Abstract
Bicomponent fibers using the high‐performance polymer poly(phenylene sulfide) (PPS) together with poly(ethylene terephthalate) (PET) were melt‐spun. Both possibilities of using PPS, either as core or as sheath material, were realized to provide special functionalities like improved thermobonding capability, flame retardancy, or chemical resistance. Parameters that guarantee stable processing of PPS and PET during coaxial extrusion with different core/sheath volume ratios were explored. Microscopic studies of the cross‐sections showed holes and cavities, which were formed at the interface between PPS and PET. Possible mechanisms for cavity formation were evaluated. Results of thermal and mechanical characterization by means of TGA, DSC, and tensile testing revealed a strong influence of the processing parameters, namely draw ratio and core/sheath volume ratio, on the crystallization and the tensile strength of the drawn fibers. By changing the core/sheath volume ratio from 2 to 0.5 in the PPS/PET fiber, the crystallinity of the PET‐component was switched from 10 to 50%, whereas the crystallinity of the PPS dropped from 68 to 7%. It was determined that bicomponent fibers can exceed the strength of monocomponent fibers up to 28%. The flammability and chemical resistance of the new developed fibers were characterized. In contrary to what was expected, the encasing of PET with PPS reduced the flame retardancy, though PPS has a higher flame resistance than PET. The chemical resistance of the PET core against hydrolysis was imparted by coextruding a PPS sheath. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007