WO2000004098A1

WO2000004098A1 - Elastomeric composition and the use thereof in an article subject to dynamic loading

Info

Publication number: WO2000004098A1
Application number: PCT/DK1999/000402
Authority: WO
Inventors: Brian Jaminson; Vivi Bjerre JØRGENSEN
Original assignee: Aktieselskabet Roulunds Fabriker
Priority date: 1998-07-16
Filing date: 1999-07-14
Publication date: 2000-01-27
Also published as: AU4770299A

Abstract

An elastomeric composition for use in an article subject to dynamic loading said composition comprising per 100 parts by weight of an elastomer 2 to 40 parts of a particulate, non-fibrous, organic, polymeric material. The elastomeric composition shows improved abrasion resistance, a higher tensile strength and modulus and a good ageing resistance.

Description

Title

Elastomeric composition and the use thereof in an article subject to dynamic loading

Technical field

The present invention relates to an elastomeric composition for use in an article subject to dynamic loading which imparts said articles excellent mechanical properties such as high abrasion resistance and high tensile strength and modulus, good processability, a long lifetime as well as a marked pilling resistance.

Articles subject to dynamic loading, such as conveyor belts and all kinds of transmission belts, such as V-belts, including belts for variable power transmission, timing belts, poly- V-belts and flat belts , must meet a number of diverse requirements . To resist strong dynamic loading, these articles must possess good ageing resistance against heat and ozone, a good abrasion resistance and a high tensile strength and modulus. Further they should show a high resistance to pilling, i.e. the formation of sticky material on the belt surface due to breakdown of the elastomeric composition by friction.

Background art

The use of various types of elastomers in articles for dynamic applications are known, these elastomers possessing diverse mechanical and chemical properties. Ethylene-α- olefin elastomers, such as ethylene-propylene copolymers (EPM) and ethylene- propylene-diene terpolymers (EPDM), ethylene-butylene copolymers, ethylene-octene copolymers, etc. are excellent general purpose elastomers, having broader operating temperature ranges than most other elastomers. Furthermore these materials show excellent oxygen and ozone resistance and they are generally less expensive than other elastomers. Other elastomeric compositions traditionally employed for dynamic applications are elastomers, such as natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber (CR), nitrile butadiene rubber (NBR), hydrogenated nitrile butadiene rubber (H-NBR), ethylene vinylacetate copolymer (EVM),and alkylat- ed, chlorosulfonated polyethylene (ACSM). Most of these elastomers possess satisfactory mechanical properties in dynamic applications, but some of these, such as natural rubber, styrene butadiene rubber, butadiene rubber, chloroprene rubber, and nitrile butadiene rubber, are less ageing and temperature resistant than ethylene-α-olefin elastomers, whereas hydrogenated nitrile butadiene rubber, and alkylated chlorosulfonated polyethylene are less flexible at low temperatures and much more expensive than ethylene-α-olefin elastomers.

Several methods for improving the mechanical properties of elastomers are known. Increasing the amount of filler or peroxide in the curing process increases hardness and modulus of the cured elastomeric composition. However, these methods also impart a reduced flex fatigue, tear strength and elongation to the elastomer. An alternative method is adding acrylate moieties as coagents for peroxide-curing. Particularly, the use of salts of metal acrylates in the curing of elastomers has generally shown to improve the mechanical and chemical properties with respect to hot tear strength, abrasion resistance, oil resistance and adhesion to metals.

The use of a metal salt of an α,β-unsaturated organic acid as reinforcing filler incorporated in an elastomer is known from EP 784.075 Al. A belt is disclosed which substantially comprises a backing, load carrying members and an elastomeric main body. The backing and/or the main body consists of a peroxidically crosslinked elasomeric mixture, which per 100 parts of rubber contain from 41 to 99 parts of EPDM and/or EPM as well as from 1 to 59 parts of H-NBR and further components, such as plasticizers and fillers, as well as at least one zinc salt of an α,β-unsaturated carboxylic acid derivative in an amount of 81-100 parts. In PCT application WO 96/13544 an elastomeric composition for incorporation in an article subject to dynamic loading is disclosed which has been cured using a free-radical promoting material, said composition comprising the reaction product of 100 parts by weight of an ethylene-α-olefin elastomer and, per 100 parts by weight of said elastomer, from about 1 to about 30 parts of a metal salt of an α, β-unsaturated organic acid and optionally a reinforcing filler.

