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.
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.
We have investigated the crystallization characteristics of melt compounded nanocomposites of poly(ethylene terephthalate) (PET) and single
walled carbon nanotubes (SWNTs). Differential scanning calorimetry studies showed that SWNTs at weight fractions as low as 0.03 wt% enhance
the rate of crystallization in PET, as the cooling nanocomposite melt crystallizes at a temperature 10 °C higher as compared to neat PET.
Isothermal crystallization studies also revealed that SWNTs significantly accelerate the crystallization process. WAXD showed oriented
crystallization of PET induced by oriented SWNTs in a randomized PET melt, indicating the role of SWNTs as nucleating sites.
Rani, Joseph(Wiley InterScience, October 22, 2006)
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Abstract:
Poly(ethylene terephthalate) (PET) nanocomposites
with single-walled carbon nanotubes (SWNTs) have
been prepared by a simple melt compounding method. With
increasing concentration (0-3 wt %) of SWNTs, the mechanical
and dynamic mechanical properties improved, corresponding
to effective reinforcement. Melt rheological characterization
indicated the effective entanglements provided by SWNTs in
the melt state as well. Thermogravimetric analysis suggested no influence of SWNTs on the thermal stability of PET. Electrical
conductivity measurements on the composite films pointed
out that the melt compounded SWNTs can result in electrical
percolation albeit at concentrations exceeding 2 wt %.
Conducting polymers are excellent microwave absorbers
and they show technological advantage when compared
with inorganic electromagnetic absorbing materials,
being light weight , easily processable, and the ability
of changing the electromagnetic properties with nature
and amount of dopants, synthesis conditions, etc. In this
paper we report the synthesis, dielectric properties, and
expected application of conducting composites based
on polyaniline (PAN). Cyclohexanone soluble conducting
PAN composites of microwave conductivity 12.5 S/m
was synthesized by the in situ polymerization of aniline
in the presence of emulsion grade polyvinyl chloride. The
dielectric properties of the composites, especially the
dielectric loss, conductivity, dielectric heating coefficient
, absorption coefficient, and penetration depth,
were studied using a HP8510 vector network analyzer.
The microwave absorption of the composites were studied
at different frequency bands i.e, S, C, and X bands
(2-12 GHz). The absorption coefficient was found to be
higher than 200 m -' and it can be used for making microwave
absorbers in space applications .
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.
Dielectric properties of polyaniline at different frequencies were studied. Cavity perturbation technique was employed for the
study. Poly aniline in the powder and pelletised forms were prepared under different environmental conditions. Different samples of
poly aniline exhibit high conductivity. However, the conductivity of samples prepared under different environmental conditions is
found to vary. All the samples in the powder form have high conductivity irrespective of the method of preparation. The high
conductivity at microwave frequency makes it possible to be used for developing microwave components like filters.
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.
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(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.