Thermoforming woodfibre-polypropylene composite sheets

Abstract

Combination of woodfibre and thermoplastics to make composite sheets is an important part of the answer to the world-wide problem of ever-growing volumes of waste which people produce. A large percentage of municipal waste consists of woodfibres and thermoplastics and in New Zealand, the most abundant woodfibre grown and utilised is Pinus Radiata, while thermoplastics of all types are used. Much research has been done to compatibilise polar woodfibres with non-polar thermoplastics, and world production of woodfibre-thermoplastic composites, including sheet products, is now growing. However, little has been published regarding the formability of woodfibre-thermoplastic sheets, information which is vital to manufacturers considering adoption of these new materials. Furthermore, many of the processes used to make composite sheets from woodfibres involve wet-processing or degrade the woodfibres during high-shear mixing. The objectives of this study are: (1) to manufacture composite sheets from Pinus Radiata HTMP woodfibre and polypropylene using a method which minimises processing degradation of the woodfibre, which is useful in a manufacturing environment and which is appropriate for using recycled resources and (2) to develop and apply appropriate thermoforming processes to these composite sheets to make 3-D parts with a view to understanding how woodfibre-polypropylene composite sheets behave during thermoforming.