FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION (See section 10, rule 13)
1. Title of the invention: AN ELASTOMERIC MASTERBATCH, PREPARATION AND
IMPLEMENTATIONS THEREOF
2. Applicant(s)
NAME NATIONALITY ADDRESS
CEAT LIMITED Indian RPG HOUSE, 463, Dr. Annie Besant Road, Worli, Mumbai Maharashtra 400030, India
3. Preamble to the description
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it
is to be performed.

FIELD OF INVENTION
[0001] The present disclosure broadly relates to the elastomer and particularly, refers to an elastomeric masterbatch and a process for preparing the same. Additionally, the present disclosure relates to a rubber compound comprising the elastomeric masterbatch.
BACKGROUND OF INVENTION
[0002] Rubbers/elastomers have been increasingly used in almost all fields of applications. The rubber compounds are extensively studied, and it has been well established that rubbers/elastomers require incorporation of reinforcement fillers to enhance various properties for different applications. The reinforcing fillers enhance the mechanical and dynamic properties of rubber and common reinforcing fillers includes silica, carbon black, clays, calcium carbonate and so on. Of these silica and carbon black are the most prominently used reinforcing fillers. Silica being commonly used filler has the disadvantage of poor dispersion and weaker filler-polymer interaction. The use of carbon black in rubber compounds such as tyres had led to increase in abrasion resistance and consequently, increase in the service life of the tyre. However, to further aid the improvement in properties, several additives were added to form elastomeric masterbatches. The incorporation of another reinforcement filler such as graphene has sparked interest which not surprisingly, is growing exponentially because of its outstanding properties and immense application possibilities. Hence there has been extensive research to identify substitution for traditional fillers.
[0003] Graphene has emerged as a highly potential material due to its incomparable properties such as superior conductivity, excellent strength and elasticity. Graphene which is a two-dimensional allotrope of carbon can be used as a reinforcing filler in different parts of tyre due to its ability to impart properties such as reduction in heat build-up, and fuel consumption, reduced weight, air permeability and improvement in mechanical strength, thermal and electrical conductivity, hardness, wet grip, impact strength and lateral stiffness.

[0004] The interest in graphene as reinforcing filler provides an unprecedented opportunity to develop promising graphene-elastomeric masterbatches. For instance, CN104151664A discloses a method of preparation of a modified graphene powder-polyethylene composite using a surface treatment agent and ethanol-water solution to modify graphene powder and a dispersing agent to disperse it, followed by mixing it with polymer in a twin-screw extruder, forming a masterbatch. The document also discloses preparing polyethylene composite pipe of graphene modification by mixing the said masterbatch with polyethylene composite pipe material. TWI532793B discloses graphene masterbatch comprising a carrier resin, a conductive carbon black, a nanographene sheet with a surface modifying layer formed by a surface modifying agent and a lubricating dispersant, co-kneaded with plastic polymer.
[0005] Although there are currently available graphene-polymer composites, it is to be noted that the cost of graphene produced using existing technology is very high due to its difficulties in bulk production, complicated preparation, purification and drying processes. As a result, it is economically not feasible to use graphene in tyre compound. Another challenge which arises is the inadequate dispersion of graphene during processing. Dry graphene being very fluffy, is very difficult to disperse.
[0006] Therefore, there is an emerging need for the development of commercial grade graphene or its dispersible functionalized derivatives such as graphene oxide as a new generation tyre reinforcement system.
SUMMARY OF THE INVENTION
[0007] In an aspect of the present disclosure, there is provided an elastomeric
masterbatch comprising: (a) graphite; and (b) an elastomer; wherein the elastomer
is dispersed between exfoliated layers of graphite; and graphite to the elastomer is
in the weight ratio range of 5:80 to 20:95.
[0008] In second aspect of the present disclosure, there is provided a process for
preparation of an elastomeric masterbatch comprising: (a) graphite; and (b) an
elastomer, the process comprising: (i) extruding graphite with an elastomer at a
temperature in the range of 70°C to 140°C with kneading block in the range of 10

to 50% and at a speed in the range of 250 to 750 rpm to obtain the elastomeric masterbatch, wherein graphite to the elastomer is in the weight ratio range of 5:80 to 20:95.
[0009] In third aspect of the present disclosure, there is provided a rubber compound comprising: (a) a rubber in the range of 70 to 100 phr; (b) an elastomeric masterbatch comprising (i) graphite; and (ii) an elastomer, in the range of 1 to 35 phr; (c) at least one carbon black in the range of 40 to 50 phr; (d) a first additive in the range of 0.01 to 15 phr; and (e) a second additive in the range of 0.05 to 8 phr; wherein the rubber compound comprises graphene in the range of 0.2 to 5 phr; the elastomer is dispersed between exfoliated layers of graphite; and graphite to the elastomer is in the weight ratio range of 5:80 to 20:95.
[0010] In fourth aspect of the present disclosure, there is provided a process for preparing the rubber compound, the process comprising: (a) obtaining an elastomeric masterbatch comprising: (i) graphite; and (ii) an elastomer; (b) mixing the elastomeric masterbatch with a rubber, at least one carbon black and a first additive to obtain a first mixture; and (c) adding a second additive to the first mixture to obtain the rubber compound; wherein the elastomer is dispersed between exfoliated layers of graphite; and graphite to the elastomer is in the weight ratio range of 5:80 to 20:95.
[0011] In fifth aspect of the present disclosure, there is provided an article comprising an elastomeric masterbatch comprising: (i) graphite; and (ii) an elastomer; or a rubber compound comprising (a) a rubber in the range of 70 to 100 phr; (b) the elastomeric masterbatch in the range of 1 to 35 phr; (c) at least one carbon black in the range of 40 to 50 phr; (d) a first additive in the range of 0.01 to 15 phr; and (e) a second additive in the range of 0.05 to 8 phr; wherein the rubber compound comprises graphene in the range of 0.2 to 5 phr; the elastomer is dispersed between exfoliated layers of graphite; and graphite to the elastomer is in the weight ratio range of 5:80 to 20:95.
[0012] These and other features, aspects, and advantages of the present subject matter will be better understood with reference to the following description and appended claims. This summary is provided to introduce a selection of concepts in

a simplified form. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
BRIEF DESCRIPTION OF DRAWINGS
[0013] Figure 1 depicts the pareto charts on the effect of different process
parameters in the preparation of elastomeric masterbatch (GRMB) on the (a) tensile
strength, (b) elongation at break, (c) hardness and (d) tear strength of rubber
compounds, in accordance with an implementation of the present disclosure.
[0014] Figure 2 depicts main effect plots of different process parameters during the
preparation of GRMB on the (a) tensile strength, (b) elongation at break, (c)
hardness and (d) tear strength of rubber compounds, in accordance with an
implementation of the present disclosure.
[0015] Figure 3 depicts response optimization using Minitab to achieve the
maximum properties of the rubber compounds, in accordance with an
implementation of the present disclosure.
[0016] Figure 4 depicts X-ray diffraction (XRD) pattern of (a) pristine graphite
(PG) and (b) extracted graphene (EG) from the elastomeric masterbatch, in
accordance with an implementation of the present disclosure.
[0017] Figure 5 depicts Raman spectra of pristine graphite (PG) and extracted
graphene (EG) from the elastomeric masterbatch, in accordance with an
implementation of the present disclosure.
[0018] Figure 6 depicts X-ray photoelectron spectroscopy (XPS) data for pristine
graphite (PG) and extracted graphene (EG) the elastomeric masterbatch, in
accordance with an implementation of the present disclosure.
[0019] Figure 7 depicts XPS spectra of C(1s) for (a) pristine graphite (PG), and (b)
extracted graphene (EG) from the elastomeric masterbatch, in accordance with an
implementation of the present disclosure.
[0020] Figure 8 depicts atomic force microscopic (AFM) images of (a) pristine
graphite (PG) and (b) extracted graphene (EG) from the elastomeric masterbatch,
in accordance with an implementation of the present disclosure.

[0021] Figure 9 depicts thermograms of pristine graphite (PG) and extracted graphene (EG) from the elastomeric masterbatch, in accordance with an implementation of the present disclosure.
[0022] Figure 10 depicts schematic presentation for the formation of GRMB, in accordance with an implementation of the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
[0023] Those skilled in the art will be aware that the present disclosure is subject
to variations and modifications other than those specifically described. It is to be
understood that the present disclosure includes all such variations and
modifications. The disclosure also includes all such steps, features, compositions,
and compounds referred to or indicated in this specification, individually or
collectively, and any and all combinations of any or more of such steps or features.
Definitions
[0024] For convenience, before further description of the present disclosure, certain
terms employed in the specification, and examples are delineated here. These
definitions should be read in the light of the remainder of the disclosure and
understood as by a person of skill in the art. The terms used herein have the
meanings recognized and known to those of skill in the art, however, for
convenience and completeness, particular terms and their meanings are set forth
below.
[0025] The articles “a”, “an” and “the” are used to refer to one or to more than one
(i.e., to at least one) of the grammatical object of the article.
[0026] The terms “comprise” and “comprising” are used in the inclusive, open
sense, meaning that additional elements may be included. It is not intended to be
construed as “consists of only”.
[0027] Throughout this specification, unless the context requires otherwise the
word “comprise”, and variations such as “comprises” and “comprising”, will be
understood to imply the inclusion of a stated element or step or group of element or
steps but not the exclusion of any other element or step or group of element or steps.
[0028] The term “including” is used to mean “including but not limited to”.
“Including” and “including but not limited to” are used interchangeably.

