PTT的纺丝稳定性和聚集态结构

利用毛细管流变仪研究PTT熔体挤出时的破裂现象,讨论PTT纺丝稳定性和初生纤维聚集态结构。结屎表明,PTT熔体是一种拉伸变稀型流体。自由挤出时,即使剪切速率达到1.5×105 s-1时,挤出熔体也没有出现明显的熔体破裂;而在纺丝过程中,在卷绕速度达到3.8 km／min(剪切速率2.1×103 s-1)时,就出现明显的熔体断裂现象。在高速纺丝中,控制PTT初生纤维取向结构的关键是喷丝头拉伸比,决定结晶结构的关键是卷绕速度。增加喷丝头拉伸比可以提高初生纤维的取向度;提高卷绕速度可以提高纤维结晶度。

Spinning stability and morphological structure of as-spun PTT fiber

The fracture of PIT melt during extrusion was studied with a capillary rheometer. The spinning stability and morphological structure of as-spun PTT fiber were discussed. The results showed that PTT melt was an extensional thinning fluid. No obvious melt fracture occurred during freely extrusion when the shear rate was 1.5 × 105 s-1. Melt fracture occurred at take-up velocity of 3. 8 km/min and shear rate of 2.1 × 10 s-1 during spinning. Spinneret draft ratio played a crucial role in controlling the orientation structure of as-spun PTT fiber during high-speed spinning. Take-up velocity was a factor determining crystallization structure. The degree of orientation of as-spun fiber can be improved by increasing spinneret draft ratio, and the fiber crystallinity can be improved by increasing take-up velocity.