Rani, Joseph; Jayamma,Francis; George,K E(Pergamon Press Ltd, December 18, 1991)
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Abstract:
The effects of modifying blends of poly(vinyl chloride) (PVC) with linear low density
polyethylene (LLDPE) by means of acrylic acid, maleic anhydride, phenolic resins and p-phenylene
diamine were investigated. Modification by acrylic acid and maleic anhydride in the presence of dicumyl
peroxide was found to be the most useful procedure for improving the mechanical behaviour and adhesion
properties of the blend. The improvement was found to be due mainly to the grafting of the carboxylic
acid to the polymer chains; grafting was found to be more effective in LLDPE/PVC blends than in pure
LLDPE.
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.
Ethylene-propylene-diene rubber (EPDM) and isobutylene-isoprene rubber (IIR) were
compounded, precured to a low degree, and then were blended with natural rubber (NR).
The compounding ingredients for NR were then added and the final curing was done. NR/
EPDM and NR/IIR blends, prepared using this method, were found to possess much
improved mechanical properties as compared to their conventional counterparts. The optimum
precuring crosslink density that has to be given to the EPDM and IIR phases has
been determined.
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.
Blends of 50/50 natural rubber (NR) and styrene-butadiene rubber (SBR) are vulcanized using
several conventional and semi-EV systems. The cure characteristics and vulcanizate properties
are compared. The quantity and quality of crosslinks in each case are deciphered by chemical
probes to correlate them with the vulcanizate properties.
Rani, Joseph(Gordon and Breach Science Publishers, Inc., August 30, 1985)
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Abstract:
Blends of natural rubber (NR) with styrene-butadiene rubber (SBR), polybutadiene
rubber (BR), ethylene-propylene terpolymer (EPDM) and acrylonitrile-butadiene
rubber (NBR) were vulcanised using an efficient vulcanisation (EV) system and a
semi-EV system. Compatible blends show a definite pattern of curing whereas the
incompatible blends show no such pattern.