Abstract. The present work deals with the effect of conductive carbon black (Ensaco 350G) on the physico-mechanical and electrical properties of chlorosulfonated polyethylene (CSM) rubber vulcanizates. The physico-mechanical properties like tensile strength, tear strength, elongation at break, compression set, hardness and abrasion resistance have been studied before and after heat ageing. Up to 30 parts per hundred rubber (phr) filler loading both tensile and tear strength increases beyond which it shows a decreasing trend whereas modulus gradually increases with the filler loading. Incorporation of carbon black increases the hysteresis loss of filled vulcanizates compared to gum vulcanizates. Unlike gum vulcanizate, in filled vulcanizates the rate of relaxation shows increasing trend. The bound rubber content is found to increase with increase in filler loading. Dielectric relaxation spectra were used to study the relaxation behavior as a function of frequency (100 to 10 6 Hz) at room temperature. Variation in real and imaginary parts of electric modulus has been explained on the basis of interfacial polarization of fillers in the polymer medium. The percolation limit of the conductive black as studied by ac conductivity measurements has also been reported.

The frequency dependent dielectric relaxation behavior of conductive carbon black reinforced chlorosulfonated polyethylene (CSM) vulcanizates has been studied for different filler loadings in the frequency range of 102–106 Hz over a wide range of temperatures (30–120°C). The effects of filler loadings on the dielectric permittivity (ε′), dielectric loss tangent (tan δ), impedance, and electrical conductivity were studied. The variation of the dielectric permittivity with the filler loadings was explained on the basis of interfacial polarization of the filler in the polymer matrix. The frequency dependence of ac conductivity has been investigated using percolation theory. The effect of filler loading on the complex and real parts of impedance was clearly observed, which can be explained on the basis of relaxation dynamics of polymer chains in the vicinity of fillers. The percolation threshold occurred near 30 phr of filler loading. Scanning electron microphotographs showed the agglomeration of the filler on and above these filler loadings. Additionally, the effect of temperature on dielectric loss tangent, dielectric permittivity, ac conductivity, and Nyquist plot of conductive black reinforced CSM vulcanizates has been studied. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers

The rheological properties of chlorosulfonated polyethylene (CSM) loaded with conductive carbon black filler were measured using capillary rheometer at three different temperatures (110, 120, and 130°C) and four different shear rates (12.26, 24.52, 61.3, and 122.6 s−1). The effect of filler and plasticizer [dioctyl phthalate (DOP)] loading on melt flow properties of CSM was also studied. The viscosities of all samples decrease with shear rate indicating their pseudoplastic or shear thinning nature. The higher shear viscosity is observed for the CSM loaded with higher filler content, which may be due to inhibition of the polymer chain motion by the filler particles. With increasing filler loading the extrudate swell clearly decreased, which is attributed to the limitation of the elastic recovery of the polymer chains by filler particulates. Further, the reduction in die‐swell ratio with increase in plasticizer loading indicates a reduction in melt elasticity compared with the composite containing no DOP. The dependence of shear viscosity on temperature obeyed the Arrhenius–Eyring expression, and the activation energy (Eγ) decreased with increasing shear rate. Extrudate swell is a non‐linear function of shear rate. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Dynamic mechanical analysis and dielectric relaxation spectra of conductive carbon black reinforced chlorosulfonated polyethylene (CSM) composites were used to study their relaxation behavior as a function of temperature and frequency, respectively. A marginal increase in glass transition temperature has been observed upto 30 phr carbon black filled polymer composite, beyond which it decreases, which has been explained on the basis of aggregation of filler particles in the polymer matrix. The strain dependent dynamical parameters were evaluated at dynamic strain amplitudes of 0.1-200%. The nonlinearity in storage modulus increases with increase in filler loading. It can be explained on the basis of filler-polymer interaction and aggregation of the filler particulates. The frequency dependent dynamical mechanical analysis has also been studied at frequency range of 0.1-100 Hz. The variation in real and complex part of impedance with frequency has been studied as a function of filler loading. The effect of filler loading on ac conductivity has been observed as a function of frequency. An increase in conductivity value has been observed with increase in filler loading. This can be explained on the basis of formation of conducting paths between filler particulates.

Curing systems play a vital role in designing rubber compounds for various industrial applications. Keeping this in view, a comparative study of the effects of four different curing systems such as sulfur, dicumyl peroxide (DCP), metal oxide (PbO) and epoxy resin on the curing characteristics, physico-mechanical, and rheological properties of chlorosulfonated polyethylene rubber (CSM) has been carried out. The highest values of maximum rheometric torque and scorch safety were observed in the peroxide-cured system, whereas sulfur-cured CSM rubber compounds possessed superior mechanical and rheological properties compared to those of the other cured systems. It is interesting to note that all curing systems exhibited increases in tensile strength, hardness, tear strength and crosslink density after aging. This may be due to post vulcanization. Unlike uncured CSM compound, in cured CSM compound the loss tangent increased with frequency, which may be due to the insufficient time available for molecular relaxation. Probable crosslinked structures for different curing systems have been proposed based on the observations of attenuated total reflectance Fourier transform infrared spectroscopy.