WO2020202178A1

WO2020202178A1 - Un-modified fuller's earth reinforced cured elastomeric composite and method thereof

Info

Publication number: WO2020202178A1
Application number: PCT/IN2020/050269
Authority: WO
Inventors: Kotnees DINESH KUMAR; Nair VISHNU RAMACHANDRAN; Sankaran Kumar; Kadambanathan THIAGARAJAN; Viswanathan Sivaramakrishnan
Original assignee: Tvs Srichakra Ltd
Priority date: 2019-03-29
Filing date: 2020-03-23
Publication date: 2020-10-08

Abstract

The present invention provides development of cured elastomeric composite comprising un-modified fuller's earth clay as reinforcing filler and mixing process thereof. Present invention discloses cured elastomeric nanocomposite comprising elastomeric compound 100 phr, with unmodified fuller's earth nano clay 1-200 phr, without any chemical modification imparts high thermal stability, high mechanical properties. The processability of the uncured compound also increased marginally by the addition of fuller's earth clay as filler. The present invention relates to cured silica or carbon black reinforced or gum elastomer compounds, comprising which can be used for making various elastomer products. Such developed elastomeric composites also function as a compression set regulator, hardness modifier and as a reinforcement material for the elastomer composites. The present invention is likely to find application in tyre and non-tyre products.

Description

UN-MODIFIED FULLER’S EARTH REINFORCED CURED ELASTOMERIC

COMPOSITE AND METHOD THEREOF

FIELD OF INVENTION

The present invention relates to the field of tyres. Particularly the invention relates to development of cured elastomeric composite comprising un-modified fuller’s earth clay as reinforcing filler. The present invention is directed to novel methods for producing elastomeric composite blends and to novel elastomeric composite blends produced using such methods. More particularly, the invention is directed to methods for producing elastomeric composite blends with un-modified fuller’s earth clay as reinforcing filler and products formed of such compositions.

BACKGROUND OF THE INVENTION:

Elastomers are conventionally reinforced with particulate reinforcing fillers such as, for example, carbon black and sometimes amorphous silica, usually precipitated silica. Conventionally in cured elastomeric-carbon black composites organically modified clay or carbon black is used as inhibitor for compression set. Conventionally in cured elastomeric-carbon black composites carbon black and silica are used as tear strength modifier as well as reinforcing filler.

GB 122023 (A) relates to fibrous plastic compositions; plastic compositions containing mica. A liquid composition for automatically closing punctures in air-tubes of tyres, consists of asbestos, pulverized cork, fullers' earth, Flaked mica, water-soluble glue, and water, with or without a preservative such as salt or boracic acid.

US2004176511 (Al) relates to a thermoplastic polyester-based flame-retardant resin composition comprising 100 parts by weight of a thermoplastic polyester resin, 3 to 50 parts by weight of a bromine-containing aromatic compound, (C) 2 to 30 parts by weight of an antimony oxide compound, (D) 0.1 to 3 parts by weight of polytetrafluoroethylene having fibril -forming abilities, and (E) 0.7 to 8 parts by weight of a lamellar filler.

GB 1138473 A relates to foamed thermoplastic material obtained by introducing under pressure an expansion fluid into a molten polymer in which are dispersed porous particles of an inorganic material which is neutral with respect to the polymer. The porous powder may be alumina, silica, activated carbon, absorbent clays, metallic oxides, silicates, carbonates e.g. fuller's earth, diatomaceous earths, magnesias, iron oxides, pumice, thorium oxides, bauxite, bentonite and molecular screens.

US2007197696A1 relates to a flame retardant resin composition comprising a polyester; wherein the polyester comprises from about 1 to about 15 mole percent of an unsaturated diol; a flame retardant compound, an organic compound comprising of at least one carboxyl reactive group.

US20080242784 relates to a composition of matter comprising a polyester composition derived from: greater than 80 mole percent of a diol derived from a disubstituted xylene glycol of the formula Fibrous fillers can be supplied in the form of, for example, rovings, woven fibrous reinforcements, such as 0-90 degree fabrics or the like; non-woven fibrous reinforcements such as continuous strand mat, chopped strand mat, tissues, papers and felts or the like; or three-dimensional reinforcements such as braids.

