due to C-O-C linkage and less intense peak at 796 cm-1. The peak corresponding to free –OH group is absent in the CIIR nanocomposite. The presence of peak around 3406 cm?1 in CIIR corresponds to the -OH groups in the CIIR, due to the adsorbed moisture or water content. Peaks at 2940, 1636, 1237, 964 cm-1 etc. are corresponds to the CH2, C–– C, C–C and C–H stretching vibrations. Strong peaks are present at 796 and 697 cm-1 corresponding to C–Cl stretching vibrations in CIIR rubber. After incorporating the filler, the absence of peak at 697 cm-1 and the reduced intensity of peak at 796 cm-1 indicates the absence of C–Cl linkage and reduced Cl content in the nanocomposite. An intensified peak at 1223 cm-1is due to the formation of C-O-C linkage in the nanocomposite.
[0024] 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 23.4° is due to the exfoliation of boron nitride with tannic acid. The peak at 14.8° is an amorphous peak. The nanocomposite shows a tensile strength of 2.64 MPa and above. The tensile strength increases with increase in tannic acid in the composite, confirming the reinforcing effect of tannic acid. Hydrogen bonding interaction of TA with h-BN through the electronegative N atoms causes reduction in the intensity of -OH groups. The remaining -OH groups may react with the C–Cl present in CIIR which leads to the elimination of H–Cl. This creates a highly crosslinked structure between TA, h-BN and CIIR and thereby better mechanical reinforcement. Excess TA present in the system also helps in crosslinking, according to one embodiment of the invention.
[0025] The nanocomposite with h-BN and TA in the ratio 1:3, 1:3 h-BN:TA/CIIRshows a degradation temperature at 248°C showing excellent stability of the nanocomposite. The nanocomposite shows excellent stability due to the uniform dispersion and complete exfoliation of h-BN by TA, according to one embodiment of the invention. The nanocomposite exhibits excellent antibacterial activity by the introduction of tannic acid exfoliated boron nitride. According to one embodiment of the invention the nanocomposite exhibits improved resistance against S. aureus with an increase in TA loading. According to one embodiment of the invention, the exfoliation using tannic acid increases the thermal decontamination efficiency of the composite and increases with increase in tannic acid in the composite. The nanocomposite exhibits a thermal decontamination efficiency value up to 99.79%, according to one embodiment of the invention. The thermal decontamination efficiency of a material is the measure of their ability to remove the solvent permeated or adsorbed on a material. Tannic acid in the nanocomposite causes adsorption of solvent on the surface of h-BN:TA/CIIR nanocomposite. The decontamination efficiency of the nanocomposite makes it usable as protective clothing. According to one embodiment of the invention, a waterproofprotective clothing comprising the nanocomposite is disclosed. The clothing has a thickness ranging from 1 mm to 2 mm.
[0026] Tannic acid adsorbs oil into the surface of nanocomposite and adsorption increases with increase in TA in the composite. The hydrophobic characteristics of the composite increases with the addition of h-BN: TA indicating the absence of free –OH groups in the CIIR composite. The contact angle values of the nanocomposite lies in the range of 91° to 93°. Contact angle increases with increase in amount of filler loading in the nanocomposite.
[0027] According to one embodiment of the invention, a method of 200 fabrication of hexagonal-Boron Nitride : Tannic acid / chlorine isobutylene isoprene rubber (h-BN:TA/CIIR) nanocomposite is disclosed. FIG. 2 shows the steps involved in the method of fabrication. The method includes dispersingtannic acid (TA) in water and adding h-BN at a predetermined ratio at 202. The predetermined ratio of h-BN to tannic acid is 1:1 to 1:4 to obtain nanocomposite 1:1 h-BN:TA/CIIR, 1:2 h-BN:TA/CIIR, 1:3 h-BN:TA/CIIR and 1:4 h-BN:TA/CIIR. The method includes obtaining uniform dispersion by bath ultrasonication for 1 hour at 204. The method next includes oven drying for 24 hours at a temperature of 75°C to obtain h-BN:TA nanofillers at 206. The method includes dispersing a predetermined quantity of h-BN:TA nanofiller in hexane and mixing with 20 g rubber swollen in hexane by probe sonication. The predetermined quantity of h-BN:TA nanofiller is 1:1 to 1:4. 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 210. The method next includes mixing cast film with 80g chlorine isobutylene isoprene rubber (CIIR) on a two-roll mill at 212. The method includes compounding using stearic acid, zinc oxide, TMTD (Tetramethylthiuram disulphide), magnesium oxide, and sulphur at 214. The method next includes compression moulding at150°C to obtain h-BN:TA/CIIR nanocomposite216.According to one embodiment of the invention, the h-BN is exfoliated using tannic acid.
[0028] According to one embodiment of the invention, a media for oil-water separation is disclosed. The media comprises Tannic acid (TA) (102) exfoliated hexagonal-boron nitride (h-BN) (104) as nanofiller (h-BN:TA) (106), incorporated into a chlorine isobutylene isoprene rubber (CIIR) (101) matrix. The ratio of h-BN:TA is in a ratio 1:4 and the nanofiller is present in an amount at 1-7 % of the matrix. The media is fabricated into sheet, pellet or granular form. The thickness of the sheet or diameter of the pellet or granular form may be in the range 1mm to 2 mm
[0029] According to another embodiment of the invention, a method of removing oil from water using the h-BN:TA/CIIR nanocomposite is disclosed. The method comprises introducing the h-BN:TA/CIIR nanocomposite media in an oil-water mixture to obtain a swelled media containing the adsorbed oil. The method further includes separating the water from the media with the adsorbed oil. Tannic acid in the composite adsorbs oil into the surface of nanocomposite and the absorption of oil into the inner part of nanocomposite is prevented due to the hydrophobic nature of boron nitride and chlorobutyl rubber. Adsorption of oil by the nanocomposite increases with increase in TA loading. The method further comprises recovering the adsorbed oil by solvent extraction using isopropyl alcohol. According to one embodiment of the invention, the nanocomposite with higher loading of tannic acid shows highest oleophilicity and adsorption of oil and thus better recovery of oil from water.
[0030] The invention in its various embodiments discloses a tannic acid exfoliated boron nitride reinforced chlobutyl rubber (CIIR) or chlorine isobutylene isoprene rubber nanocomposite. Tannic acid is a bio based 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. The nanocomposite shows high mechanical performance and tensile strength and can be used for fabrication of protective clothing or gloves. The fabricated nanocomposite can be used for oil water separation. The oil spill in water resources may adversely affect the life in water by creating a harsh environment in water. Even the human life will critically affect the pollution of water which should be eliminated by the creation of materials which helps to prevent the situation. The fabricated h-BN:TA/CIIR nanocomposite satisfactorily helps to remove the oil spill in water and hence being a part to generate clean environment. The nanocomposite shows high decontamination efficiency and the fabricated CIIR nanocomposite by the incorporation of less amount of filler and more amount of bio exfoliating agent will reduce the health risk and increase the safety while using protective clothing. In addition, the reusability of the prepared CIIR nanocomposite significantly supports their promising use in glove and protective clothing fabrication. The nanocomposite shows excellent thermal stability and reduced rate of thermal degradation. The fabricated nanocomposite exhibits antibacterial activity and will be helpful to create extra care from biological hazards generated while wearing safety clothing. The developed h-BN:TA/CIIR nanocomposite with enhanced mechanical, antibacterial, thermal decontamination, oleophilic and hydrophobic nature can be effectively used for oil-water separation and for the fabrication of reusable gloves and chemical protective clothing.

