(200e) Temperature Responsive PBT Bicomponent Fibers for Dynamic Thermal Insulation

Novel self-crimping polyester fibers in a side-by-side configuration based on mismatching modulus and coefficient of thermal expansion (CTE) between the two fiber components are fabricated by bicomponent melt-spinning; the filament fibers will be primary constituents for either knitted or nonwoven fabrics that can provide dynamic thermal insulation in the temperature range of -30 °C to 30°C. The two halves are made of Crastin, a polybutylene terephthalate resin, and Hytrel, a thermoplastic elastomer. The fibers were cold drawn at various draw ratios to study the effects on mechanical and thermal properties along with fiber morphology. All the fibers showed excellent interfacial adhesion as evidenced by absence of debonding during tensile tests which also showed an increase in modulus and decrease in elongation at break which was attributed to strain-induced orientation of the molecular chains during drawing. Thermal analysis using DSC showed increased crystallinity for the PBT melting peaks with higher draw ratio fibers and absence of cold crystallization for all the draw ratios indicated low amorphous content. Thermo-mechanical analysis on the fibers show that the coefficient of linear thermal expansion (CLTE) increases with fiber diameter. These fibers were first knitted into fabrics and then cut from rolls to obtain battings which showed a systematic marked variation in the thermal resistance as compared to the control samples.