ELSEVIER Polymer Testing 16 (1997) 335-347 0 1997 Elsevier Science Ltd PII: SO142-9418(97)00055-4 Printed in Great Britain. All rights reserved 0142-9418/97/$17.00 Investigation of the Influence of Duration of Compression and Recovery on the Electrical Conductivity of HAF-Loaded Rubber Vulcanizates G. M. Nasr,* E. Ateia, M. M. Badawy & S. S. Hamza Physics Department, Faculty of Science, Cairo University, Cairo, Egypt (Received 2 April 1996; accepted 24 October 1996) ABSTRACT zyxwvutsrqponmlkjihgfedcbaZYXWVU The influence of previous straining for different times (0, IL?, I, 5, 7 and 24 h) on the electrical conductivity of HAF black loaded (SBR, NR and BR) vulcanizates was studied. It was found that previous compression to a given hydrostatic pressure (CO.42 Mpa) increases the conductivity level with time, but, for compression (~0.42 Mpa) the effect lessens with increase of pressure. The recovery of conductivity with time of standing at room temperature (for all samples) after straining was also inves- tigated. 0 1997 Elsevier Science Ltd 1 INTRODUCTION Electrical conductivity is important in many rubber and plastic compounds including anti-static applications, wire and cable sheathing and shielding against electro-magnetic interference (EMI). Elastomers and plastics are insu- lators (dielectrics) to which conductivity is imparted by the addition of a finely divided or colloidal filler of high intrinsic conductivity, such as carbon black. I,* A good dispersion of carbon black in the rubber matrix is very important in obtaining optimum mechanical properties of the compound.3 An appropriate method to detect the different degrees of dispersion is based on measurements of the electrical conductivity of the rubber compounds.44 In recent years, different factors affecting the conductivity of the compounds have been stud- *To whom correspondence should be addressed. 335