[0029] The term "at least one" is used to mean one or more and thus includes individual components as well as mixtures/combinations.
[0030] The term “an elastomer” used herein refers to an elastic polymer in the form of latex or dispersion or solution. In the present disclosure, the term “an elastomer” includes, but not limited to, natural rubber, butadiene rubber, styrene butadiene rubber or combinations thereof.
[0031] The term “natural rubber” used herein refers to polymeric compound of isoprene monomer, additionally consisting of water and minor impurities. It is obtained as latex from rubber-producing plants. In the present disclosure, the term “natural rubber” refers to RSS4.
[0032] The term “graphite” used herein refers to naturally occurring crystalline form of carbon arranged in a hexagonal structure. In the present disclosure, the term “graphite” includes, but not limited to, virgin graphite, oxidized graphite. [0033] The term “phr” used herein refers to parts per hundred rubber/resin. It is a unit well defined in the field of rubber technology to define the amount of ingredients used. The unit “phr” can also be interchangeably used with the unit “gram” as both denote phr/gram of ingredient per 100 phr/gram of rubber. [0034] The term “rpm” used herein refers to rotations/revolutions per minute. It is a unit well used in the field of rubber technology to define the speed of any rotating part of the machine, in this disclosure especially for co-rotating twin screw extruder (CRTSE).
[0035] The term “peptizer” used herein refers to the substances which break down polymer chains and reduce rubber viscosity during its processing. In the present disclosure, the peptizer includes but not limited to 2,2'-dithiobisbenzanilide (DBD), and pentachlorothiophenol (PCTP).
[0036] The term “activator” used herein refers to the substances that have a strong activation effect of increasing the vulcanization speed in the cross-linking reaction of rubbers. Activators are required to achieve the desired vulcanization and end-user properties. In the present disclosure, the activator includes but not limited to magnesium oxide, zinc oxide, and stearic acid.

[0037] The term “antioxidant” used herein refers to the substances that are used to protect rubber articles against the attack of oxygen. The antioxidants help in protecting the rubber from degradation during processing and in storage. In the present disclosure, the antioxidant includes but not limited to p-phenylene diamine (6PPD), microcrystalline (MC) wax, and 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ).
[0038] The term “processing aid” used herein refers to the substances which helps in rubber processing. The processing aid facilitate handling of rubber for instance reduce stickiness while processing. In the present disclosure, the processing aid includes but not limited to wood rosin, and processing oil.
[0039] The term “crosslinking agent” used herein refers to the substances that are used to form chemical links between molecular chains to form a three-dimensional network of connected molecules. Vulcanization/hardening of rubber using sulphur is an example for crosslinking. In the present disclosure the crosslinking agent includes but not limited to sulphur, peroxide, metal oxide, and resin.
[0040] The term “accelerator” used herein refers to the substances used with a
crosslinking agent to increase the speed of vulcanization of rubber and enhance its
physical properties. In the present disclosure, the accelerator includes but not
limited to N-cyclohexyl-2-benzothiazole sulfenamide (CBS), 2-
mercaptobenzothiazole (MBT), bis(2-benzothiazole) disulfide (MBTS), diphenyl guanidine (DPG), diorthotolyl guanidine (DOTG), tetramethyl thiuram monosulfide (TMTM), tetramethyl thiuram disulfide (TMTD), diethyl dithiocarbamate (ZDEC), and dibutyl-dithiocarbamate (ZDBC).
[0041] The term “retarder” used herein refers to the substances added to rubber compounds to delay premature vulcanization during its processing. Retarders are also be as called a pre-vulcanization inhibitor (PVI). In the present disclosure, the retarder includes but not limited to benzoic acid, salicylic acid, and N-(cyclohexylthio) phthalimide (CTP).
[0042] The term “ML (1+4) @ 100°C” (or Mooney Viscosity at 100°C) used herein refers to conditions maintained while performing viscosity analysis on a sample of rubber or any other compound. It indicates the effect of temperature and time on

the viscosity of rubber compounds. It is measured in terms of torque, required to rotate the disk embedded in the rubber compound under specified conditions. Normally a pre-heat period is given to the elastomer following which the disc starts to rotate. The highest viscosity is recorded initially which later starts to decrease with time and reaches its lowest value. Viscosity measured with a large rotor is twice of that measured with a small rotor. Viscosity is measured in Mooney Units (MU) denoted herein by M. With reference to present disclosure, L refers to Large rotor, 1 refers preheat time in minutes, 4 refers to time in minutes after starting the rotor at which reading is taken, and 100°C refers to the test temperature. [0043] The term “moving die rheometer” or “MDR” used herein refers to rheological properties of rubber measured using a rheometer which is an instrument used to measure the viscoelastic properties of rubber during its curing process. A sample of rubber is placed inside a die cavity of the rheometer and a positive pressure is applied to it at a constant temperature. As the sample gets heated under pressure, its viscosity and torque vary with time which is recorded as ML and MH values. ML (moment lowest) is recorded at room temperature when the sample has minimum viscosity and torque. As further curing occurs, the torque exerted on the rotor increases and attains its maximum value denoted by MH (moment highest). All the measurements in the rheometric curve are recorded in terms of dN*m with varying time. With reference to the present disclosure, ts-30 min and ts-90 min refers to the time at which 30% of MH torque value and 90% of MH torque value has been achieved.
[0044] The term “modulus at 300% elongation” used herein refers to the force required for 300% elongation of a material. It is measured in units of pressure as MPa (mega pascal) or kg/cm2.
[0045] The term “tensile strength” used herein refers to the maximum load a material can withstand before fracture, breaking, tearing, etc. It is measured in the units of pressure as MPa (mega pascal) or kg/cm2.
[0046] The term “elongation at break %” used herein refers to the percentage change in elongation of a material at the instant of break. Elongation at break also referred as fracture strain and is the ratio between changed length and initial length

after breakage of the test specimen i.e. the rubber. It expresses the capability of rubber compound to resist changes of shape without crack formation.
[0047] The term “hardness shore A” used herein refers to the resistance of a material to indentation. It is measured using a device called shore durometer. There are several scales of a durometer out of which the two most common scales are A and D. Scale A is used for measuring the hardness of soft materials, such as polymers, elastomers and rubber.
[0048] The term “angle tear strength” used herein refers to the maximum force required to tear or rupture a specified angle-shaped test specimen. It is measured in the units of pressure as MPa or kg/cm2.
[0049] The term “elastomeric masterbatch” refers to a composition comprising graphite and the elastomer, wherein the elastomer is dispersed between the exfoliated layers of graphite, thereby forming graphene-elastomeric masterbatch. The exfoliated layers of graphite are the graphene and the elastomer is dispersed between these layers of graphene. The elastomeric masterbatch comprises graphene in the ratio range of 5:20 with respect to the elastomer. The term “elastomeric masterbatch” may also be referred as graphene elastomer masterbatch or graphene-rubber masterbatch (GRMB). The elastomeric masterbatch is further used in the preparation of the rubber compound as disclosed in the present disclosure. The terms graphene elastomer masterbatch, graphene rubber masterbatch, elastomeric masterbatch can be used interchangeably.
[0050] The term “graphene” refers to the allotrope of carbon arranged in a hexagonal lattice. In the present disclosure, the rubber compounds comprise the GRMB comprising graphene in the range of 0.2 to 5 phr. The graphene in GRMB may also be in oxide form as graphene oxide.
[0051] The term “kneading block” refers to the kneading elements present in the screw shaft of an extruder, especially the co-rotating twin screw extruder. In the kneading zone the rubber and other ingredients are mixed homogenously while subjecting to melting. In the present disclosure, 10 to 50% kneading elements or zone was used to obtain the elastomeric masterbatch.