[0031] EXAMPLES
[0032] Example 1:Exfoliation of boron nitride using tannic acid and fabrication of h-BN:TA/nanocomposites:
[0033] Exfoliation of boron nitride using tannic acid: h-BN, tannic acid and CIIR dispersions were prepared using hexane as solvent. Exfoliation of h-BN using TA was carried out using simple bath ultrasonication process. The amount of h-BN was kept constant, and the amount of tannic acid was varied. Briefly, h-BN:TA dispersions in the ratios 1:1, 1:2, 1:3 and 1:4 were prepared by separately dispersing various loadings of TA in millipore water followed by the addition of h- BN. Uniform dispersions were obtained after bath sonication for 1 h and oven dried for 24 h at a temperature of 75°C.
[0034] Fabrication of h-BN:TA/CIIR nanocomposites; The CIIR nanocomposites were prepared using solution intercalation method. The amount of filler added to CIIR matrix was fixed as 3 g. At first, 3 g of 1:1, 1:2, 1:3, and 1:4 h-BN:TA nanofillers were separately dispersed in hexane using bath sonication and mixed with 20 g rubber swollen in the same solvent via probe sonication. The nanocomposites obtained were cast on a petri dish at room temperature to get a thin film. The evaporation of solvent was permitted at room temperature. The obtained nanocomposite films were dried in a vacuum oven at 60 ?C till there was no variation in weight. The control film was prepared by mixing 3 g of h-BN in hexane with 20 g CIIR. The 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 3(1:1 h-BN:TA)/CIIR, 3(1:2 h-BN:TA)/ CIIR, 3(1:3 h-BN:TA)/CIIR, and 3(1:4 h-BN:TA)/CIIR containing 3 g of 1:1, 1:2, 1:3, and 1:4 h-BN:TA nanofillers respectively.
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 3