Both of the above documents disclose elastomeric compositions comprising metal salts of α, β-unsaturated organic acids. Such salts do, however, show a number of disadvantages. Thus, metal salts of α, β-unsaturated organic acids are only applicable as coagents in non-halogen-containing elastomers. Further, the metal salts of α, β-unsaturated organic acids are local irritants which limit their applicability or necessitate special precautions to be taken during processing. Also, during the preparation of elastomeric articles, the metal salts cause the elastomer to adhere to the mould necessitating the use of specific release agents. Finally, these metal salts are expensive, and an alternative thereto would be highly appreciated.

Other conventionally used reinforcing agents are fibres, such as textile fibres, including cotton, polyester, polyamide and aramide fibres. Thus, US 4,235, 119 discloses an elastomeric composition comprising from about 0.5 to about 40 parts by weight of fibres per 100 parts by weight of elastomeric composition. The fibres are preferably non- metallic, organic fibres having a fibre diameter of from 0.025 to 1.25 mm and a fiber length of from 0.025 to 25 mm. The fibres may e.g. be polyester fibres.

US 4,504,342 discloses an elastomeric composition, e.g. neoprene rubber, loaded with non metallic, organic fibres having a diameter of from about 0.003 to 0.1 mm and a length of from about 0.003 mm to 3 mm.

US patent specification No 4.775.357 discloses an elastomeric body composed of a single thermosetting rubber comprising from about 2 to about 30 parts by weight of fibre flock per 100 parts by weight of thermosetting rubber. The fibres have a length to diameter ratio of less than 10: 1 and may be composed of aliphatic polyamides , aromatic polyamides, cotton, rayon, nylon, polyester and fibre glass.

EP No 0633408 A2 discloses a power transmission belt comprising an elastomer containing 5 to 30 parts by weight of fibres per 100 parts by weight of rubber. The fibres may be synthetic fibres of nylon, vinylon, polyester, aramid or a combination thereof or natural fibres, such as cotton or pulp.

However, the incorporation of fibres may pose disadvantages in different respects.

Thus, fibres tend to reduce the flexibility of the end product and to result in a decrease of the ultimate tensile strength and elongation at break.

Further, in fibre reinforced elastomeric compositions the fibres are oriented so as to give anisotropic properties in the resulting material. Prior to building of the ultimate belt rolls thus have to be cut and realigned so that the fibres are oriented in the transverse direction instead of the longitudinal direction. Such a separate process step clearly increases the cost of the resulting elastomeric article.

The prior art also teaches elastomeric compositions containing organic, polymeric particles.

WO 87/01309 discloses an elastomer PTFE composition comprising 25 to 80 per cent by weight of polytetrafluoro ethylene, up to 30 per cent by weight of molybdenum disul- fide, and the rest elastomeric material. The polytetrafluoro ethylene component may be a powder of a particle size of up to lOOμm.

US patent specifications Nos 5.510.419 and 4.104.210 disclose elastomeric compositions comprising finely dispersed rubber particles. However, the prior art does not teach the incorporation of particles, which improve the mechanical properties and which does not necessitate additional process steps.

Thus there still exists a need for inexpensive and environmentally desirable additives effective to improve the mechanical performance such as flex resistance at high modules and abrasion resistance without compromising a satisfactory tensile strength and elongation at break of elastomers used in dynamic applications.

Brief description of the invention

Surprisingly, it has been shown that the incorporation of a particulate, non-fibrous, organic, polymeric material in an elastomeric composition imparts improved properties in terms of a high abrasion resistance, a high tensile strength and modulus, good processability, a long lifetime and a marked pilling resistance. In addition, the use of a particulate, non-fibrous, organic, polymeric material according to the invention for improving the properties of said elastomers has the advantage of resulting in lower costs, less hazard to the environment as well as making the elastomeric composition less sticky during processing. Further, since said particles reinforce the elastomeric composition, the hitherto required incorporation of conventional fibres may be dispensed with either partly or wholly.

