Melt spinning and laser‐heated drawing of a new semiaromatic polyamide, PA9‐T fiber

Fibers of PA9-T, a new semiaromatic polyamide containing a long aliphatic chain, were prepared by melt spinning. As-spun fibers were subsequently drawn with a CO2 laser-heated drawing system at different draw ratios and various drawing velocities. On-line observations of drawing points deciphered two drawing states; namely, flow drawing and neck drawing, over the entire range of drawing. Drawing stress revealed that flow drawing is induced by slight drawing stress under a low draw ratio up to 3, and neck drawing is induced by relatively high drawing stress under a higher draw ratio. The effect of drawing stress and drawing velocity on the development of the structure and properties has been characterized through analysis of birefringence, density, WAXD patterns, and tensile, thermal, and dynamic viscoelastic properties. For the neck-drawn fibers, almost proportional enhancements of crystallinity and molecular orientation with drawing stress were observed. The flow-drawn fibers have an essentially amorphous structure, and birefringence and density do not always have a linear relation with properties. The fibers drawn at high drawing speed exhibit improved fiber structure and superior mechanical properties. The maximum tensile strength and Young's modulus of PA9-T drawn fibers were found to be 652 MPa and 5.3 GPa, respectively. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 433–444, 2004