[0035] Example 2: Characterization of h-BN:TA/CIIR nanocomposite
[0036] h-BN:TA dispersions and h-BN:TA/CIIR nanocomposites were characterized through various microscopic and spectroscopic techniques. The FTIR spectrum of h-BN:TA/CIIR nanocomposite is shown in FIG. 3. FIG. 3 shows the FTIR spectrum of the nanocomposite, 1:1 h-BN:TA/CIIR, 1:2 h-BN:TA/CIIR, 1:3 h-BN:TA/CIIR, 1:4 h-BN:TA/CIIR, having h-BN and TA in 1:1, 1:2 and 1:3 ratios. The FTIR analysis of h-BN:TA/CIIR nanocomposite shows a broad peak around 3500cm?1 corresponding to the free -OH groups in TA. The presence of peak around 3406 cm?1 in CIIR corresponds to the -OH groups in the CIIR, due to the adsorbed moisture or water content. The hydrophobic characteristics of the composites is increasing with the addition of 1:1 h-BN: TA, 1:2 h-BN: TA, 1:3 h-BN: TA etc. indicating the absence of free -OH groups in the CIIR composites Peaks at 2940, 1636, 1237, 964 cm?1 etc. corresponds to the CH2, C–– C, C–C and C–H stretching vibrations. The strong peaks present in at 796 and 697 cm?1 corresponds to the C–Cl stretching vibrations in the CIIR rubber. After incorporating the filler, the absence of peak at 697 cm?1 and the reduced intensity of peak at 796 cm?1 is indicative of the absence of C–Cl linkage. The absence of Cl is due to the removal of HCl by the interaction of -OH groups in the TA with the Cl of CIIR during the composite fabrication process leading to the formation of highly crosslinked network structure. This can be further confirmed by the intensified peak at 1223 cm?1 due to the formation of C-O-C linkage and shift of peak observed at 796 cm?1 to lower wave number indicating the reduced Cl content in CIIR. Thus, the composites show hydrophobic behaviour due to the absence of free -OH in TA. But as the concentration of TA increases, in 3(1:4 h-BN: TA)/CIIR, due to the self-assembly of TA, it starts to agglomerate, and the filer-matrix interaction reduces. This can be evident from the pronounced peak corresponding to C–Cl.
[0037] XRD analysis of h-BN:TA/CIIR nanocomposites was performed to evaluate the nature of dispersion of TA exfoliated h-BN filler in CIIR matrix and the X-ray diffraction spectrum is shown in FIG. 4. As shown in FIG. 4, CIIR showed an amorphous peak at 14.8? in addition to the peaks at 12.2?, 26.9?, 31.9?, 34.6?, 36.4?, and 56.7?. The successful incorporation of h-BN:TA filler in CIIR matrix was confirmed by the presence of CIIR peaks in all h-BN:TA/CIIR nanocomposite spectra. h-BN has a sharp and crystalline peak at 26.8? and the incorporation of h-BN into CIIR matrix will result in the introduction of crystallinity in CIIR nanocomposites. This was confirmed by the increased intensity of CIIR peaks in 3(h-BN)/CIIR spectrum. But the intensity of CIIR peaks was reduced in all h-BN:TA/CIIR nanocomposites which indicates the disruption of the layered nature and loss of crystallinity of h-BN by TA. The characteristic peak of h-BN at 26.8? was visible in all the h-BN:TA/CIIR spectrum and showed a shift to lower theta value of 23.4? indicating the effective exfoliation of the filler. The intensity of h-BN peak is reduced from 3(1:1 h-BN:TA)/CIIR to 3(1:3 h-BN: TA)/CIIR nanocomposite which indicates enhanced intercalation of polymer between the layers of h-BN. Reduced intensity of BN peaks in CIIR shows the clear evidence for the fine dispersion of BNNS in the CIIR matrix. The intensity of h-BN peak is slightly increased in 3(1:4 h-BN:TA)/CIIR nanocomposite which may be attributed to the agglomeration of filler happened after introducing into the CIIR matrix.
[0038] Morphology analysis : The morphology of h-BN:TA in CIIR matrix and the extent of exfoliation was analyzed by SEM images. In the CIIR nanocomposite incorporated with unmodified h-BN, the surface of filler looks smooth and are not disturbed. The uniform distribution of individual BN layers was observed. The surface of CIIR showed a uniform texture instead of roughened nature.Whereas, 3(1:3 h-BN:TA)/CIIR sample exhibited a roughened surface owing to the disturbances caused by excess TA. Moreover, the surface of boron nitride is disturbed due to the presence of TA which indicates the good exfoliation of boron nitride by TA. The excess TA present in the CIIR matrix is uniformly distributed without any agglomeration and this helps in the enhancement of mechanical properties.
[0039] Example 3: Thermal and mechanical analysis of the composite
[0040] Thermal stability of h-BN:TA/CIIR nanocomposites was evaluated via TGA analysis. Thermal degradation temperature of h-BN:TA/CIIR nanocomposites was increased compared to h-BN/CIIR and control nanocomposites. Pure CIIR starts degradation at 232°C but in case of 3(1:3 h-BN:TA)/CIIR sample, the degradation temperature was greatly increased to 248°C which indicates the excellent stability of the nanocomposite owing to the uniform dispersion and complete exfoliation of h-BN by TA. The incorporation of TA exfoliated h-BN helped to increase the stability of CIIR which was evident from the increased residual mass of h-BN:TA/CIIR nanocomposites. 3(1:3 h-BN: TA)/CIIR have highest residual mass of 10.98 % compared to all other samples which indicates excellent stability and reduced rate of thermal degradation.
