Biodegradable Poly(butylene adipate-co-terephthalate) Nanocomposites Reinforced with In Situ Fibrillated Nanocelluloses

The enhancement of mechanical properties is highly required for the expanded applications of biodegradable polymers like poly(butylene adipate-co-terephthalate) (PBAT). The use of nanocellulose as reinforcing fillers is one of the effective approaches while preserving the biodegradability of polymers, but the dispersion of nanofibers in polymer matrixes is a great challenge. Here, we report an in situ fibrillation method to prepare nanocellulose-reinforced PBAT composite films with superior mechanical properties and enhanced degradability while promoting the easy dispersion of natural plant fibers in the polymer matrix, which overcome the limitation of natural fiber composites for thin film applications. A hemicellulose-rich holocellulose fiber was selected and silanized prior to melt compounding with PBAT, in which in situ fibrillation of fibers and the dispersion of in situ fibrillated cellulose nanofibrils (CNFs) occurred simultaneously. The nanostructure, mechanical properties, and degradability of the resulting composite films were characterized. Compared with pristine PBAT, the incorporation of 1 wt % CNF fillers increased the tensile modulus by 82% while possessing a tensile strength of 26 MPa, an elongation of 372%, and a toughness of 75 MJ/m3, surpassing most reported data. Moreover, the degradability of PBAT was enhanced as well. Altogether, this study paves a new way of making biodegradable nanocomposites, which expand the application areas, especially where films are required.