a b s t r a c t
Fracture in rubber, like in all other materials, is initiated at imperfections inadvertently
present or introduced in the body of the material or on the surface during processing. The
point of initiation of fracture in the rubber is usually at flaws which are macroscopic or
microscopic imperfections or inhomogeneities in the rubber. In order to investigate the
effect of these flaws on the properties of a natural rubber compound, cuts to mimic weld
lines were introduced before and near scorch at various cure temperatures, and the time
for a complete healing of these cuts determined. The tensile properties were not significantly
affected by the introduction of weld lines before scorch provided sufficient time was
allowed for healing. Healing time reduced with increase in cure temperature. The intrinsic
flaw sizes in a material inherently affect the material tensile properties and depend
significantly on the size of the flaw. Pinhole flaws of varying sizes introduced after cure had
a significant effect on both tensile strength and fatigue life with the pinhole equivalent
intrinsic flaw size estimated to be about 200 mm.
Crown Copyright 2009 Published by Elsevier Ltd. All rights reserved.