Evaluation On Flow Behaviour Of Polypropylene/Kaolin Composites At High Shear Stress
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Date
2010-12
Authors
Jikan, Suzi Salwah
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
In this study, Polypropylene (PP)/kaolin composite was compounded on a
heated two roll-mill prior to testing via capillary rheometer in order to improve the
rheological properties of the samples. Whereas, the extrudate from melt flow indexer
(MFI) were analyzed to calculate their melt densities. The results showed that the
melt density decreased linearly with an increase in processing temperature and it
increased slightly with the addition of kaolin filler. On the other hand, for the
investigation of melt flow properties, thermal behaviour, morphological analysis and
viscoelastic phenomenon of PP/kaolin composite, the sample was subjected to
extrusion process by means of capillary rheometer. The flow behaviour of all
samples revealed that the system appears to be pseudoplastic over one range of shear
rates but dilatant over another. The influences of kaolin content, processing
temperature and shear stress on crystallization of all samples, including isothermal
and nonisothermal crystallization behaviour were investigated by differential
scanning calorimetry (DSC). The results showed that increasing kaolin content,
processing temperature and shear stress have shifted the crystallization exothermic
peak to higher temperature and reduced the overall crystallization time. The
crystallization activation energy calculated using Kissinger’s method displayed a
decreasing trend with increasing kaolin content, processing temperature and shear
stress. A study of nucleation activity revealed that kaolin filler had a slight nucleation
effect on PP matrix. A thorough observation on nucleation effect also revealed that
the incorporation of kaolin in chorus with increasing temperature and shear stress
have contributed to successive heterogeneous nucleation in the system. The
morphological analysis of the extrudate was analyzed using SEM and EDX in order
to investigate the effect of shear stress, processing temperature and filler loading.
Description
Keywords
Evaluation on flow behaviour of Polypropylene , kaolin composites at High shear stress