Thus, the present invention relates to an elastomeric composition for incorporation in an article subject to dynamic loading comprising:

a) 100 parts by weight of a primary elastomer, b) 2 to 40 parts by weight of said elastomer of a particulate, non-fibrous, organic, polymeric material, c) optionally conventional adjuvants, additives and the like,

and which has been cured employing conventional vulcanisation aids. Furthermore, the invention relates to the use of a particulate, non-fibrous, organic, polymeric material for reinforcing the elastomeric composition according to the invention.

Finally, the present invention relates to an article subject to dynamic loading comprising the elastomeric composition according to the invention.

Brief description of the drawings

The accompanying drawings illustrate preferred embodiments of the invention. In the drawings

Fig. 1 is a perspective view, with parts in section, of a V-ribbed belt.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description.

Best mode for carrying out the invention

Referring to Fig. 1 , a typical V-ribbed belt 5 is illustrated. The belt 5 comprises a ribbed compression layer 4 and a tension layer 1. The compression layer 4 comprises the elastomeric composition according to the invention. The tension layer 1 may comprise an elastomeric composition according to the invention or may alternatively comprise a rubberised textile fabric. In a preferred embodiment the tension layer 1 comprises the elastomeric composition according to the invention. Positioned between the tension layer 1 and the compression layer 4 reinforcing cords are aligned longitudinally along the length of the belt 5. In the embodiment illustrated in Fig. 1, said reinforcing cords are embedded in a cushion layer 2. The cushion layer 2 may comprise any elastomeric composition compatible with the elastomer of the tension layer 1 and the compression layer 4, and may also be identical with either of these. It must, however, be understood that the cushion layer 2 is not indispensable and may be omitted provided the tension layer 1 and the compression layer 4 provide a suitable bedding of the reinforcing cords 3.

The elastomeric composition according to the invention comprises as the primary elastomeric component a primary elastomer preferably selected from the group comprising natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR), chloro- prene rubber (CR), nitrile butadiene rubber (NBR), hydrogenated nitrile butadiene rubber (HNBR), alkylated, chlorosulfonated polyethylene (ACSM), ethylene-vinyl acetate copolymers (EVM), and ethylene-α-olefin elastomers or mixtures thereof.

In a preferred embodiment the primary elastomer is selected among chloroprene rubber (CR), alkylated, chlorosulfonated polyethylene (ACSM), ethylene-vinyl acetate copoly- mers (EVM), and ethylene-α-olefm elastomers.

The ethylene-α-olefms useful in the present invention include, but are not limited to copolymers of ethylene and propylene units (EPM), ethylene and butene units, ethylene and pentene units, or ethylene and octene units (EOM), and terpolymers composed of ethylene and propylene units and an unsaturated component (EPDM), as well as mix- tures thereof. As non-limiting examples of dienes can be mentioned non-conjugated compounds, such as 1,4-hexadiene, dicyclopentadiene, ethylidene norbonen, methylene norbornen or methyltetrahydroinden. A preferred elastomer is ethylene-propylene-diene terpolymer (EPDM).

In the case of employing an ethylene-propylene-copolymer or ethylene-propylene-diene copolymer, the ethylene content thereof should preferably lie in the range between 30 to 80% by weight, preferably between 50 and 70% by weight. The diene proportion should be in the range 1 to 10, preferably 2 to 8% by weight.

A wide range of the above elastomers are readily commercially available. Thus, EPDM is available from DSM, The Netherlands, under the trade name KELTAN^®, or from Dupont Dow Elastomers, USA, under the trade name NORDEL^®. EOM is available from Dupont Dow Elastomers under the trade name ENGAGE^®. The primary elastomer may also comprise a polychloroprene rubber, such as NEOPRENE GW, available from Dupont Dow Elastomers, or alkylated chlorosulfonated polyethylene (ACSM), available under the trade name ACSIUM^® from Dupont Dow Elastomers.

