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.
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
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.
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
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(Huthig & Wepf Verlag, Basel, April 29, 1986)
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Abstract:
Tribasic lead sulphate is tried as a practical curing agent for polychloroprene. The
cure characteristics of the compounds as well as the technical properties of the
vulcanizates show that it can act as a potential curative.
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.
Carboxy Terminated Liquid Natural Rubber (CTNR) was
prepared by photochemical reaction using maleic anhydride and masticated
natural rubber (NR). The use of CTNR as an adhesive in bonding rubber to
rubber and rubber to metal was studied. The peel strengths and lap shear
strengths of the adherends which were bonded using CTNR were determined.
The effect of using a tri isocyanate with CTNR in rubber to metal bonding was
also studied. It is found that CTNR can effectively be used in bonding rubber to
rubber and rubber to mild steel.
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.
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.
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(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.