Physical properties of carbon black filled poly(ethylene-co-vinyl acetate) composites K. Priya Dasan* 1 , G. Unnikrishnan 2 , A. P. Haseena 2 and E. Purushothaman 1 The effects of three types of carbon blacks, namely, semireinforcing furnace, high abrasion furnace and intermediate super abrasion furnace on the physical properties of poly(ethylene-co- vinyl acetate) have been studied. The properties studied include cure characteristics, mechanical properties, solvent transport behaviour, dielectric properties and the thermal characteristics. The properties were evaluated in terms of the particle size and amount of the fillers used. The mechanical properties of the matrix such as tensile strength, abrasion resistance and hardness were observed to be increasing with filler incorporation. Solvent resistance of the composite has also been observed to be increasing with filler incorporation. The dielectric constant and thermal behaviour of the composite has been studied and explained in terms of the particle size of the filler used. Keywords: Composites, Mechanical properties, Fillers, Diffusion, Dielectric properties Introduction The incorporation of carbon black in polymers generally gives improved performance related properties. 1–8 From the structural point of view, carbon blacks are poly- crystalline materials consisting of very small graphite lamellae arranged in a turbostatic and disordered way. 9 The interaction between carbon black particles and the polymer matrix occurs both by physical and chemical processes. 10–12 The physical binding occurs due to the entrapment of the polymeric chains in the carbon black microstructural defects and superﬁcial porosities. The chemical process depends on the nature of the electron acceptor sites on the cluster surfaces of carbon black and the polymer macroradicals formed by mechanochemical degradation during compounding. Reinforcement of carbon black in elastomers has been reported by many researchers. 13–15 Kraus 16 examined the various aspects of carbon black reinforced elasto- mers. The structure of carbon blacks and the ﬁller surface chemistry have been followed by them. The studies by Kurian et al. 17 found that the physical properties of zinc sulphonated ethylene-propylene-diene terpolymer (EPDM) of high ethylene content were improved with high abrasion furnace (HAF) black incorporation. They examined the hardness, stress– strain characteristics and abrasion resistance of the ﬁlled system. Images (SEM) of the tear fractured and abraded surfaces showed changes in failure mode of the polymer on carbon black incorporation. Das et al. 18 investigated the mechanical properties of carbon black ﬁlled ethylene vinyl acetate (EVA)/EPDM blend along with their electrical properties. The addition of carbon black resulted in an increase in the tensile strength and elongation at break of the blend as well as those of the components alone. The studies by Varghese et al. 19 on carbon black ﬁlled nitrile rubber/EVA system indicated an improvement in mechanical properties of the blends on ﬁller incorporation. The effects of type and propor- tion of carbon black ﬁller on the mechanical properties and electrical conductivity of nitrile rubber composites containing particulate carbon black and short carbon ﬁbres have been studied by Pramanik et al. 20 Bulgin 21 followed the increase in strength properties of amor- phous polymers ﬁlled with carbon black and silica. The improvement in strength was found to be accompanied by a proportional increase in hysteresis loss, attributable to a viscoelastic process in the polymer. For ﬁller content up to 30 volumes loading, the effects were found to be proportional to the actual surface area of the ﬁller in the polymer. The inﬂuence of carbon black on solvent transport through elastomer networks has gained the attention of scientists for many years. Porter 22 studied the degree to which the addition of HAF black reduced the swelling of conventionally vulcanised natural rubber in n-decane. Candia et al. 23 investigated the transport properties of networks ﬁlled with carbon black, in order to obtain information about rubber–ﬁller interactions. Kwei and Kumins 24 found that the sorption of chloroform by an epoxy resin was lowered by about 70% when 5% ﬁller was added. Anﬁmova et al. 25 reported the equilibrium swelling in benzene of natural rubber vulcanisates having different degrees of crosslinking, ﬁlled with technical carbon. The diffusivity and solubility of argon, methane, oxygen and carbon dioxide in two EPDM based polymers, one formulated with 34 wt-% carbon black and the other without carbon black, have been studied by Rutherford et al. 26 A linear relationship was 1 Department of Chemistry, University of Calicut, Calicut 673635, India 2 Polymer science and technology laboratory, NITC, Calicut 673601, India *Corresponding author, email kpriyadasan@yahoo.com ß Institute of Materials, Minerals and Mining 2009 Published by Maney on behalf of the Institute Received 10 April 2008; accepted 8 October 2009 DOI 10.1179/146580109X12540995045480 Plastics, Rubber and Composites 2009 VOL 38 NO 9/10 457