[0041] The mechanical properties of CIIR rubber after the incorporation of h-BN and TA exfoliated h-BN was evaluated. The results of mechanical analysis are displayed in FIG. 5. Block A shows the tensile strength of CIIR without any fillers in FIG. 5A. The obtained value of 1.94 MPa is increased to 2.64 MPa in Block B, when the CIIR matrix is incorporated with 3 g of h- BN. Block C shows a reduced tensile strength value of 1.91 for 3 g 1:1 h- BN/TA incorporated CIIR owing to the reduction in h-BN amount. But interestingly, the tensile strength value gets increased with the addition of 3 g 1:2 h-BN/TA and 3 g 1:3 h-BN/TA to CIIR. Even though the amount of h-BN is kept constant at 1 g, the tensile strength gets increased with an increase in tannic acid loading which confirms the reinforcing effect of tannic acid in addition to the exfoliating effect. In 3 g 1:3 h-BN/ TA added CIIR sample, the value increases to 2.5, which is identical to the tensile strength of 3 g h-BN/CIIR composites. The result confirms that the property enhancement can be done with a low amount of h-BN nanofiller by exfoliating them with tannic acid owing to the reinforcing effect of tannic acid. The possibility of hydrogen bonding interaction of TA with h-BN through the electronegative N atoms causes reduction in the intensity of -OH groups. The remaining -OH groups will react with the C–Cl present in CIIR which leads to the elimination of H–Cl. This creates a highly crosslinked structure and thereby better mechanical reinforcement. Excess TA present in the system also helps incrosslinking. Overall, CIIR contains cross links from TA on the h-BN surface as well as excess tannic acid. Instead of adding 3 g h-BN into the CIIR matrix, the addition of 3 g 1:3 h-BN:TA filler will provide the same mechanical enhancement to CIIR matrix. Moreover, the use of green, low-cost biomaterial tannic acid will make the fabrication of CIIR nanocomposite, an economically viable one. As the amount of TA was increased further, the value gradually declined due to agglomeration of excess tannic acid. Based on the above result, it is possible to fabricate a nanocomposite material with enhanced properties using minimal amount of nanofiller by employing tannic acid as an exfoliation agent. The elongation at break values shown in Fig. 9B and tensile modulus values shown in Fig. 9C increases for 3 g h-BN and 3 g 1:3 h-BN:TA incorporated CIIR matrix which supports the above conclusion. Since the fabrication of a protective clothing requires good mechanical performance, the sample meets the requirement with an advantage of using low amount of filler and high amount of bio-exfoliating agent.
[0042] Example 4: Thermal decontamination using h-BN:TA/CIIR nanocomposite:
[0043] The thermal decontamination efficiency of a material is the measure of their ability to remove the solvent permeated or adsorbed on the material. The CIIR nanocomposite samples were swelled in toluene and maximum swelling was observed after one day. After swelling process, thermal decontamination studies were conducted by placing the samples in a hot-air oven at 95 ?C for 16 h. Weight of the samples before swelling, after maximum swelling and after 16 h in oven was measured. Based on this, the thermal decontamination efficiency of the sample was calculated. The cycle was repeated three times and the efficiency was calculated in each case. %Decontamination efficiency = (Weight loss/Weight gain)×100. The decontamination efficiency increased with increase in TA loading and a higher efficiency value of 99.79 % was observed for 1:4 h-BN:TA/CIIR sample after first decontamination cycle. The results of thermal decontamination studies were summarized in TABLE 2. A tortuous path was created by the excess TA which causes the adsorption of solvent on the surface of h-BN:TA/CIIR sample instead of permeating into the sample. As a result, the solvent was easily desorbed from the samples which was evident from the enhancement of decontamination efficiency values for h-BN:TA/CIIR composites with increase in TA loading, even after two decontamination cycles. Five decontamination cycles were performed, and the efficiency values remain greater than 95 % for all samples. Also, the decontamination efficiency of samples increased with increase in TA loading and the trend remained the same for all the cycles which indicates their excellent reusability. Even maximum swelling of CIIR can be achieved by using toluene as the solvent, the increased value of decontamination efficiency for toluene by h-BN:TA/CIIR composites indicates their ability to remove other solvents. The decontamination efficiency of fabricated CIIR nanocomposite by the incorporation of less amount of filler and more amount of bio exfoliating agent will reduce the health risk and increase the safety while using protective clothing.
TABLE 2 : Thermal decontamination efficiency of the different nanocomposites
Decontamination cycle (16 h@95°C) Decontamination efficiency (%)
3h- BN/ CIIR 3(1:1 h- BN:TA)/ CIIR 3(1:2 h- BN:TA)/ CIIR 3(1:3 h- BN:TA)/ CIIR 3(1:4 h- BN:TA)/ CIIR
1 99.25 99.14 99.61 99.21 99.79
2 98.88 98.71 98.53 98.82 99.38
3 98.50 98.07 97.91 98.04 98.56
4 97.21 96.79 96.88 97.19 97.74
5 96.69 95.58 95.91 96.52 97.04

