Comparative study on the properties of rice straw/polypropylene and micaceous clay/polypropylene composites
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Date
2009
Authors
Kry Nallis
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Abstract
Comparative study on the properties of an agricultural waste, rice straw (RS),
reinforced polypropylene composites and mineral filler, micaceous clay (MC),
reinforced polypropylene composites was investigated in this study. Micaceous clay
reinforced polypropylene (MC/PP) composites were prepared with different MC
contents from 0 to 70% by weight. However, for rice straw reinforced polypropylene
(RS/PP) composites, only composites with rice straw contents from 0 to 60% by
weight were prepared. The mixture was prepared by mixing in a Brabender
Plasticorder PLE331 (50rpm, 1800C) and hot press molding method (1800C, 1500psi)
followed by cold pressing. Both types of composites obtained were characterized for
impact strength, tensile properties (0 wt%-40 wt%), dry and wet flexural properties,
water absorption and expansion in thickness. The tensile fracture surface, impact
fracture surfaces and flexural fracture surfaces were analyzed using scanning
electron microscopy (SEM).
From the test results, tensile strength and impact strength of RS/PP and
MC/PP composites decreased as the filler contents increased and the tensile and
impact strength of MC/PP are better than the tensile and impact strength of RS/PP
composite. On the other hand, dry and wet flexural strength of MC/PP composites
reached maximum 20 wt% of MC content. The dry flexural strength of MC/PP
composites and RS/PP composites is higher than its wet flexural strength. However,
the dry and wet flexural strengths of MC/PP composites is higher than dry and wet
flexural strength of RS/PP composites. In the modulus case, the dry and wet flexural
modulus and tensile modulus of RS/PP composites and MC/PP composites increased
with increasing RS and MC contents. Nevertheless, the dry and wet flexural modulus
and tensile modulus of MC/PP composites are higher compared to the dry and wet
flexural modulus and tensile modulus of RS/PP composites. Moreover, RS/PP
composites absorbed more water than MC/PP composites. The water absorption of
RS/PP and MC/PP increased with increasing RS and MC contents. Expansion in
thickness of RS/PP composites and MC/PP composites simultaneously increased as
the water absorption increased. In addition, morphological observation of MC/PP
composites indicates a gradual change of tensile fracture behavior from ductile to
brittle and poor interaction between PP and MC. However, the morphological study
on RS/PP composites showed the cavities and pull out of rice straw at higher RS
contents for tensile and impact fracture surfaces which indicate a poor interaction
between fillers and the matrix polymer. However, the flexural fracture surfaces
showed blisters in the composites at lower RS contents as a result of using
compression molding during the sample preparations.
Description
Master
Keywords
Chemical science , Rice straw/polypropylene , Micaceous clay/polypropylene