[0052] The term “number of passes” refers to the number of times the masterbatch was allowed to pass through the extruder for obtaining the elastomeric masterbatch. The number of passes in the present disclosure is in the range of 1 to 30. The number of passes plays a significant role in obtaining the elastomeric masterbatch for a rubber compound with desired properties.
[0053] The term “barrel temperature” refers to the temperature at which the elastomeric masterbatch was prepared.
[0054] The term “fill factor” refers to volume of the total material with respect to the volume of the preparation chamber. In the present disclosure, the fill factor refers to the total volume of all the components of the rubber compound with respect to the volume of the mixer used in the preparation of the rubber compound. [0055] Ratios, concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a temperature range of 70 ℃ to 140 ℃ should be interpreted to include not only the explicitly recited limits of 70 ℃ to about 140 ℃, but also to include subranges, such as 85℃ to 100 ℃, 113℃, 115 ℃ to 130 ℃ and so forth, as well as individual amounts, including fractional amounts, within the specified ranges, such as 91.4 ℃, 113.13℃, and 125.8 ℃, for example.
[0056] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure, the preferred methods, and materials are now described. All publications mentioned herein are incorporated herein by reference.
[0057] As discussed in the background, the existing processes of preparing graphene-elastomer composites involve use of additional dispersing agents and surface treatment agents to modify and disperse graphene into the elastomer

compound since graphene is very difficult to disperse and thus results in inadequate dispersion during processing. This makes the process cost-intensive. The graphene used in the preparation of these composites also involves high cost method of preparation owing to the difficulties in its bulk production, purification and drying process. This further makes the composites and the process involved economically less feasible for use.
[0058] In view of the aforementioned shortcomings, it can be understood that an efficient and low-cost process of preparing graphene elastomeric masterbatch is required in order to obtain well dispersed graphene in elastomeric masterbatch with improved properties. This is achieved in the present disclosure using graphite and elastomer (rubber) as starting material and subsequently converting it to graphene-rubber master batch using co-rotating twin screw extruder. The present disclosure provides an elastomeric masterbatch and process of preparing said masterbatch which is simple, quick, low-cost and does not involve purification and drying steps. This lowers the manufacturing cost and makes the masterbatch economically feasible for use in different applications like tyre compounds.
[0059] The present disclosure is not to be limited in scope by the specific embodiments described herein, which are intended for the purposes of exemplification only. Functionally-equivalent products, compositions, and methods are clearly within the scope of the disclosure, as described herein. [0060] In an embodiment of the present disclosure, there is provided an elastomeric masterbatch comprising: (a) graphite; and (b) an elastomer; wherein the elastomer is dispersed between exfoliated layers of graphite; and graphite to the elastomer is in the weight ratio range of 5:80 to 20:95.
[0061] In an embodiment of the present disclosure, there is provided an elastomeric masterbatch comprising: (a) graphite; and (b) an elastomer; wherein the elastomer is dispersed between exfoliated layers of graphite; and graphite to the elastomer is in the weight ratio range of 5.5:82 to 18:94.5. In another embodiment of the present disclosure, wherein graphite to the elastomer is in the weight ratio range of 6.5:85 to 15:93.5. In yet another embodiment of the present disclosure, wherein graphite

to the elastomer is in the weight ratio of 6.7:93.3. In one another embodiment of the present disclosure, wherein graphite to the elastomer is in the weight ratio of 15:85. [0062] In an embodiment of the present disclosure, there is provided an elastomeric masterbatch, wherein graphite is virgin graphite or oxidized graphite. In another embodiment of the present disclosure, wherein graphite is virgin graphite. [0063] In an embodiment of the present disclosure, there is provided an elastomeric masterbatch comprising: (a) virgin graphite; and (b) an elastomer; wherein the elastomer is dispersed between exfoliated layers of graphite; and graphite to the elastomer is in the weight ratio range of 5:80 to 20:95.
[0064] In an embodiment of the present disclosure, there is provided an elastomeric masterbatch as disclosed herein, wherein the elastomer is selected from natural rubber, butadiene rubber, styrene butadiene rubber, or combinations thereof. In another embodiment of the present disclosure, wherein the elastomer is natural rubber. In yet another embodiment of the present disclosure, the elastomer is ribbed smoked sheet (RSS).
[0065] In an embodiment of the present disclosure, there is provided an elastomeric masterbatch comprising: (a) graphite; and (b) an elastomer selected from natural rubber, butadiene rubber, styrene butadiene rubber, or combinations thereof; wherein the elastomer is dispersed between exfoliated layers of graphite; and graphite to the elastomer is in the weight ratio range of 5:80 to 20:95.
[0066] In an embodiment of the present disclosure, there is provided an elastomeric masterbatch comprising: (a) a virgin graphite; and (b) an elastomer selected from natural rubber, butadiene rubber, styrene butadiene rubber, or combinations thereof; wherein the elastomer is dispersed between exfoliated layers of graphite; and graphite to the elastomer is in the weight ratio range of 5:80 to 20:95. In another embodiment of the present disclosure, there is provided an elastomeric masterbatch comprising: (a) a virgin graphite; and (b) a natural rubber; wherein the natural rubber is dispersed between exfoliated layers of graphite; and graphite to the natural rubber is in the weight ratio range of 5:80 to 20:95.
[0067] In an embodiment of the present disclosure, there is provided a process for preparation of an elastomeric masterbatch, the process comprising: (a) extruding

graphite with an elastomer at a temperature in the range of 70°C to 140°C with kneading block in the range of 10 to 50% and at a speed in the range of 250 to 750 rpm to obtain the elastomeric masterbatch, wherein graphite to the elastomer is in the weight ratio range of 5:80 to 20:95.
[0068] In an embodiment of the present disclosure, there is provided a process for preparation of an elastomeric masterbatch as disclosed herein, wherein extruding is carried out at a temperature in the range of 75°C to 135°C. In another embodiment of the present disclosure, wherein extruding is carried out at a temperature in the range of 80°C to 120°C. In yet another embodiment of the present disclosure, wherein extruding is carried out at a temperature in the range of 110°C to 115°C. [0069] In an embodiment of the present disclosure, there is provided a process for preparation of an elastomeric masterbatch as disclosed herein, wherein extruding is carried out with kneading block in the range of 15 to 45%. In another embodiment of the present disclosure, wherein extruding is carried out with kneading block in the range of 22 to 42%. In yet another embodiment of the present disclosure, wherein extruding is carried out with kneading block of 40%. In one another embodiment of the present disclosure, wherein extruding is carried out with kneading block of 20%.
[0070] In an embodiment of the present disclosure, there is provided a process for preparation of an elastomeric masterbatch as disclosed herein, wherein extruding is carried out at a speed in the range of 300 to 700 rpm. In another embodiment of the present disclosure, wherein extruding is carried out at a speed in the range of 400 to 600 rpm. In yet another embodiment of the present disclosure, wherein extruding is carried out at a speed in the range of 500 to 600 rpm . In one another embodiment of the present disclosure, wherein extruding is carried out at a speed in the range of 500 rpm to 520 rpm.
[0071] In an embodiment of the present disclosure, there is provided a process for preparation of an elastomeric masterbatch comprising: (a) graphite; and (b) an elastomer; wherein the elastomer is dispersed between exfoliated layers of graphite; the process comprising: (i) extruding graphite with an elastomer at a temperature in the range of 70°C to 140°C with kneading block in the range of 10 to 50% and at a

speed in the range of 250 to 750 rpm to obtain the elastomeric masterbatch, wherein graphite to the elastomer is in the weight ratio range of 5:80 to 20:95.
[0072] In an embodiment of the present disclosure, there is provided a process for preparation of an elastomeric masterbatch as disclosed herein, wherein extruding is carried out with number of passes in the range of 1 to 30. In another embodiment of the present disclosure, wherein extruding is carried out with number of passes in the range of 1 to 20. In yet another embodiment of the present disclosure, wherein extruding is carried out with number of passes in the range of 1 to 10. In one another embodiment of the present disclosure, wherein extruding is carried out with number of passes of 2.
[0073] In an embodiment of the present disclosure, there is provided a process for preparation of an elastomeric masterbatch comprising (i) graphite; and (ii) an elastomer, the process comprising: (a) extruding graphite with an elastomer at a temperature in the range of 70°C to 140°C with kneading block in the range of 10 to 50% at a speed in the range of 250 to 750 rpm and the number of passes in the range of 1 to 30 to obtain the elastomeric masterbatch, wherein graphite to the elastomer is in the weight ratio range of 5:80 to 20:95.
[0074] In an embodiment of the present disclosure, there is provided a rubber compound comprising: (a) a rubber in the range of 70 to 100 phr; (b) an elastomeric masterbatch in the range of 1 to 35 phr; (c) at least one carbon black in the range of 40 to 50 phr; (d) a first additive in the range of 0.01 to 15 phr; and (e) a second additive in the range of 0.05 to 8 phr; and wherein the rubber compound comprises graphene in the range of 0.2 to 5 phr.
[0075] In an embodiment of the present disclosure, there is provided a rubber compound comprising: (a) a rubber in the range of 71 to 100 phr; (b) an elastomeric masterbatch in the range of 1.5 to 34 phr; (c) at least one carbon black in the range of 40 to 50 phr; (d) a first additive in the range of 0.01 to 12 phr; and (e) a second additive in the range of 0.05 to 5 phr; and wherein the rubber compound comprises graphene in the range of 0.25 to 5 phr. In yet another embodiment of the present disclosure, wherein the rubber compound comprises graphene of 1.0 phr. In one

