Chemical Modification of Starch-Protein Material Performed in Order to Obtain a Half Product for Thermoplastic Processing

Abstract

This article presents the results of tests which were carried out on a starch-protein biomaterial produced from wheat. The research was performed in order to assess optimal conditions for performing the chemical modification (acetylation and oxidation reactions) and its influence on the physico-chemical properties of the new biomaterial. Modifying agents were acetic acid anhydride with the presence of NaOH and K 2 CO 3 activators as well as hydrogen peroxide, whose effects were catalysed with Cu 2+ ions. Modified polymers with a degrees of substitution from 0.38 to 2.45 and oxidation from 1.0 to 35% were obtained in the process. The polymers obtained were characterized with various levels of starch degradation, minimal when the acetylation reaction activated with the K 2 CO 3 method was used, moderate to high when the acetylation reaction was activated by NaOH, and maximal starch degradation was observed when oxidation was catalysed with Cu 2+ ions. The modified polymers showed minor thermal granulation abilities and did not achieve thermoplastic abilities. Evaluation of the modification effects was carried out with absorption spectroscopy in infra-red radiation with the Fourier transformation (FTIR) technique, DSC, scanning electron microscopy and determining the boundary viscosity value.