Publication: Optimization of zeolite as filler in polypropylene composite
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Date
2009-05-01
Authors
Mohd Zaharri, Nur Diyana
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Abstract
Optimization of natural zeolite as filler in polypropylene composite was studied. Two types of coupling agents which are stearic acid and vinyl silane were used in order to study the effect of filler surface treatment on the composite mechanical properties. Prior to mixing process, zeolite was grinded by ring mill into a powder form. Zeolite/polypropylene (PPZ), stearic acid treated zeolite/polypropylene (PPZ SA) and vinyl silane treated zeolite/polypropylene composites (PPZ VS) were prepared using Thermo Haake Polydrive internal mixer and were then compression molded according to standard test specimen. Torque-time curves were plotted to investigate the processing behavior of the composites. The torque value increased with increasing zeolite content from 5 vol. % to 25 vol. % but decreased with the presence of the coupling agents in PPZ composite. Tensile test and impact test were performed to characterize the mechanical properties of PPZ, PPZ SA and also PPZ VS. The obtained experimental values of tensile modulus were then related to the theoretical predictions using a Halpin Tsai equation. The theoretical prediction results in greater values of tensile modulus compared to the experimental values. Fourier Transform Infra red (FTIR) spectra analyses were performed on the composites to study the interaction between the polypropylene and functional group of stearic acid and vinyl silane. Besides, morphological study was done on the tensile fractured surface using a scanning electron microscopy (SEM). It was found that the tensile strength (TS), elongation at break (EAB) and impact strength (IS) decreased but the tensile modulus (E) increased with increasing zeolite content. The addition of coupling agents was proved to enhance the mechanical properties of PPZ. However, stearic acid has little effect in improving the composite mechanical properties in comparison with vinyl silane.