Reinforcement of thermoplastic starch films with cellulose fibres obtained from rice and coffee husks

Abstract

Cellulosic fibres from coffee (CF) and rice (RF) husks have been obtained applying chemical treatments and characterized as to their microstructure and thermal behaviour. These materials have been incorporated into glycerol plasticised thermoplastic starch (TPS) films obtained by melt blending and compression moulding at 1 wt%, 5 wt% and 10 wt%. Microstructure, thermal behaviour and optical, tensile and barrier properties of the composites were analysed. Both kinds of micro-fibres improve the film stiffness while reduced the film stretchability. However, CF better maintained the film ductility at 1 and 5 wt%. A network of fine oriented fibres was observed on the surface of the films, while internal fibres exhibited a good adherence to the polymer network. The water vapour permeability of TPS films was not reduced in composites, although oxygen permeability was lowered by about 17%. Film transparency decreased by fibre addition in the UV-VIS range. Thermal stability of composites was slightly higher than net TPS films.