Structure and Properties of Bicomponent Core-Sheath Fibers from Poly(ethylene Terephthalate) and Biodegradable Aliphatic Polyesters

Abstract

Bicomponent core-sheath fibers are prepared by coextrusion of poly(ethylene terephthalate) (PET) as the core and poly(butylene succinate/L-lactate) (PBSL) or poly(L-lactic acid) (PLLA) as the sheath. Their morphological and crystallographic variations in the process of melt- and cold-drawings are examined in detail. During drawing and annealing of the conjugate fibers, the PET core filament gains a higher crystallinity compared with that of a single PET fiber, while the sheath polymers remain in an amorphous state. With the increased crystallinity of the PET core, the tenacity of the conjugate fibers became higher. The enhanced mechanical properties of the conjugate fibers compared with a single PET fiber are reasonably attributed not only to crystal orientation, but also to the strong interfacial adhesion between the core and sheath polymers induced by the interfacial reaction during melt-spinning. Alkali treatment of the conjugate fibers yields a denier-decreased fiber with a rough surface because the sheath polymer is not completely eliminated from the surface of the PET core. This fact also supports the interfacial reaction of the polymers. The alkali treatment can be an environmentally friendly process for decreasing the denier of polyester fibers. Conjugate fibers may also potentially be used as biomedical and marine fibers.

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