New oligomer-bound antioxidants have been prepared by condensation reaction. The efficiency and permanence of these oligomer-
bound paraphenylene diamines as antioxidants has been compared with conventional amine type antioxidants in NR, SBR,
IIR and NBR and in elastomer blends like NR/BR and NR/SBR. The oligomer-bound antioxidants are found to impart improved
ozone, flex resistance and mechanical properties to the vulcanizates of NR, SBR, IIR and NBR and to blends of NR/BR and NR/
SBR in comparison with those containing conventional antioxidants.
Zinc salts of ethyl, isopropyl, and butyl xanthates
were prepared in the laboratory. The effect of these
xanthates in combination with zinc diethyldithiocarbamate
(ZDC) on the vulcanization of silica-filled NBR compounds
has been studied at different temperatures. The cure times
of these compounds were compared with that of NBR compounds
containing tetramethylthiuram disulphide/dibenzthiazyl
disulphide. The rubber compounds with the xanthates
and ZDC were cured at various temperatures from
60 to 150°C. The sheets were molded and properties such as tensile strength, tear strength, crosslink density, elongation
at break, compression set, abrasion resistance, flex resistance,
heat buildup, etc. were evaluated. The properties
showed that zinc salt of xanthate/ZDC combination has a
positive synergistic effect on the cure rate and mechanical
properties of NBR compounds.
Rani, Joseph(Indian Academy of Sciences, February 24, 2003)
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Abstract:
Significant results of our experimental investigations on the dependence of pH on real time
transmission characteristics on recording media fabricated by doping PVC with complexed methylene blue
are presented. The optimum pH value for faster bleaching was found to be 4 . 5. In typical applications, the
illumination from one side, normal to the surface of this material, initiates a chemical sequence that records
the incident light pattern in the polymer. Thus direct imaging can be successfully done on this sample. The
recorded letters were very legible with good contrast and no scattering centres. Diffraction efficiency
measurements were also carried out on this material.
Poly(ethylene terephthalate) (PET) based nanocomposites have been prepared with single walled carbon nanotubes
(SWNTs) through an ultrasound assisted dissolution-evaporation method. Differential scanning calorimetry studies
showed that SWNTs nucleate crystallization in PET at weight fractions as low as 0.3%, as the nanocomposite melt crystallized
during cooling at temperature 24 °C higher than neat PET of identical molecular weight. Isothermal crystallization
studies also revealed that SWNTs significantly accelerate the crystallization process. Mechanical properties of the PETSWNT
nanocomposites improved as compared to neat PET indicating the effective reinforcement provided by nanotubes
in the polymer matrix. Electrical conductivity measurements on the nanocomposite films showed that SWNTs at concentrations
exceeding 1 wt% in the PET matrix result in electrical percolation. Comparison of crystallization, conductivity and
transmission electron microscopy studies revealed that ultrasound assisted dissolution-evaporation method enables more
effective dispersion of SWNTs in the PET matrix as compared to the melt compounding method
Rani, Joseph(American Institute of Physics, January 13, 2007)
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Abstract:
Poly(methyl)methacrylate was made photoconducting by molecular doping and the
photoconductivity was investigated using modulated photocurrent technique . Low-temperature
current-voltage measurements showed that the transport mechanism was thermally activated
hopping. An experimental investigation of the photoconductivity action spectrum along with
theoretical calculation enabled an estimation of the diffusion coefficient of the material. The
presence of states with a distribution of lifetimes could be understood from the frequency response
of the photocurrent . The photocurrent was due to the field-assisted dissociation of these states
This 'study' deals with a preliminary study of automatic beam
steering properly in conducting polyaniline . Polyaniline in its undoped and
doped .state was prepared from aniline by the chemical oxidative polymerization
method. Dielectric properties of the samples were studied at S-band
microwave frequencies using cavity perturbation technique. It is found that
undoped po/vanihne is having greater dielectric loss and conductivity contpared
with the doped samples. The beam steering property is studied using
a perspex rod antenna and HP 85/OC vector network analyzer. The shift in
the radiated beam is studied for different do voltages. The results show that
polyaniline is a good nutterial far beam steering applications.