US20090030129 relates to a composition of matter comprising a thermoplastic resin composition derived from (i) a polyester derived from a cycloaliphatic diol, and an aromatic diacid; (ii) a polycarbonate derived from at least from 20 mole percent to 100 mole percent of an aromatic diol derived from structure II ##STR00001## wherein R.sup.3 and R.sup.4 are independently selected from the group consisting of C.sub.l-C.sub.30 aliphatic, C.sub.2-C.sub.30 cycloaliphatic and C.sub.2-C.sub.30 aromatic groups, X is CH.sub.2 and m is an integer from 3 to 7, n is an integer from 1 to 4, p is an integer from 1 to 4, and from 0 mole percent to 80 mole percent of a second aromatic dihydroxy compound.

US2001009930A1 relates to a foamed elastomer, manufactured from a foam precursor composition comprising an ethylene-propylene-diene resin, a melamine-formaldehyde resin, a curing agent, and a blowing agent.

The elastomer composition optionally further includes cure activators, polymerization accelerators, and a filler material. The invention is disclosing a process for the manufacture of an elastomer material which is of cell structure

EP2291454A1 relates to a composition comprises, based on the total weight of the composition: from 10 to 80 wt. % of a modified polybutylene terephthalate copolymer that is derived from polyethylene terephthalate component selected from the group consisting of polyethylene terephthalate and polyethylene terephthalate copolymers and has at least one residue derived from the polyethylene terephthalate component; from 10 to 80 wt. % of a polycarbonate; from 0 to 20 wt. % of an impact modifier; from 1 to less than 25 wt. % of a reinforcing filler; from 0.1 to less than 2.5 wt. % of a fibrillated fluoropolymer; from 0 to 5 wt. % of an additive selected from the group consisting of antioxidants, mold release agents, colorants, quenchers, stabilizers, and combinations thereof.

US20170088695 relates to a plasticizer composition, polymeric compositions containing the plasticizer composition, and conductors coated with the polymeric composition. The plasticizer composition includes a first plasticizer comprising epoxidized fatty acid alkyl esters and a second plasticizer comprising an epoxidized natural oil.

US20180105667 relates to Monomodal foamed polymeric compositions containing clay nucleating agents.

IN3970/DELNP/2004 relates to a nanocomposite comprising a clay and an elastomer comprising at least C2 to CIO olefin derived units; wherein the elastomer also comprises functionalized monomer units pendant to the elastomer. Desirable embodiments of the elastomer include poly(isobutylene- co-^A-alkylstyrene) elastomers and poly(isobutylene-co-isoprene) elastomers, which are functionalized via Friedel-Crafts reaction with a Lewis acid and a functionalizing agent such as acid anhydrides and/or acylhalides. The clay is exfoliated in one embodiment by the addition of exfoliating agents such as alkyl amines and silanes to the clay.

The main difference between un-modified nanoclay and organically modified nanoclay is, organically modified nanoclay undergoes several chemical treatments to incorporate / insert certain types of organo modifiers in between the silicate layers of the nanoclay. This is mainly done to increase the distance between the silicate layers of the nanoclay to facilitate the penetration of the polymer chains into silicate layers and also to improve the compatibility of the nanoclay with the polymer which depends on the type of modifiers used (polar or non-polar). These types of modifications generally lead to enhanced reinforcement. Till date, these modified nano-clays do not find any commercial and industrial significance because of the various challenges associated with the modification procedures such as large amount of time involved in modification process and also because of cost associated with the modification process.

US2005203236A1 relates to a silicone resin composition which includes a silicone resin such as a silicone elastomer and a particulate kaolin filler pretreated with an amino- or vinyl-functionalized organosilane or organosiloxane.

US4187210A relates to solid, homogeneous, particulate, highly-filled polyolefin composites which comprise (a) about 10-75% by weight of polyolefin having an inherent viscosity of at least about 2, and (b) about 25-90% by weight of finely-divided, inorganic filler compound having catalytically- active transition metal compound interacted at its surface, said polyolefin being polymerized onto the surface of said filler, and said composite having a 10-second micronization homogeneity of at least about 50% and a micronization homogeneity index of at least about 20. The temperature to which the sheet is heated can vary from about 105.degree. to about 225. degree. C. A particularly preferred class of fillers is aluminum silicate clays of the formula Al.sub.2 0.sub.3.xSi0.sub.2.nH.sub.2 O where x is 1 to 5 and n is 0 to 4.

