Sunil,K Narayanankutty(Taylor & Francis, November 13, 2000)
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Abstract:
Cure characteristics and mechanical properties of short nylon fiber reinforced
acrylonitrile butadiene rubber-reclaimed rubber composites were studied. Minimum
torque, (maximum-minimum) torque and cure rate increased with fiber
concentration. Scorch time and cure time decreased by the addition of fibers.
Properties like tensile strength, tear strength, elongation at break, abrasion loss
and heat build up were studied in both orientations of fibers. Tensile and tear
properties were enhanced by the addition of fibers and were higher in the longitudinal
direction. Heat build up increased with fiber concentration and were
higher in the longitudinal direction. Abrasion resistance was improved in presence
of short fibers and was higher in the longitudinal direction. Resilience increased
on the introduction of fibers. Compression set was higher for blends.
Blends of nitrile rubber and reclaimed rubber containing different levels of a
coupling agent, Si 69 (bis(3- triethoxysilyl propyl)(tetrasulphide) were prepared
and the cure characteristic's and mechanical properties were studied. Optimum
loading of Si-69 was found to be a function of blend ratio. 3 phi- of Si 69 in a
70:30. Blend was found to be the optimum combination with respect to the
mechanical properties. The rate and state of cure were also affected bv the
conp/ing agent. Tensile strength, tear strength and abrasion resistance were
improved in the presence of coupling agent. While the state of cure improved,
the cure rate and scorch time decreased with increasing silane content. Ageing
studies showed that the blends containing the coupling agent were inferior to
the unmodified blends.
Blends of Acrylonitrile rubber with Maleic anhydride grafted Whole Tyre
Reclaim WTR (MA-g-WTR) have been prepared and the cure and mechanical
properties have been studied with respect to reclaim content. Control
compounds containing unmodified WTR were also prepared for comparison.
Grafting was confirmed by IR studies. Blends containing grafted WTR showed
higher minimum torque and (max-min) torque. They also showed longer cure
time, scorch time and lower cure rate. Grafting of the WTR with maleic
anhydride also resulted in the improved tensile strength, abrasion resistance,
compression set and resilience. However, the heat build up under dynamic
loading was marginally higher for the blends containing grafted reclaimed
rubber.