Kinetics of crystallization for polypropylenepolyethylenehalloysite nanotube nanocomposites
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Date
2018-06
Authors
Ong, Mun Yee
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Abstract
Polypropylene (PP) is commonly used due to its affordable price and high
performance but its low impact strength limits its applications which can be improved by
blending with high density polyethylene (HDPE). Crystallization rate of PP/HDPE is lower
compared to pure PP. Therefore, provides the need to use nanofiller as nucleating agent such
as HNT. The aim of this thesis is to investigate the effects of HNT on the thermal properties
of PP/HDPE blends and the kinetics of non-isothermal crystallization of PP/HDPE/HNT
nanocomposites by using Avrami, Kissinger and Mo model. In this study, the incorporation
of HNT nanoparticles decreases the crystallization temperature (𝑇𝑐) and increases the degree
of crystallinity (𝜒𝑐
). From the Avrami model, the Avrami exponent (n) is in the range of 1 to
2 for all PP/HDPE/HNT nanocomposites indicating instantaneous nucleation while the
crystallization rate constant (𝑍𝑡) values of PP/HDPE increased with the addition of HNT.
This indicates that addition of HNT increases crystallization rate. The reduction of half
crystallization time (𝑡1/2) for PP/HDPE as the increasing HNT loading indicates faster
crystallization rate. Kissinger model showed that the activation energy (𝐸𝑎) of crystallization
for the PP/HDPE decreases with the addition of HNT. In Mo model, the cooling rate chosen
at unit crystallization time F(T) values for PP/HDPE decreases with the addition of HNT. In
summary, the most suitable HNT loading for PP/HDPE blend is 8 wt% HNT as it increases
the overall crystallization rate of PP/HDPE blend.