The article entitled“Non-black fillers for elastomers” talks about the non-blackfillers for elastomers that are calcium carbonate, kaolin clay, precipitated silica, talc, barite, amorphous silica, diatomite, etc. This papers deals with three most widely used types of non-black fillers: calcium carbonate, kaolin clay and precipitated silica [Adnan Mujkanovic, Ljubica Vasiljevic, Gordana Ostojic; 13th International Research/Expert Conference, 16-21 October 2009].

The article entitled “Nanokaolin clay as reinforcing filler in nitrile rubber” talks about the nanocomposites prepared by incorporating varying amounts of nanokaolin clay and vinyl silane grafted nanokaolin clay in NBR, on a two roll mill [Preetha Nair K, Dr. Rani Joseph; International Journal of Scientific & Engineering Research Volume 3, Issue 3, March -2012].

The article entitled“The potential of kaolin as a reinforcing filler for rubber composites with new sulfur cure systems” investigated the effect of a large amount of kaolin (China clay) on the viscosity, cure, hardness, Young’s modulus, tensile strength, elongation at break, stored energy density at break, tear energy and compression set resistance of some sulfur-cured natural rubber, polybutadiene rubber and ethylene -propylene-diene rubber composites. The kaolin surface had been pre-treated with 3-mercaptopropyltrimethoxysilane to improve its dispersion in the rubbers [Saad H Sheikh, Xuena Yin, Ali Ansarifar, Keith Yendall; Journal of Reinforced Plastics and Composites, June 14, 2017]

The referred publications relate to different non-black fillers which are of spherical or lamellar structures.

Pandey et ah, J Appl Polym Sci, 30 October 2009, “Polyvinyl alcohol fuller's earth clay nanocomposite films”. It discloses nano fuller's earth prepared by milling and subsequent sonication of clay. The polyvinyl alcohol (PVA) and PVA -Nano clay composite films were prepared by solution casting method. The referred article relates to the development of a polyvinylalcohol based composite which is water soluble.

In view of the above prior arts, current invention employs unmodified fuller’s earth nanoclay as a potential reinforcing agent in the rubber matrix and has significant scope from commercial and industrial point of view.

Hence, the present invention aims to provide a cured elastomeric nanocomposite with un -modified fuller's earth which is of needle like structure as reinforcement filler.

OBJECTS OF THE INVENTION

It is the primary object of the present invention to provide development of cured elastomeric composite comprising fuller’s earth clay as reinforcing filler and mixing process thereof.

Another object of the present invention is to provide cured elastomer-fuller’s earth clay nano composite which is amorphous and non-soluble in water.

Yet another object of the present invention is to provide un-modified fuller’s earth clay as a compression set inhibitor, thermal degradation inhibitor, tear strength modifier and as a reinforcement for cured elastomeric composites. Still another object of the present invention is to provide cured elastomeric composites imparting high thermal stability, high mechanical properties.

Another object of the present invention is to provide use of environment friendly inorganic filler as an alternative for the conventional carbon black.

Yet another object of the present invention is to provide application of the composite of the invention in tyre and non-tyre products.

SUMMARY OF THE INVENTION:

According to the present invention, there is provided a cured elastomeric nanocomposite, comprising of:

one or more elastomeric compounds - 100 phr;

a reinforcing filler - 1-200 phr;

one or more accelerators - 0.2-1 phr;

a vulcanization agent - 1-4 phr;

cure activators - 1.5-3 phr; and

anti-degradants - 0.2 - 1 phr,

wherein the reinforcing filler is unmodified fuller’s earth nano clay comprising of length between 1-3000 nanometer and diameter of 1-30 nanometer without any chemical modification.

It is another aspect of the present invention to provide a cured elastomeric nanocomposite, wherein the ratio of elastomeric compound to the reinforcing filler is 100 : (5-50).

