Preparation of poly(lactic acid) from Prosopis juliflora and incorporation of chitosan for packaging applications

Abstract

The biodegradable polylactic acid (PLA) materials, environmentally friendly alternatives to petroleum-derived plastics, and fermentative production of optically pure lactic acid from cheap raw materials have aroused interest among researchers in the recent years due to its high potential for packaging applications. In this study, we have experimented for the lactic acid production using Lactobacillus delbrueckii MTCC 911 with Prosopis juliflora as a substrate for fermentation. As a result, 38.23g/L of lactic acid was produced. Modified ring-opening polymerization with direct polycondensation method was followed to convert lactic acid into polylactic acid, and membrane prepared with 0.25mm thickness having PLA/chitosan 60/40 composition shows better results with a tensile strength of 17.809MPa and an elongation at break of 300.11%. The oxygen transmission rate results show low permeability of 1614.21 (cm3/(m2·day·atm)). Compatible PLA/chitosan membrane so produced by solvent casting shows good thermal stablity and less permeability to oxygen and increased mechanical properties. This was evident from the instrumental analysis of Fourier-transform infrared spectroscopy, thermogravimetry/derivative thermogravimetry, scanning electron microscope, and high-performance liquid chromatography results.