POLY (ETHER-ETHER-KETONE): MELT SPINNING AND FIBER PROPERTIES

Abstract

PEEK, a poly (aryl-ether-ether-keton), was subjected to melt spinning and hot drawing to prepare a thermal resistant fiber. The temperatures of spinning and drawing were preliminary estimated from the thermal analyses for a film specimen: The DTA traces imply that Tm is 337°C, Tg 143°C, Tch (the crystallization temperature on heating) 173°C, and Tcc, (the crystallization peak on cooling) 280°C. The TGA revealed that the onset of thermal decomposition was at temperature above 400°C even in the presence of oxygen. PEEK, however, fairly colored and degraded at 400°C in the actual melt spinning. A smooth and steady spinning could be performed at 380°C. Four as-spun fibers ranging in the spin-stretch ratio from 3 to 36 were prepared for the hot drawing experiments. The maximum draw ratio slightly increased with increasing drawing temperature: It varied from 2.8 at 140°C to 3.5 at 270°C for the most highly spin-stretched fiber. Similarly the drawability was a function of the preceeding spin-stretching. The tensile properties at elevated temperatures were compared to those measured at the ambient temperature: The tensile strength was 0.29 GPa at 235°C, corresponding to 42% of that at 25°C, while more than 30% of the tensile modulus for 25°C was retained at 235°C.