It is another aspect of the present invention to provide a cured elastomeric nano composite, wherein elastomeric compound is selected from one or more of natural rubbers, poly isoprene rubber, styrene butadiene rubber (SBR), poly butadiene rubber, isoprene butadiene rubber (IBR), styrene-isoprene- butadiene rubber (SIBR), ethylene-propylene rubber, ethylene -propylene -diene rubber (EPDM), poly sulfide, nitrile rubber, propylene oxide polymers, star branched butyl rubber and halogenated star branched butyl rubber, brominated butyl rubber, chlorinated butyl rubber, star branched poly isobutylene rubber, star branched brominated butyl (poly isobutylene/ isoprene copolymer) rubber; isobutylene/ alkyl styrene copolymers such as iso butylenes / meta- bromomethyl styrene, isobutylene/bromomethyl styrene, iso butylene / chloramethyl styrene, halogenated isobutylene cyclopentadiene and isobutylene / chloromethyl styrene and mixtures thereof.

It is another aspect of the present invention to provide cured elastomeric nanocomposite, wherein the elastomeric compound comprises of silane coupled solution styrene butadiene rubber (SSBR) Butadiene Rubber in a weight ratio of 70:30.

It is another aspect of the present invention to provide cured elastomeric nanocomposite, wherein accelerators comprises N-cyclohexyl-2-benzothiazole sulfonamide and diphenyl guanidine.

It is another aspect of the present invention to provide a cured elastomeric nanocomposite, wherein vulcanization agent is sulfur.

It is another aspect of the present invention to provide a cured elastomeric nanocomposite, wherein cure activators comprises Zinc oxide and Stearic acid.

It is another aspect of the present invention to provide a cured elastomeric nanocomposite, wherein anti-degradants comprises 6PPD [N-( 1,3-dimethyl butyl)-N’ -phenyl -p-phenylene diamine], TMQ [2, 2, 4-Trimethyl- 1,2-Dihydro quinoline] and Microcrystalline wax (MC-Wax).

It is another aspect of the present invention to provide a process of preparation of cured elastomeric nanocomposite, comprising of the steps:

Master batch mixing comprising of steps

mastication of elastomers for 25-30 seconds;

addition of reinforcing filler;

addition of cure activators along with anti-degradants;

addition of vulcanization agent;

addition of accelerators;

mixing of ingredients in an internal mixer up to 240 seconds with rotor speed of 40 rpm , rotor temperature at 50°C, chamber temperature at 50°C and ram pressure to 5 Kp/Sq.cm.;

sweeping off the chemicals from the chamber walls and further mixing upto 120 seconds; dumping of mixed elastomeric nanocomposite at temperature of 150°C; and

Final batch mixing by

warming of master batch mix for 15-45 seconds;

addition of cure activators and accelerators;

mixing for 50 -100 seconds in an internal mixer with rotor speed of 30 -60 rpm with initial temperature at 30°C and ram pressure is maintained upto 5 kp/sq.cm; and dumping at temperature range of 105°C - 120°C,

It is another aspect of the present invention to provide a process of preparation of cured elastomeric nanocomposite, wherein the elastomeric compound comprises of silane coupled solution styrene butadiene rubber (SSBR) and Butadiene rubber in a weight ratio of 70: 30.

It is another aspect of the present invention to provide a process of preparation of cured elastomeric nanocomposite, wherein the cure activators comprises zinc oxide and stearic acid.

It is another aspect of the present invention to provide a process of preparation of cured elastomeric nanocomposite, wherein vulcanization agent is sulfur.

It is another aspect of the present invention to provide a process of preparation of cured elastomeric nanocomposite, wherein the accelerators comprises of N-cyclohexyl-2-benzothiazole sulfonamide and diphenyl guanidine.

It is another aspect of the present invention to provide a process of preparation of cured elastomeric nanocomposite, wherein anti-degradants comprises of 6PPD [N-( 1,2-dimethyl butyl)-N’ -phenyl-p- phenylene diamine], TMQ [2, 2, 4-Trimethyl- 1,2-Dihydro quinoline] and Microcrystalline wax (MC wax).

BRIEF DESCRIPTION OF DRAWINGS

The annexed drawings show an embodiment of the present invention, wherein Figure 1: illustrates the thermal degradation patterns of pristine Fuller’s earth (FE) powder, unfilled silane coupled solution styrene butadiene rubber (SSBR) / Butadiene rubber (BR) blend, 20 phr and 50 phr unmodified FE nano clay loaded SSBR/BR-70/30 blend.

