DESC:FIELD OF INVENTION
The present invention relates to microwave energy assisted coupling of precipitated silica with poly-co-styrene-butadiene rubber aided by unsymmetrical dihydroxy benzene. More particularly, the present invention provides harnessing clean, rapid heating initiated internally through microwave energy induced dipole-dipole molecular/ functional group in the rubber macromolecule. Particularly the invention relates to the microwave energy assisted coupling of precipitated silica with poly-co-styrene-butadiene rubber aided by unsymmetrical dihydroxy benzene. More particularly, the present invention, relates to a method of preparation of microwave energy assisted coupling of precipitated silica with poly-co-styrene-butadiene rubber composition and a tyre product from the composition.

BACKGROUND OF INVENTION
There has been a constant search for alternatives to the current practice of using silane coupling agents in promoting rubber- silica interactions. The reasons are manifold including cost, undesirable reaction during mixing and evolution of noxious ethanol. Microwave energy field is an upcoming technique in terms of its clean system, homogeneous internal heating through dipole- dipole collision and above all, the reactions are fast. Poly co styrene- butadiene rubber of solution grade is the most sought-after rubber because of the feasibility of tailoring the end properties. Hydrated or precipitated silica known for high structure and large surface area is considered as potential reinforcing filler for rubber. However, owing to its hydrophilic surface the interaction with rubber is much limited. The silane coupling agents are used to overcome the limitation and promote rubber- filler interaction to a greater extent.

US2016369015A1 relates to backbone-modified elastomeric polymer compositions comprising such modified polymers, to the use of such compositions in the preparation of vulcanized polymer compositions, and to articles prepared from the same. The invention may be converted into polymer compositions (first stage mixing [representing the mixing step in which the silica filler is added to the modified polymer] and second stage mixing comprising silica filler and modified polymer according to the invention). The samples were prepared by a microwave-assisted reaction.

US20050022914A1 relates to a process of preparation of components and articles of manufacture containing at least one of such components, such as tires, and the resulting prepared components and fabricated articles, by use of directed high frequency energy internally heated silica-rich rubber compositions which contain sulfur curative and a significant content of high softening point polymer, namely a polymer and/or elastomer.
US20130284340A1 relates to a rubber tire with the use of microwave frequencies and the use of conductive materials in a pre-molded rubber using one or more layers of rubber formulations and determining the frequency parameters, vulcanization temperature and cure time by the type and quality of the elastomeric raw material.

US20100243150A1 relates to a method of bonding silicone rubber parts characterized by placing an adhesive-agent layer formed from a hydrosilylation-curable silicone rubber composition, which contains 2 to 50 mass % calcium carbonate powder, between the silicone rubber parts and then irradiating the adhesive-agent layer with high-frequency or microwave radiation.

Seghar et al, 2015, article entitled “Devulcanization of styrene butadiene rubber by microwave energy: Effect of the presence of ionic liquid” [eXPRESS Polymer Letters Vol.9, No.12, 1076-1086, 25 April 2015], talks about the styrene butadiene rubber (SBR) devulcanized using microwave irradiation. In particular, effect of ionic liquid (IL), pyrrolidinium hydrogen sulfate [Pyrr][HSO4], on the devulcanization performance was studied.

The present invention aims at providing microwave energy assisted coupling of precipitated silica with poly co styrene- butadiene rubber aided by unsymmetrical dihydroxy benzene.

OBJECTS OF THE INVENTION:
Principal object of the present invention is to provide microwave energy assisted coupling of precipitated silica with poly co styrene- butadiene rubber aided by unsymmetrical dihydroxy benzene.

Another object of the present invention is to provide a clean, energy efficient reaction mechanism with effective control over temperature to prevent hot spots and thermal overruns.

Yet another object of the present invention is to use simple, familiar, easily available organic molecule as reagent.

Still another object of the present invention is to provide considerable saving of energy of mixing as a result of reduction in stock viscosity.

Yet another object of the present invention is to harness clean, rapid heating initiated internally through microwave energy induced dipole- dipole molecular/ functional group in the rubber macromolecule.

