Sunil K Narayanankutty(Marcel Dekker , Inc., 2004)
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Abstract:
Blends of styrene butadiene rubber (SBR) with maleic anhydride
grafted whole tire reclaim (MA-g-WTR) have been prepared and the
cure and mechanical properties have been studied with respect to the
reclaim content. The grafting was carried out in the presence of
dicumylperoxide (DCP) in a Brabender Plasticorder at 150'C. The
presence of anhydride group on the WTR was confirmed by infrared
spectrometry (IR) study. The properties were compared with those of
the blends containing unmodified WTR. Though the cure time was marginally higher, the mechanical properties of the blends containing
grafted WTR were better than that of the unmodified blends.
Sunil K Narayanankutty(Taylor & Francis LLC, 2005)
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Abstract:
The thermal degradation of short nylon-6 fiber reinforced acrylonitrile
butadiene rubber (NBR) composites with and without epoxy-based bonding
agent has been studied by thermogravimetric analysis (TGA). It was found that
the onset of degradation shifted from 330.5 to 336.1°C in the presence of short
nylon fiber, the optimum fiber loading being 20 phr. The maximum rate of degradation
of the composites was lower than that of the unfilled rubber compound,
and it decreased with increase in fiber concentration. The presence of epoxy
resin-based bonding agent in the virgin elastomer and the composites improved
the thermal stability. Results of kinetic studies showed that the degradation of
NBR and the short nylon fiber reinforced composites followed first-order
kinetics.
Sunil K Narayanankutty(Taylor & Francis Inc., August 23, 2004)
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Abstract:
The rheological characteristics of short Nylon-6 fiber-reinforced Styrene
Butadiene rubber (SBR) in the presence of epoxy resin-based bonding agent were
studied with respect to the effect of shear rate, fiber concentration , and temperature
on shear viscosity and die swell using a capillary rheonzeter. All the composites
containing bonding agent showed a pseudoplastic nature, which decreased
with increasing temperature. Shear viscosity was increased in the presence of
fibers. The temperature sensitivity of the SBR matrices was reduced on introduction
of fibers. The temperature sensitivity of the melts was found to be lower at
higher shear rates. Die swell was reduced in the presence of fibers. Relative viscosity
of the composites increased with shear rate. In the presence of epoxy resin
bonding agent the temperature sensitivity of the mixes increased. Die swell was
larger in the presence of bonding agent.
Sunil K Narayanankutty(Taylor & Francis Inc., 2005)
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Abstract:
The rheological characteristics of short Nylon-6 fiber reinforced styrene butadiene
rubber (SBR) were studied using a capillary rheometer. The study was done with
respect to the effect of shear rate, fiber concentration, and temperature on shear
viscosity and die swell. All the melts showed pseudoplastic nature, which
decreased with increasing temperature. Shear viscosity increased in the presence
of fibers. Introduction of fiber reduces the temperature sensitivity of the rubber
matrix. A reduction in die swell was found in presence of fibers.
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.
Chloroprene rubber was blended with whole tire reclaimed rubber
(WTR) in presence of different levels of a coupling agent Si69 [bis-
(3-(triethoxysilyl)propy1)tetrasuIfide] and the cure characteristics and
mechanical properties were studied. The rate and state of cure were
also affected by the coupling agent. While the cure time was increased,
the cure rate and scorch time were decreased with increasing silane
content. Tensile strength, tear strength, and abrasion resistance were
improved in the presence of coupling agent. Compression set and
resilience were adversely affected in presence of silane-coupling agent.Aging 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.
Sunil K Narayanankutty(Rapra Technology, August 29, 2006)
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Abstract:
Mechanical properties and thermal degradation of natural rubber compounds
containing castor oil were studied to evaluate its suitability as plasticizer.
Naphthenic oil was used as a reference plasticizer. The cure time was marginally
lower in the case of castor oil mixes, probably due to the presence offree fatty acids
in it. The tear strength and modulus were better in the case of mixes containing
castor oil, while most of the other mechanical properties were comparable to
the mixes containing naphthenic oil. The heat build up and compression set were
higher than that of the naphthenic oil mixes. Thermal studies showed an increase
of 8 °C in the temperature of initiation of degradation and an increase of 6 °C in
the temperature at which the peak rate of degradation occurred. The peak rate
of degradation was comparable to that of the reference compound
Mechanical properties and thermal degradation characteristics of natural rubber compounds
captaining coconut oil were compared with that of a control compound containing naphthenic oil.
Cure time was marginally lower in the case of coconut oil mixes, probably due to the presence of
free fatty acids. Tensile strength , tear strength, resilience and abrasion resistance were better than
the naphthenic oil-based compounds . Compression set and hardness were marginally inferior
The coconut oil mixes had a crosslink density comparable to that of the reference compound.
Thermal studies showed that the temperature of initiation of degradation was increased by 10°C
and the temperature at which the peak rate of degradation occured was increased by 7°C. The
peak rate of degradation was compa rable to the control compound.