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Abstract
The present work is mainly concerned with the effect of the order of addition,
concentration and working temperature of two types of carbon black namely GPF and HAF on
the electrical, mechanical and physicomechanical properties of Styrene Butadiene Rubber
composites.
In the present work, a trial has been made to follow up and understand the conduction
mechanism if two types of carbon black are added to rubber vulcanizates with fixed total
concentration but different order of addition.
Two groups of samples were composed. In the first, named HGs, the HAF carbon black
was added first with different concentration and then GPF black was added such that the total
concentration of both types was 60 phr. In the second named GHs, the GPF carbon black was
added first and the total concentration was also 60 phr.
The unvulcanized samples were cured under a heater press at 150CO and 200 KN/m2 . The
conductivities of these samples were measured during vulcanization as a function of time. For
all samples, the electrical conductivities show an increase and reach an optimum value ”am” after
a characterisitic time for each sample ”t•”. The constancy of conductivity was followed up to 24
hrs. This was taken as an indication of a completeness of vulcanization process.
The current voltage characteristics of both groups of vulcanized samples were studied at
room temperature and also at different temperatures. These characteristics show an Ohmic
behaviour up to certain limits of applied voltage ”Y””, after which the samples may be heated
up by Joule effect.