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
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.
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.
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.
Rani, Joseph(OPA (Overseas Publishers Association) N.V., July 23, 1997)
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Abstract:
Selected grades of low density polyethylene (LDPE) polystyrene (PS) were extruded in a
laboratory extruder by varying the feeding rate at different revolutions per minute and
temperatures. The mechanical properties of the extruded plastic sheets were determined.
LDPE shows a marked variation in mechanical properties with feeding rate while PS
shows a marginal change in mechanical properties with feeding rate. However, for both
plastics there is a particular feeding rate in the starved region which results in maximum
mechanical properties.
Rani, Joseph(John Wiley & Sons, Inc., October 22, 1997)
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Abstract:
Rubber solutions were prepared and used for bonding wood pieces. The
effect of the variation of chlorinated natural rubber (CNR) and phenolformaldehyde
(PF) resin in the adhesive solutions on lap shear strength was determined. Natural
rubber and neoprene-based adhesive solutions were compared for their lap shear
strength. The storage stability of the adhesive prepared was determined. The change
in lap shear strength before and after being placed in cold water, hot water, acid,
and alkali was tested. The bonding character of these adhesives was compared with
different commercially available solution adhesives. The room-temperature aging
resistance of wood joints was also determined. In all the studies, the adhesive prepared
in the laboratory was found to be superior compared to the commercial adhesives.
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.
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.
Rani, Joseph(John Wiley & Sons. Inc, August 20, 1998)
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Abstract:
ABSTRACT: Rubber seed oil was used as a multipurpose ingredient in natural rubber
(NR) and styrene butadiene rubber (SBR) compounds. The study shows that the oil,
when substituted for conventional plasticiser, imparts excellent mechanical properties
to NR and SBR vulcanizates. Further, it also improves aging resistance, reduces cure
time, increases abrasion resistance and flex resistance, and reduces blooming.
Rani, Joseph(John Wiley & Sons, Inc., February 16, 1999)
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Abstract:
Microcellular (MC) soles based on polybutadiene (BR) and low-density
polyethylene (LDPE) blends for low-temperature applications were developed. A part of
BR in BR-LDPE blend was replaced by natural rubber (NR) for property improvement.
The BR-NR-LDPE blend-based MC sole shows good technical properties. Sulphur
curing and DCP curing were tried in BR-LDPE and NR-BR-LDPE blends. Study
shows that sulphur-cured MC sheets possess better technical properties than DCPcured
MC sheets. 90/10 BR-LDPE and 60/30/10 BR-NR-LDPE blend combinations are
found to be suitable for low-temperature applications.
Rani, Joseph(John Wiley & Sons, Inc., March 20, 2000)
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Abstract:
ABSTRACT: Zinc salts of ethyl, isopropyl, and butyl xanthates were prepared in the
laboratory. They were purified by reprecipitation and were characterized by IR, NMR,
and thermogravimetric analysis techniques. The melting points were also determined.
The rubber compounds with different xanthate accelerators were cured at temperatures
from 30 to 150°C. The sheets were molded and properties such as tensile strength,
tear strength, crosslink density, elongation at break, and modulus at 300% elongation
were evaluated. The properties showed that all three xanthate accelerators are effective
for room temperature curing.
Rani, Joseph(John Wiley & Sons, Inc., November 1, 2000)
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Abstract:
ABSTRACT: p-Phenylenediamine was chemically attached to low molecular weight chlorinated
paraffin wax. The polymer-bound p-phenylenediamine was characterized by
vapor-phase osmometry (VPO), proton magnetic resonance spectroscopy ('H-NMR),
infrared spectroscopy (IR), and thermogravimetric analysis (TGA). The efficiency and
permanence of the polymer-bound p-phenylenediamine as an antioxidant was compared
with a conventional amine-type antioxidant in natural rubber vulcanizates. The
vulcanizates showed improved aging resistance in comparison to vulcanizates containing
a conventional antioxidant. The presence of liquid polymer-bound p-phenylenediamine
also reduces the amount of the plasticizer required for compounding.
Rani, Joseph(John Wiley & Sons, Inc., November 8, 2000)
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Abstract:
ABSTRACT: The dipping characteristics of radiation-vulcanized natural rubber latex
and natural rubber latex compounds were investigated with a lab-model semiautomatic
dipping machine. The effect of the variation of the speed of immersion and withdrawal,
dwell time, compound viscosity, and concentration of coagulant on the thickness of the
latex deposit was investigated. The results of the study show that the deposit thickness
depends on the withdrawal speed of the former, the concentration of the coagulant,
dwell times, and the viscosity of the latex compounds