Rani, Joseph(Gordon and Breach Science Publishers, Inc., November 28, 1986)
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Abstract:
Polymer-solvent interaction parameters for the blends of natural rubber (NR) with
styrene-butadiene rubber (SBR) and polybutadiene rubber ( BR) are calculated using
the Flory-Rehner equation by equating the network density of the vulcanizates in
two solvents.
ABSTRACT: Phenol was chemically attached to low molecular weight
chlorinated polyisobutylene and stearic acid respectively. These phenolic
antioxidants were characterised by IR, 1H NMR and TGA. The efficiency and
permanence of these bound antioxidants were compared with conventional
antioxidants in natural rubber vulcanisates. The vulcanisates showed comparable
ageing resistance in comparison to vulcanisates containing conventional
antioxidants. The presence of liquid polymer bound phenol reduce the amount of
plasticiser required for compounding.
Rani, Joseph(Wiley InterScience, October 22, 2006)
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Abstract:
Polymers exhibit low electron density and
they are radiolucent. Polymers can be made radiopaque
by different techniques. We report a method for the preparation
of radiopaque material from natural rubber (NR).
NR in its latex form was iodinated. Iodinated natural
rubber (INR) was characterized by using UV, thermo
gravimetric analysis (TGA), and X-ray images. INR was
compounded at high and low temperatures and its physical properties were measured. The low temperature
cured samples show good radiopacity and conductivity.
The optical density of low temperature cured samples
was measured.
Low-protein content natural rubber latex
was produced by using a nonionic surfactant-polyethylene
glycol (PEG). Extractable protein content of natural rubber
latex was found to decrease with PEG treatment and
reduction increased with increase in the molecular weight
of PEG. The low-protein latex samples were characterized
by tensile testing, Fourier transform infrared and thermogravimetric
analysis. The results have shown 35% reduction in the extractable protein content, without any compromise
on the mechanical properties of the latex; however,
thermal stability of low-protein latex was found to be
reduced marginally with PEG treatment.
Rani, Joseph(Wiley lnterScience, February 12, 2006)
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Abstract:
It is observed that reclamation of natural rubber
latex based rubber using 2,2'-dibenzamidodiphenvldisulphide
as reclaiming agent is an optional methodology for
recycling of waste latex rubber (WLR). For progressive replacement
of virgin natural rubber by the reclaim, two alternatives
curing system were investigated: adjustment or reduction of
the curing system with increasing reclaim content, to compensate
for the extra amount of curatives brought along by the reclaim.
For fixed curing system, as if the reclaim were equivalent
to virgin NR. The cure behavior, final crosslink density
and distribution, mechanical properties, and dynamic
viscoelastic properties of the blends with reclaimed WLR are
measured and compared with the virgin compound. The morphology of the blends, sulfur migration, and final distribution
are analyzed.The mechanical and dynamic viscoelastic
properties deteriorate for both curing systems, but to a lesser
extent for fixed curing system compared to adjusted curing
system. With the fixed cure system, many properties like tensile
strength and compression set do still deteriorate, but tan 6
and Mrrr„/Murxr, representative for the rolling resistance of tires
are improved. On the other hand, with the adjusted cure system
both mechanical and dynamic properties still deteriorate.
A new photopolymerizable recording media is introduced based on poly
(vinyl alcohol) and vinyl acetate sensitized with methylene blue. It is observed
that this MBPVA/VAc system can be reused a number of times without
significant decrease in diffraction efficiency. The PVA-VAc ratio was optimized
at 2:1. Diffraction efcienc4y of 6.3% was obtained without any fixing at a dye
concentration of 9.3 x 10- mol/l at an exposure of 750mJ/cm2. The material is
attractive on account of its reusability.
