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.
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.
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(Wiley Inter Science, December 14, 2005)
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Abstract:
Polypyrrole/poly (vinyl chloride) semi-interpenenzrtirtg
networks of different compositions are prepared using anunonitun per
sulfate initiator at room temperature in pellet.form and lilrrt form and
their dielectric properties are studied at different microwave frequencies.
An HP 8510 Vector network analyzer interfaced with a computer
is used. The cavity-perturbation technique is employed for the
study
Rani, Joseph(Wiley Periodicals, Inc., October 23, 2003)
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Abstract:
Poly(o-toluidine) (PoT) and poly(o-toluidine
co aniline) were prepared by using ammonium persulfate
initiator, in the presence of 1M HCI. It was dried under
different conditions: room temperature drying (48 h), oven
drying (at 50°C for 12 h), or vacuum drying (under vacuum,
at room temperature for 16 h). The dielectric properties, such
as dielectric loss, conductivity, dielectric constant, dielectric
heating coefficient, loss tangent, etc., were studied at microwave frequencies. A cavity perturbation technique was used
for the study. The dielectric properties were found to be
related to the frequency and drying conditions. Also, the
copolymer showed better properties compared to PoT alone.
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
The effect of an external flaw on the tensile strength of short kevlar fiber-thermoplastic
composites has been studied with respect to fiber content, fiber orientation,
location of the external flaw, and the temperature of test. The composites showed
a three-step reduction in tensile strength with increasing flaw size. The critical flaw-length
region was shifted to higher flaw-size levels with increasing fiber content. With increasing
temperature, the critical flaw length was increased in the case of unfilled TPU, whereas it
remained more or less constant in the case of short kevlar fiber-filled-TPU composite.
Sunil,K Narayanankutty(Technomic Publishing Co., Inc., June 1, 1992)
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Abstract:
The flammability of short Kevlar aramide fiber-thermoplastic
polyurethane (TPU) has been investigated with respect to fiber loading and
various flame retardant additives such as halogen containing polymers, antimony
oxide/chlorine donor combination, zinc borate, and aluminum hydroxide.
Smoke generation was reduced drastically, while the oxygen index was reduced
marginally in the presence of short fibers. The best improvement in the oxygen
index was obtained with antimony oxide/chlorinated paraffin wax combination,
in the weight ratio 1:6. A 70 phr loading of aluminum hydroxide improved LOI
and reduced smoke generation.
Latex waste products contain rubber hydrocarbon of very high
quality, which is only lightly cross linked. Selected wastes such as thread waste
and glove waste were modified into processable materials by a novel economic
process and thermoplastic elastomers were prepared by blending these modified
waste materials with high density polyethylene in various proportions. The
mechanical properties as well as the rheological behaviour of these blends were
evaluated and compared with those of the natural rubber-high density
polyethylene blends.
Latex waste like glove waste was effectively modified using a new reclaiming
agent, thiocarbanilide. This modified waste was blended with linear low-density
polyethylene (LLDPE) to develop a novel thermoplastic elastomer. Both uncrosslinked
and dynamically crosslinked blends were prepared and their properties
were studied. The results were found to be comparable to those of conventional
thermoplastic elastomers.
Zinc butyl xanthate [Zn(bxt)2] was prepared
in the laboratory . The effect of this xanthate with zinc
diethyl dithiocarbamate (ZDC) on the vulcanization of natural
rubber ( NR), polybutadiene rubber (BR), and NR/BR
blend has been studied at different temperatures. The
amounts of Zn (bxt)2 and ZDC in the compounds were optimized
by varying the amount of ZDC from 0 . 75 to 1.5 phr
and Zn (bxt)2 from 0 . 75 to 1 .5 phr. The cure characteristics
were also studied . HAF filled NR, BR, and NR / BR blend
compounds were cured at different temperatures from 60 to
150 C. The sheets were molded and properties such as tensile strength, tear strength, crosslink density and elongation
at break, compression set, abrasion resistance, etc. were
evaluated. The results show that the mechanical properties
of 80NR/20BR blends are closer to that of NR vulcanizates,
properties of 60NR/40BR blends are closer to BR vulcanizates,
while the 70NR/30BR blends show an intermediate
property.
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.
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.
Sunil,K Narayanankutty(Taylor & Francis Inc., March 26, 2001)
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Abstract:
Cure characteristics and mechanical properties of styrene butadiene rubber
reclaimed rubber blends were studied. The blends showed improved processability,
as indicated by the minimum torque values. Cure characteristics like minimum
torque, (maximum-minimum) torque, cure time and cure rate decreased in the
presence of reclaimed rubber. Tensile strength, tear strength, elongation at break
were higher for blends. Resilience decreased with reclaim content. Compression set
and abrasion loss were higher in the blends.
Rani, Joseph(Indian Academy of Sciences., September 30, 2005)
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Abstract:
Natural rubber/isora fibre composites were cured at various temperatures. The solvent swelling
characteristics of natural rubber composites containing both untreated and alkali treated fibres were investigated
in aromatic and aliphatic solvents like toluene, and n-hexane. The diffusion experiments were conducted by
the sorption gravimetric method. The restrictions on elastomer swelling exerted by isora fibre as well as the
anisotropy of swelling of the composite have been confirmed by this study. Composite cured at 100°C shows
the lowest percentage swelling. The uptake of aromatic solvent is higher than that of aliphatic solvent for the
composites cured at all temperatures. The effect of fibre loading on the swelling behaviour of the composite was
also investigated in oils like petrol, diesel, lubricating oil etc. The % swelling index and swelling coefficient of
the composite were found to decrease with increase in fibre loading. This is due to the increased hindrance exerted
by the fibres at higher fibre loadings and also due to the good fibre-rubber interactions. Maximum uptake
of solvent was observed with petrol followed by diesel and then lubricating oil. The presence of bonding agent in
the composites restrict the swelling considerably due to the strong interfacial adhesion. At a fixed fibre loading,
the alkali treated fibre composite showed lower percentage swelling compared to the untreated one.
Zinc salts of ethyl, isopropyl and butyl xanthates were prepared in the laboratory. The
effect of these xanthates with zinc diethyldithiocarbamate (ZDC) on the vulcanization
of HAF filled NR compound has been studied at different temperatures. The
rubber compounds with the three xanthate accelerators and ZDC were cured at various
temperatures from 60°C to 150°C. The sheets were moulded and properties such as tensile
strength , tear strength , cross-link density, elongation -at-break, compression set, heat
build up, abrasion resistance, flex resistance , etc. were evaluated . The properties
showed that zinc xanthate/ZDC accelerator combination has a positive synergistic effect
on the mechanical properties of NR compounds. The curing of HAF filled NR compound
containing zinc xanthate /ZDC is slightly slower than the curing of the corresponding gum
compounds . It is observed that, by gradually increasing the amount of the accelerator, the
cure time of black filled NR compound can be made equal to that of the gum compou