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
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.
Eby Thomas, Thachil; Unnikrishnan, K P; Benny Cherian, A; Jenish, Paul(Universal Research Publications, December , 2011)
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Abstract:
In this study, pendant epoxy functional poly dimethyl siloxanes were synthesized by the hydrosilylation reaction of pendant silyl hydride functional polydimethyl siloxane with allyl glycidyl ether. The hydrosilylation reaction was characterized by spectroscopic techniques. Samples of pendant epoxy functional poly dimethyl siloxanes and pendant silyl hydride functional polydimethyl siloxane were blended with commercial epoxy resin, diglycidyl ether of bis-phenol A, at various ratios using a polyamine as curing agent. The results show that the addition of functionalised poly dimethyl siloxanes increases the flexibility of the cross linked network and also the thermal stability and water resistance
Description:
Advances in Polymer Science and Technology: An International Journal 2011; 1 (2): 22-29
Sunil,K Narayanankutty(Elsevier Science Publishers Ltd., August 29, 1991)
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Abstract:
The thermal degradation of short kevlar fibre-thermoplastic polyurethane
(TPU) composites has been studied by Thermogravimetric Analysis (TGA)
and Differential Scanning Calorimetry (DSC). TGA showed that the thermal
degradation of TPU takes place in two steps with peak maxima (T1max and
T2ma,) at 383°C and 448°C, respectively. In the presence of 10-40 phr of short
kevlar fibres, T1_ and T2max were shifted to lower temperatures. The
temperature of onset of degradation was increased from 245 to 255°C at 40
parts per hundred rubber (phr) fibre loading. Kinetic studies showed that the
degradation of TPU and kevlar-TPU composite follows first-order reaction
kinetics. The DSC study showed that there is an improvement in thermal
stability of TPU in the presence of 20 phr of short kevlar fibres.
Sunil,K Narayanankutty(Taylor & Francis Inc., October 28, 2004)
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Abstract:
The thermal properties of short Nylon-6 fiber-reinforced Styrene butadiene rubber
(SBR) composites were studied by Thermogravimetric Analysis (TGA). The effect
of epoxy-based bonding agent on thermal degradation of the gum and the composites
was also studied. The thermal stability of the SBR was enhanced in the presence
of Nylon-6 fibers and the stability of the composites increased in the presence
of bonding agent. The epoxy resin did not significantly change the thermal stability
of SBR gum vulcanizate. Results of kinetic studies showed that the degradation
of SBR and the short nylon fiber-reinforced composites with and without
bonding agents followed first-order kinetics.
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
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.