Mixed morphology nanocrystalline cellulose from sugarcane bagasse fibers/poly(lactic acid) nanocomposite films: synthesis, fabrication and characterization

Abstract

Fully green nanocomposite films with excellent mechanical properties were prepared using mixed morphology nanocrystalline cellulose obtained by the dual acid hydrolysis of sugarcane bagasse fibers as the reinforcing and poly(lactic acid) (PLA) as the matrix member. Sugarcane bagasse fibers were subjected to alkaline pretreatment and bleaching for de-lignification and partial acid hydrolysis resulting in the formation of microcrystalline cellulose (MCC). Nanocrystalline cellulose (NCC) was obtained by the dual acid hydrolysis of MCC using sulfuric acid and hydrochloric acid followed by ultrasonication. The nanocomposite films were solution cast from chloroform in varied compositions. Mixed morphology and surface topography characteristics of NCC and PLA/NCC films were established using microscopic studies. Changes in the functionality and molecular chemistry with subsequent treatments in the fibers were evaluated using FTIR. NCC exhibited better dispersion characteristics, increased crystallinity and rendered thermally stable from room temperature to 230 °C. Degradation profiles of samples were obtained from thermogravimetry, while the reinforcing effects of NCC in PLA were established by analyzing crystallization characteristics from X-ray diffraction studies. X-ray diffraction was utilized to estimate the increase in crystalline constituents and their state. The increase in tensile strength of the films confirmed the increased and effective positive interaction at the matrix–filler interfaces.