Morphological and performance characteristics of nanocomposite films based on poly(lactic acid) compounded with nanocrystalline cellulose and chitin whiskers using melt extrusion

Abstract

The purpose of this work was to evaluate the morphological, mechanical, barrier and phase-transition properties of poly(lactic acid) (PLA) films with nanofillers such as nanocrystalline cellulose (NCC, 1–5%) and chitin whiskers (CHW, 3%). Nanofiller addition using melt extrusion led to decrease in heat capacity change at glass transition as observed from differential scanning calorimetry data. Transmission electron microscopy and x-ray diffraction studies showed that the nanofillers were dispersed in the polymer matrix. This indicated confinement of the motion of polymer chains between layers of nanofillers. Tensile strength (TS) of PLA-based nanocomposite films increased from 50.2 to 70.9 MPa with addition of 5% NCC to PLA. However, addition of CHW did not significantly improve TS. Addition of 3% NCC reduced oxygen transmission rate of films from 209.9 to 180.8 cm3/m2/day, which further reduced to 109.3 cm3/m2/day by adding compatibilizer, methylene diphenyl diisocyanate (MDI, 4%). Water vapor transmission rate of PLA reduced from 44.4 to 28.6 g/m2/day with 3% NCC and 4% MDI addition. This research suggested the promising application of NCC as a nanofiller in PLA films with enhanced thermal, mechanical and barrier properties, and potential application in bio-based food packaging.