Figure 2: illustrates the tear strength of different compounds.

Figure 3: illustrates the tensile strength and maximum elongation of different compounds.

Figure 4: illustrates the tan d verses temperature graph for unfilled SSBR/BR-70/30 blend, 20 phr and 50 phr unmodified FE nano clay loaded SSBR/BR-70/30 blend and highlighting the values at 0°C and at 60°C.

Figure 5: illustrates the transmission electron microscopy images of SSBR/BR-70/30 blend with 20 phr unmodified FE nano clay for showing the size and structure of FE nanoclay.

Figure 6: illustrates the compression set values of the compounds at 70°C for 22 hours.

DETAILED DESCRIPTION OF THE INVENTION ACCOMPANYING FIGURES

Hereinafter, a cured elastomeric nanocomposite comprising un-modified fuller’s earth (FE) nano clay as reinforcing filler and the process of preparation of cured elastomeric nano-composite comprising un-modified FE nano clay as reinforcing filler will be described.

The present invention provides development of cured elastomeric composite comprising un modified fuller’s earth clay as reinforcing filler and mixing process thereof. Cured elastomeric composites developed by such method imparts high thermal stability, high mechanical properties. The process ability of the uncured compound also increased marginally by the addition of fuller’s earth clay as filler. The present invention relates to cured silica or carbon black reinforced or gum elastomer compounds, which can be used for making various elastomer products. Such developed elastomeric composites also function as a compression set regulator, hardness modifier and as a reinforcement material for the elastomer composites. The present invention is likely to find application in tyre and non-tyre products.

The present invention relates to the development of a cured elastomeric nanocomposite having unmodified fuller’s earth (FE) clay as reinforcing filler. The elastomer(s) is a blend of silane coupled solution styrene butadiene rubber (SSBR) and butadiene rubber (BR).

The composition according to the invention also contains conventional additives in conventional amounts. The materials used for the development of unmodified FE clay reinforced cured elastomeric nanocomposites are unmodified FE clay as filler, ZnO, Sulphur, stearic acid, CBS[6], DPG[7] and it does not contain carbon black, process oil, process aid etc.

The cured elastomer(s) compositors of the invention are composed of, based on 100 parts of elastomer(s) about 1-200 parts by Fuller’s Earth clay as a compression-set regulator, thermal degradation reducer, tear resistance promoter and (or) reinforcement additive for elastomers. The elastomer can be a single or blend of two or more elastomers. Elastomer(s) can be natural rubbers, polyisoprene rubber, styrene butadiene rubber (SBR), polybutadiene rubber, isoprene butadiene rubber (IBR), styrene-isoprene-butadiene rubber (SIBR), ethylene -propylene rubber, ethylene- propylene-diene rubber (EPDM), polysulfide, nitrile rubber, propylene oxide polymers, star- branched butyl rubber and halogenated star-branched butyl rubber, brominated butyl rubber, chlorinated butyl rubber, star-branched polyisobutylene rubber, star-branched brominated butyl (polyisobutylene/isoprene copolymer) rubber; isobutylene/alkylstyrene copolymers such asisobutylene/meta-bromomethylstyrene, isobutylene/bromomethylstyrene, isobutylene/ chloromethylstyrene, halogenated isobutylene cyclopentadiene, and isobutylene/ chloromethylstyrene and mixtures thereof.

Table 1 shows the composition details of the compound according to the present invention and different formulations prepared having ratio of SSBR/BR/FE from 70:30:0 to70:30:50 -

Table 1: Compound design

*- per hundred grams of rubber by weight

[1] Solution polymerized styrene -butadiene rubber terminally di-functionalized with an alkoxysilane group and a primary amine group from Japan Synthetic Rubber (JSR).

[2] Polybutadiene Rubber or simply Butadiene Rubber from Relflex elastomers CISAMER PBR 1220, Cobalt (Co) Catalyst, Cis-1, 4 Configuration (%)96, Mooney Viscosity ML (1+4) @ 100 °C,

MU 45

[3] Fuller’s earth clay having length between 1-3000 nanometer and diameter of 1-30 nanometer without any chemical modification (Figure 5.).

