Agro-industrial residue from starch extraction of Pachyrhizus ahipa as filler of thermoplastic corn starch films

Abstract

Biocomposites films based on thermoplastic corn starch (TPS) containing 0.5% w/w fibrous residue from Pachyrhizus ahipa starchextraction(PASR) were obtainedbymelt-mixing andcompressionmolding. PASR ismainly constituted by remaining cell walls and naturalfibers, revealed by Scanning ElectronMicroscopy (SEM). Chemical composition of the residue indicated that fiber and starch were the principal components. Biocomposites thermo-stability was determined by Thermo-Gravimetric Analysis. A continuous PASR-TPS interface was observed by SEM, as a result of a good adhesion of the fibrous residue to starch matrix. Likewise, films containing PASR presented fewer superficial cracks than TPS ones, whereas their fracture surfaces were more irregular. Besides, the presence of PASR increased starch films roughness, due to fibers agglomerates. Films reinforced with PASR showed significantly lower water vapor permeability (WVP). In addition, PARS filler increased maximum tensile strength and Young’s modulus of TPS films, thus leading to more resistant starch matrixes.