Characterization and properties of chitosan-filled rubber compuonds

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Date
2016-06-01
Authors
Shazlin Mohamed Shaari
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Extending the utilization of renewable resources based reinforcements in natural rubbers are highly beneficial due to the fact that the utilization of renewable resources fillers is inexpensive while at the same time, they could minimize the environmental pollution owing to the characteristic biodegradability. Therefore, this study was carried out to look into the feasibility of using chitosan as filler in natural rubber (NR). In this study, the influence of chitosan loading, different types of rubber, different types of vulcanising system and the use of silane coupling agent on the cure characteristics, mechanical and physical properties and degradability of the NR compounds were studied. The chitosan-filled NR compounds incorporated with 0 – 40 phr chitosan was prepared using the laboratory two-roll mill. The study showed that the incorporation of chitosan enhanced the cure characteristics of the NR compounds such as reducing the cure time by more than 60% with the incorporation of 10 phr chitosan. In contrast, the increasing chitosan loading proves to be detrimental to the strength, the flexibility and fatigue life of the rubber compounds. Likewise, the incorporation of chitosan in different types of rubber; NR, Epoxidized natural rubber (ENR) and Styrene-butadiene rubber (SBR) and the use of different cure systems; conventional vulcanization (NR/semiEV) and peroxide based vulcanization (NR/DCP) systems depicts similar trends of declining mechanical properties at higher chitosan loadings. It was observed that chitosan-filled NR vulcanizates displays the highest mechanical and physical properties followed by chitosan-filled ENR and chitosan-filled SBR. Similarly, the chitosan-filled NR/CV vulcanizates exhibit better properties compared to the NR/semiEV and NR/DCP vulanizates. The addition of 3-Aminopropyltriethoxysilane (APTES) showed a positive effect on most of the properties of the chitosan-filled NR vulcanizates. The silane coupling agent has effectively improved the chitosan dispersion and the adhesion of chitosan to the NR matrix and leads to better properties. Upon exposure to natural weathering and soil burial, the exposed samples experienced a progressive decay in tensile strength, elongation at break and tensile modulus with prolonged exposure period. Chemical changes were found to occur in the test samples after exposure to both conditions. Carbonyl indices obtained from the FTIR spectra confirmed that deterioration and degradation occurred during natural weathering and soil burial. The SEM micrographs studies proved that the severity of the surface deterioration and degradation of vulcanizates increased with chitosan loading and exposure period thus, results in higher rate of weight loss. In conclusion, chitosan particles can be employed in rubber compounds as non-reinforcing filler to serve certain purpose such as to modify the cure properties, to reduce the use of expensive commercial filler and to impart biodegradability to the rubber compounds.
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