Design and characterization of reversible thermodynamic SMPU-based fabrics with improved comfort properties

In recent years, great efforts have been made to research and develop advanced thermodynamic textiles that can change their thermal behavior in response to external stimuli. More specifically, shape memory alloys and shape memory polymer coatings have used for thermal comfort applications. However, the use of shape memory polymers in the form of filament yarns integrated in the fabrics has not yet reported. These fabrics have some advantages related to versatility in shape design. The aim of this study was to develop woven SMPU-based fabrics with reversible thermodynamic properties induced by weft SMPU filament yarns interlaced into polyester (PES) fabrics. To this end, PES woven fabrics with different ratios of weft SMPU filament yarns (PES/SMPU 1:0; 3:1; 1:1; 1: 3, and 0:1) were developed and their thermodynamic properties (thermal resistance, water vapor resistance, and permeability index), shape memory effect, and mechanical performance were evaluated and compared to the 100% PES reference fabric. All the SMPU-based fabrics developed were classified as extremely breathable (water vapor resistance <6 m2.Pa/W) and thermally comfortable (water vapor permeability index <0.3). The fabrics integrating the SMPU filament yarns reacted dynamically to the temperature stimuli over and below Tg, whereas the 100% PES fabric showed passive thermodynamic behavior. This dynamism led to an improvement in thermal protection against an increase in ambient temperature, reaching values of 13.18 mK.m2/W in thermal resistance (PES/SMPU 0:1), while also maintaining good moisture management properties, reaching values of 5.19 m2.Pa/W in water vapor resistance (PES/SMPU 0:1).