Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
  • C08L9/06—Copolymers with styrene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
  • B60C1/0016—Compositions of the tread
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
  • B60C1/0025—Compositions of the sidewalls
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
  • B60C2001/0066—Compositions of the belt layers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/26—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers modified by chemical after-treatment

Definitions

• the present disclosure relates to a rubber blend composition with improved properties.
• Rubber compositions are used in a variety of applications, including tire components such as tread, sidewall, belts, hoses and the like.
• tire components such as tread, sidewall, belts, hoses and the like.
• the development of various tire components with improved properties such as high abrasion resistance, low heat build-up and cut and chip resistance is continuously in demand.
• the development of a new polymeric material, in order to meet each and every specific requirement in the polymer industry, is not feasible. Instead of envisaging a new polymer to meet the requirement for a new material bestowed with the desired properties, blending of various polymer components to obtain a material with significantly improved properties as compared to their individual counterparts is one of the highly preferred techniques in the rubber industry.
• the blending of polymers/elastomers is a well-known procedure for modifying and improving the properties of the individual polymers.
• the judicious selection of individual polymers, their weight proportions and proper blending procedures help in achieving a polymer blend composition with the desired properties.
• CR chloroprene
• SBR styrene butadiene
• NBR acrylonitrile butadiene rubber
• EPDM ethylene-propylene-diene monomers
• US4,257,934 suggests a composition comprising a blend of EPDM, styrene-butadiene rubber (SBR) and styrene-butadiene resin (SB) that has l greatly improved modulus value by the incorporation of about 1 to 20 parts of a tackifier resin per hundred parts of the blend composition.
• the tackifier resin as disclosed in the aforementioned US patent includes coumarone-indene resin, phenolic modified terpene resin, styrene-acrylic copolymer resin and alpha-methyl styrene resin.
• EP0508169 suggests a tire tread composition that contains a sulfonamide modified EPDM terpolymer.
• the sulfonamide modified EPDM terpolymer imparts improved abrasion resistance, improved ozone resistance and improved hysteresis properties to the tire tread composition.
• EP0282153 recites a molded compositions having good water resistance, impact resistance and heat sag resistance, made from blends of polyamide resins, polyester resins and EPDM rubber modified with maleic anhydride.
• compositions have only specific and limited properties with respect to tire tread applications..
• Cut and Chip resistance in the context of the present disclosure refer to a property of the tire tread composition and provides an idea about relative cut resistance and chipping or tearing of the tread when subjected to off the road surfaces.
• heat build-up in the context of the present disclosure refers to the temperature rise within a rubber blend composition due to hysteresis and low thermal conductivity.
• the heat build-up is used also used to compare the fatigue characteristics and rate of heat generation of different rubber vulcanizates when they are subjected to dynamic compressive strains.
• abrasion resistance in the context of the present disclosure refers to an ability of a rubber blend composition to resist damage that can lead to visible, deep or wide trenches.
• the measurement of abrasion resistance of rubbers is basically a subject to abrasive/frictional wear in actual service.
• tensile strength in the context of the present disclosure refers to the maximum longitudinal stress of a rubber blend composition which can withstand without any fracture or permanent deformation.
• hardness in the context of the present disclosure refers to measure of the indentation resistance of a rubber blend composition based on the depth of penetration of a ball indentor.
• un-vulcanized rubber blend composition in the context of the present disclosure refers to a rubber blend composition without any chemical crosslinking induced by vulcanizates.
• vulcanized rubber blend composition in the context of the present disclosure refers to a rubber blend composition having chemical crosslinking in the presence of vulcanizates.
• ASTM compound in the context of the present disclosure refers to the rubber standards depicted by an instrument in specifying, testing, and assessing the physico-mechanical and chemical properties of diversified materials and the products that are made of rubber and its elastomeric derivatives.
• sidewall compound method in the context of the present disclosure refers that, the sidewall compound is formulated for resistance to weathering, ozone, abrasion, tear, radial and circumferential cracking, excellent flex property and for good fatigue life of a tire.
• the sidewall is an essential component of the tire and hence an indispensable part of the tire industry.
• Another object of the present disclosure is to provide a rubber blend composition for use in the potential applications of pneumatic tires.
• Still another object of the present disclosure is to provide a rubber blend composition with improved properties including, but not limiting to, high abrasion resistance, cut and chip resistance, low heat build-up, fatigue to failure properties, hardness and ageing as compared to the standard blend compositions available in the market.