SUMMARY OF THE INVENTION
Thus, according to the present invention, there is provided a microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition, comprising of: poly-co-styrene-butadiene rubber- 100 Phr
precipitated silica -30-60 phr;
coupling agent - 2 - 5 Phr;
catalyst-1 - 2 Phr;
surfactant - 2 - 3 Phr;
cure activator - 2.0-3 Phr;
process aid -2 - 3 Phr;
curative - 1.5-3 Phr;
primary accelerator -1.5-2.5 Phr; and
secondary accelerator - 0.5-1.5 Phr,
wherein the coupling agent comprises functionalization reagents consisting unsymmetrical dihydroxy benzene dispersed in base polymer, in the catalyst Tin (II) chloride dispersed in base polymer, and
wherein the functionalization agents are irradiated by microwave, act as electrophiles and bridge the Si-OH of the silica filler providing coupling of Silica with rubber.

It is another aspect of the present invention to provide a microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition, wherein the said poly-co-styrene-butadiene rubber is selected from Solution Styrene Butadiene Rubber (SSBR).

It is another aspect of the present invention to provide a microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition, wherein the mother stock base polymer is Ethylene Propylene Diene Monomer (EPDM).

It is another aspect of the present invention to provide a microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition, wherein the functionalization is preferably selected from 1,3- dihydroxy benzene and 1,4- dihydroxy benzene.

It is another aspect of the present invention to provide a microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition, wherein the weight ratio of functionalized reagents to the base polymer is 30: 70parts in the mother stock and the weight ratio of mother stock base polymer to the catalyst is 70: 30.

It is another aspect of the present invention to provide a microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition, wherein the surfactant is Triethanol Amine (TEA).

It is another aspect of the present invention to provide a microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition, wherein the cure activators are zinc oxide.

It is another aspect of the present invention to provide a microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition, wherein the process aid is stearic acid.

It is another aspect of the present invention to provide a microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition, wherein the curative is sulphur.

It is another aspect of the present invention to provide a microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition, wherein the primary accelerator is N-cyclohexyl-2-benzothiazole sulphenamide (CBS) or N-Tertiarybutyl-2-benzothiazole sulphenamide (TBBS).

It is another aspect of the present invention to provide a microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition, wherein the secondary accelerator is DPG.

It is an additional object of the present invention to provide a process of microwave assisted coupling of precipitated silica with Poly-co-styrene-butadiene rubber, comprising of steps:
Preparation of mother stock comprising of dispersion of the functionalization agents to base polymer in a weight ratio of 30:70 by weight in a two roll rubber mill:
initial mastication of base polymer;
addition of functionalization reagents;
preparation of master batch by:
mastication of selected poly-co-styrene-butadiene rubber at temperature range of 45°C to 50°C;
addition of 50 % of filler comprising precipitated silica and mother stock of functionalization reagents and mixing at a temperature rangeof 80°C to 85°C;
addition of remaining 50% of filler comprising precipitated silica and mixing at a temperature range of 105°C to115°C;
sweeping down in the orifice at a temperature range of 140°C to 145°C; and
dumping at a temperature range of 150°C to 155°C,
wherein the master batch rubber compound containing functionalization reagents is cut into small pieces and subjected to uniform volumetric heating,
wherein the microwave irradiation comprises subjecting the rubber compound with functionalization reagents to a frequency of 900MHz and energy of the single photon that is being absorbed by the material which is being exposed to microwave irradiation is 6.02×10-25 J,
wherein the exposure time for microwave irradiation is divided into ten intervals spanning over five minutes total exposure time, with equal,
preparation of final batch by:
sheeting out the master batch rubber samples exposed to microwave irradiation, milling in two-roll mill to form sheet;
addition of cure package in the order comprising;
mixing of cure activators followed by process aid for a duration of 2 to 3 min, mixing of curative for 2 to 3 min, mixing of secondary accelerator, surfactant, primary accelerator for minutes;
sheeting out the final batch rubber compound for 1 to 3 min to yield final batch of rubber sheet; and
conditioning of final batch of rubber compound at a temperature of 25°C to 27°C for 48 hrs.

DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to microwave energy assisted coupling of precipitated silica with poly-co-styrene- butadiene rubber aided by unsymmetrical dihydroxy silica mixing with the silane coupling agent formulations is unique and unconventional. In microwave energy field gainfully, plain reagents like dihydroxy benzenes are reacted so that they form effective bridge between the rubber and silica. As the reaction may pass through expulsion of nascent water molecule, tin (II) chloride is used as a catalyst. The invention relates to increasing the interaction of Silica with Rubber in tyre industry. Particularly Silica being hydrophilic, it is a challenge to get good bonding with rubber. Poly co styrene- butadiene rubber of solution grade is the most sought after rubber because of the feasibility of tailoring the end properties. Hydrated or precipitated silica known for high structure and large surface area is considered as potential reinforcing filler for rubber. However, owing to its hydrophilic surface the interaction with rubber is much limited. The silane coupling agents per se are used to overcome the limitation and promote rubber- filler interaction to a greater extent. The present invention provides functionalization agents that consists of the reactive sites to attach silanol groups of precipitated silica and the aromatic group of the rubber. They are incorporated to improve or enhance the bonding between the reinforcing filler and the rubber. The functionalization agents as per embodiments of the present invention are Reagent 1, 2 and 3.

An embodiment of the present invention relates to microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition, comprising of: poly-co-styrene-butadiene rubber- 100 Phr, precipitated silica -30-60 phr;coupling agent - 2 - 5 Phr;catalyst-1 - 2 Phr, surfactant - 2 - 3 Phr, cure activator - 2.0-3 Phr, process aid -2 - 3 Phr, curative - 1.5-3 Phr, primary accelerator -1.5-2.5 Phr, and secondary accelerator - 0.5-1.5 Phr, wherein the coupling agent comprises functionalization reagents consisting unsymmetrical dihydroxy benzene dispersed in base polymer, in the catalyst Tin (II) chloride dispersed in base polymer, and wherein the functionalization agents are irradiated by microwave, act as electrophiles with free reactive sites and bridge the Si-OH of the silica filler providing coupling of Silica with rubber resulting of homogeneously dispersed silica bound SBR, and the entire mass is defined as soft rubber, powdery silica and low melting flaky molecule.

Formulation design:
The formulation was designed for the typical rubber mixture. As silica is being acidic in nature due to the presence of OH (Silanol groups) in its surface, it can retard the cure by absorbing the accelerator such as CBS (N-Cyclohexyl-2-benzothiazole sulfenamide) on its surface. Silica proposed here, owing to its method of manufacture is of very high fineness (surface area) and bears adsorbed water molecules. To reduce the absorption, TEA (Triethanol Amine) was used to bound the silanol surface groups such as -OH on the surface of silica since it has ethanol group containing -OH. It is also used to activate the curing process due to the presence of -NH2 (Amine) groups in its structure.

Triethanol Amine serves the purpose of both as a surface binding agent and cure activator in this mixture.

Selection of functionalization reagents:
The reagents were selected such that it consists of the reactive sites to attack silanol groups of precipitated silica and the aromatic group of the rubber. Reagent 1 and reagent 2 consists of the two hydroxyl groups attached to di-substituted aromatic structure and reagent 3 consists of group IV metal halide.
Reagent 1 is 1, 3 Dihydroxybenzene. Reagent 2 is 1,4 Dihydroxybenzene.
Reagent 3 is Stannous Chloride.
The reagent 1&2 (as per Table 1) acts as a coupling agent for the silica with the rubber due the presence of -OH (Hydroxyl) groups substituted on the conjugated aromatic ring. The reagent 3 acts as a catalyst for the reaction. The weight ratio of functionalized reagents to the base polymer is 30: 70 parts in the mother stock and the weight ratio of mother stock base polymer to the catalyst is 70: 30. Details of the mother stock are given below.

The particular reagents with dihydroxy group/functionality present in 1, 4-dihydroxybenzene acts as a targeting molecule in the coupling agents. As soon as the reagents is cleaved during microwave irradiation, it starves for electrons or it is an electron accepting or electrophile. In this way this becomes the target molecule for bridging the Si-OH present in the silica filler, which is an electron donor or nucleophile. The mechanism of the cleavage is the molecular excitation caused by the deep penetration of the microwave generated in the microwave oven which is explained below. Microwave energy induced dipole- dipole molecular/ functional group in the rubber macromolecule. Plain reagents like dihydroxy benzenes are reacted so that they form effective bridge between the rubber and silica. As the reaction may pass through expulsion of nascent water molecule, tin (II) chloride is used as a catalyst. In SBR, the five residual active sites (sparing one site for CH= CH2 which involves in polymerization and chain growth) of the benzene ring containing 6 carbon atoms in a cycle with pi electron cloud) is expected to support electrophilic reaction (electrophile like H3O+ which may be donated by a third molecule like dihydroxy phenol or from silica). The presence of the third molecule is very likely to cause the reaction under simple reaction condition.

