EFFECTS OF DRAW CONDITIONS ON DEFORMABILITY AND DRAW EFFICIENCY OF HIGH-MOLECULAR-WEIGHT POLY(ETHYLENE-TEREPHTHALATE) FIBERS

The effects of draw conditions on the deformability and efficiency of uniaxial draw were studied for solution-spun fibres from high molecular weight poly(ethylene terephthalate)(intrinsic viscosity = 2.6 dl g-1). The fibres could be drawn up to a draw ratio of 16.4 by three stages of draw (tensile draw at 80-degrees-C + solid-state coextrusion at 90-degrees-C + tensile draw at 200-degrees-C). During the solid-state coextrusion, crystal destruction and orientation of non-crystalline segments in the predrawn fibres took place, leading to further deformation at the third stage of draw. The tensile modulus and strength of the resultant highly drawn fibres reached 39 and 2.3 GPa, respectively. The improved ductility and efficiency of draw developed as a result of changes in supermolecular structure and in the number of net points due to entanglements and stress-induced crystals during deformation.