another embodiment of the present disclosure, wherein the rubber compound comprises graphene of 0.5 phr.
[0076] In an embodiment of the present disclosure, there is provided a rubber compound, wherein the rubber is selected from natural rubber, butadiene rubber, styrene butadiene rubber, or combinations thereof. In another embodiment of the present disclosure, wherein the rubber is natural rubber which ribbed smoked sheet (RSS4).
[0077] In an embodiment of the present disclosure, there is provided a rubber compound as disclosed herein, wherein the carbon black is N134.
[0078] In an embodiment of the present disclosure, there is provided a rubber compound as disclosed herein, wherein the first additive is selected from a peptizer, an activator, an antioxidant, a processing aid, or combinations thereof; and the second additive is selected from a crosslinking agent, an accelerator, a retarder, or combinations thereof.
[0079] In an embodiment of the present disclosure, there is provided a rubber
compound, wherein the peptizer is selected from 2,2'-dithiobisbenzanilide (DBD),
pentachlorothiophenol (PCTP), or combinations thereof; the activator is selected
from zinc oxide, stearic acid, magnesium oxide, or combinations thereof; the
antioxidant is selected from N-1,3-dimethylbutyl-N'-phenyl-p-
phenylenediamine (6PPD), MC wax, 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ),
or combinations thereof; the processing aid is selected from wood rosin, processing
oil, or combinations thereof; the crosslinking agent is selected from sulphur,
peroxide, metal oxide, resin or combinations thereof; the accelerator is selected
from N-cyclohexylbenzothiazole-2-sulphenamide (CBS), 2-
mercaptobenzothiazole (MBT), bis(2-benzothiazole) disulfide (MBTS), diphenyl guanidine (DPG), diorthotolyl guanidine (DOTG), tetramethyl thiuram monosulfide (TMTM), tetramethyl thiuram disulfide (TMTD), diethyl dithiocarbamate (ZDEC), dibutyl-dithiocarbamate (ZDBC) or combinations thereof; and the retarder is selected from N-(cyclohexylthio) phthalimide (CTP), benzoic acid, salicylic acid, phthalic anhydride or combinations thereof.

[0080] In an embodiment of the present disclosure, there is provided a rubber
compound, wherein the first additive is selected 2,2'-dithiobisbenzanilide (DBD),
pentachlorothiophenol (PCTP), zinc oxide, stearic acid, magnesium oxide, N-1,3-
dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD), MC wax, 2,2,4-trimethyl-
1,2-dihydroquinoline (TMQ), wood rosin, processing oil, or combinations thereof;
and the second additive is selected from sulphur, peroxide, metal oxide, N-
cyclohexylbenzothiazole-2-sulphenamide (CBS), 2-mercaptobenzothiazole
(MBT), bis(2-benzothiazole) disulfide (MBTS), diphenyl guanidine (DPG),
diorthotolyl guanidine (DOTG), tetramethyl thiuram monosulfide (TMTM),
tetramethyl thiuram disulfide (TMTD), diethyl dithiocarbamate (ZDEC), dibutyl-
dithiocarbamate (ZDBC) N-(cyclohexylthio) phthalimide (CTP), benzoic acid,
salicylic acid, phthalic anhydride or combinations thereof.
[0081] In an embodiment of the present disclosure, there is provided a rubber compound, wherein the peptizer is in the range of 0.01 to 0.1 phr; the activator is in the range of 4.0 to 7.0 phr; the antioxidant is in the range of 2.0 to 5.0 phr; the processing aid is in the range of 0.5 to 2.0 phr; the crosslinking agent is in the range of 1.0 to 3.0 phr; the accelerator is in the range of 0.2 to 2.0 phr; and the retarder is in the range of 0.1 to 1.0 phr.
[0082] In an embodiment of the present disclosure, there is provided a rubber compound, wherein the first additive is selected from a peptizer in the range of 0.01 to 0.1 phr; an activator in the range of 4.0 to 7.0 phr; an antioxidant in the range of 2.0 to 5.0 phr; a processing aid in the range of 0.5 to 2.0 phr; or combinations thereof; and the second additive is selected from a crosslinking agent in the range of 1.0 to 3.0 phr; an accelerator in the range of 0.2 to 2.0 phr; a retarder in the range of 0.1 to 1.0 phr; or combinations thereof.
[0083] In an embodiment of the present disclosure, there is provided a rubber compound as disclosed herein, wherein the rubber compound has modulus at 300% elongation in the range of 100 to 170 kg/cm2. In another embodiment of the present disclosure, wherein the rubber compound has modulus at 300% elongation in the range of 105 to 165 kg/cm2. In yet another embodiment of the present disclosure,

wherein the rubber compound has modulus at 300% elongation in the range of 110
to 160 kg/cm2.
[0084] In an embodiment of the present disclosure, there is provided a rubber compound as disclosed herein, wherein the rubber compound has tensile strength in the range of 220 to 320 kg/cm2. In another embodiment of the present disclosure, wherein the rubber compound has tensile strength in the range of 240 to 310 kg/cm2. In yet another embodiment of the present disclosure, wherein the rubber compound has tensile strength in the range of 260 to 310 kg/cm2.
[0085] In an embodiment of the present disclosure, there is provided a rubber compound as disclosed herein, wherein the rubber compound has angle tear strength in the range of 100 to 150 kg/cm2. In another embodiment of the present disclosure, wherein the rubber compound has angle tear strength in the range of 100
to 140 kg/cm2.
[0086] In an embodiment of the present disclosure, there is provided a rubber compound comprising: (a) a rubber in the range of 70 to 100 phr; (b) an elastomeric masterbatch in the range of 1 to 35 phr; (c) at least one carbon black in the range of 40 to 50 phr; (d) a first additive in the range of 0.01 to 15 phr; and (e) a second additive in the range of 0.05 to 8 phr; wherein the rubber compound comprises graphene in the range of 0.2 to 5 phr; the rubber compound has modulus at 300% elongation in the range of 100 to 170 kg/cm2; tensile strength in the range of 220 to 320 kg/cm2; and angle tear strength in the range of 100 to 150 kg/cm2. [0087] In an embodiment of the present disclosure, there is provided a rubber compound as disclosed herein, wherein the rubber compound comprises an elastomeric masterbatch in the range of 1 to 35 phr; and the elastomeric masterbatch comprises 1 to 30 phr of an elastomer with respect to the rubber compound. [0088] In an embodiment of the present disclosure, there is provided a process for preparing the rubber compound, the process comprising: (a) obtaining an elastomeric masterbatch as disclosed herein; (b) mixing the elastomeric masterbatch with a rubber, at least one carbon black and a first additive to obtain a first mixture; and (c) adding a second additive to the first mixture to obtain the rubber compound.

[0089] In an embodiment of the present disclosure, there is provided a process for preparing the rubber compound as disclosed herein, wherein mixing the elastomeric masterbatch with a rubber, at least one carbon black and a first additive is carried out at a temperature in the range of 120 to 160 °C at a speed of 50 to 90 rpm for a time period in the range of 40 to 550 seconds. In another embodiment of the present disclosure, wherein mixing the elastomeric masterbatch with a rubber, at least one carbon black and a first additive is carried out at a temperature in the range of 130 to 155 °C at a speed of 55 to 80 rpm for a time period in the range of 45 to 500 seconds. In yet another embodiment of the present disclosure, wherein mixing the elastomeric masterbatch with a rubber, at least one carbon black and a first additive is carried out at a temperature of 150 °C at a speed of 60 rpm for a time period in the range of 45 to 490 seconds. In one another embodiment of the present disclosure, wherein mixing the elastomeric masterbatch with a rubber is carried out at a speed of 60 rpm for 45 seconds and further mixing one part at least one carbon black and a first additive carried out at a speed of 60 rpm for 60 seconds followed by adding another part of at least one carbon black and a first additive at a speed of 60 rpm for 45 seconds to obtain the first mixture. In further embodiment of the present disclosure, the first mixture is subjected to mixing for a time period of 340 seconds for a temperature of 150°C.
[0090] In an embodiment of the present disclosure, there is provided a process for preparing the rubber compound, the process comprising: (a) obtaining an elastomeric masterbatch comprising (i) graphite and (ii) an elastomer; (b) mixing the elastomeric masterbatch with a rubber, at least one carbon black and a first additive at a temperature in the range of 120 to 160 °C at a speed of 50 to 90 rpm for a time period in the range of 45 to 550 seconds to obtain a first mixture; and (c) adding a second additive to the first mixture to obtain the rubber compound. [0091] In an embodiment of the present disclosure, there is provided a process for preparing the rubber compound as disclosed herein, wherein the first mixture is kept for relaxation for a time period in the range of 6 to 24 hours and further subjected to remixing for a time period of 210 seconds at 70 rpm.