In an embodiment of the present invention the irradiation is done by domestic oven.
The microwave frequency and the energy of the microwave irradiation was calculated as given below:
• Frequency of the microwave= 900*106 Hz.
• Wavelength= Speed of the light/Frequency=2.998*108 ms-1/900*106s-1 = 0.33m? = 0.33 metres. The energy of single microwave photon was calculated by E=h? = h(Planck’s constant)= h*(C/?) h= 6.626 *10-34 JS
• Frequency of the photon = 900*106 S-1
• E= (6.626* 10-34 JS) * *[(900*106S-1)/0.33m)
• E= 6.02*10-25 J.

This is the energy of the single photon that is being absorbed by the material which is being exposed to microwave irradiation.

Table 1: Properties of the reagents:
Properties 1,3 Dihydroxybenzene 1,4 Dihydroxybenzene Stanneous Chloride (SnCl2)
Density (g/cm3) 1.28 1.3 3.95
Molecular Weight (g/mol) 110.11 110.1 189.6
PKa (Disassociation Constant) 9.2,10.9 9.9, 11.6 -7, -1
Dipole Moment (Debye, D) 2.071 0 0
Boiling Point (°C) at 101.3 Kpa 277 287 623

The reagents which were used for rubber silica coupling were dispersed in EPDM Rubber in the 70:30 (70 parts of EPDM rubber and 30 parts of functionalization reagent) ratios. Mother stock preparation is a convenient method that envisages pre-dispersing active chemicals in an inert rubber medium. The fraction of mother stock containing the exact, correct proportion of the active chemical is made as part of formulation. The mother-stock is basically used to enable facile dispersion.

Thus the mother stocks consisting of respective reagents were made. The weight equivalent of the rubber & reagent according to the given dosage of the reagent in the formulation was mixed along with the rubber silica mixture during mixing. The master batch is prepared using banbury mixer (please refer Table 3) to ensure filler dispersion to the optimal level and the final batch (consisting of the curatives) is prepared using two roll-mill (please refer Table 4). The formulation which consists of the dosage of the several ingredients used is given below in Table-2.

Table 2: Formulation:
Compound Nos
Chemical ingredients 1 2 3 4 5 6 7 8 9 10 11
SSBR 100 100 100 100 100 100 100 100 100 100 100
Precipitated silica 40 40 40 40 40 40 40 40 40 40 40
Si-69 0 4 0 0 0 0 0 0 0 0 0
Motherstock of 1,3 Dihydroxy benzene * 0 0 4 2 4 2 4 2 4 2 3
Motherstock of 1,4 Dihyroxy benzene * 0 0 4 2 4 4 2 4 2 2 3
Motherstock of stanneous chloride* 0 0 5 3 3 3 5 5 3 5 4
DPG 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5
TEA 2 2 2 2 2 2 2 2 2 2 2
CBS 2 2 2 2 2 2 2 2 2 2 2
Sulphur 3 3 3 3 3 3 3 3 3 3 3
Zinc Oxide 3 3 3 3 3 3 3 3 3 3 3
Stearic acid 2 2 2 2 2 2 2 2 2 2 2
Note: All quantities are in parts per hundred rubber (PHR).

*The quantities represented in PHR are the contents of the active reagents excluding the base polymer (EPDM) in which the reagents are dispersed.

Preparation of mother stock:
EPDM rubber (Ethylene Propylene Diene Monomer) is taken and it is masticated in the two-roll rubber mill. After the initial mastication, reagents are added, respectively. The weight of the reagent to be added in the formulation is selected as per the ratio of reagent to the EPDM rubber.

The compound number 1 and 2 in Table 2 was kept as a reference due to the absence of the functionalization reagent in these compounds.

The fill factor was selected to be 0.7 (70% of the total volume of the chamber). The ingredients are weighed to match the fill factor of the banbury, and sequence of mixing is given below.