In some instances, such as in order to improve specific properties, for example oil resistance or processability, the elastomeric composition according to the invention may, in addition to the primary elastomer, comprise up to 25% by weight, based on the weight of the primary elastomer, of a second elastomeric material selected from the group consisting of:

a) silicone rubber, b) epichlorohydrin, c) chlorinated polyethylene, d) chlorosulfonated polyethylene, e) trans-polyoctenamer, f) polyacrylic rubber and

mixtures thereof.

The elastomeric composition according to the invention comprises a particulate, non- fibrous, organic, polymeric material as a reinforcing material. Thus, it has surprisingly been found that the incorporation of such particles imparts a greatly improved abrasion resistance of the elastomeric composition, coupled with a higher modulus and a high tensile strength. The particulate, non-fibrous, organic, polymeric material for incorporation in the elastomeric composition according to the invention is preferably a material polymerised from monomers comprising ethylenic unsaturation, such as polyethylene, polypropylene and polyvinylchloride.

In a preferred embodiment said particulate, organic, polymeric material is selected from the group comprising:

low density polyethylene (LDPE), linear low density poly-ethylene (LLDPE), high density polyethylene (HDPE), ultra high molecular weight poly-ethylene (UHMWPE) and polypropylene (PP), preferably among LDPE, LLDPE and UHMWPE.

The particulate, non-fibrous, organic, polymeric material is present in an amount from 2 to 40, preferably from about 5 to 30, and particularly from about 8 to 20 parts by weight of the elastomer. Thus, amounts in excess of 40 parts by weight have shown to lead to a continuous phase of said material being built up throughout the matrix resulting in considerable stiffness and rapid crack growth, whereas the inclusion of less than 2 parts by weight of the particulate, organic, polymeric material will lead to an insignificant improvement of the abrasion resistance and modulus.

The particulate organic, polymeric material must be in a finely divided state, preferably with a greater dimension : smaller dimension ratio of < 5 : 1 , especially < 2: 1 and particularly preferred being particles or pellets with an average greater particle dimension in the range of from about 5 to about 500 μm, preferably from about 10 to about 400 μm, and particularly from about 20 to about 350 μm.

In a specifically preferred embodiment of the invention said particulate, non-fibrous, organic, polymeric material is present as roughly spherical particles having a greater particle dimension of about 150 μm to about 350 μm. Examples of commercially available particulate, non-fibrous, organic, polymeric materials comprise i.a. Stamylex^® XL 400 UP, a linear polyethylene containing peroxide from DSM, Hostalen^® GUR 2122, an ultra high molecular weight polyethylene available from Ticona, and Lupolen^® SP 15, a linear polyethylene available from BASF.

The elastomeric composition according to the invention may further comprise a number of conventional adjuvants, additives and fillers. As non-limiting examples of fillers can be mentioned carbon black, silica, calcium carbonate, talc, clay or mixtures thereof. Furthermore, the incorporation of fibres is envisaged, such fibres comprising e.g. aramide, such as those sold under the trademark KEVLAR^® by E.I. du Pont de Nemours & Company, the trademark TWARON^®, sold by Enka, The Netherlands, and TECHNORA^®, sold by Teijin, Japan. Further examples of fibre reinforcement materials comprise staple or filament fibres of polyesters, polyamides, polyvinyl alcohol, cotton and other cellulose fibres which may be added in order to further improve the modulus and abrasion resistance. Furthermore, conventionally used process aids, softeners and plastisizers, such as mineral oil, ethers, esters etc., binders and compatibilizers, such as paraffins, waxes, etc. may be included.

Other conventional additives such as anti-oxidants, pigments, etc. may be added in accordance with conventional methods for the preparation of elastomeric compositions.