[0092] In an embodiment of the present disclosure, there is provided a process for preparing the rubber compound as disclosed herein, wherein adding a second additive to the first mixture to obtain the rubber compound is carried out at a temperature in the range of 60 to 100 °C for a time period in the range of 50 to 250 seconds. In an embodiment of the present disclosure, wherein adding a second additive to the first mixture to obtain the rubber compound is carried out at a temperature in the range of 70 to 100 °C for a time period in the range of 80 to 220 seconds.
[0093] In an embodiment of the present disclosure, there is provided a process for preparing the rubber compound, the process comprising: (a) obtaining an elastomeric masterbatch as disclosed herein; (b) mixing the elastomeric masterbatch with a rubber, at least one carbon black and a first additive to obtain a first mixture; and (c) adding a second additive to the first mixture at a temperature in the range of 60 to 100 °C for a time period in the range of 50 to 250 seconds to obtain the rubber compound.
[0094] In an embodiment of the present disclosure, there is provided a process for preparing the rubber compound, the process comprising: (a) obtaining an elastomeric masterbatch as disclosed herein; (b) mixing the elastomeric masterbatch with a rubber, at least one carbon black and a first additive at a temperature in the range of 120 to 160 °C at a speed of 50 to 90 rpm for a time period in the range of 45 to 550 seconds to obtain a first mixture; and (c) adding a second additive to the first mixture at a temperature in the range of 60 to 100 °C for a time period in the range of 50 to 250 seconds to obtain the rubber compound. [0095] In an embodiment of the present disclosure, there is provided an article comprising the elastomeric masterbatch or the rubber compound as disclosed herein.
[0096] Although the subject matter has been described in considerable detail with reference to certain examples and implementations thereof, other implementations are possible.

EXAMPLES
[0097] The disclosure will now be illustrated with working examples, which is intended to illustrate the working of disclosure and not intended to take restrictively to imply any limitations on the scope of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice of the disclosed methods and compositions, the exemplary methods, devices and materials are described herein. It is to be understood that this disclosure is not limited to particular methods, and experimental conditions described, as such methods and conditions may apply. [0098] The forthcoming examples explains that how the present disclosure provides a process for preparing an elastomeric masterbatch comprising graphite and an elastomer. The elastomeric masterbatch is henceforth referred to as graphene-rubber masterbatch (GRMB). The present disclosure exemplifies the process for preparing the elastomeric masterbatch i.e., the graphene-rubber masterbatch. The process uses a co-rotating twin screw extruder (CRTSE) for mixing graphite with elastomer/rubber, resulting in graphene-rubber masterbatch. Further, the rubber compound is prepared by mixing carbon black and additives into the prepared masterbatch. The working examples show variation in the measured properties of the prepared rubber compounds upon variation in the different parameters of the extrusion process.
Materials and Methods
[0099] For the purpose of the present disclosure, following raw materials with the
specified grades/brands were used.
a) Ribbed smoked sheet (RSS4) the standard sheet rubber - RPD Cochin India;
b) Graphite from SD Fine Chemicals, India
c) Carbon black grades N134, N- from PCBL, India;
d) Zinc oxide of W.S. Luxmi brand from JG chemicals pvt. Ltd;
e) Stearic acid i.e stearic acid lubstric 995 from Godrej Industries Ltd;
f) 6PPD i.e. Vulkanox 4020 from Lanxess India Pvt Ltd;

g) Wood rosin R2 from Dujodwala resins and terpins;
h) Pilnox TDQ (TMQ) from National Organic Chemical Ind. Ltd;
i) Wax from Raj Petro Specialities Pvt. Ltd
j) Volcosulf 18 (Sulphur) from Solar Chemferts Pvt. Ltd;
k) Accitard RE (CTP) from PMC Rubber Chemicals India P.Ltd
l) CBS from Nocil Ltd., India The elastomeric masterbatch was prepared using co-rotating twin screw extruder, Alpha 25, Steer Engineering Pvt. Ltd., India. For the preparation of the rubber compound Haake Rheomix OS mixer was used. Tensile strength, Elongation at break, angle tear strength was carried out using Toyoseiki strograph AE-CT. The stress vs. strain (tensile and elongation at break) test was performed according to ASTM D412, C type dumbbell specimen was used, distance between grips was 60 mm and stretching speed 500 mm.min-1. For each sample 5 specimen were tested and mean of 5 results were reported. Angle tear strength was measured as per ASTM D624 - 00(2020). Hardness was measured using Durometer, MonTech. The shore A hardness rubber samples were measured according to ASTM-D2240-03.
EXAMPLE 1
Preparation of graphene-rubber master batch (GRMB) by extrusion [0100] In an example, the graphene-rubber master batch (GRMB) was prepared from mixing virgin graphite with RSS4 rubber (elastomer) at high shear speed, in a co-rotating twin-screw extruder. The rubber (elastomer) to graphite weight ratio fed into the extruder was 93.3:6.7. The % kneading zone of the extruder was set at 40%. The barrel temperature was maintained at 100 °C and the extruder screw speed was set at 500 rpm. The number of passes of the rubber-graphite mixture through the extruder was 2. The parameters such as weight ratio, % kneading zone, the barrel temperature, the screw speed and the number of passes were varied in the preparation of the graphene-rubber masterbatch. The various GRMB samples prepared were used for the preparation of the rubber compounds and their properties were measured.
Preparation of rubber compound with GRMB

[0101] The process of preparation of the rubber compound is explained herein. The graphene-rubber masterbatch prepared as explained above was mixed with the natural rubber RSS4, N134 and the first additives in a mixer (Haake Rheomix OS, Thermo Scientific) to obtain a first mixture. The first additive comprised the combination of peptizer, activator, antioxidants and processing aid. Fill factor (FF) of 68% was maintained. To the first mixture, second additives comprising combination of crosslinking agent, accelerator and retarder were added and processed to result in the rubber compound. The standard formulation is shown in Table 1. The obtained GRMB is added to a rubber formulation and the loading of graphene in the final rubber compound was found to be 1 phr. Table 1

Raw Materials Control With GRMB
Natural Rubber (RSS4) 100.00 86.00
Peptizer 0.06 0.06
Carbon black (N134) 44.00 44.00
(activator)Zinc Oxide 3.50 3.50
(activator) Stearic Acid 2.00 2.00
(antioxidant)6PPD 2.00 2.00
(antioxidant) MC Wax 1.00 1.00
(processing aid) Wood Rosin 1.00 1.00
(antioxidant) TMQ 0.70 0.70
GRMB 0.00 15.00
(retarder) CTP 0.25 0.25
(crosslinking agent) Sulphur 2.00 2.00
(accelerator) CBS 0.75 0.75
[0102] In an actual process of preparation of the rubber compound, the rubber and GRMB were incorporated and mixed for 45 seconds at a speed of 60 rpm. Then half of all ingredients (as per Table 1) comprising the N134, peptizer, zinc oxide, stearic acid, 6PPD, TMQ, MC wax and wood rosin were incorporated and mixed again for 60 seconds at a speed of 60 rpm. After that, remaining half of the

ingredients were incorporated and mixed again for 45 seconds at a speed of 60 rpm. The mixing was continued for 340 seconds and the rpm was varied to maintain the temperature at 150 ℃. Then the first mixture was obtained. The first mixture was kept overnight for relaxation and was further subjected to remixing for 210 seconds at 70 rpm. To this first mixture, the second additives comprising the CTP, Sulphur and CBS were incorporated and mixed for 200 seconds at 100 ℃ to obtain the rubber compound. The control refers to the rubber compound without GRMB prepared for the comparative purpose.
WORKING EXAMPLES EXAMPLE 2
Effect of % kneading zone and number of passes in the preparation of GRMB [0103] This example involves the study of effect of varying % of kneading block (zone) and number of passes during the preparation of the graphene-rubber master batch in the extruder. The graphene-rubber master batch (GRMB) was prepared by mixing graphite with elastomer at high shear speed, in a co-rotating twin-screw extruder. The elastomer to graphite weight ratio fed into the extruder was 93.3:6.7. The barrel temperature was maintained at 100 °C and the extruder screw speed was set at 500 rpm. The % of kneading zone and the number of passes of the rubber-graphite mixture through the extruder were varied as follows: (i) kneading zone: 20%, number of passes: 10-30, and (ii) kneading zone: 40%, number of passes: 1-10. The rubber compounds were prepared from the standard formulation in Table 1. The obtained GRMB was added to a rubber formulation so that the loading of graphene in the final compound is 1 phr.
[0104] The prepared rubber compounds were then subjected to determine various properties including modulus at 300% elongation, tensile strength, elongation at break, hardness (Shore A) and angle tear strength. These properties were compared for each variable parameter in (i) and (ii).
[0105] The properties measured for rubber compounds prepared with GRMB produced in extruder using 20% kneading zone with different number of passes (10 to 30) is provided in Table 2. Table 2

