Biodegradable polymers from renewable resources: Effect of proteinic impurity on polycondensation products of 2-hydroxypropanoic acid

Abstract

The goal of the presented work is to describe the proteinic impurity (as possible residual component from biotechnological lactic acid production from whey) in the reaction mixture with 2-hydroxypropanoic acid (lactic acid) for its direct polycondensation into poly(lactic acid). The impurity presence study was carried out in the range from mass fractions 0 % up to 2 %. For an evaluation of the impurity effect on the values of molecular weight, melting and glass transition temperatures the measurements of intrinsic viscosity, gel permeation chromatography and differential scanning calorimetry were used. Results show slight reduction of molecular weight and increase in polydispersity with rising amount of the impurity. The thermal properties investigation shows noticeable reduction of melting temperature and moderate decrease in glass transition temperature. The results reveal considerable role of lactose on formation of structural irregularities in lactic acid polycondensates.