Preparation and Mechanical Properties of Thermoplastic Heat-Moisture-Treated Rice Starch/Rice Husk Biocomposite

Thanatepon Tungpatanatana^a, Patcharaporn Srion^a, Rungsan Kanyadoi^a, Amnard Sittattrakul^a, Wanchai Lerdwijitjarud^{a *}

^a Department of Materials Science and Engineering, Faculty of Engineering and Industrial Technology, Silpakorn University, Nakorn Pathom 73000, THAILAND

* Corresponding Authour Email: wanchail@su.ac.th

Abstract

Thermoplastic starch is one of the most interesting biodegradable materials nowadays.  A composite of thermoplastic rice starch/rice husk is prepared in present study.  Rice starch was heat moisture treated (HMT) with the moisture content of 20% (%weight of dry starch) at 100 ^oC for 4 hours. Rice husk powder with an average diameter of 60 microns was used as reinforcing filler.  HMT starch and rice husk were mixed in an internal mixer by using glycerol as a plasticizer.  The rice husk content in the composite was varied at 5%, and 10%w/w.  The testing specimens were fabricated by compression molding method.  The scanning electron micrographs reveal a well dispersion of rice husk in starch matrix and a good adhesion at filler/matrix interface.  The composite with higher rice husk content show the lower value in elongation at break, whereas Young’s modulus and tensile strength of the composites monotonically increase with increasing rice husk content.  Young’s modulus of composite reinforced with 10% rice husk content is higher than that of unfilled thermoplastic HMT starch around 123%.

Keywords: thermoplastic starch, biocomposite, biodegradable materials, heat-moisture-treated starch, rice husk