Large-scale manufacturing of helical auxetic yarns using a novel semi-coextrusion process

• Published in: Textile research journal 2018-11, Vol.88 (22), p.2590-2601
• Main Authors: Zhang, Guanhua, Ghita, Oana R, Lin, Congping, Evans, Kenneth E
• Format: Article
• Language: English
• Subjects: Coextrusion; Extrusion; Manufacturing; Materials research; Parameter identification; Parameter sensitivity; Poisson's ratio; Tensile properties; Yarns
• ISSN: 0040-5175; 1746-7748
• DOI: 10.1177/0040517517725125

This paper introduces a novel extrusion process for manufacturing helical auxetic yarn (HAY). A range of semi-coextruded HAYs have been manufactured in a cost-effective, consistent and readily usable form. The semi-coextruded HAYs were compared to the conventional spun yarns in terms of tensile properties and auxetic behavior. The results show the presence of the auxetic effect in newly fabricated semi-coextruded HAYs. Similar to the traditional spun HAYs, the new HAYs are sensitive to parameters such as the initial wrap angle, the core/wrap diameter ratio and component moduli. Importantly, a few new manufacturing parameters have been identified for tailoring the auxetic behavior of the semi-coextruded HAYs. The semi-coextruded HAYs are auxetic when an instantaneous true Poisson’s ratio analysis method is applied. The semi-coextruded HAYs give a larger maximum negative Poisson’s ratio than the conventional HAYs due to the advantages of the pre-formed helical wrap structure.