To improve the mechanical properties of poly(glycolic acid) (PGA) fibers prepared by the direct spin-drawing process, the concept of “melt structure control” was introduced. A heating chamber was installed in the vicinity of the spinning head and a low take-up velocity in the melt spinning process was adopted to reduce the Deborah number in the spin-line. As a result, improvement of the toughness of as-spun fibers prepared by the melt-spinning process was accomplished, and the drawn fibers of high-strength and high-toughness were obtained by applying an additional in-line drawing process. Entanglement density reduction in the melt spinning process was found to be suppressed by installing a heating chamber as well as by lowering the take-up velocity. Through the matching of the true stress versus true strain curves of in-line drawn fibers by shifting the curves along the true-strain axis, the network draw ratio of the drawn fibers was estimated and the master curves for individual spinning conditions were prepared. The master curves were found to show steeper increases from lower true-strains for the lower Deborah number conditions, whereas the increases in birefringence and strength of the drawn fibers proceeded from the lower network draw ratios.

为了改善通过直接纺丝拉伸工艺制备的聚乙醇酸（PGA）纤维的机械性能，引入了“熔融结构控制”的概念。在纺丝头附近安装一个加热室，在熔融纺丝过程中采用低卷取速度以降低纺丝线中的德博拉数。结果，通过熔纺工艺制备的初纺纤维的韧性得以改善，并且通过应用额外的在线拉伸工艺获得了高强度和高韧性的拉伸纤维。发现通过安装加热室以及降低卷取速度可以抑制熔融纺丝过程中缠结密度的降低。通过沿着直应变轴移动曲线，将直线拉伸纤维的真实应力曲线与真实应变曲线进行匹配，可以估算拉伸纤维的网络拉伸比，并准备各个纺丝条件的主曲线。发现在较低的Deborah数条件下，主曲线显示出从较低的真实应变开始的陡峭增加，而拉伸纤维的双折射和强度的增加则从较低的网络拉伸比开始。