[4] N-(l,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine

[5]2, 2, 4-Trimethyl- 1 ,2-Dihydroquinoline

[6] N-cyclohexyl-2-benzothiazolesulfenamide

[7] Diphenyl guanidine

Method of preparation of a cured elastomeric nanocomposite

An embodiment of the present invention discloses a method of preparation of the cured elastomeric nanocomposite with different concentrations of fuller’s earth nano clay as reinforcing filler, comprising of the steps:

Master batch mixing process:

The ingredients are initially mixed in an internal mixture. The rotor speed is maintained constantly around 30-70 rpm. The temperature of rotor of the internal mixer is maintained around 40-60°C and the temperature of chamber of the internal mixer is maintained around 40-60°C.The ram pressure is kept to 5 kp/cm2. The batch weight is decided based in the chamber volume of the mixer. The fill factor of the chamber is 0.70-0.90. The total mixing time of the master batch compound is around 4- 8 minutes. Rubber is initially masticated for 20-60 seconds. This also ensures effective blending of fuller’s earth with SSBR. The rubber chemicals, fuller’s earth clay and processing oil is added to the masticated rubber. Further, the chemicals are loaded in the following order: cure activators selected from ZnO(Zincoxide), Stearic acid and anti-degradants selected from 6PPD [N-(l,3-dimethylbutyl)- N’ -phenyl -p-phenylenediamine], TMQ (2, 2, 4-Trimethyl- 1,2-Dihydroquinoline), MC-wax (Microcrystalline wax) respectively. The initial addition of fuller’s earth clay helps in fine dispersion of the nanomaterial into the rubber matrix. The mixing process is carried out for 180-250 seconds. This is followed by sweeping off the chemicals from the chamber walls and again the mixing is continued up to 80-160 seconds. Finally, the mixed rubber nanocomposite is dumped. The dump temperature of the rubber nanocomposite is 140-170°C.

Final Batch Mixing Process:

Rotor speed is maintained at 30-60 rpm and the starting temperature of mixing is 30°C. The ram pressure is kept to 5 kp/cm². The master batch is warmed for 15-45 seconds. The cure chemical and accelerator were added further and mixed for 50-100 seconds. The dump temperature varies between 105°C-120°C.

EXAMPLES

Example 1

Master batch mixing process:

The ingredients are initially mixed in an internal mixture. The rotor speed is maintained constantly around 40 rpm. The temperature of rotor of the internal mixer is maintained around 50°C and the temperature of chamber of the internal mixer is maintained around 50°C.The ram pressure is kept to 5 kp/cm². The batch weight is decided based in the chamber volume of the mixer. The fill factor of the chamber is 0.90. The total mixing time of the master batch compound is around 7 minutes. Rubber is initially masticated for 30 seconds. This also ensures effective blending of FE with SSBR. The rubber chemicals and FE clay is added to the masticated rubber. Further, the chemicals are loaded in the following order: cure activators selected from ZnO(Zincoxide), Stearic acid and anti- degradants selected from 6PPD [N-(l,3-dimethylbutyl)-N’ -phenyl -p-phenylenediamine], TMQ (2, 2, 4-Trimethyl- 1,2-Dihydroquinoline), MC-wax (Microcrystalline wax) respectively. The initial addition of FE clay helps in fine dispersion of the nanomaterial into the rubber matrix. The mixing process is carried out for 240 seconds. This is followed by sweeping off the chemicals from the chamber walls and again the mixing is continued up to 120 seconds. Finally, the mixed rubber nanocomposite is dumped. The dump temperature of the rubber nanocomposite is 150°C. Example 2

Final Batch Mixing Process:

Rotor speed is maintained at 30 rpm and the starting temperature of mixing is 30°C.

The ram pressure is kept to 5kp/cm². The master batch is warmed for 30seconds. The cure chemical and accelerator were added further and mixed for 100 seconds. The dump temperature is kept at 110°C.

