Sunil,K Narayanankutty(Taylor & Francis LLC, 2005)
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Abstract:
The thermal degradation of short nylon-6 fiber reinforced acrylonitrile
butadiene rubber (NBR) composites with and without epoxy-based bonding
agent has been studied by thermogravimetric analysis (TGA). It was found that
the onset of degradation shifted from 330.5 to 336.1°C in the presence of short
nylon fiber, the optimum fiber loading being 20 phr. The maximum rate of degradation
of the composites was lower than that of the unfilled rubber compound,
and it decreased with increase in fiber concentration. The presence of epoxy
resin-based bonding agent in the virgin elastomer and the composites improved
the thermal stability. Results of kinetic studies showed that the degradation of
NBR and the short nylon fiber reinforced composites followed first-order
kinetics.
Isora fibre-reinforced natural rubber (NR) composites were cured at 80, 100, 120 and
150°C using a low temperature curing accelerator system. Composites were also prepared using a
conventional accelerator system and cured at 150°C. The swelling behavior of these composites at
varying fibre loadings was studied in toluene and hexane. Results show that the uptake of solvent
and volume fraction of rubber due to swelling was lower for the low temperature cured vulcanizates
which is an indication of the better fibre/rubber adhesion. The uptake of aromatic solvent was higher
than that of aliphatic solvent, for all the composites. As the fibre content increased, the solvent
uptake decreased, due to the superior solvent resistance of the fibre and good fibre-rubber interactions.
The bonding agent improved the swelling resistance of the composites due to the strong interfacial
adhesion. Due to the improved adhesion between the fibre and rubber, the ratio of the change in
volume fraction of rubber due to swelling to the volume fraction of rubber in the dry sample (V,) was
found to decrease in the presence of bonding agent. At a fixed fibre loading, the alkali treated fibre
composite showed a lower percentage swelling than untreated one for both systems showing superior
rubber-fibre interactions.
Poly(propylene) (PP) reinforced with short glass fiber was modified with
precipitated nanosilica (pnS) by melt mixing. The weight of the glass fiber was varied
by keeping the pnS at optimum level. The properties of the composites were studied
using universal testing machine, dynamic mechanic analyser (DMA), differential
Scanning calorimetry (DSC) and thermo gravimetric analyser (TGA). The amount of the
glass fiber required for a particular modulus could be reduced by the addition of
nanosilica.
Sugunan, S; Binitha, N N(Journal of Applied Polymer Science,Wiley InterScience, March 16, 2007)
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Abstract:
In situ polymerization of aniline is done
inside the pillared clay matrix. The nonswellable pillared
clay confined matrix allows efficient polymerization that
leads to nanofibrous morphology. As a result high polymer
order and crystallinity is attained and is evident from
XRD patterns. The strong interaction between the clay
layers and polyaniline (PANI) is understood from FTIR and DRS spectra. Additionally these analytical results suggest that the prepared PANI is in the doped state. The
PANI/pillared clay nanocomposite formation gives additional
thermal stability to the polymer backbone and is clear from the DTG curves.
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.
Polytetrafluoroethylene (PTFE) composites
filled with Sr2Ce2Ti5O16 ceramic were prepared by a powder
processing technique. The structures and microstructures
of the composites were investigated by X-ray diffraction
and scanning electron microscopy techniques. Differential
scanning calorimetry showed that the ceramic filler
had no effect on the melting point of the PTFE. The effect
of the Sr2Ce2Ti5O16 ceramic content [0–0.6 volume fraction
(vf)] on the thermal conductivity, coefficient of thermal
expansion (CTE), specific heat capacity, and thermal diffusivity
were investigated. As the vf of the Sr2Ce2Ti5O16 ceramic increased, the thermal conductivity of the specimen
increased, and the CTE decreased. The thermal conductivity
and thermal expansion of the PTFE/Sr2Ce2Ti5O16
composites were improved to 1.7 W m21 8C21 and 34
ppm/8C, respectively for 0.6 vf of the ceramics. The experimental
thermal conductivity and CTE were compared
with different theoretical models.