• Yet another object of the present disclosure is to provide a rubber blend composition with improved self- healing property, thereby repairing itself in the gum state under ambient conditions.
• a rubber blend composition comprising, based on parts per hundred of rubber (phr), 60 to 95 phr of a styrene-butadiene rubber (SBR), 4 to 24 phr of a polybutadiene rubber (BR) and 1 to 16 phr of a modified ethylene-alpha-olefm-diene rubber (modified EPDM); said modified EPDM rubber is a graft copolymer comprising ethylene-alpha-olefm-diene rubber (EPDM) as a polymer backbone having grafted thereon a compound of the following formula (I),
• A is H, SCH 3 , OH, SH, COOCH 3 and B is H or CH 3 .
• the weight ratio of the SBR, BR and modified EPDM rubbers can be 60:38:02.
• the modified EPDM rubber can comprise from 0.002 to 0.025 mole percent of the compound of the formula (I) with respect to the 100 mole % of constituent monomer of the EPDM rubber.
• the EPDM rubber can be a terpolymer of 20 to 75 wt% of ethylene, 80 to 25 wt% of alpha-olefin and 1 to 15 wt% of diene monomers.
• the rubber blend composition in accordance with the present disclosure has a self- healing nature and exhibits a tensile strength in the range of 10 to 22 MPa, as measured in accordance with ASTM-D-412; abrasion resistance in the range of 0.07 to 0.14 g, as measured in accordance with DIN 53516; and fatigue to failure in the range of 100 to 500 kc, measured in accordance with ASTM D4482.
• A is H, SCH 3 , OH, SH, COOCH 3 and B is H or CH 3 ;
• the method step of mixing can be accomplished by using a two-roll mixer at a rotor speed varying between 40 rpm and 60 rpm at a temperature varying between 140 °C and 160 °C and for a time period varying between 2 minutes and 10 minutes.
• the styrene butadiene, polybutadiene rubbers and the modified EPDM rubber can be mixed in amounts, based on parts per hundred of rubber, varying between 60 phr and 95 phr, 4 phr and 24 phr and lphr and 16 phr, respectively.
• the process in accordance with the present disclosure further comprises a method step of adding at least one additive selected from the group consisting of fillers, antioxidants, antiozonants, plasticizers, vulcanizing agents, and processing aids.
• at least one additive selected from the group consisting of fillers, antioxidants, antiozonants, plasticizers, vulcanizing agents, and processing aids.
• FIG. 1 of the accompanying drawings shows a schematic diagram for the process of preparation of a modified ethylene-alpha-olefin-diene rubber (modified EPDM), in accordance with an embodiment of the present disclosure
• FIG. 2 of the accompanying drawings shows a schematic diagram for the process of preparation of a rubber blend composition, in accordance with the present disclosure
• Figure 3 of the accompanying drawings shows a schematic diagram for the process of preparation of a modified EPDM of the present disclosure and a plausible reaction mechanism for an increased cross-linking density in the modified EPDM rubber that leads to improved mechanical and self- healing properties in the rubber blend composition of the present disclosure;
• Figure 4 of the accompanying drawings shows a self-healing characteristic of the rubber blend composition of the present disclosure, as seen through Polarized optical microscope image, wherein Figure 4(a) demonstrates two cracks/cuts which are deliberately made on the rubber blend composition in gum form at room temperature; and Figure 4(b) demonstrates that the cracks/cuts as demonstrated in Figure 4(a) almost heal themselves at around 60 °C without changing the overall morphology of the rubber blend composition.
• the present disclosure provides a rubber blend composition for use in the potential applications of the rubber industry, said rubber blend composition comprising, based on parts per hundred of rubber (phr),
• SBR styrene-butadiene rubber
• poly-butadiene rubber in an amount varying from 4 to 24 phr;
• modified EPDM modified ethylene-alpha-olefin-diene rubber
• modified ethylene-alpha-olefm-diene rubber used in the rubber blend composition of the present disclosure is a graft copolymer comprising ethylene- alpha-olefin-diene rubber (EPDM) as a polymer backbone having grafted thereon a compound of the following formula (I),
• A is H, SCH 3 , OH, SH, COOCH 3
• B is H or CH 3 .
• the compound of the formula (I) is attached to the EPDM backbone through the carbon atom of the carbonyl group containing moiety (refer to formula (II)):
• the inventors of the present disclosure have advantageously optimized the rubber blend composition of the present disclosure in order to achieve the desired end properties in the rubber blend composition.
