In this article, we report the preparation of
conducting natural rubber (NR) with polyaniline (Pani). NR
was made into a conductive material by the compounding
of NR with Pani in powder form. NR latex was made into a
conductive material by the in situ polymerization of aniline
in the presence of NR latex. Different compositions of Pani-
NR semi-interpenetrating networks were prepared, and the
dielectric properties of all of the samples were determined
in microwave frequencies. The cavity perturbation techpique was used for this study. A HP8510 vector network analyzer
with a rectangular cavity resonator was used for this
study. S bands 2-4 GHz in frequency were used. Thermal
studies were also carried out with thermogravimetric analysis
and differential scanning calorimetry.
Rani, Joseph(Wiley InterScience, February 18, 2006)
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Abstract:
In this paper we report the preparation and
dielectric properties of poly o-toluidine:poly vinyl chloride
composites in pellet and film forms. The composites were
prepared using ammonium persulfate initiator and HCl
dopant. The characterization is done by TGA and DSC. The
dielectric properties including dielectric loss, conductivity,
dielectric constant, dielectric heating coefficient, absorption
coefficient, and penetration depth were studied in the
microwave field. An HP8510 vector network analyzer with
rectangular cavity resonator was used for the study. Sbands (2-4 GHz), C band (5-8 GHz), and X band (8-12
GHz) frequencies were used in the microwave field. Comparisons
between the pellet and film forms of composites
were also included. The result shows that the dielectric
properties in the microwave field are dependent on the frequency
and on the method of preparation.
A series of short-isora-fiber-reinforced natural
rubber composites were prepared by the incorporation of
fibers of different lengths (6, 10, and 14 mm) at 15 phr loading
and at different concentrations (10, 20, 30, and 40 phr) with a
10 mm fiber length. Mixes were also prepared with 10 mm
long fibers treated with a 5% NaOH solution. The vulcanization
parameters, processability, and stress-strain properties
of these composites were analyzed. Properties such as tensile
strength, tear strength, and tensile modulus were found to be
at maximum for composites containing longitudinally oriented
fibers 10 mm in length. Mixes containing fiber loadings of 30 phr with bonding agent (resorcinol-formaldehyde [RF]
resin) showed mechanical properties superior to all other
composites. Scanning electron microscopy (SEM) studies
were carried out to investigate the fiber surface morphology,
fiber pullout, and fiber-rubber interface. SEM studies showed
that the bonding between the fiber and rubber was improved
with treated fibers and with the use of bonding agent.
Sunil,K Narayanankutty(Technomic Publishing Co., Inc., April , 1998)
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Abstract:
The stress relaxation behavior of polyurethane elastomer and
short polyester fiber filled elastomer composites with and without bonding
agents at different strain levels and strain rates was studied. It was found that
these compounds exhibit a multistage relaxation mechanism and that the rate
of relaxation and cross-over time depend on the strain level and strain rate.
The incorporation of fibers reduced the stage-I relaxation rate and increased
the cross-over time of the gum vulcanisate. A higher rate of relaxation (first
stage) was shown by the composites with longitudinal fiber orientation and
composites with bonding agents.
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