Preparation of Master Batch and Final Batch
Preparation of master batch is done by mastication of selected poly-co-styrene-butadiene rubber at temperature range of 45°C to 50°C, addition of 50 % of filler comprising precipitated silica and mother stock of functionalization reagents and mixing at a temperature range of 80°C to 85°C, addition of remaining 50% of filler comprising precipitated silica and mixing at a temperature range of 105°C to115°C, sweeping down in the orifice at a temperature range of 140°C to 145°C; and dumping at a temperature range of 150°C to 155°C, wherein the master batch rubber compound containing functionalization reagents is cut into small pieces and subjected to uniform volumetric heating, wherein the microwave irradiation comprises. The mixing procedure for preparation of master batch using a Banbury mixer is represented in Table 3.

After the master-batch is made (consisting of the functionalization reagents), the rubber compound (rubber sheet) is cut into small pieces of (2×2 cm2) to treat the rubber compound by microwave irradiation. The cut pieces are weighed to 50% of the container volume (1 liter) to expose the rubber mixture uniformly to the field of microwave irradiation. The rubber mix in the container is set in the microwave exposure region of the microwave domestic oven. The exposure time is divided into 10 intervals spanning over 5 min total exposure time.

Subjecting the rubber compound with functionalization reagents to a frequency of 900MHz and energy of the single photon that is being absorbed by the material which is being exposed to microwave irradiation is 6.02×10-25 J, wherein the exposure time for microwave irradiation is divided into ten intervals spanning over five minutes total exposure time, with equal preparation of final batch by:
sheeting out the master batch rubber samples exposed to microwave irradiation, milling in two-roll mill to form sheet;
addition of cure package in the order comprising;
mixing of cure activators followed by process aid for a duration of 2 to 3 min, mixing of curative for 2 to 3 min, mixing of secondary accelerator, surfactant, primary accelerator for minutes ; and
sheeting out the final batch rubber compound for 1 to 3 min to yield final batch of rubber sheet
conditioning of final batch of rubber compound at a temperature of 25°C to 27°C for 48 hrs to yield the rubber composition.

Table 3: Mixing Procedure for the preparation of master batch (Banbury Mixer)

Sl No Process Time (seconds) Temperature (°C)
1 Rubber Mastication 30 45
2 50% Filler Addition+ Functionalization Reagents 90 85
3 50% Filler Addition 90 110
4 Sweep 120 145
5 Dump 155
Total Mixing Time 300

After the samples are exposed to microwave irradiation, the cut pieces are milled in the two-roll mill to form a sheet. The sheet is then added with the cure package as per the formulation in the two-roll mill. The two-roll mill mixing sequence for making the final batch is given as follows in Table 4.

Table 4: Mixing Procedure for the preparation of final batch (Two-roll mill)
Materials
Process Time (minutes)
Master batch Master batch compound
Zinc oxide Cure Activator 3
Stearic acid Process aid
Sulphur Curative 3
DPG Secondary accelerator 8
TEA Surfactant
CBS Primary accelerator
Sheet out 1
Total time 15

After the final batches were made the rubber sheet was conditioned in laboratory conditions at 25°C for 48 hrs. The properties of the compound were reported in Table 5.

Table 5: Test results of compounds

Compound No Tensile Strength (MPa) Abrasion Volume Loss (in cubic mm) Mooney Viscosity (ML (1+4) @ 100 °C Hardness (Shore A) Dispersion (Out of scale 10) Green Strength (MPa)
1 6.7 189 108 70 7.9 0.17
2 10.1 167 99 71 7.2 0.37
3 4.9 182 56 58 10 0.25
4 11.0 136 71 63 6.5 0.45
5 4.5 208 57 60 8.5 0.31
6 7.9 154 66 60 6.3 0.44
7 6.6 157 59 58 7.3 0.27
8 8.6 149 60 58 10 0.27
9 6.1 187 63 60 10 0.29
10 9.5 140 59 60 10 0.27
11 8.5 162 61 61 8.6 0.31
An embodiment of the present invention discloses a tyre made up of the said composition using microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition

Results:
From the above values, it can be known that the compound no: 4 (as per formulation) performs better than compound no: 2 (compound which consists of silane) in physical properties such as tensile strength, abrasion. Also, a significant reduction in the Mooney viscosity is observed compared to the compound which consists of a silane coupling agent. This indicates that the reagent added to the mixture prevents agglomeration by the effective coupling of silica molecules to its active ends.