Results

The present invention relates to the improved thermal degradation resistance of the unfilled SSBR/BR-70/30 blend by the addition of unmodified FE nanoclay. The polymer degradation temperature of un-filled SSBR/BR-70/30 blend is recorded as 330°C and after adding 50phr un modified FE nanoclay, it is increased substantially to 347 °C. The degradation patterns of the un filled SSBR/BR-70/30 blend and composites having different loading of un modified FEnanoclay clearly shows the delayed degradation rate and thus it is confirmed that the addition of the un modified FE nanoclay imparts thermal degradation resistance to the SSBR/BR-70/30 blend. These studies were conducted using an advanced thermogravimetric analyzer machine (model: TGA 8000, PerkinElmer, MA, USA) and resulting thermo-grams are reported as shown in Figure 1 and Table 2- Table 2: Thermal degradation data

The tear strength of a material is its resistance to withstand a load without tearing off and is tested and reported in accordance with ASTM standard D-624.

Tear strength of the samples were tested using a universal testing machine (model: 5966, Instron, MA, USA). The unfilled SSBR/BR-70/30 blend has a tear strength of 7.5 N/mm and addition of unmodified FE nano-clay increases the tear strength. The nanocomposite with 50 phr dosage of unmodified FE addition has highest tear strength of 35.37 N/mm, showing a 371% increase from the initial value as shown in Figure 2 and Table 3. Table 3: Tensile strength, Compression set, Tear strength and Maximum elongation of compounds

The tensile strength of a composite can be interpreted as a measure of its physical strength. Tensile strength is tested in accordance with ASTM standard D 412 and was measured using a universal testing machine (model: 5966, Instron, MA, USA). The unfilled SSBR/BR-70/30 blend has a tensile strength of 1.78 MPa and on addition of unmodified FE nanoclay it has reached up to 11.37 MPa at concentration of 50 phr unmodified FE nanoclay addition, showing a 538% increase from the initial value.

Also, the maximum elongation for the unfilled SSBR/BR blend is 243% and is increased up to 404% by the addition of 50 phr unmodified FE nanoclay as shown in Figure 3 and Table 3. These results are evident for the reinforcing effect of the unmodified FE nanoclay in an elastomeric matrix.

The dynamic mechanical analysis of the SSBR/BR-70/30 blend with 50phr unmodified FE nanoclay has been done in temperature sweep mode at 0.1% dynamic strain and at 20Hz frequency from - 50°C to +60°C using a dynamic mechanical analyzer (DMA) (model: DMA+1000, Metravib, Fimonest, France). Conventionally, the values for damping coefficient (tan d) at 0°C is taken as a measure of wet grip for elastomeric compounds. For unfilled SSBR/BR-70/30 blend composite, tan d at 0°C is found to be 0.45235 and for 50 phr unmodified FE nanoclay loaded SSBR/BR-70/30 blend it is 0.48637 which is higher than the unfilled blend and thus offers an improved wet grip (Figure 4).

Compression set is measured in accordance with the standard ASTM D 395 at 70°C for 22 hours and it is found that the nanocomposites regulates the compression set, typically at the higher loading of FE (Table 3, Figure 6).

Advantages of the present invention

The cured elastomeric rubber-rubber blend nanocomposite, wherein the nanocomposite comprising of 70 phr of solution polymerized styrene -butadiene rubber terminally di-functionalized with an alkoxysilane group and a primary amine group and 30 phr of polybutadiene rubber or simply butadiene rubber with 50 phr of unmodified FE nanoclay, ZnO 3phr, Stearic acid 1.50phr, N-(l,3- dimethylbutyl)-N’-phenyl-p-phenylenediamine (6PPD) lphr, 2, 2, 4-Trimethyl- 1,2-Dihydroquinoline (TMQ) lphr, MC-wax lphr, Sulphur 3.13phr, N-cyclohexyl-2-benzothiazolesulfenamide (CBS) lphr, Diphenyl guanidine (DPG) 0.20phr having an improved thermal degradation resistance of about 17°C in thermal degradation initiation than the parent rubber -rubber blends without the unmodified FE nanoclay.

The cured elastomeric rubber-rubber blend nanocomposite, wherein the nanocomposite has 371% improvement in tear strength than the unfilled parent rubber-rubber blends without the unmodified FE nanoclay.

The cured elastomeric rubber-rubber blend nanocomposite, wherein the said nanocomposite has an improved tensile strength of about 538% than the parent rubber-rubber blend without the unmodified FE nanoclay.

