Scale, order and complexity in polymer processing

Abstract

From slow beginnings in the 1860s, the evolution of the polymer industry has been marked in the second half of the twentieth century by rapid increases in the scales of production, by increasing power to control order at the molecular level, and by the variety and complexity γ of the resultant processes and products. The paper reviews some of the key developments over the last 100 years or so with a view to identifying themes likely to be of continuing importance in the new century. A general model for the cost of a processing technology is proposed in terms of the factors Q and γ involved in producing a given artefact. Particular technologies are discussed in terms of the order in which basic processing functions are carried out. A major trend likely to continue into the twenty-first century is the way in which the supramolecular organization of the polymer chains is increasingly being brought under control, either directly by processing or indirectly by self-ordering properties of the polymers themselves. Self-organization of reinforcing fibres during processing to produce optimal performance of polymer composites is a parallel trend also likely to develop further into the next century. To illustrate these ideas the paper draws on examples from major polymer processes: extrusion, injection moulding, film blowing, reaction moulding, thermoforming, fibre making and coating.