PROPERTIES Control GRMB
prepared
by 10
passes GRMB
prepared
by 20
passes GRMB
prepared
by 30
passes
Modulus at 300 % Elongation (kg/cm2) 109.8 122.4 133.8 133.5
Tensile Strength (kg/cm2) 277.0 303.1 307.8 304.6
Elongation at Break (%) 559.4 559.0 541.7 533.3
Hardness (Shore A) 65.3 66.1 66.9 66.5
Angle Tear Strength (kg/cm2) 118.5 121.4 135.1 103.1
[0106] Table 2 shows that among the varying number of passes the GRMB was subjected to, the final rubber compound prepared using GRMB produced by 20 passes exhibited improvement in properties. It was further observed that the properties of the rubber compounds prepared using GRMB produced by 10 passes improved by increasing the number of passes to 20. However, with further increasing number of passes to 30, properties deteriorate, which may be due to the too much breakdown of polymer chains.
[0107] Further, the properties measured for rubber compounds prepared with GRMB produced in extruder using 40% kneading zone with different number of passes (1 to 10) is provided in Table 3. Table 3

GRMB GRMB GRMB GRMB GRMB
PROPERTIES Contro l prepare d by 1 prepare d by 2 prepare d by 3 prepare d by 4 prepare d by 10
pass passes passes passes passes

Modulus at 300
%
Elongation (kg/c
m2) 109.8 116.15 129.37 123.0 120.1 119.0
Tensile Strength (kg/cm2) 277.0 284.9 288.5 284.2 283.2 282.3
Elongation at Break (%) 559.4 546.6 536.5 545.5 539.0 529.7
Hardness (Shore A) 65.3 69.1 69.6 69.6 68.2 67.8
Angle Tear Strength (kg/cm2) 118.5 109.4 131.1 117.0 103.5 100.4
[0108] Table 3 shows that among the varying number of passes the GRMB was subjected to, the final rubber compound prepared using GRMB produced by 2 passes exhibited improvement in properties. It was further observed that the properties of the compounds prepared using GRMB produced by 1 pass improve by increasing the number of passes to 2. However, with further increasing number of passes, properties deteriorate, which may be due to the too much breakdown of polymer chains which is due to excessive shear force. It was also observed that the improvement in properties with GRMB produced in extruder by 20 passes using 20% kneading zone was similar to that of 2 passes using 40% kneading zone. Hence, for further study GRMB was produced in extruder by 2 passes using 40% kneading zone.
EXAMPLE 3
Effect of temperature in the preparation of GRMB
[0109] This example involved study of effect of temperature in the production of
graphene-rubber master batch in extruder. The rubber to graphite weight ratio fed
into the extruder was 93.3:6.7. The % kneading zone of the extruder was set at 40%.
The extruder screw speed was set at 500 rpm. The number of passes of the rubber-

graphite mixture through the extruder was 2. The barrel temperature was varied between 80 °C and 120 °C. Barrel temperature above 120 °C was not preferred to avoid degradation of the elastomer. The rubber compounds were prepared from the standard formulation in Table 1. The obtained GRMB was added to a rubber formulation so that the loading of graphene in the final compound is 1 phr. [0110] The prepared rubber compounds were then subjected to determine various properties including modulus at 300% elongation, tensile strength, elongation at break, hardness (Shore A) and angle tear strength. These properties were compared for each variable temperature. Properties of the final rubber compounds prepared with graphene-rubber master batch (GRMB) produced in extruder at different processing temperature is provided in Table 4. Table 4

PROPERTIES Control GRMB
prepared at
80°C GRMB
prepared at
100°C GRMB
prepared at
120°C
Modulus at 300 % Elongation (kg/cm2) 109.8 121.5 129.4 125.4
Tensile Strength (kg/cm2) 277.0 290.5 288.5 294.0
Elongation at Break (%) 559.4 549.2 536.5 546.5
Hardness (Shore A) 65.3 67.1 69.6 68.4
Angle Tear Strength (kg/cm2) 118.5 99.8 131.1 139.9
[0111] Table 4 shows that the properties of the final rubber compound prepared using GRMB produced both at 100 °C and 120 °C exhibited better properties compared to that of 80 °C. And for further study the preparation of GRMB was carried out at 100 °C to avoid degradation at higher temperatures.
EXAMPLE 4
Effect of screw speed in the preparation of GRMB

[0112] The example involves study of effect of screw speed during the production of graphene-rubber master batch in extruder. The rubber to graphite weight ratio fed into the extruder was 93.3:6.7. The % kneading zone of the extruder was set at 40%. The barrel temperature was maintained at 100 °C and the number of passes of the rubber-graphite mixture through the extruder was 2. The extruder screw speed was varied between 300 and 700 rpm. The rubber compounds were prepared from the standard formulation in Table 1. The obtained GRMB was added to a rubber formulation so that the loading of graphene in the final rubber compound is 1 phr.
[0113] The prepared rubber compounds were then subjected to determine various properties including modulus at 300% elongation, tensile strength, elongation at break, hardness (Shore A) and angle tear strength. These properties were compared for each variable screw speed. Properties of the final compounds prepared with graphene-rubber master batch (GRMB) produced in extruder at different screw speed is provided in Table 5. Table 5

PROPERTIES Control GRMB
prepared at
300 rpm GRMB
prepared at
500 rpm GRMB
prepared at
700 rpm
Modulus at 300 % Elongation (kg/cm2) 109.8 96.8 129.4 121.4
Tensile Strength (kg/cm2) 277.0 219.6 288.5 286.6
Elongation at Break (%) 559.4 532.7 536.5 542.3
Hardness (Shore A) 65.3 68.0 69.6 68.2
Angle Tear Strength (kg/cm2) 118.5 130.0 131.1 104.3
[0114] Table 5 shows that the properties of final rubber compounds were observed better when GRMB was produced at a screw speed of 500 rpm. At lower screw

speed (300 rpm), shear force was not enough to insert elastomer between the graphite layers and at higher screw speed (700 rpm), there might be breakdown of rubber chains due to high shear force leading to the deterioration of properties. Therefore, further study was carried out at a screw speed of 500 rpm in the preparation of the GRMB.
EXAMPLE 5
Effect of weight ratio of rubber to graphite (R/G) in the preparation of GRMB [0115] The example involves study of effect of graphite to rubber ratio during the production of graphene-rubber master batch in extruder. The % kneading zone of the extruder was set at 40%. The barrel temperature was maintained at 100 °C and the extruder screw speed was set at 500 rpm. The number of passes of the rubber-graphite mixture through the extruder was 2. The rubber(elastomer) to graphite (R/G) weight ratio fed into the extruder was varied between 80:20 and 93.3:6.7. The rubber compounds were prepared from the formulation in Table 6. The obtained GRMB is added to a rubber formulation so that the loading of graphene in the final compound is 1 phr. Table 6

Raw Materials/(phr) Control R/G: 93.3/6.7 R/G: 90/10 R/G: 85/15 R/G: 80/20
Natural rubber (RSS4) 100.00 86.00 91.00 94.33 96.00
Peptizer 0.06 0.06 0.06 0.06 0.06
Carbon black (N134) 44.00 44.00 44.00 44.00 44.00
Zinc Oxide 3.50 3.50 3.50 3.50 3.50
Stearic Acid 2.00 2.00 2.00 2.00 2.00
6PPD 2.00 2.00 2.00 2.00 2.00
MC Wax 1.00 1.00 1.00 1.00 1.00
Wood Rosin 1.00 1.00 1.00 1.00 1.00
TMQ 0.70 0.70 0.70 0.70 0.70
GRMB 0.00 15.00 10.00 6.67 5.00

CTP 0.25 0.25 0.25 0.25 0.25
Sulphur 2.00 2.00 2.00 2.00 2.00
CBS 0.75 0.75 0.75 0.75 0.75
[0116] The prepared rubber compounds were then subjected to determine various properties including modulus at 300% elongation, tensile strength, elongation at break, hardness (Shore A) and angle tear strength. These properties were compared for each variable weight ratio. Properties of the final compounds prepared with graphene-rubber master batch (GRMB) produced in extruder having different ratio of rubber to graphite is provided in Table 7. Table 7

PROPERTIES Control GRMB with R/G:
93.3/6.7 GRMB with R/G: 90/10 GRMB with R/G: 85/15 GRMB with R/G: 80/20
Modulus at 300 % Elongation (kg/cm2) 109.8 129.4 140.1 151.6 160.9
Tensile Strength (kg/cm2) 277.0 288.5 291.3 299.1 286.3
Elongation at Break (%) 559.4 536.5 514.5 521.5 481.8
Hardness (Shore A) 65.3 69.6 70.1 71.6 72.2
Angle Tear Strength (kg/cm2) 118.5 131.1 132.8 134.3 104.6
[0117] Table 7 shows that with increasing graphite percentage in GRMB all the properties, except elongation at break, of final rubber compounds were increasing progressively till 15% of graphite loading. Properties of final rubber compounds with 20% graphite loading were deteriorated. Hence the graphite was maintained within the weight percentage range of 5 to 20% for the preparation of GRMB.

