Controlling the shrinkage of polymers for customized shoe sole manufacturing

• Published in: International journal of computer integrated manufacturing Vol. 17; no. 7; pp. 633 - 644
• Main Authors: Amaro, Walter, Diviani, Luca, Montorfano, Davide, Oberrauch, Ermanno, Depinto, Gabriele, Segalini, Simona, Levi, Marinella, Turri, Stefano
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Ltd 01.10.2004
• ISSN: 0951-192X; 1362-3052
• DOI: 10.1080/0951192042000273203

Selected polymers and polymer blends suitable for shoe sole manufacturing were processed by means of two different moulding technologies (injection and compression) and the shrinkage of standard square specimens were measured. This paper, the experimental work of which was performed according to design of experiments techniques, aims to understand the influence of composition and process factors, with the ultimate objective of mastering shrinkage control to a satisfactory degree. In the case of injection moulding, the polymer of choice was a thermoplastic styrene-butadiene-styrene block copolymer with a shrinkage reducing agent additive. Process conditions were fixed and shrinkage control was obtained by subjecting the moulded parts to thermal treatment at an appropriate temperature, according to a calibration curve. For the compression moulding process, elastomeric polyurethane or its blends with EVA (ethylene vinyl acetate copolymer) and talc were used. Here also, the process conditions were fixed, shrinkage was controlled by an appropriate formulation of polymer compound and statistical models were generated allowing shrinkage to be predicted. As all this work was based on laboratory polymer specimens, setting up rules for real-world shoe sole manufacture is beyond its scope. Nevertheless, the results obtained so far represent a sound experimental background for evaluating the feasibility of further process developments.