The elastomeric composition according to the invention may be cured employing con- ventional vulcanisation aids. These include for natural rubber and styrene butadiene rubbers sulphur and an accelerator; for chloroprene rubber and alkylated, chlorosulfonated poly-ethylene metal oxides and an accelerator therefor; for hydrogenated nitrile butadiene rubber and ethylene-α-olefin polymers ionising radiation and peroxides with optional coagents. As non-limiting examples of organic peroxides can be mentioned dicumyl peroxide, t-butyl perbenzoate, di-t-butyl peroxide, 2,5-dimethyl-2,5-di-t-butyl peroxyhexane or α,α-bis-(t-butylperoxy)-diisopropylbenzene. The elastomeric composition according to the invention may in a further preferred embodiment also comprise 1 to 30, preferably 2 to 20 parts by weight of the elastomer or one or more metal salts of α, β-unsaturated organic acids, such as zinc, aluminium, magnesium, cadmium, sodium and calcium salts of acrylic, methacrylic, maleic, fuma- ric, ethacrylic, vinyl-acrylic, itaconic, methyl itaconic, aconitic, methyl aconitic, croto- nic, α-methylcrotonic, cinnamic, or 2,4-dihydroxy cinnamic acids, preferably zinc diacrylate or zinc dimethacrylate. A commercially available zinc diacrylate is SARET^® 633, marketed by Sartomer, USA, and zinc dimethacrylate, marketed by Sartomer under the trademark SARET^® 634.

The elastomeric composition according to the invention may be incorporated in an article subject to dynamic loading, such as conveyor belts or transmission belts, for example V-belts, including belts for variable power transmission, timing belts, poly V- belts, continuously variable transmission belts and flat belts.

The elastomeric composition according to the invention is prepared using any conven- tional technology, such as e.g. by mixing the ingredients in an internal mixer or a two roll mill.

The curing or vulcanisation is performed using conventional technology, such as in a press, in a continuous vulcanisation equipment, or in an autoclave as disclosed further in the following.

The following examples are submitted for the purpose of further illustrating the nature of the present invention and are not intended as a limitation on the scope thereof. Parts and percentages referred to in the examples and throughout the specification are by weight unless otherwise indicated. Examples

Examples 1 to 5

Table I below illustrates elastomeric compositions comprising different combinations of elastomers and particulate, non-fibrous, organic, polymeric materials. Table II illustrates test results obtained for the elastomeric compositions of Table I.

In the examples the elastomer processing was carried out in the following manner:

Mixing Process

The compositions of examples 1 and 5 were mixed in a 260 1 Werner & Pfleiderer GK 255 N tangential internal mixer at a rotor speed of approximately 30 rpm. The composi- tions of examples 2, 3 and 4 were mixed in a 1.61 Werner & Pfleiderer GK2 tangential internal mixer at a rotor speed of approximately 50 rpm.

The compositions of examples 1 to 5 were produced according to a two-step process. Apart from peroxides and vulcanisers, all the ingredients of the compositions of examples 1 to 5 were added in step 1, and the mixing sequence is as stated in Table I.

The first step of the process for preparing the compositions of examples 1 to 5 was carried out at a temperature of 140° C, and the second step at 100°C.

Test

Sheets of the elastomeric compositions were subjected to a vulcanisation for 20 min. at 160°C.

Physical tests were performed according to the following international standards:

Production of belts

Elastomeric sheets for the production of poly V-belts were made from the elastomeric mass by means of a calender. In the case of fibre-containing elastomeric compositions, the sheets were cross-turned such that said fibres were positioned transverse to the moving direction of the belts by the subsequent processing.

The belts were produced in the following manner:

A thin sheet of elastomeric material of approximately 0.6 mm, cross-turned if fibre- containing, was wound around a mandrel, whereafter a layer of polyester cord material was wound around said mandrel. Subsequently, several sheets of elastomeric material, cross-turned if fibre-containing, were wound around the cord until the desired thickness had been reached.

The polyester cord material had been pretreated with an elastomer-to-polyester binder system including an isocyanate pretreatment, a resorcinole-formaldehyde treatment, and finally a binder impregnation. The assembly of the mandrel and the elastomeric material was placed in an autoclave, a rubber membrane being placed around the assembly to transfer pressure and to protect against steam. The elastomeric material was vulcanised in the autoclave for about 50 minutes at 160° C. Subsequently, the vulcanised elastomeric cylinder was cooled on the mandrel and thereafter removed.