[0118] Table 8 depicts the variation in process parameters used in the preparation of GRMB, and the properties of the rubber compounds prepared from the corresponding GRMB. In the examples provided in Table 8, graphene was maintained as 1 phr in the rubber compound. Table 8

Run
Ord
er
1 2 3 4 5 6 7 8 Graph ite %
in GRM
B Barr
el Tem
p (°C) Scre
w spee
d
(rpm
) Tensil
e
Streng
th
(kg/c m2) Elongati
on at
break
(%) Modulus@
300
(kg/cm2) Hardn
ess (Shore
A) Tear
Streng
th
(kg/c m2)

10 100 500 291 514.5 140 70.1 133

10 120 600 298 541.8 138 67.6 121

10 100 600 290 555.9 132 68.5 106

15 100 600 297 559.2 150 70.6 108

10 120 500 294 541.6 130 68.0 140

15 120 500 301 543.5 142 69.9 141

15 100 500 299 521.5 152 71.6 134

15 120 600 302 548.5 150 69.3 122
[0119] Pareto charts were drawn (Figure 1) on the effect of different process
parameters during the preparation of GRMB on the (a) tensile strength, (b)
elongation at break, (c) hardness and (d) tear strength of the rubber compounds. It
can be understood from Figures 1a
and 1b that percentage of graphite in the GRMB i.e., graphene % in the rubber compound is the most significant parameter on the tensile strength and hardness of the rubber compound, whereas screw speed is the most significant process parameter on the elongation strength and tear strength (Figure 1c and d). Barrel temperature influenced all the properties of the rubber compound.
[0120] Main effects plots (Figure 2) of different process parameters during the preparation of GRMB on the (a) tensile strength, (b) elongation at break, (c) hardness and (d) tear strength of final rubber compounds was also drawn to understand the extent and type of effects of input parameters on the properties of

the rubber compounds. Main effect plots revealed that percentage of graphite in GRMB had the most significant positive effect on the tensile strength, and hardness and negligible positive effect on elongation and tear strength. Barrel temperature had strong positive effect on tensile strength, moderate positive effect on elongation and tear strength and strong negative effect on hardness. Screw speed had the strong positive effect on elongation at break, weak positive effect on tensile strength, moderate negative effect on hardness and strong negative effect on tear strength. [0121] Therefore, the optimized process parameters obtained are presented in Table 9 and Figure 3. From optimization, the process parameters were selected as graphite: 15%, barrel temperature: 115oC, screw speed: 520 rpm, number of passes: 2 with 40% kneading zone. Table 9

Graphit e % Barrel
Temp
(°C) Screw speed (rpm) Tear Strengt
h (kg/cm2) Hardne ss Mod@3
00 (kg/cm2) Elongati
on
at break
(%) Tensile
Strengt
h
(kg/cm2
)
15 113.13 515.15 135.3 70.4 146 538.63 300.2
Optimization of dosage of GRMB in rubber compound
[0122] GRMB, was prepared using optimized process conditions as shown in Table 9. GRMB thus produced was added with varied parts (phr) per 100 parts (wt.) of rubber (phr) in TBR (Truck and Bus Radial) tyre tread compound as per formulation shown in Table 10 to optimize the dosage of graphene from GRMB required to achieve the rubber compound with improved properties. Graphene in the rubber compound was varied from 0.2 to 5.0 phr. Properties of the rubber compound is presented in Table 10. With increasing loading of graphene until 0.5 phr all properties were improved. With further increasing in graphene loading all properties were deteriorated. This may be due to the poor dispersion at higher loading of graphene at higher loading. Moreover, during the preparation of GRMB because of shear and heat energy, rubber chains were broken into smaller fragments leading to the softer mass formation. When higher phr of GRMB in the rubber

compound, proportion of fragmented rubber also increased leading to the suppression of properties. From the results it was evidenced that 0.5 phr of graphene was the optimized quantity required to obtain improved properties of the rubber compound. Table 10

Raw Materials/ Dosage of graphene in rubber compound 0.0 phr 0.25 phr 0.5 phr 0.75 phr 1.0 phr 2.0 phr 3.0 phr 5.0 phr
Natural Rubber (RSS4) 100.0 100.0 97.17 100.0 94.33 88.67 83.00 71.67
Peptizer 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06
Carbon black (N134) 44.00 44.00 44.00 44.00 44.00 44.00 44.00 44.00
Zinc Oxide 3.50 3.50 3.50 3.50 3.50 3.50 3.50 3.50
Stearic Acid 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00
6PPD 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00
MC Wax 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
Wood Rosin 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
TMQ 0.70 0.70 0.70 0.70 0.70 0.70 0.70 0.70
GRMB 0.00 1.67 3.33 5.00 6.67 13.33 20.00 33.33
CTP 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25
Sulphur 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00
CBS 0.75 0.75 0.75 0.75 0.75 0.75 0.75 0.75
[0123] Table 11 illustrates the properties of the rubber compounds prepared as in Table 10 with different dosage of graphene. Table 11

Dosage of graphene in rubber compound
PROPERTIES 0.0 phr 0.25 phr
129 291 0.5 phr 0.75 phr 1.0 phr 2.0 phr 3.0 phr 5.0 phr
Modulus at 300 % Elongation (kg/cm2) 110
139 133 129 122 123 130
Tensile Strength (kg/cm2) 277
305 295 292 288 279 269

Elongation at Break (%) 559.4 558 69.5 128 571.9 560.0 557.6 551.4 549.5 526.6
Hardness (Shore A) 65.3
70.1 69.3 68.5 68.0 69.8 70.1
Angle Tear Strength (kg/cm2) 119
135 133 129 105 104 101
[0124] The above examples clearly illustrate that the process of preparation of GRMB depends on various parameters such as weight ratio ranges of graphite/rubber, screw speed, temperature, number of passes and the % kneading zone. The properties of the rubber compound using GRMB also varied with variation in the preparation process of GRMB. Hence, it is essential to maintain all the parameters well within the said ranges and the process of preparation required to be performed as explained above. Any deviation in the process or the parameters outside the disclosed ranges would result in rubber compounds of undesired properties.
EXAMPLE 6
Extraction of graphene from GRMB
[0125] 100 g of GRMB, as prepared using optimized process conditions shown in Table 10, was dissolved in 500 ml of toluene by stirring in a magnetic stirrer at 65°C for 4 hrs. The solution was then centrifuged in Remi-PR24 Research Centrifuge for 15 mins. The liquid was slowly decanted off to a beaker. The process was repeated for two times. The residue was washed thoroughly by toluene twice followed by methanol. It was then dried in an oven at 105°C for 30 mins. The graphene thus separated was characterized with x-ray diffraction (XRD), Raman spectroscopy, x-ray photoelectron spectroscopic analysis (XPS), atomic force microscopic technique (AFM) and thermogravimetric analysis (TGA) to understand the degree of exfoliation of graphite and insertion of rubber chains between the graphite layers.
X-Ray diffraction (XRD) study
[0126] The XRD pattern of pristine graphite (PG) and extracted graphene samples were presented in Figure 4. The d-spacing (D) between the graphitic layers was determined by Debye-Scherrer (powder) method using Bragg’s relation nλ=2D

sinθ, where, n is an integer, X is the wavelength of the X-ray which is 1.54 Å for Cu target, θ is the angle between the incident and reflected rays. All samples displayed a strong peak at 26.5° (2Theta) corresponding to interlaminar distance of 3.36Å, due to 002 plane and a weak peak at 55° corresponding to interlaminar distance of 1.67Å, due to 004 plane. However, extracted graphene (EG) exhibited an additional broad peak between 10-20° (2Theta) corresponding to interlaminar distance of 4.44 - 8.84Å, indicating significant exfoliation of graphitic layers in GRMB.
Raman spectroscopy
[0127] The Raman shift of PG and EG is shown in Figure 5. From Figure 5, it was evidenced that PG exhibited only G band 1580 cm-1, whereas EG exhibited both D-band and G-band peaks at 1350 and 1580 cm-1, respectively. It can be understood that, G band corresponds to purity of graphite and D band corresponds to defects in graphite. The results showed that PG did not have significant defect, whereas EG exhibited defects in structure. The appearance of additional D band in EG might be due to the exfoliation of graphitic layers, oxidation and insertion of rubber chains between graphene layers.
X-Ray photoelectron spectroscopy
[0128] X-ray photoelectron spectroscopy (XPS) study was also performed to investigate the chemical change in graphite during the manufacturing of GRMB. The survey scans of XPS spectra for different PG and EG is shown in Figure 6. The PG showed a very strong peak at a binding energy of 284 eV corresponding to the C(1s) element along with a very weak peak of O(1s) at 532 eV. However, for EG the O(1s) peak intensity was significantly higher than that of PG. This may be due to the oxidation of graphite during GRMB preparation.
[0129] The C(1s) peaks of PG and EG were deconvoluted to quantify different functional groups present in these samples. The deconvolution was carried out in Origin Pro software using a Gaussian function as presented in Figure 7 and the deconvoluted results of different functional groups were shown in Table 12. Binding energy (B.E.) for sp2 and sp3 hybridised carbons are generally observed at 283.8 eV and 284.6 eV, respectively. It is very difficult to separate the peaks mixed with sp2/sp3. The B.E. for C-O and C=O bonds appeared at 285.8 eV and 288.2 eV,

respectively. PG with sp2 hybridized carbon atom exhibited a broad asymmetric peak of C(1s) around 283.9 eV. A small hump was observed at around 284.8 eV due to the presence of some C-C bonds in graphite. Along with this, a shake-up peak was also observed at around 290.1 eV due to π-π* transition (Figure 7a). Deconvolution of C(1s) peak for EG sample (Figure 7b) gave rise to four different peaks. The sharp symmetrical peak at 284.6 eV was due to sp3 hybridized carbon atom formed because of oxidation of graphite. The peaks at 285.8 eV and 288.8 eV were due to the C-O and C=O bonds, respectively. The intensity of peaks for C-O and C=O bonds are stronger in EG than that of PG. Higher amount of oxygen was observed for EG compared to that of PG (Table 12). The results indicated that graphite was getting oxidized during the preparation of GRMB. Table 12

