Novel bio-composites based on whole utilisation of wheat straw

Abstract

This thesis reports research work in the development of biocomposites based on whole utilisation of renewable wheat straw for industrial applications. The concept of “whole utilisation” is based on a previous work on a novel twin-screw extrusion technology for processing of feedstock in wheat straw reinforced bio-composites. It demonstrated that straw raw material could be restructurised into a feedstock with cellulose fibre finely dispersed in the non-cellulose matrix, which can be utilised as a bonding phase without having to be removed as in conventional processes to extract the cellulose. The whole straw can thus be utilised to avoid waste of materials and the negative impacts to environment associated with the extraction process. Raw wheat straw in this research was prepared in three ways: size reduction through mechanical milling, pre-treatment by aqueous NaOH solution and deep preparation with aqueous NaOH solution soaking followed by extrusion fractionation. Prepared wheat straws were processed into varieties of forms according to the applications. They were hot-compressed into self-reinforced composite with good flow ability and also processed through extrusion and compression moulding to compound with other biopolymers as good filler. The relationships of processing parameter and property, as well as formulation and property were established for each form of product, which provides a key understanding of the whole development circle of an end product. Through this research, scientific and technical problems has been addressed in materials formulation/processing, product design/manufacturing, enhancement of functionality/ performance as well as economical/environmental assessment so as to develop a series of cost-effective bio-composites and products, which satisfy diverse technical and environmental performance requirements in the industrial sectors across packaging, horticulture, building/construction and shooting sports.