Preparation and Mechanical Properties of Thermoplastic Cassava Starch reinforced with Cellulose Whisker from Bacterial Cellulose

Kanokkorn Karnwiboon^a, Teeraseth Ariyathanakul^a, Jirath Thienchaimongkol^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

The primary aim of this work is to investigate the effect of cellulose whisker content on the mechanical properties of thermoplastic cassava starch/cellulose whisker biocomposite.  Cellulose whisker was prepared from bacterial cellulose by using H₂SO₄-acid hydrolysis and dialysis technique.  Transmission electron microscopy (TEM) was used to examine size and shape of cellulose whisker. The obtained whisker has rod-like shape with 896±215 nm in length and 45±11 nm in diameter corresponding to the aspect ratio of 20.  Glycerol-plasticized thermoplastic cassava starch reinforced with 3% and 5% (w/w) cellulose whisker specimens were prepared by internal mixer and compression molding machine.  A good dispersion of reinforcing filler in the starch matrix is obtained for 3%-filler content specimen, whereas some whisker agglomeration is observed for 5%-filler content specimen.  The Young’s modulus of the biocomposite monotonically increases with increasing whisker content.  The composite with 5% whisker content show 37% higher in modulus comparing with that of unfilled specimen.  However tensile strength and stain at break of the composite are lower than those of unreinforced thermoplastic starch.

Keywords: cassava starch, cellulose whisker, bacterial cellulose, biocomposite, biodegradable materials