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.
Sunil,K Narayanankutty(Taylor & Francis Inc., August 23, 2004)
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Abstract:
The rheological characteristics of short Nylon-6 fiber-reinforced Styrene
Butadiene rubber (SBR) in the presence of epoxy resin-based bonding agent were
studied with respect to the effect of shear rate, fiber concentration , and temperature
on shear viscosity and die swell using a capillary rheonzeter. All the composites
containing bonding agent showed a pseudoplastic nature, which decreased
with increasing temperature. Shear viscosity was increased in the presence of
fibers. The temperature sensitivity of the SBR matrices was reduced on introduction
of fibers. The temperature sensitivity of the melts was found to be lower at
higher shear rates. Die swell was reduced in the presence of fibers. Relative viscosity
of the composites increased with shear rate. In the presence of epoxy resin
bonding agent the temperature sensitivity of the mixes increased. Die swell was
larger in the presence of bonding agent.
The rheological behavior of a short-polyester-fiber-filled polyurethane
elastomer composite containing different bonding agents
has been studied in the temperature range 120-160°C and in the
shear rate range 63-608 s-'. The composite with and without
bonding agents showed a pseudoplastic behavior which decreased
with the increase of temperature. Composites containing bonding
agents based on polypropyleneglycol and 4,4'-diphenylmethanediisocyanate
showed the lowest viscosity values at a particular
shear rate, whereas composites containing a glycerol- (GL) based
bonding agent showed the highest viscosity. The viscosity of the
composite decreased sharply after a particular temperature (140°C) and the fall was less drastic in the composite containing
a GL-based bonding agent.
Sunil,K Narayanankutty(Taylor & Francis Inc., 2005)
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Abstract:
The rheological characteristics of short Nylon-6 fiber reinforced styrene butadiene
rubber (SBR) were studied using a capillary rheometer. The study was done with
respect to the effect of shear rate, fiber concentration, and temperature on shear
viscosity and die swell. All the melts showed pseudoplastic nature, which
decreased with increasing temperature. Shear viscosity increased in the presence
of fibers. Introduction of fiber reduces the temperature sensitivity of the rubber
matrix. A reduction in die swell was found in presence of fibers.
Fully burnt rice hull (rice hull ash) was tried as a low cost filler in place of precipitated
silica in NBR/PVC based microcellular soles. The mechanical properties of the soles
containing silica and ash are found to be comparable. The expansion is marginally
higher in the presence of ash, which permits to reduce the amount of blowing agent. Cell
structure of microcellular sheets remains unchanged when silica is replaced by ash.
Eby Thomas, Thachil; Renju, V S; Vidya Francis, K F; Ayswarya, E P(Elsevier, April , 2012)
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Abstract:
This paper presents the results of a study on the use of rice husk ash (RHA) for property modification of
high density polyethylene (HDPE). Rice husk is a waste product of the rice processing industry. It is used
widely as a fuel which results in large quantities of RHA. Here, the characterization of RHA has been done
with the help of X-ray diffraction (XRD), Inductively Coupled Plasma Atomic Emission Spectroscopy
(ICPAES), light scattering based particle size analysis, Fourier transform infrared spectroscopy (FTIR)
and Scanning Electron Microscope (SEM). Most reports suggest that RHA when blended directly with
polymers without polar groups does not improve the properties of the polymer substantially. In this
study RHA is blended with HDPE in the presence of a compatibilizer. The compatibilized HDPE-RHA blend
has a tensile strength about 18% higher than that of virgin HDPE. The elongation-at-break is also higher
for the compatibilized blend. TGA studies reveal that uncompatibilized as well as compatibilized HDPERHA
composites have excellent thermal stability. The results prove that RHA is a valuable reinforcing
material for HDPE and the environmental pollution arising from RHA can be eliminated in a profitable
way by this technique.
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.