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Polymers 2018, 10(5), 472; https://doi.org/10.3390/polym10050472

Modeling of Flexible Polyurethane Foam Shrinkage for Bra Cup Moulding Process Control

1
Apparel & Art Design College, Xi’an Polytechnic University, 19 Jinhua South Road, Xi’an 710048, China
2
The Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
3
Hong Kong Community College, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
*
Author to whom correspondence should be addressed.
Received: 22 March 2018 / Revised: 20 April 2018 / Accepted: 21 April 2018 / Published: 26 April 2018
(This article belongs to the Special Issue Polymer Processing for Enhancing Textile Application)
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Abstract

Nowadays, moulding technology has become a remarkable manufacturing process in the intimate apparel industry. Polyurethane (PU) foam sheets are used to mould three-dimensional (3D) seamless bra cups of various softness and shapes, which eliminate bulky seams and reduce production costs. However, it has been challenging to accurately and effectively control the moulding process and bra cup thickness. In this study, the theoretical mechanism of heat transfer and the thermal conductivity of PU foams are first examined. Experimental studies are carried out to investigate the changes in foam materials at various moulding conditions (viz., temperatures, and lengths of dwell time) in terms of surface morphology and thickness by using electron and optical microscopy. Based on the theoretical and experimental investigations of the thermal conductivity of the foam materials, empirical equations of shrinkage ratio and thermal conduction of foam materials were established. A regression model to predict flexible PU foam shrinkage during the bra cup moulding process was formulated by using the Levenberg-Marquardt method of nonlinear least squares algorithm and verified for accuracy. This study therefore provides an effective approach that optimizes control of the bra cup moulding process and assures the ultimate quality and thickness of moulded foam cups. View Full-Text
Keywords: polyurethane foams; bra cup moulding; process control; thermal conductivity; shrinkage polyurethane foams; bra cup moulding; process control; thermal conductivity; shrinkage
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Wu, L.; Yick, K.-L.; Ng, S.; Sun, Y. Modeling of Flexible Polyurethane Foam Shrinkage for Bra Cup Moulding Process Control. Polymers 2018, 10, 472.

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