• the optimized rubber blend composition comprises SBR, BR and the modified EPDM elastomer in the weight ratio of 60:38:02.
• the modified EPDM elastomer comprises from 0.002 to 0.025 mole percent of the compound of the formula (I) with respect to the 100 mole % of constituent monomer of the EPDM elastomer.
• the styrene-butadine rubber (SBR) used in the rubber blend composition of the present disclosure is a copolymer of styrene and butadiene, and is advantageously used as an abrasion resistant replacement for natural rubber.
• the styrene-butadiene rubber can be conventionally prepared by the solution polymerization and by emulsion polymerization.
• the commercially available styrene-butadiene rubber can also be used.
• the styrene-butadiene rubber has a molecular weight ranging between 320,000-400,000 (M v ). It has good abrasion resistance and good aging stability when protected by additives, and is widely used in car tires, where it may be blended with other rubber.
• the polybutadiene rubber used in the rubber blend composition of the present disclosure is a synthetic rubber formed from the polymerization of 1,3-butadiene monomers and is advantageously used to provide high resistance wear property to the rubber blend composition of the present disclosure. Similar to the styrene butadiene rubber, the polybutadiene rubber can be conventionally prepared, for example, by solution polymerization and by emulsion polymerization or can be procured from the market. The polybutadiene rubber having molecular weight of 50,000 to 100,000 (M v ) is preferred. Polybutadiene is widely used in truck and passenger tires, where its very low glass transition temperature gives excellent resilience and excellent abrasion resistance.
• the ethylene-alpha-olefin-diene rubber (EPDM) used in the rubber blend composition of the present disclosure is a terpolymer of ethylene, alpha-olefin monomers and diene monomers.
• alpha-olefin monomers useful for the present disclosure include propylene, 1-butene, 1-pentene, and 1-hexene.
• the preferred alpha-olefin monomer is propylene.
• diene monomers useful for the present disclosure include ethylidene, norbornene, dicyclopentadiene, 1,4-hexadiene and the like.
• the EPDM rubber in un-modified form, contains 20 to 75 wt% of ethylene, 80 to 25 wt% of alpha-olefin and 1 to 15 wt% of diene monomers.
• the EPDM rubber has a molecular weight ranging from 1 ⁇ 10 5 to 2* 10 5 .
• EPDM rubber as a synthetic rubber in the rubber blend compositions is well-known in the art due to their potential low cost and high resistance to weather, age, heat and ozone.
• a major deficiency of the EPDM rubber is their poor abrasion resistance as compared to other rubbers such as SBR. Therefore, several modifications in the EPDM rubbers have been reported to improve their abrasion resistance property.
• Such modifications mainly include grafting on to these rubbers as backbones, different side chain polymers, for example, grafting of side chain polymers of alkyl acrylates and methacrylates monomers on the backbone of EPDM rubber; sulfonamide modified EPDM polymer with improved abrasion resistance, improved ozone resistance and improved hysteresis; and a maleic anhydride modified EPDM rubber.
• the modified EPDM rubber useful for the present disclosure is a graft copolymer that comprises ethylene-propylene-diene rubber as a polymer backbone having grafted thereon a compound of the formula (I).
• the inventors of the present disclosure have emphasized on modifying the EPDM rubber in such a way which leads to increased crosslinking density in the modified EPDM rubber.
• the modified EPDM rubber with improved cross-linking density when used in the rubber blend composition leads to the rubber blend composition which is self -healing in nature and has improved properties such as abrasion resistance, wear resistance and the like.
• the method of producing the modified EPDM rubber of the present disclosure is not specific and any conventional methods known for the modifications of the EPDM rubbers can be employed.
• the method for producing thermoplastic elastomer composition containing a carbonyl-containing group and a nitrogen containing group can be used, the contents of which are hereby incorporated by reference in its entirety.
• the process for the preparation of the modified EPDM rubber in accordance with the present disclosure is a two-step process.
• an unmodified EPDM rubber reacts with a carbonyl containing compound, such as di-carboxylic acids and derivatives thereof that include acid anhydrides, esters, ketones and the like.
• the carbonyl containing compound is maleic anhydride.
• a toluene solution of maleic anhydride and EPDM rubber react together in the presence of a free radical initiator at room temperature or under heating in a nitrogen atmosphere to obtain a maleic anhydride modified EPDM rubber (refer to Figure-1 and figure-3 of the accompanying drawings).