The product that is resulted is homogeneously dispersed silica bound SBR, which is very essential for production. The invention targets the application of simple laboratory chemical in promoting the interaction between a synthetic rubber and hydrated silica. This rubber and particulate filler combination has great impact towards the technology of materials that are used in pneumatic tyres immensely. ,CLAIMS:WE CLAIM:
1. A microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition, comprising of:
poly-co-styrene-butadiene rubber- 100 Phr;
precipitated silica -30-60 phr;
coupling agent - 2 - 5 Phr;
catalyst-1 - 2 Phr;
surfactant - 2 - 3 Phr;
cure activator - 2.0-3 Phr;
process aid -2 - 3 Phr;
curative - 1.5-3 Phr;
primary accelerator -1.5-2.5 Phr; and
secondary accelerator - 0.5-1.5 Phr,
wherein the coupling agent comprises functionalization reagents consisting unsymmetrical dihydroxy benzene dispersed in base polymer, in the catalyst Tin (II) chloride dispersed in base polymer, and
wherein the functionalization agents are irradiated by microwave, act as electrophiles and bridge the Si-OH of the silica filler providing coupling of Silica with rubber.

2. The microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition as claimed in claim 1, wherein the said poly-co-styrene-butadiene rubber is selected from Solution Styrene Butadiene Rubber (SSBR).

3. The microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition as claimed in claim 1, wherein the mother stock base polymer is Ethylene Propylene Diene Monomer (EPDM).

4. The microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition as claimed in claim 1, wherein the functionalization is preferably selected from 1, 3- dihydroxy benzene and 1,4- dihydroxy benzene.

5. The microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition as claimed in claim 1, wherein the weight ratio of functionalized reagents to the base polymer is 30 : 70 parts in the mother stock and the weight ratio of mother stock base polymer to the catalyst is 70 : 30.

6. The microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition as claimed in claim 1, wherein the surfactant is Triethanol Amine (TEA).

7. The microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition as claimed in claim 1, wherein the cure activators is zinc oxide.

8. The rubber composition for tyres as claimed in claim 1, wherein the process aid is stearic acid.

9. The microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition as claimed in claim 1, wherein the curative is sulphur.

10. The microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition as claimed in claim 1, wherein the primary accelerator is N-cyclohexyl-2-benzothiazole sulphenamide (CBS) or N-Tertiarybutyl-2-benzothiazole sulphenamide (TBBS).

11. The microwave assisted precipitated silica coupled poly-co-styrene-butadiene rubber composition as claimed in claim 1, wherein the secondary accelerator is DPG.

12. A process of microwave assisted coupling of precipitated silica with Poly-co-styrene-butadiene rubber, comprising of steps:
Preparation of mother stock comprising of dispersion of the functionalization agents to base polymer in a weight ratio of 30:70 by weight in a two roll rubber mill:
initial mastication of base polymer;
addition of functionalization reagents;
preparation of master batch by:
mastication of selected poly-co-styrene-butadiene rubber at temperature range of 45°C to 50°C;
addition of 50 % of filler comprising precipitated silica and mother stock of functionalization reagents and mixing at a temperature rangeof 80°C to 85°C;
addition of remaining 50% of filler comprising precipitated silica and mixing at a temperature range of 105°C to115°C;
sweeping down in the orifice at a temperature range of 140°C to 145°C; and
dumping at a temperature range of 150°C to 155°C;
wherein the master batch rubber compound containing functionalization reagents is cut into small pieces and subjected to uniform volumetric heating,
wherein the microwave irradiation comprises subjecting the rubber compound with functionalization reagents to a frequency of 900MHz and energy of the single photon that is being absorbed by the material which is being exposed to microwave irradiation is 6.02×10-25 J,
wherein the exposure time for microwave irradiation is divided into ten intervals spanning over five minutes total exposure time, with equal,
preparation of final batch by:
sheeting out the master batch rubber samples exposed to microwave irradiation, milling in two-roll mill to form sheet;
addition of cure package in the order comprising;
mixing of cure activators followed by process aid for a duration of 2 to 3 min, mixing of curative for 2 to 3 min, mixing of secondary accelerator, surfactant, primary accelerator for minutes;
sheeting out the final batch rubber compound for 1 to 3 min to yield final batch of rubber sheet; and
conditioning of final batch of rubber compound at a temperature of 25°C to 27°C for 48 hrs.