Design, preparation and characterization of braiding auxetic yarns with a high negative Poisson’s ratio

In recent years, research work on auxetic textile materials has become more and more popular. Helical auxetic yarns realize a negative Poisson’s ratio effect at the yarn level, wherein the braided auxetic yarns are prepared to realize the structural stability of the auxetic yarns. However, the degree of the elongation auxetic effect has not been solved. In this paper, composite braided auxetic yarns and re-braided auxetic yarns were successfully fabricated by a ring spinning machine and a high-speed braiding machine, and the Poisson’s ratio curves of the two yarns were tested by image analysis. Through the measurement of the Poisson’s ratios of these two yarns, the experimental results show that they both have a good negative Poisson’s ratio effect, and the degree of auxetic effect increases correspondingly. The composite braid technology makes the auxetic yarns retain the original auxetic effect while the degree of auxetic effect was increased. The preparation of these two kinds of auxetic yarns provides a certain experimental basis for the development of auxetic textile materials in the future, and also provides more improvement ideas for scholars.