• the EPDM rubber and the maleic anhydride are reacted in a weight portion suitable for obtaining the maleic anhydride modified EPDM rubber having maleic anhydride in a mole percent varying from 0.005 to 0.05 based on 100 mole % of the constituent monomers of the EPDM rubber.
• the amount of the maleic anhydride that reacts with the EPDM rubber is in the range of 2 to 5 wt% with respect to total weight of the EPDM rubber.
• the functionalization of EPDM rubber with maleic anhydride in presence of peroxide initiator such as benzoyl peroxide, dicumyl peroxide etc. is carried out in a Brabender Plasticorder under the following reaction conditions: rotor speed: 40-60 rpm; temperature: 140-160 °C; and residence time: 3-5 minutes.
• maleic anhydride modified rubber is reacted with a nitrogen containing heterocyclic compound in the same brabender and the conditions employed are: maleic anhydride: nitrogen bearing heterocyclic compound in a weight ratio of : 1 : 10 to 10: 1 ; rotor speed: 40-60 rpm; temperature: 140-160 °C; residence time: 3-5 minutes.
• the maleic anhydride of the maleic anhydride modified EPDM rubber when reacted with the nitrogen containing compound, for example, 3-amino-l, 2, 4-triazole, forms an open ring structure (refer to figure-3 of the accompanying drawings).
• the nitrogen containing compound for example, 3-amino-l, 2, 4-triazole
• the nitrogen containing compound for example, 3-amino- 1 ,2,4-triazole
• the amount of the nitrogen containing compound, for example 3- amino-l,2,4-triazole, that reacts with the modified EPDM rubber typically ranges between 0.1 to 1 mole % with respect to 100 mol % of the carbonyl containing group.
• Ring-opening polymerization is a form of chain-growth polymerization in which the terminal end of a polymer acts as a reactive center, where further cyclic monomers join to form a larger polymer chain through ionic propagation.
• the treatment of some cyclic compounds with catalysts brings about cleavage of the ring followed by polymerization to yield high-molecular-weight polymers.
• the rubber blend composition in accordance with the present disclosure further comprise various additives such as antioxidants, antiozonants, fillers, plasticizers, vulcanizing agents, and the like for further improving the desired properties of the rubber blend composition.
• various additives as herein above described is well known in the art and accordingly those additives may be used in the rubber blend composition of the present disclosure.
• Fillers useful for the rubber blend composition of the present disclosure includes one or more filler selected from the group consisting of black, non-black and nano-fillers;
• the fillers are small spherical particles or rod shaped objects and flakes with at least one critical dimension below 100 ran.
• suitable black fillers are: carbon black N326, carbon black N134 and the like;
• suitable non-black fillers are calcium carbonate, kaolin clay, precipitated silica and the like.
• the amount of the fillers typically ranges from 5 to 60 parts per hundred parts of rubbers (phr).
• Plasticizer useful for the rubber blend composition of the present disclosure includes hydrocarbon plasticizer oil such as aromatic, paraffinic and naphthenic oil.
• suitable plasticizers are: phosphates, dialkylether diesters, and polymeric plasticizers.
• the amount of the plasticiser typically ranges from 2 to 10 parts per hundred parts of rubbers.
• the anti-degradants useful for the rubber blend composition of the present disclosure are staining and non-staining antioxidants and antiozonants.
• Suitable examples of staining antioxidants/antiozonants are: monophenols, bisphenols, thiobisphenols, phophites, nickel dibutyldithiocarbamate and the like.
• Suitable examples of non- staining antioxidants/antiozonants are napthylamines, diphenyl amine derivatives, para-phenylenediamine derivatives and the like.
• the amount of the anti-degradant mixed with the rubber blend composition typically ranges from 0.5 to 2 phr.
• the rubber blend composition of the present disclosure also comprises a curative.
• Any curative conventionally known for the vulcanization of the rubber blend composition may be used, for example, sulphur and non-sulphur cures.
• the amount of the sulphur cures ranges from 0.5 to 2 phr, depending on the type of the vulcanization system.
• non-sulphur cure vulcanizing agents are metal oxides, difunctional compounds, organic peroxides and the like.
• the amount of the non-sulphur cure typically ranges from 0.5 to 5 phr.
• the rubber blend composition may also comprise curative accelerator.
• curative accelerator suitable for the purpose of the present disclosure include sulfenamides, thiazole and the like.
