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.

Report to Marks and Spencer

S F Bush

Executive Summary

This report summarizes for the period 1st January 2002 to 16th May 2003 the salient points arising:

• from the six Progress Reviews by M&S/SS/UMIST
• Feedback from the M&S and UMIST wearer trials
• Actions by UMIST in the light of these reviews and feedbacks
• Things still to do.

 
This report also provides:

• A complete record of all 74 batches made at UMIST up to 16th May 2003 [Appendix A].
• A listing of the six progress reports and operation manual for the Granex line, which together cover product characterisation, wearer trial results, process settings and pultrusion die designs used for the different SMARTFORMS produced [Appendix B].

 
With reference to the starting point at 1st January 2002, the results of the programme show:

1. Smartforms with attractive white appearance, smooth surface, made to apply to the MS20 bra design, having a reasonable thread-up time.
2. UMIST Wearer trials of the MS20 type which report good comfort and support for 34C and 36D. Larger cup sizes still show a tendency to bulge forward after around 10 wear-and-washing sequences. It is probable that a proportionate increase in the SMARTFORM cross section will correct this tendency.
3. A stable, easily-managed Granex pultrusion process running at 3 times the speed at 1st February 2002.
4. A Smartform process able to reproduce a wide range of shapes and curvatures with minimal changes to the basic process.
5. An end-capping process which produces rounded ends and reduces the chance of snagging during thread up.