Sample Atomic Atomic % sp2-C sp3-C C-O C=O Unknown
% of O(1s) of C(1s) (%) 283.8 (%) 284.6 (%) 285.8 (%) 288.8 291.4 eV
eV eV eV eV
PG 2.21 97.79 83.54 16.46 - - -
EG 12.06 87.94 - 46.8 30.9 17.6 4.7
Atomic force microscopy
[0130] Atomic Force Microscopy (AFM) was used to investigate the formation of
graphene from pristine graphite. The AFM phase images of PG and EG were shown
in Figure 8a and 8b, respectively.
[0131] From AFM analysis, it was observed that PG showed agglomerated
morphology where several graphitic layers were stacked together. The individual
graphene layers were not identifiable separately. On the other hand, for EG
individual layers were recognizable. The layers were separated forming graphene
nano sheets.
Thermogravimetric analysis (TGA)
[0132] TGA analysis was performed for PG and EG under N2 atmosphere up to 800oC. The weight loss (%) of all the samples was plotted as a function of temperature as shown in Figure 9. There was no weight loss for PG, whereas for

EG, there was approximately 55% weight loss within the temperature range of 200-800oC. This weight loss was due to the degradation of rubbers inserted in the graphene layers during the preparation of GRMB.
[0133] From the above analysis, it was evidenced that graphite was oxidized, and graphitic layers were exfoliated because of the thermal energy applied during manufacturing of GRMB. Shear force provided by co-rotating twin screw extruder helped in further separation of exfoliated graphene layers, scission of rubbers chains and its insertion between graphene layers. A schematic presentation for the formation of GRMB was shown in Figure 10. Therefore it can be clearly understood that the graphene formation from graphite provided the rubber compound an enhanced physical and mechanical properties. The incorporation of graphene into rubber compound from graphite made the process cost effective and also provides improved properties obtained by incorporation of graphene. It is also necessary that the amount of the graphite used in the preparation of GRMB should be within the disclosed ranges, so that the graphene is proportionately present in the rubber compound enabling the improved rubber properties.
Advantages of the present disclosure
[0134] The present disclosure discloses an elastomeric masterbatch comprising graphite and an elastomer, wherein elastomer is dispersed between exfoliated layers of graphite and graphite to the elastomer is in the weight ratio range of 5:80 to 20:95, and a process for preparation of said graphene elastomer masterbatch. The present disclosure also discloses a rubber compound and a process for preparing the rubber compound from said graphene elastomer masterbatch. The process for preparing the elastomeric masterbatch does not involve any additional purification or drying process or use of any dispersing or surface-active agents for improving dispersion of graphene, thereby reducing the cost of manufacture. This allows the application of graphene elastomer masterbatch to be economically feasible in various compounds such as tyres. The elastomeric masterbatch and its process for preparation enhances usefulness of graphene as a reinforcing filler in different rubber compounds. The process of present disclosure provides a low-cost production of graphene incorporated rubber compound by using a cheaper source

i.e. graphite yet resulting in rubber compounds with advantages same as that of direct incorporation of graphene. The present disclosure provides rubber compounds which may improve properties such as reduced heat build-up, air permeability and improved mechanical strength, thermal and electrical conductivity, hardness, wet grip, impact strength, lateral stiffness of the rubber compound, without much increase in the cost of the compound.

I/We Claim:
1. An elastomeric masterbatch comprising:
a) graphite; and
b) an elastomer;
wherein the elastomer is dispersed between exfoliated layers of graphite; and graphite to the elastomer is in the weight ratio range of 5:80 to 20:95.
2. The masterbatch as claimed in claim 1, wherein graphite is virgin graphite or oxidized graphite; and the elastomer is selected from natural rubber, butadiene rubber, styrene butadiene rubber, or combinations thereof.
3. A process for preparation of the elastomeric masterbatch as claimed in claims 1 to 2, the process comprising:
a) extruding graphite with an elastomer at a temperature in the range of 70°C to 140°C with kneading block in the range of 10 to 50% and at a speed in the range of 250 to 750 rpm to obtain the elastomeric masterbatch,
wherein graphite to the elastomer is in the weight ratio range of 5:80 to 20:95.
4. The process as claimed in claim 3, wherein extruding is carried out with number of passes in the range of 1 to 30.
5. A rubber compound comprising:

a) a rubber in the range of 70 to 100 phr;
b) the elastomeric masterbatch as claimed in claims 1 to 2 in the range of 1 to 35 phr;
c) at least one carbon black in the range of 40 to 50 phr;
d) a first additive in the range of 0.01 to 15 phr; and
e) a second additive in the range of 0.05 to 8 phr;
wherein the rubber compound comprises graphene in the range of 0.2 to 5 phr.
6. The rubber compound as claimed in claim 5, wherein the rubber is selected
from natural rubber, butadiene rubber, styrene butadiene rubber, or
combinations thereof; the carbon black is N134; the first additive is selected

from a peptizer, an activator, an antioxidant, a processing aid, or combinations thereof; and the second additive is selected from a crosslinking agent, an accelerator, a retarder, or combinations thereof.
7. The rubber compound as claimed in claim 5, wherein the peptizer is in the range of 0.01 to 0.1 phr selected from 2,2'-Dithiobisbenzanilide (DBD), pentachlorothiophenol (PCTP), or combinations thereof; the activator is in the range of 4.0 to 7.0 phr selected from zinc oxide, stearic acid, magnesium oxide, or combinations thereof; the antioxidant is in the range of 2.0 to 5.0 phr selected from N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD), MC wax, 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), or combinations thereof; the processing aid is in the range of 0.5 to 2.0 phr selected from wood rosin, processing oil, or combinations thereof; the crosslinking agent is in the range of 1.0 to 3.0 phr selected from sulphur, peroxide, metal oxide, resin, or combinations thereof; the accelerator is in the range of 0.2 to 2.0 phr selected from N-cyclohexylbenzothiazole-2-sulphenamide (CBS), 2-mercaptobenzothiazole (MBT), bis(2-benzothiazole) disulfide (MBTS), diphenyl guanidine (DPG), diorthotolyl guanidine (DOTG), tetramethyl thiuram monosulfide (TMTM), tetramethyl thiuram disulfide (TMTD), diethyl dithiocarbamate (ZDEC), dibutyl-dithiocarbamate (ZDBC), or combinations thereof; and the retarder is in the range of 0.1 to 1.0 phr selected from N-(cyclohexylthio) phthalimide (CTP), benzoic acid, salicylic acid, phthalic anhydride, or combinations thereof.
8. The rubber compound as claimed in claim 5, wherein the rubber compound has modulus at 300% elongation in the range of 100 to 170 kg/cm2; tensile strength in the range of 220 to 320 kg/cm2; and angle tear strength in the range of 99 to 150 kg/cm2.
9. A process for preparing the rubber compound as claimed in claim 5, the process comprising:

a) obtaining the elastomeric masterbatch as claimed in claims 1 to 4;
b) mixing the elastomeric masterbatch with the rubber, the at least one carbon black and the first additive to obtain a first mixture; and

c) adding the second additive to the first mixture to obtain the rubber compound.
10. The process as claimed in claim 9, wherein the mixing the elastomeric masterbatch with the rubber, the at least one carbon black and the first additive is carried out at a temperature in the range of 120 to 160 °C at a speed of 50 to 90 rpm for a time period in the range of 45 to 550 seconds.
11. The process as claimed in claim 9, wherein the adding the second additive to the first mixture to obtain the rubber compound is carried out at a temperature in the range of 60 to 100 °C for a time period in the range of 50 to 250 seconds.
12. An article comprising the elastomeric masterbatch as claimed in claim 1 or the rubber compound as claimed in claim 5.