• the amount of the curative accelerator typically ranges from 0.2 to 2 phr.
• the rubber blend composition in accordance with the present disclosure may also comprise processing aids which increase the process-ability of the rubber blend composition.
• processing aids are: lubricants, tackifiers, homogenizers, chemicals dispersing agents, peptizers, plasticizers, flow promoter, oil and the like.
• the processing aids are present in an amount typically ranging from 0.5 to 25 phr.
• the present disclosure provides a process for preparing the rubber blend composition of the present disclosure.
• a method for preparing the rubber blend composition of the present disclosure Any conventional mixing techniques can be suitably used for preparing the rubber blend composition of the present disclosure, such as kneading, extruding, rolling, and stirring and the like. The sequence of mixing various ingredients and other process conditions are well known to a person skilled in the art.
• a useful method for preparing the rubber blend composition of the present disclosure comprises the use of a rolling mixer wherein various components of the rubber blend composition such as styrene- butadiene rubber, poly-butadiene rubber and modified EPDM rubber are blended together for a time period and at a temperature sufficient for achieving uniform dispersion thereof.
• the various rubber components are blended together in a Brabender Plasticorder at a rotor speed varying from 40 to 60 rpm for a time period varying from 2 to 10 minutes at a temperature in the range of 140 to 160 °C.
• the various additives as herein above described such as anti-oxidants, anti-ozonants, fillers, and processing aids are also added during the blending of the rubber components.
• the additives are typically added in a weight proportion based on parts per hundred of rubber (phr) i.e. parts per hundred of the sum of styrene-butadiene rubber, polybutadiene rubber and modified EPDM rubber.
• the rubber blend composition thus obtained is an un-vulcanized rubber blend composition.
• the un- vulcanized rubber blend composition is further mixed in a two roll mill and blended with a curative, such as sulphur and non-sulphur types.
• a curative such as sulphur and non-sulphur types.
• the vulcanized rubber blend composition thus obtained is then compression molded at 140-160 °C and under 5 MPa compressive pressure for the optimum cure time determined from Rheometer in an electrically heated press to obtain rectangular sheets of dimensions 120x 120x 1.5 mm 3 .
• the compression molded rubber blend composition thus obtained is used for testing purpose.
• the performance evaluation of the compression molded rubber blend composition is carried out by measuring its properties that include: abrasion resistance, hardness, cut and chip resistance, tensile strength, heat build-up, ageing and self-healing property. The results are shown in tables 2-8.
• the rubber blend composition of the present disclosure shows better tensile strength as compared to the conventional standard blends such as blends of SBR/BR, SBR/EPDM, and SBR/BR/EPDM. Further, the rubber blend composition of the present disclosure demonstrates shows better or comparable properties with respect to hardness, cut and chip resistance, heat build-up and abrasion loss as compared to the conventional standard blends of blends of SBR/BR, SBR/EPDM (refer to data as provided in table-2).
• the rubber blend composition of the present disclosure also demonstrates better tensile strength and ageing properties in comparison to other comparative rubber blend compositions. Further, the rubber blend composition of the present disclosure also demonstrates better self -healing characteristic as compared to the conventional rubber blend composition, as is evident from figure-4 of the accompanying drawings.
• the improved/enhanced properties of the rubber blend composition of the present disclosure can be attributed to a number of cooperative hydrogen bonding present in the rubber blend composition of the present disclosure (refer to figure 3 of the accompanying drawings) that leads to increased cross-linking density.
• the cross-link density of the rubber blend composition of the present disclosure shows higher value (1.10* 10 "4 gmol/cm 3 ) as compared to the standard SBR/BR blend (SB 1) (0.87 gmol/cm 3 ), which indirectly reflects the generation of cooperative H-bonding in the rubber blend composition.
• the cooperative H-bonding is assumed to impart inherent self-healing characteristics and enhanced mechanical, ageing as well as dynamic properties to the rubber blend composition of the present disclosure.
• the rubber blend composition in accordance with the present disclosure can be used in a number of applications that include, but are not limited to, the manufacturing of various automobile parts such as tire tread, sidewalls, body plies, chafer and bead compounds.
• the study of self healing properties of such end use application products has been carried out and shown in tables 9- 15.
• the present disclosure provides a tire, characterized with that at least a portion of the tire is composed of the rubber blend composition of the present disclosure.
• the compression molded rubber blend composition was then evaluated for physical properties.