Ribs were ground in the elastomeric body by means of a profiled diamond abrasive wheel and belts cut out of the cylinder.

In the tables below, the following components were used:

Elastomers KELTAN^® 378 EPDM from DSM KELTAN^® 1446 EPDM from DSM NORDEL^® 1040 EPDM from DuPont Dow elastomers NORDEL^® 1320 EPDM from DuPont Dow elastomers ENGAGE^® 8400 EOM from DuPont Dow elastomers NEOPRENE GW Polychloroprene rubber from DuPont Dow elastomers

ACSIUM^® HPR-6932 ACSM from DuPont Dow elastomers

Particulate, non-fibrous, organic, polymeric materials

Stamylex^® XL 400UP linear polyethylene containing peroxide, 330 μm*, DSM

Hostalen^® GUR ultra high molecular weight polyethylene,

170 μm*, Ticona Lupolen^® SP 15 linear polyethylene, 280 μm*, BASF

*Weight average particle size derived from sieve analysis. Antioxidants

TMQ 2,2,4-trimethyl-l ,2-dihydroquinoline WINGSTAY 100 diaryl substituted paraphenylene diamine from

Goodyear

VULKANOX 3100 diaryl substituted paraphenylene diamine from

Bayer

VULKANOX OCD octylated diphenylamine from Bayer

Vulcanisers

PERKADOX^® 14-40 MB gr bis(tert-butylperoxyisopropyl)benzene from Akzo Nobel

TRIGONOX^® 29-40 mb gr 1 , l-bis(tert-butylperoxy)-3,3,5-trimethylcyclo- hexane from Akzo Nobel HVA-2 N,N'-m-phenylene-dimaleimide from DuPont

VULKACIT^® CRV 3-methyl-thiazolidine-thion-2 from Bayer VULKACΓΓ DM dibenzothiazole disulphide from Bayer ROBAC P25 PM dipentamethylene dithiuram disulphide from Robinson Brothers

Activators

Safacid 18/22 Stearic acid from Jahres Fabriker A/S Zinkweiss Zinc oxide from Zinkweiss Handelsgesellschaft Rotsiegel Magnesium oxide Magnesium oxide from Lehmann & Voss & Co. Light type N 50 Pentaerythritol from Hercules Fillers

Carbon black N-550 Degussa

Carbon black N-772 Degussa

Softeners Flexway RP10 Paraffmic oil from Statoil

Enerthene 1849-1 Naphtenic oil from BP Oil

Dioctyl sebacate Inspec UK Co.

Fibres

Ground Claremont Flock Corporati

Table I

Elastomeric compositions

Belts made from the above compositions were subjected to physical tests as mentioned above. The following results were obtained. Table π

Examples 6 to 20

In a further series of experiments the effect of different particulate organic, polymeric materials in different amounts was tested in different elastomers . The elastomer processing was carried out analogously with the processing of the compositions of examples 1 to 5.

The results of these tests are illustrated in the below Tables III to VI.

Table III

The effect of the amount of particulate, polymeric material on the properties of the elastomeric composition

Thus, a significantly improved abrasion resistance is obtained by the compositions according to the invention compared to a prior art composi tion, as well as a higher tensile strength and higher modulus.

Table IV

The effect of adding a particulate polyethylene material to an EPDM elastomer

As it appears, a significantly improved abrasion resistance, coupled with a higher tensile strength and a higher modulus, is obtained. Table V

The effect of adding a particulate polyethylene material to an ACSM elastomer

Table VI

The effect of adding a particulate polyethylene material to a polychloroprene elastomer.

As it appears from the above, a significantly higher tensile strength and modulus as well as a pronounced improved abrasion resistance were obtained in the elastomeric compositions according to the invention compared to prior art elastomeric compositions having no particulate, organic, polymeric material incorporated.

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the appended claims.

Claims

1. An elastomeric composition for use in an article subject to dynamic loading comprising:

a) 100 parts by weight of a primary elastomer,

b) 2 to 40 parts by weight of said elastomer of a particulate, non-fibrous, organic, polymeric material,

c) optionally conventional adjuvants, additives and the like,

and which has been cured employing conventional vulcanisation aids.

