A new process for making Smart Composite Materials
July 7th, 2003
Paper to the 19th Annual Meeting of the Polymer Processing Society, Melbourne, Australia, 7th-10th July 2003
S F Bush with D R Blackburn and K J Jamieson
Abstract
This paper describes a new process for the production of certain types of smart composite materials, which under prescribed temperature fields spontaneously adopt prescribed shapes. These shapes are quite stable at room temperature plus about 50 oC. At or near the forming temperatures the shapes may revert to their original forms. Articles of this type can thus be seen as the polymer composite equivalent of bimetallic strips or shape memory metal alloys.
The purpose of this process which is under commercial development under the acronym SMARTFORM© is to be able to make shapes from straight rods and flat sheet feedstock which are either impossible to mould or very expensive to do so by conventional processes. The key to the new process is the placing of mixtures of heat shrinkable synthetic and natural fibres in precise positions in the cross-section of pultruded profiles – notably rods and sheet. When subsequently cut to size, the rods or sheet elements are passed on belts through a series of heating zones for prescribed times which cause them to curl or twist into the shapes required. The process is economical since both the pultrusion stage and the thermal forming stage are continuous, not requiring manual intervention.