5.1 Introduction

In this chapter, the processes used to manufacture articles from biopolymeric materials will be discussed. Some of these methods are specific to biopolymers, for example, the Shimada press, used to produce lignin bound wood fibre extrusions mostly used for fuel briquettes. Some are fundamental raw material production processes such as fibre spinning, and some, such as the Davis-Standard woodtruder are normally used with fossil polymers, but having a clear potential for use with biopolymers.

The methods under discussion are all based on established polymer manufacturing techniques, but the control and application of these methods must be varied to cope with certain factors associated with exploiting the advantages of biopolymers. For a biomass origin polymer to be used to full advantage, it must be biodegradable at the end of its useful life. This means that enough of its molecular structure must retain enough similarity to a biological structure to enable bacteria and fungi to digest it. The conditions under which biological structures can survive are limited in terms of temperature (degradation starts with the denaturing of the tertiary structure (the way a protein molecule is coiled ) of proteins at about 45 C: to consider the effect of this, think about what happens to the white of an egg during cooking. In terms of the kitchen, the process continues through caramelisation to incineration resulting in an inedible (non-biodegradable) materials that is largely carbon. The temperatures reached during polymer processing exceed the range found in the kitchen by up...