Structure and properties of laser drawn new polyterephthalamide (PA9-T) fiber
Ahmed Jalal Uddin, Yutaka Ohkoshi, Yasuo Gotoh, Masanobu Nagura
Shinshu University, Japan
Japan
Keywords: semiaromatic polyamide, laser drawing, structure
Melt spinning of a new long aliphatic chain contained semiaromatic polyamide namely PA9-T, synthesized by random copolymerization of 1,9-nonanediamine and 2-methyl-1,8-octanediamine, was carried out extruding the pellet through a single-hole spinneret of 1 mm diameter at 295șC following winding speed from 100 to 2000 m/min. Asspun fiber having lowest orientation, wound at 100 m/min, was selected for our present study which was subsequently drawn in CO2 laser drawing device with different feed speed and different draw ratio along with on-line measurement of drawing stress and drawing points observation by a high-speed camera. Birefringence, tensile properties, WAXD patterns, DMTA and DSC measurements were accomplished. In case of draw ratio 2 & 3, minimal drawing stresses caused unstable flow drawing whereas from the draw ratio 4 to maximum 5.5, substantial neck was observed with considerable increase in drawing stress with draw ratio. Furthermore, for the same draw ratio, higher drawing stress was reported for higher drawing speed. Draw ratio and drawing stress exhibited the direct influences on birefringence. WAXD patterns illustrated no clear standing of crystallinity and orientation for flow-drawn fibers and the crystal orientation occurrences from draw ratio 4. Tensile strength and Youngs modulus followed the same increasing trend with draw ratio and drawing speed. Tand curves expressed the a, b, g relaxations at around 150șC, -60șC and -150șC respectively along with a lower endothermic shoulder at 50-70șC. The characteristics of these relaxations were found to be strongly depending on the absorbed moisture and that moisture essentially exists in the amorphous region of polymer. The mechanism of the g-relaxation is associated with the motions of both the polar and methylene units whereas that of the b-relaxation is postulated to originate with motions of both non-hydrogen-bonded polar groups and polymer-water complex units. DSC curves revealed some double or multiple melting peaks. Studies are going on in this regard.