Rani, Joseph(OPA (Overseas Publishers Association), December 3, 1996)
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Abstract:
Filled and gum compounds of Isobutylene-Isoprene rubber were extruded through a
laboratory extruder at various feeding rates, different temperatures and revolutions per
minute. The extruded compounds were vulcanized up to their optimum cure times and
the mechanical properties of the vulcanizates were determined. The properties suggest
that there is a particular feeding rate in the starved fed region, which results in maximum
mechanical properties. The study shows that running the extruder at a slightly
starved condition is an attractive means of improving the physical properties.
Reactive extrusion is an attractive means of polymer processing since the shaping
and reaction take place in a single operation. In this paper we report the silane
grafting of polyethylenes in a single screw extruder. The optimum conditions for
silane grafting, viz. temperature, shear rate, silane and DCP concentrations, were
determined on a torque rheometer and then actual extrusion was performed
using these conditions. The study shows that an optimum low level of grafting/
crosslinking can be introduced into polyethylene during its extrusion for better
mechanical behavior and=or thermal stability without affecting the processability.
Filled compounds of natural rubber, isobutylene-isoprene rubber
and styrene-butadiene rubber compounds were extruded through a laboratory
extruder by varying the feeding rate at different temperatures and revolutions
per minute. The extruded compounds were vulcanized up to their optimum cure
times and the mechanical properties of the vulcanizates were determined. The
properties suggest that there is a particular feeding rate in the starved fed region
which results in maximum mechanical properties. The study shows that running
the extruder at a slightly starved condition is an attractive means of improving
the physical properties.
Gum and filled compounds of styrene-butadiene rubber are extruded
through a laboratory extruder by varying the feeding rase at different temperatures
and screw speed (rpm). The extruded compounds are vulcanized
up4o their optimum cure times and the mechanical properties of the vulcanizates
are determined. From the properties data obtained it Is concluded that
there is a specific feeding rate wit in the starved fed region, which results In
maximum Improved mechanical properties . The enhancement In properties
is found to be due to better thermal and shear homogeneity.
Sunil,K Narayanankutty(Technomic Publishing Co., Inc., April , 1998)
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Abstract:
The stress relaxation behavior of polyurethane elastomer and
short polyester fiber filled elastomer composites with and without bonding
agents at different strain levels and strain rates was studied. It was found that
these compounds exhibit a multistage relaxation mechanism and that the rate
of relaxation and cross-over time depend on the strain level and strain rate.
The incorporation of fibers reduced the stage-I relaxation rate and increased
the cross-over time of the gum vulcanisate. A higher rate of relaxation (first
stage) was shown by the composites with longitudinal fiber orientation and
composites with bonding agents.
Rani, Joseph(Hitthig & Wepf Verlag, Basel, October 13, 1986)
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Abstract:
A carbon black filled 50/50 natural rubber (NR)/styrene-butadiene rubber (SBR)
blend is vulcanized using several conventional curing systems designed by varying the
amounts of sulphur and accelerator. The cure characteristics and the properties of the
vulcanizates are compared. The quantity and quality of crosslinks in each case are
evaluated by chemical probes to correlate them with the properties.
Sunil,K Narayanankutty(Sage Publications, April , 2002)
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Abstract:
Cure characteristics and mechanical properties of acrylonitrile
butadiene rubber/reclaimed rubber blends were studied. Minimum torque,
(ma)dmum -minimum) torque, scorch time, cure time and cure rate decreased in
presence of reclaimed rul3ber. Tensile strength, elongation at break and
compression set increased'with increase in reclaim content. Resilience and
abrasion resistance decreased with reclaim loading. Heat build up was higher for
the blends. The ageing resistance of the blends was inferior to that of the gum
compound.
Sunil,K Narayanankutty(Sage Publications, April , 2002)
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Abstract:
Acrylonitrile butadiene rubber (NBR) matrix was reinforced with
different levels of short nylon fiber loading. Cure characteristics and mechanical
properties of composites in longitudinal and transverse directions have been
studied. Cure time was reduced while processability, as indicated by the
minimum torque, was marginally reduced with increase in fiber loading. Tensile
and tear properties improved with fiber concentration and the values were
higher in longitudinal direction of fiber orientation. Abrasion resistance,
resilience and compression set were increased in presence of fibers. Elongation
at break values showed a drastic drop on introduction of fibers. Heat build up
was higher for composites.
Rani, Joseph(John Wiley & Sons,Inc., December 29, 1997)
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Abstract:
ABSTRACT: The electrical conductivity of silicone rubber vulcanizates containing carbon
blacks [e.g., acetylene black, lamp black, and ISAF (N-234) black] were investigated.
The change in electrical conductivity with varying amounts of carbon blacks and the
temperature dependence was measured. The mechanical properties like tensile
strength, tear strength, elongation at break, hardness, etc., of the vulcanizates were
determined. A comparative study of the electrical conductivity of the composites revealed
that the electrical conductivity of the composites made with acetylene black was
higher than that of the composites made of other blacks.
