Priya, Viswanath; Dr. Eby Thomas, Thachil(Cochin University of Science and Technology, September , 2007)
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Abstract:
Research in the field of polymer modified cement has been carried out for
the last 70 years or more. Polymers are mostly used to enhance durability and
sustainability of cement concrete and in combination with classical construction
materials a synergistic effect is obtained. In this work different polymers were
added to Portland cement in various proportions and the mechanical and
chemical resistance properties of the resultant composites when exposed to
chemical environments were studied. Microstructural studies were also carried
out to investigate the morphology of the composite and analyse the nature of
interactions taking place between the cement and polymer phases. Though most
polymers did not improve the compressive strength of the cement paste, it was
found that they enhanced the resistance of the virgin cement paste to external
chemical environments. The polymers seal the pores in the cement matrix and
bridge the microcracks within the composite. Some of the polymers underwent
chemical interactions with the cement paste thereby interfering in the hydration
of cement. Polymers also decreased the leachability of water soluble components
of virgin cement resulting in composites having improved durability. An attempt
to correlate the structure of the polymers with the properties of the resultant
composites is also presented.
Description:
Department of
Polymer Science and Rubber Technology, Cochin University of
Science and Technology
Vidya, Francis; Dr. Eby Thomas, Thachil(Cochin University of Science and Technology, November , 2012)
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Abstract:
LLDPE was blended with poly (vinyl alcohol) and mechanical, thermal, spectroscopic properties and biodegradability were investigated. The biodegradability of LLDPE/PVA blends has been studied in two environments, viz. (1) a culture medium containing Vibrio sp. and (2) a soil environment over a
period of 15 weeks. Nanoanatase having photo catalytic activity was synthesized by hydrothermal method using titanium-iso-propoxide. The synthesized TiO2 was characterized by X-Ray diffraction (XRD), BET studies, FTIR studies and scanning electron microscopy (SEM). The crystallite size of titania was calculated to be ≈ 6nm from the XRD results and the surface area was found to be about
310m2/g by BET method. SEM shows that nanoanatase particles prepared by this method are spherical in shape. Linear low density polyethylene films containing polyvinyl alcohol and a pro-oxidant (TiO2 or cobalt stearate with or without vegetable oil) were prepared. The films were then subjected to natural weathering and UV exposure followed by biodegradation in culture medium as well as in soil environment. The degradation was monitored by mechanical property measurements, thermal studies, rate of weight loss, FTIR and SEM studies. Higher weight loss, texture change and greater increments in carbonyl index values were observed in samples containing cobalt stearate and vegetable oil. The
present study demonstrates that the combination of LLDPE/PVA blends with (I) nanoanatase/vegetable oil and (ii) cobalt stearate/vegetable oil leads to extensive photodegradation. These samples show substantial degradation when subsequent exposure to Vibrio sp. is made. Thus a combined photodegradation and biodegradation process is a promising step towards obtaining a biodegradable
grade of LLDPE.
Description:
Department of Polymer Science and Rubber Technology, Cochin University of Science and Technology