[0044] Example 5: Antibacterial Analysis of the nanocomposite:
[0045] Antibacterial analysis of the various ratios of TA exfoliated h-BN nanofillers was performed. Tannic acid and boron nitride nanosheets are excellent antibacterial agents. The antibacterial activity of h-BN:TA nanofillers against Gram-positive bacteria (S. aureus) increased with increase in TA loading owing to the excellent bacterial resistance property of TA and the results are summarized in TABLE 3. Exfoliating boron nitride with TA will enhance the bacterial resistance of the filler. Improved antibacterial action in the TA containing BN samples may arise due to the synergistic effect of both the exfoliated BNNS and from the excess TA.
TABLE 3: Antibacterial analysis performed in h-BN/CIIR and h-BN:TA/CIIR nanocomposites:
Bacteria Sample Zone of inhibition (mm)
1:1 h-BN/TA 19 mm
1:2 h-BN/TA 20 mm
1:3 h-BN/TA 21 mm
Gram-positive bacteria (S. aureus) 1:4 h-BN/TA 22 mm
TA 22 mm
h-BN 10 mm
Gram-negative bacteria (E. coli) 1:1 h-BN/TA 18 mm
1:2 h-BN/TA 19 mm
1:3 h-BN/TA 19 mm
1:4 h-BN/TA 20 mm
h-BN 8 mm

