Abstract: Polybutylene terephthalate-polydimethylsiloxane (PBT－PDMS) as the masterbatch was used for blend spinning with polybutylene terephthalate (PBT). PBT/PDMS blended fibers with different PDMS content were prepared by controlling the amount of PBT－PDMS added, and the effects of PDMS content on fiber softness and other properties were discussed. The results showed that PDMS as a modifying component had good compatibility with PBT in the blend spinning process; the spinnability was good when the mass fraction of PDMS was 6%, and became worse when the mass fraction of PDMS continued to increase to 8%;with the increase of PDMS content, the initial modulus of PBT/PDMS blend fibers decreased significantly,the breaking strength decreased slightly, the elongation at break and breaking work both increased gradually,and the dyeing properties also improved. When the mass fraction of PDMS was 6% and the draw ratio was 2.8,the breaking work of PBT/PDMS blend fibers reached 0.92 cN/dtex, the initial modulus was relatively low,reaching 22.9 cN/dtex; the stiffness of produced 1/2 twill fabric was 2.595 cm, the bending rigidity B was 0.109 8 cN·cm2/cm (warp direction), 0.154 2 cN·cm²/cm (weft direction), and the hysteresis of bending 2HB was 0.228 3 gf·cm/cm (warp direction), 0.297 6 gf·cm/cm (weft direction), the flexibility of PBT/PDMS blend fibers and fabric was obviously improved, and the comprehensive properties were optimized.

Key words: polybutylene terephthalate fiber; polydimethylsiloxane; blend spinning; dyeability; flexibility