• the hardness (Hs) of each compression molded rubber blend composition was measured with a hardness tester at 25°C in accordance with ASTM D2240. (Shore A hardness testing). The larger the value is, the harder the composition is.
• the method determines the resistance of compression molded rubber blend composition to abrasion by means of a rotating cylindrical drum device.
• the volume loss due to the abrasive action of rubbing a test piece of the compression molded rubber blend composition over a specified grade of abrasive sheet was determined. This corresponds to the test method of DIN 53516 and to Method A (Relative volume loss) of ISO 4649: 1985.
• the rotational frequency of the circular cutting die was approximately 1200 rpm.
• the center axis of the test piece holder was an angle of 3° to the perpendicular in the direction of rotation and the center of the test piece was within approximately 1mm directly above the longitudinal axis of the drum.
• the Goodrich Flexometer is used to measure the heat build-up characteristics of a compression molded rubber blend composition test piece when applied test amplitude by constant strain control. This conforms to a test method of ASTM D 623. The test was carried out under the following conditions: test frequency: 20 Hz; static load: 142.9 PSI; stroke: 4.5 mm and temperature: 100 °C. A higher measured value indicates higher heat build-up. It is already reported in the literature that heat-build up of a vulcanizates increases with decreasing crosslink density.
• crosslink density and heat build-up of vulcanizate SBR/BR are 0.87X 10 "4 gmol/cm 3 and 20 °C, respectively whereas crosslink density and heat build-up of vulcanizate SBR/BR/EPDM m are ⁇ . ⁇ ⁇ ⁇ "4 gmol/cm 3 and 18 °C, respectively.
• the tensile strength of the compression molded rubber blend compositions of the present disclosure were measured in accordance with a test method ASTM D-412 and the study is provided in table 3.
• the rubber blend composition containing modified EPDM rubber (Ex-1 , Ex-2, Ex-3 and Ex-4) showed better tensile strength properties in comparison to the conventional standard blend (Comp Ex-1, Comp Ex-2, Comp Ex-3 and Comp Ex-4). It was observed that the tensile strength was marginally improved when SBR:BR:EPDM was used in rubber blend composition. Moreover, the improvement was more prominent in case of modified EPDM rubber in comparison to unmodified EPDM rubber which can be seen in table-3.
• DeMattia Flexing Fatigue Tester conforms to ASTM D-430 method "B” and ASTM D-813 standards to measure the ability of soft rubber compounds to resist dynamic fatigue. It is basically used to determine the crack growth of vulcanized rubber, leather, etc. when subjected to repeated bending strain or flexing. It is also used to measure the resistance to dynamic fatigue of vulcanized rubbers/ elastomers test specimen when subjected to repeated bending and extension.
• the cross-link density of the rubber blend compositions (e.g. Ex-1, Ex-2, Ex-3 and Ex-4) showed higher values as compared to the SBR/BR blend in the presence of unmodified EPDM rubber (Comp Ex-4) which indirectly reflects the generation of cooperative H-bonding in the system. It was difficult to compare the cross-link density of above stated blend with Comp Ex-1 due to their different kind of nature. All the above specified blends are ternary blend whereas Comp Ex-1 is a binary blend. From the table 7, it can be seen that the higher the cooperative H-bond in the system, higher will be the cross-link density. But, it is worth to mention that a certain composition of all the ternary systems plays a significant role to balance all the desired properties.
• the cooperative H-bonding is assumed to impart inherent self-healing characteristics. Due to cooperative H-bonding present in the self-healing material, it ultimately exhibits enhanced mechanical, ageing as well as dynamic properties. Table 7 illustrates the comparison with conventional SBR, BR composition.
• Example 5 & 6 (Ex-5 & Ex-6) and comparative example 5 & 6 (Comp Ex-5 & Comp Ex-6)
• Example 5 and 6 shows remarkable improvement in flexing property after incorporation of self-healing rubber in NR blend too (in the consecutive section). This subsequently implies that blend containing modified EPDM imparts self-healing characteristic. Since there was improvement in flexing property after including self- healing elastomer in the blend, the performance evaluation study was carried out a large number of experiments based on the end use application.
• Table 12 A Physical properties of Unaged samples
• Table 12B Physical properties of Aged samples
• Table 14 B DeMattia cut propagation study at room temperature
• Table 14 C DeMattia cut propagation study at higher temperature (70 °C)

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• 2015
  • 2015-01-16 WO PCT/IN2015/000026 patent/WO2015114653A2/en active Application Filing
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