[0046] Example 6: Oleophilicity and hydrophobicity of the nanocomposite
[0047] Oil-water separation efficiency of CIIR, h-BN/CIIR, h-BN:TA/CIIR nanocomposites was analyzed. Oil-water mixture in 1:4 ratio was taken for each sample analysis for samples bare CIIR, 3 h-BN/CIIR, 3(1:1 h-BN:TA)/CIIR, 3(1:2 h-BN:TA)/ CIIR, 3(1:3 h-BN:TA)/CIIR, and 3(1:4 h-BN:TA)/CIIR. The samples were inserted in oil-water mixture and checked after 1 hour. Reduction in oil quantity was clearly visible due to the adsorption of oil owing to the increased oleophilic nature of h-BN:TA/ CIIR samples with increase in TA loading. The adsorbed oil can be recovered after the insertion of swelled samples into isopropyl alcohol. Generally, when the concentration of TA is increasing the hydrophilic characteristics become more pronounced. But in contrast, the hydrophobic characteristics of the composites is increasing with the addition of 1:1 h-BN: TA, 1:2 h-BN: TA, 1:3 h-BN: TA etc. indicating the absence of free -OH groups in the CIIR composites. 3(1:4 h-BN: TA)/CIIR nanocomposite with higher TA loading showed highest oleophilicity. Tannic acid adsorbs oil into the surface of nanocomposite and the adsorption increases with increase in TA loading. Even though, the absorption of oil into the inner part of nanocomposite was prevented due to the hydrophobic nature of boron nitride and chlorobutyl rubber. Hydrophobicity of the matrix played an important role in the easy recovery of oil from the surface after inserting the sample in isopropylalcohol. Contact angle was measured for evaluating the hydrophobicity of CIIR, h-BN/CIIR and h-BN:TA/CIIR samples and the values are summarized in TABLE 4. Contact angle increased with increase in the filler loading.
TABLE 4: Contact angle values of CIIR nanocomposites
Sample Contact angle (°)
CIIR 85.6°
3 h-BN/CIIR 87.9°
3(1:1 h-BN:TA)/CIIR 88.2°
3(1:2 h-BN:TA)/CIIR 91.1°
3(1:3 h-BN:TA)/CIIR 91°
3(1:4 h-BN:TA)/CIIR 92.9°

