Jose Sebastian; Dr. Eby Thomas Thachil(September 23, 2015)
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Abstract:
Organic-inorganic nanocomposites combine unique properties of
both the constituents in one material. Among this group of materials,
clay based as well as ZnO, TiO2 nanocomposites have been found to
have diverse applications. Optoelectronic devices require polymerinorganic
systems to meet certain desired properties. Dielectric
properties of conventional polymers like poly(ethylene-co-vinyl acetate)
(EVA) and polystyrene (PS) may also be tailor tuned with the
incorporation of inorganic fillers in very small amounts. Electrical
conductivity and surface resistivity of polymer matrices are found to
improve with inorganic nanofillers. II-VI semiconductors and their nano
materials have attracted material scientists because of their unique
optical properties of photoluminescence, UV photodetection and light
induced conductivity. Cadmium selenide (CdSe), zinc selenide (ZnSe)
and zinc oxide (ZnO) are some of the most promising members of the IIVI
semiconductor family, used in light-emitting diodes, nanosensors,
non-linear optical (NLO) absorption etc. EVA and PS materials were
selected as the matrices in the present study because they are
commercially used polymers and have not been the subject of research
for opto-electronic properties with semiconductor nanomaterials
Renjanadevi, B; Dr.George, K E(Cochin University of Science & Technology, July , 2008)
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Abstract:
The present work focuses on the modification of the commonly used
thermoplastics, polypropylene and polystyrene using nanosilica preparcd
from a cheap source of sodium silicate. Melt compounding technique has
been used for nanocomposite preparation as it is simple and suited to
injection moulding. Nanosilica in a polymer matrix provide significant
enhancement in strength, stiffness and impact strength. Incorporation of silica
particles in a polymer also improves its thennal stability. To achieve better
dispersion of fillers in polymer matrices the mixing was done at different
shear rates. The enhancement in material properties indicates that at higher
shear rates there is greater interaction between particles and the matrix and it depends on filler concentration and type of polymer used. N anosilica is a
useful filler in thennoplastic polymers and has been applied in automotive
applications, electronic appliances and consumer goods.This thesis is divided into six chapters. General introduction to the
topic is described in chapter 1. Salient features of polymer nanocomposites,
their synthesis, properties and applications are presented. A review of
relevant literature and the scope and objectives are also mentioned in this
chapter.The materials used and the vanous experimental method and
techniques employed in the study are described in chapter 2. Preparation of
nanocomposites by melt blending using Thenno Haake Rheocord,
preparation of samples, evaluation of mechanical and thennal properties
using UTM, Impact testing and characterization using DMA, TGA and DSC
and morphology by SEM are described.The preparation of nanosilica from a laboratory scale to a pilot plant
scale is described in chapter 3. Generation of surface modified silica,
evaluation of kinetic parameters of the synthesis reaction, scale up of the
reactor and modeling of the reactor are also dealt with in this chapter.The modification of the commodity thennoplastic, Polypropylene using
nanosilica is described in chapter 4. Preparation of PP/silica nanocomposites,
evaluation of mechanical properties, thermal and crystallization characteristics,
water absorption and ageing resistance studies are also presented.The modification of Polystyrene using synthesized nanosilica IS
described in chapter 5. The method of preparation of PS/silica nanocomposites, evaluation of mechanical properties (static and dynamic),
thermal properties melt flow characteristics using Haake Rheocord, water
absorption and ageing resistance of these nanocomposites are studied.
Description:
Department of Polymer Science and Rubber Technology,
Ccchin University of Science and Technology
Ramakrishnan, R; Dr. Manoj Raama Varma; Dr. J. D. Sudha(Cochin University of Science and Technology, July 25, 2014)
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Abstract:
Recent developments on nanostructured conducting polymer-inorganic
composites systems have receieved considerable research interest owing to their
unique synergestic properties compared with their individual bulk counter parts
which make them promising candidates for a broad spectrum of high technological
applications such as in energy conversion, electronic devices, storage, sensors,
actuators, memory devices, and biomedical devices. Nanostructured conducting
polymers possess unique features such as high specific surface area, high charge
carrier concentration, high electrical conductivity, high mechanical flexibility, light
weight, solution processability and printability over a large area which make them
favourable for their high tech applications. Among the conducting polymers,
polyanilline, poly(3,4-ethylene dioxy thiophene), poly(N-vinylcarbzole) are
receiving much importance due to their low cost, environmental stability and
unique doping mechanism. Conversely, semiconducting inorganic metal oxide such
as zinc oxide and titania nanomaterials have emerged as an area of intense research
interest motivated by their potential applications in electronics, non-linear optics,
and magnetic devices due to their low band gap, small crystalline size and unique
opto-electronic properties. In this perspective, studies on the development and
applications of semiconducting polymer-inorganic metal oxide nanocomposite are
interesting since it is expected to exhibit synergistic properties arising from the
molecular level mixing of conducting polymer and inorganic counter parts.