Effect of lignin removal on mechanical, thermal, and morphological properties of polylactide/starch/rice husk blend used in food packaging

Abstract

ABSTRACTThe aim of this work was to investigate the possibility of using cost‐effective natural filler in a biodegradable polymer and find new set of materials for green biocomposites to be used in food packaging. In this regard, rice husk (RH) and bleached rice husk (BRH) have been used in the form of powder and the effect of lignin removal on mechanical and thermal properties of prepared composites with poly(l‐lactide) and starch were studied. Using FTIR technique, the lignin removal from RH has been approved. The tensile, charpy impact, and hardness tests were implemented to investigate the mechanical properties. It was concluded that filler caused increase both in the toughness and the Young modulus of samples. It was also found that the lack of lignin in BRH samples improves the mechanical properties. It was clearly observed that the BRH samples show larger modulus, charpy impact strength, and hardness compared to those filled with RH. Despite larger values for the elongations at break of RH samples, the mechanical properties showed a significant improvement (between 25 and 50% improvements) on lignin removal. The differential scanning calorimetry thermograms revealed an improvement in crystallization behavior and reduction of Tg from 47 to 31°C in the case of BRH‐filled samples. Finally, due to the removal of toxic lignin in the samples and modification of mechanical properties by this method, the BRH could have the ability of wide use in the bioplastics and food packaging industries. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41095.