[0048] 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 use as reusable protective clothing and for oil water separation, comprising:
tannic acid (TA) (102) exfoliated hexagonal-boron nitride (h-BN) (104) as nanofiller (h-BN:TA) (106), incorporated into a chlorine isobutylene isoprene rubber (CIIR) (101) matrix, wherein the ratio of h-BN:TA varies from 1:1 to 1:4 and the nanofiller is present in an amount at 1-7 % of the matrix.

2. The nanocomposite as claimed in claim 1, wherein the FT-IR analysis of the composite gives peaks at 2940, 1636, 1237, 964 cm?1 along with an intensified peak at 1223 cm?1due to C-O-C linkage and a less intense peak at 796 cm-1.

3. The nanocomposite 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 23.4° indicating the exfoliation of boron nitride with tannic acid in the CIIR nanocomposite.

4. The nanocomposite as claimed in claim 1, wherein the tannic acid exfoliated boron nitride/CIIR nanocomposite shows a tensile strength of 2.64 MPa and above.

5. The nanocomposite as claimed in claim 1, wherein the nanocomposite having h-BN and TA in the ratio 1:3, 1:3 h-BN:TA/CIIR exhibits a degradation temperature of 248°C or more.

6. The nanocomposite as claimed in claim 1, wherein the nanocomposite exhibits antimicrobial activity by the introduction of tannic acid exfoliated boron nitride and shows enhanced resistance against S. aureus bacteria with an increase in TA loading.

7. The nanocomposite as claimed in claim 1, wherein the exfoliation using tannic acid increases the thermal decontamination efficiency of the composite and increases with increase in tannic acid.

8. The nanocomposite as claimed in claim 1, wherein the nanocomposite exhibits a thermal decontamination efficiency value up to 99.79 %.

9. A waterproof protective clothing comprising the nanocomposite as claimed in claim 1, wherein the clothing has a thickness ranging from 1 mm to 2 mm.

10. The nanocomposite as claimed in claim 1, wherein the contact angle value of the nanocomposite lies in the range of 91° to 93°.

11. A method of (200) fabrication of hexagonal-Boron Nitride : Tannic acid / chlorine isobutylene isoprene rubber (h-BN:TA/CIIR) nanocomposite, comprising:
dispersing (202) tannic acid (TA) in water and adding h-BN at a predetermined ratio;
obtaining uniform dispersion by bath ultrasonication (204) for one hour and oven drying (206) for 24 hours at a temperature of 75°C to obtain h-BN:TA nanofillers;
dispersing (208) a predetermined quantity of h-BN:TA nanofiller in hexane and mixing with 20 g rubber swollen in hexane by probe sonication;
casting (210) on a petri dish at room temperature to obtain a thin film and drying in vacuum oven at 60°C;
mixing (212) cast film with 80 g CIIR on a two-roll mill;
compounding (214) using stearic acid, zinc oxide,tetramethylthiuram disulfide(TMTD), magnesium oxide, and sulphur; and
compression moulding (216) at 150°C to obtain h-BN:TA/CIIR nanocomposite.

12. The method as claimed in claim 11, wherein the h-BN is exfoliated using tannic acid.

13. The method as claimed in claim 11, wherein the predetermined ratio of h-BN : TA varies from 1: 1 to 1:4 in the nanocomposite.

14. A media for oil-water separation comprising:
tannic acid (TA) (102) exfoliated hexagonal-boron nitride (h-BN) (104) as nanofiller (h-BN:TA) (106), incorporated into a chlorine isobutylene isoprene rubber (CIIR) (101) matrix, wherein the ratio of h-BN:TA is in a ratio 1:4 and the nanofiller is present in an amount at 1-7 % of the matrix, wherein the media is fabricated into sheet, pellet or granular form.

15. The media as claimed in claim 14, wherein the thickness of the sheet or diameter of the pellet or granular form is in the range 1 mm to 2 mm.

16. A method of removing oil from water using the nanocomposite claimed in claim 14, comprising; introducing the h-BN:TA/CIIR nanocomposite media in an oil-water mixture to obtain a swelled media containing adsorbed oil, and separating the water from the media with the adsorbed oil.

17. The method as claimed in claim 16, comprising recovering the adsorbed oil by solvent extraction using isopropyl alcohol.

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