Rani, Joseph(Gordon and Breach Science Publishers S.A., October 16, 1992)
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Abstract:
Butyl (IIR) tube reclaim (RR) was mixed with carbon black filled natural rubber (NR) compounds at
various percentages. The blend containing a low percentage of RR was found to show improved ageing
resistance and improved processability with out much reduction in the mechanical properties.
The self adhesion behaviour of thermoplastic polyurethane (TPU) in itself and its
composite with short Kevlar fibre with respect to contact time, temperature, pressure, and fibre
loading has been studied. The adhesion strength showed two linear increments of different slopes
with respect to the square root of time: with temperature and pressure of contact, the adhesion
strength was improved. The maximum strength was obtained with 20 phr of short fibre in only one of
the mating substrates in the peel test sample. The duration for wetting and diffusion was shifted to
longer time intervals with fibres loaded in both the substrates.
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.
Rani, Joseph(Huthig & Wepf Verlag,Basel, April 16, 1993)
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Abstract:
Scrap latex products contain rubber hydrocarbon of very high quality, that is only
slightly crosslinked. A novel economic technique for converting such latex waste into
a processible material is developed. This paper reports the effect of adding this latex
reclaim to natural rubber. It is shown that latex reclaim can replace raw natural rubber
up to about 50 wt.% without affecting mechanical properties.
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.
Rani, Joseph(OPA (Overseas Publishers Association), July 15, 1994)
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Abstract:
The mechanical properties of filled natural rubber latex vulcanizates were found to be improved by the
addition of polyethylene glycols of different molecular weight and glycerol. There is a slight reduction
in the optimum cure times of the compounds containing PEG/Glycerol. The morphology study shows
that the filler distribution is more uniform in the compounds containing PEG/Glycerol.
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.
ABSTRACT: The rheological and extrudate behaviour of natural rubber/latex
reclaim blends were evaluated using a capillary viscometer . The study shows
that the viscosity of natural rubber decreases marginally on the addition of
latex reclaim while the variation of viscosity with shear rate is not affected.
The temperature sensitivity of the blends is not affected significantly with the
addition of latex reclaim . The extrudates of natural rubber/latex reclaim
blends are smooth up to the addition of about 50 wt. percent latex reclaim in
filled natural rubber compounds.
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
The cure characteristics of short fiber-polyurethane elastomer
were studied with respect to different fiber-matrix bonding agents. A hexamethylenetetramine-
resorcinol -hydrated silica based bonding agent was found to affect
the stability of the composite. A new bonding agent, TP resin, based on polymeric
toluenediisocyanate and polypropylene glycol has been developed. Cure characteristics
of the composite with and without TP resin at different fiber loadings were
also compared. Minimum torque, scorch time and optimum cure time increased
with fiber content. Maximum torque was consistently higher with TP resin at all
fiber loadings.
Rani, Joseph(OPA (Overseas Publishers Association), May 28, 1995)
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Abstract:
Amine Terminated Liquid Natural Rubber (ATNR) was used as a plasticiser in filled NR and NBR
compounds replacing oil/DOP. The scorch time and cure time were found to be lowered when ATNR
was used as the plasticiser. ATNR was found to improve the mechanical properties like tensile strength,
tear strength and modulus of the vulcanizates . The ageing resistance of the vulcanizates containing ATNR
was superior compared to the vulcanizates containing oil/DOP.
ABSTRACT: Linseed oil is used in the dual roles of the plasticizer and the fatty
acid component of the activator in nitrile rubber vulcanizates. The study shows
that the substitution can substantially improve the mechanical properties in
addition to other advantages such as increased cure rate, reduced leachability
and reduced compound cost.
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.
Waste latex products are converted to a processabto material by a novel
economical process developed in our laboratory , It contains rubber hydrocarbon
of very high quality and Is lightly cross -linked. Styrene-butadlene
rubber is mixed with latex reclaim In different proportions . The mechanical
properties are found to be improved up to 60 percent replacement of
styrene-butadlene rubber by latex reclaim . The curing of styrene-butadiene
rubber Is found to be accelerated by the addition of latex reclaim. The
processablllty study shows that the blends can be processed similar to
SBRINR blends.
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.
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(OPA (Overseas Publishers Association), January 7, 1997)
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Abstract:
Cure characteristics of short polyester fiber-polyurethane composites with respect to
different bonding agents (MD resins) based on 4, 4' diphenylmethanediisocyanate (MDI)
and various diols like propyleneglycol (PG), polypropyleneglycol (PPG) and glycerol
(GL) were studied. Tmax. - Tmin. of composites having MD resin were found to be
higher than the composite without MD resin. Minimum torque and Tmax. - Tmin.,
scorch time and optimum cure time were increased with the increase of MDI equivalence.
Optimum ratio of MDI / -of in the resin was found to be within the range of
1-1.5. It was observed from the cure characteristics that for getting better adhesion
between short polyester fiber and the polyurethane matrix the best choice of MD resin
was one based on MDI and 1:1 equivalent mixture of polypropyleneglycol and glycerol.
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.
Sunil,K Narayanankutty(Elsevier Science Limited, May 17, 1997)
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Abstract:
The thermal degradation of short polyester fiber reinforced polyurethane composites
with and without different bonding agents has been studied by thermogravimetric
analysis . It was found that degradation of the polyurethane takes
place in two steps and that of the composites takes place in three steps. With
the incorporation of 30 phr of fiber in the matrix , the onset of degradation was
shifted from 230 to 238 ° C. The presence of bonding agents in the virgin elastomer
and the composite gave an improved thermal stability . Results of kinetic studies
showed that the degradation of polyurethane and the reinforced composites with
and without bonding agents follows first -order reaction kinetics