Cellulose Functionalized High Molecular Weight Stereocomplex Polylactic Acid Biocomposite Films with Improved Gas Barrier, Thermomechanical Properties

Abstract

This work presents a facile, solvent-free approach for the fabrication of PLA biocomposites, followed by melt extrusion process to prepare stereocomplex PLA films with excellent thermomechanical and gas barrier properties. The presence of stereocomplex crystallites improves the thermal properties of polylactic acid (PLA); however, the formation of stereocomplex crystallites is predominantly lesser compared to homocrystallites in case of high molecular weight poly(l-lactic acid) and poly(d-lactic acid) blend. Grafting of biofillers with polymer matrix chains may help in homogeneous dispersion and formation of stereocomplex crystallites. Henceforth, stereocomplex PLA was fabricated with cellulose microcrystals (CMC) as filler, after chemical modification by in situ ring opening polymerization of d-lactide. The stereocomplexation in the blend system was found to be enhanced by the extended molecular surface area provided by grafted CMC. As confirmed by morphological analysis, the modification of CMC drives t...