Carbon Black is incorporated In natural rubber latex in , the presence of
polyethylene glycol. The dispersion of carbon blade in the vulcanizatea is
analyzed using polaroid M.4 land camera The mechanical properties of the
carbon black meeterbatched NR/SBR blend Is compared with that of conventional
NR/SBR blend before and after ageing , The resilience, flex resistance
and hardness are found to be superior for N-LCMISBR compounds.
The compression set and abrasion resistance are comparable for both types
of blends . The processebiity and die swell of these blends at different shear
rates are also compared.
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.
Paraphenylenediamine and diphenylamine were chemically
attached to natural rubber during mastication . The rubber bound antioxidants
were characterized by TLC, 'H-NMR, IR and TGA. The efficiency and
permenance of these bound antioxidants were compared with a conventional
amine type antioxidant in filled natural rubber vulcanizates . The rubber
bound antioxidants were found to be less volatile and less extractable as compared
to conventional antioxidants. The vulcanizates showed improved ageing
resistance as compared to vulcanizates containing conventional antioxidants.
This semisolid rubber bound antioxidant can reduce the amount of plasticizer
required for compounding.
Rani, Joseph(Elsevier Science Limited, July 3, 1994)
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Abstract:
Diphenylamine was chemically attached to depolymerised natural rubber by
photochemical reaction. The rubber-bound diphenylamine was characterised
by TLC, HNMR, IR and TGA. The efficiency and permanence of the bound
diphenylamine was compared with conventional amine type antioxidant in
natural rubber vulcanizates. The rubber-bound diphenylamine was found to be
less volatile and less extractable compared to the conventional antioxidant.
The vulcanizates showed improved ageing resistance in comparison to vulcanizates
containing conventional antioxidant . Also, the presence of liquid
rubber-bound diphenylamine reduces the amount of plasticiser required for
compounding.
Para-phenylenediamine (PD) was chemically attached to depolymerized natural rubber by
a photochemical reaction . The rubber bound PD was characterized by TLC, 1H-NMR, IR,
and TGA. The efficiency and permanence of the bound PD were compared with conventional
antioxidants in NBR vulcanizates . The rubber bound PD was found to be less volatile and
more resistant to water and oil extraction . The vulcanizates showed improved aging resistance
in comparison to vulcanizates containing conventional antioxidants. The liquid rubber
bound antioxidant reduces the amount of plasticizer required for compounding
Studies conducted on butadiene-acrylonitrile copolymer (NBR)/poly(vinyl chloride) (PVC)
blends at different temperatures indicate that an optimum temperature exists for the formation
of a particular blend. The mechanical properties of the blends confirm this observation.
PVC stabilizer based on, magnesium oxide , zinc oxide, and stearic acid was found to be very
useful in NBR/PVC blends.
Rani, Joseph(Huthig & Wepf Verlag, Basel, June 5, 1991)
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Abstract:
Antioxidants were attached to hydroxy-terminated liquid natural rubber by modified
Friedel-Crafts alkylation reaction using anhydrous zinc chloride as catalyst. The rubber
bound antioxidants were found to be less volatile and less extractable compared to
conventional antioxidants. The bound antioxidants were tried both in latex compounds
and dry rubber compounds. The vulcanizates showed improved ageing resistance
compared to vulcanizates based on conventional antioxidants.
Rani, Joseph(John Wiley & Sons,Inc., July 31, 1998)
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Abstract:
ABSTRACT: Nylon tire cord (1680/2) was dipped in different adhesives based on resorcinol
formaldehyde resin and latex (RFL) and was bonded to natural rubber-based
compounds. The resin-rubber ratio in the RFL adhesive was optimized. The variation
of pull-through load was studied by varying the drying and curing temperature of the
dipped nylon tire cord. RFL adhesive based on vinylpyridine latex was found to have
better rubber-to-nylon tire cord bonding, compared with the one based on natural
rubber latex. Addition of a formaldehyde donor into the RFL adhesive/rubber compound
improves adhesion.
In natural rubber/high styrene resin microcellular sheets, part of
natural rubber was replaced by latex reclaim prepared from waste
latex products. The mechanical properties and cell structure of
the products were evaluated. It was found that latex reclaim can
replace about 30% of natural rubber without affecting the technical
properties of the microcellular sheets.
Rani, Joseph(Gordon and Breach Science Publishers, Inc., November 13, 1986)
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Abstract:
A carbon black filled 50/50 Natural Rubber (NR)/Polybutadiene Rubber (BR) blend
is vulcanized using several conventional systems designed by varying the amounts of
sulphur and accelerator . The cure characteristics and the vulcanizate properties are
compared. The quality and quantity of crosslinks in each case are deciphered by
chemical probes to correlate them with the vulcanizate properties.
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.