The cured elastomeric rubber-rubber blend nanocomposite, wherein the said nanocomposite regulates the compression set at 70°C for 22 hours similar to the parent rubber-rubber blend without the unmodified FE nanoclay.

Claims

WE CLAIM:

1. A cured elastomeric nanocomposite, comprising of:

one or more elastomeric compounds - 100 phr;

a reinforcing filler - 1-200 phr;

one or more accelerators - 0.2 - 1 phr;

a vulcanization agent - 1-4 phr;

cure activators - 1.5 - 3 phr; and

anti-degradants - 0.2 -1 phr,

2. The cured elastomeric nanocomposite as claimed in claim 1, wherein the ratio of elastomeric compound to the reinforcing filler is 100: (5-50).

3. The cured elastomeric nanocomposite as claimed in claim 1, wherein said elastomeric compound is selected from one or more of natural rubbers, poly isoprene rubber, styrene butadiene rubber (SBR), poly butadiene rubber, isoprene butadiene rubber (IBR), styrene-isoprene -butadiene rubber (SIBR), ethylene-propylene rubber, ethylene -propylene -diene rubber (EPDM),poly sulfide, nitrile rubber, propylene oxide polymers, star branched butyl rubber and halogenated star branched butyl rubber, brominated butyl rubber, chlorinated butyl rubber, star branched poly-isobutylene rubber, star branched brominated butyl (poly isobutylene / isoprene co polymer) rubber; isobutylene / alkyl styrene copolymers such as isobutylenes / meta-bromomethyl styrene, isobutylene / bromomethyl styrene, iso butylenes / chloramethyl styrene, halogenated iso butylenes cyclopentadiene and isobutylene / chloromethyl styrene and mixtures thereof.

4. The cured elastomeric nanocomposite as claimed in claim 1, wherein the elastomeric compound comprises of silane coupled solution styrene butadiene rubber (SSBR) and butadiene rubber in a weight ration of 70:30.

5. The cured elastomeric nanocomposite as claimed in claim 1, wherein said accelerators comprises N-cyclohexyl-2-benzothiazole sulfonamide and diphenyl guanidine.

6. The cured elastomeric nanocomposite as claimed in claim 1, wherein said vulcanization agent is sulfur.

7. The cured elastomeric nanocomposite as claimed in claim 1, wherein said cure activators comprises zinc oxide and stearic acid.

8. The cured elastomeric nanocomposite as claimed in claim 1, wherein said anti-degradants comprises 6PPD [N-( 1,3-dimethyl butyl)-N’ -phenyl -p-phenylene diamine], TMQ [22,4-Trimetyl- 1, 2-Dihydro quinoline] and Microcrystalline wax (MC-wax).

9. A process of preparation of cured elastomeric nanocomposite comprising of the steps:

Master batch mixing comprising of steps

mastication of elastomers for 25-30 seconds;

addition of reinforcing filler;

addition of cure activators along with anti-degradants;

addition of vulcanization agent;

addition of accelerators;

sweeping off the chemicals from the chamber walls and further mixing upto 120 seconds;

dumping of mixed elastomeric nanocomposite at temperature of 150°C; and

Final batch mixing by

warming of master batch mix for 15-45 seconds;

addition of cure activators and accelerators;

10. The process of preparation of cured elastomeric nanocomposite as claimed in claim 9, wherein the elastomeric compound comprises of silane coupled solution styrene butadiene rubber (SSBR) and Butadiene Rubber in a weight ratio of 70:30.

11. The process of preparation of cured elastomeric nanocomposite as claimed in claim 9, wherein said cure activators comprises Zinc oxide and Stearic acid.

12. The process of preparation of cured elastomeric nanocomposite as claimed in claim 9, wherein said vulcanization agent is selected from sulfur.

13. The process of preparation of cured elastomeric nanocomposite as claimed in claim 9, wherein said accelerators comprises N-cyclohexyl-2-benzothiazole sulfonamide and diphenyl guanidine.

14. The process of preparation of cured elastomeric nanocomposite as claimed in claim 9, wherein said anti-degradants comprises 6PPD [N-( 1,3-dimethyl butyl)-N’-phenyl-p-phenylene diamine],

TMQ [2, 2, 4-Trimethyl- 1,2-Dihydro quinoline] and Microcrystalline wax (MC-Wax).