Effects of poly(vinyl butyral)/poly(ethylene terephthalate) sheath-core composite fibers on the structure and tensile strength of a needle-punched nonwoven

Polyvinyl butyral (PVB)/polyethylene terephthalate (PET) sheath-core composite fibers with a sheath/core volume ratio of 1:1 were spun and drawn. The obtained fibers were mixed into a PET fiber web at 20 wt%, after that it was needle-punched. The influence of the PVB sheaths on the structure and tensile strength of the resulting nonwoven after heat pressing at 100 °C for 10 min were investigated. There were almost no defects in the PVB-sheath of the as-spun fibers, and their diameter variation coefficient was less than 5 %. Furthermore, the peeling stress, when pressed at 100 °C for 60–600 s, imparted by the PVB sheaths was higher than that for PET alone. The nonwoven containing the PVB/PET sheath-core composite fibers showed a Young's modulus and tensile strength nearly 50- and 1.5-fold that of the PET nonwoven, respectively, due to the generation of numerous fused entanglement points, while leaving voids for the passage of air intact.