2. The elastomeric composition of claim 1, wherein said primary elastomer is selected from the group comprising:

natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber (CR), nitrile butadiene rubber (NBR), hydrogenated nitrile butadiene rubber (HNBR), alkylated, chlorosulfonated polyethylene (ACSM), ethylene-vinyl acetate copolymers (EVM), and ethylene-╬▒-olefin elastomers or mixtures thereof.

3. The elastomeric composition of claim 2, wherein said primary elastomer is selected from the group comprising:

chloroprene rubber (CR), alkylated, chlorosulfonated polyethylene (ACSM), ethylene- vinyl acetate copolymers (EVM), and ethylene-╬▒-olefin elastomers, particularly an ethylene-propylene copolymer (EPM), ethylene-propylene-diene terpolymer (EPDM) or ethylene-octene copolymer (EOM) or mixtures thereof, preferably EPDM.

4. The elastomeric composition according to any of claims 1 to 3, wherein said primary elastomer is blended with up to 25 % by weight based on the weight of the primary elastomer of a second elastomeric material selected from the group consisting of:

a) silicone rubber, b) epichlorohydrin, c) chlorinated polyethylene, ) chlorosulfonated polyethylene, e) trans-polyoctenamer , f) poly aery lie rubber and

mixtures thereof.

5. The elastomeric composition of any one of claims 1 to 4, wherein said particulate, non-fibrous, organic, polymeric material is a material polymerised from monomers comprising ethylenic unsaturation.

6. The elastomeric composition of any one of claims 1 to 5, wherein said particulate, non-fibrous, organic, polymeric material is selected from the group comprising:

low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE), ultra high molecular weight polyethylene (UHMWPE) and polypropylene (PP), preferably among LDPE, LLDPE and UHMWPE.

7. The elastomeric composition of any one of claims 1 to 6, wherein said particulate, non-fibrous, organic, polymeric material is present in an amount of from 5 to 30, preferably 8 to 20 parts by weight of the elastomer.

8. The elastomeric composition of any of claims 1 to 7, wherein said particulate, non- fibrous, organic, polymeric material has a greater dimension : smaller dimension ratio of < 5: 1 , especially < 2: 1 and has an average greater particle dimension in the range of from about 5 to about 500 ╬╝m, preferably from about 10 to about 400 ╬╝m, particularly from about 20 to about 350 ╬╝m.

9. The elastomeric composition of claim 8, wherein said particulate, non-fibrous, organic, polymeric material is present as roughly spherical particles having a greater particle diameter of about 150 ╬╝m to about 350 ╬╝m.

10. The elastomeric composition of any one of claims 1 to 9, wherein said conventional adjuvants and additives are selected from the group comprising:

plasticizers, softeners, antioxidants, fibres, anti-aging agents, fillers, pigments, binders, compatibilisers and process aids.

11. The elastomeric composition of any one of claims 1 to 10 further comprising 1 to 30, preferably 2 to 20 parts by weight of the elastomer, of one or more metal salts of ╬▒, ╬▓-unsaturated organic acids.

12. The elastomeric composition of claim 11 , wherein said metal salt of the ╬▒, ╬▓-unsaturated organic acid is selected from the group comprising:

zinc, aluminium, magnesium, cadmium, sodium and calcium salts of acrylic, methacry- lic, maleic, fumaric, ethacrylic, vinyl-acrylic, itaconic, methyl itaconic, aconitic, methyl aconitic, crotonic, ╬▒-methylcrotonic, cinnamic, or 2,4-dihydroxy cinnamic acids, preferably zinc diacrylate and zinc dimethacrylate.

13. A use of a particulate, non-fibrous, organic, polymeric material for reinforcing an elastomeric composition according to any one of claims 1 to 12.

14. An article subject to dynamic loading comprising an elastomeric composition of any one of claims 1 to 12.

15. The article of claim 14, characterised by being a conveyor belt or transmission belt, such as a V-belt, including belts for variable power transmission, timing belts, poly-V- belts, continuously variable transmission belts and flat belts.