Copolyester studies. VI. Melt spinning and mechanical properties of tetramethylene terephthalate–poly(tetramethylene oxide) random block copolymers

Fibers were prepared from tetramethylene terephthalate–polytetrahydrofuran (PTHF) random block copolymers, containing the latter in the range of molecular weights 1000–5000 with up to 30% by weight incorporation, using a conventional melt spinning technique. The spinnability of the copolymer and the mechanical properties of these undrawn fibers were evaluated. The changes in mechanical properties brought about by the incorporation of PTHF groups in 4GT units were related to the PTHF block size and content in the copolymer. X-ray diffraction data are also discussed briefly in terms of the structural differences.