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 g 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 g 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.

Effects of pipe angular velocity and oven configuration on tube temperature distribution in the radiative heating of PVC pipes

“…View factor between finite extension elements (-) g Lamps switch off temperature when they are controlled by a traditional pyrometer (K) T s Softening temperature of PVC (K) th Pipe thickness (mm) x Generic coordinate along lamp extension (mm) x Non-dimensional coordinate along lamp extension in a transversal plane perpendicular to cylinder axis (-) x 1 Non-dimensional coordinate x calculated at the first end of the lamp (-) x 2 Non-dimensional coordinate x calculated at the second end of the lamp (-) …”

“…In the second half of the twentieth century, a rapid increase in the production scales and in the variety and complexity of manufacturing processes characterized the evolution of the polymer industry [1]. In industrial applications like thermoforming, aimed at obtaining products by deforming polymeric preforms or sheets, the study of the thermal stage allows to get a successful forming process and directly affects the mechanical properties of the end product [2].…”

Rapid integrated rheo-optical and polarized Fourier-transform infrared spectrometry measurement system for polymer films undergoing chemo-mechanical changes

“…1,2 Detailed analysis of complex sequence of molecular processes by off line characterization techniques is often hampered as the earlier processes may mask the later ones. 3 It is critical to understand the dynamics of the molecular mechanisms during these processing steps and the ability to connect the processing conditions to molecular orientation, structural hierarchy and their effects on the final properties of the films.…”