Transient crystallization during drawing from ultra-high molecular weight polyethylene melts having different entanglement characteristics
Transient crystallization during drawing from ultra-high molecular weight polyethylene melts having different entanglement characteristics
复制标题
DOI：
10.1016/j.polymer.2006.07.073
复制
发表时间：
2006-10-30
期刊：
影响因子：
4.6
通讯作者：
Uehara, Hiroki
中科院分区：
文献类型：
--
作者：
Kakiage, Masaki;Yamanobe, Takeshi;Uehara, Hiroki
结合原位X射线测量和应力分布分析，探讨了超高分子量聚乙烯（HDPE）熔体拉伸过程中的缠结特性与瞬态结晶的关系。具有不同缠结特性的膜通过将具有1.07 × 10（7）（较高）和1.73 × 10（6）（较低）的粘度平均MW的较高和较低MW样品溶液共混，然后在180 ℃下压缩模塑来制备。在高于135 ° C的熔融温度155 ° C下记录的应力分布表现出平台应力区域，对于用更多的较低MW组分制备的膜，其应力水平较低。随着拉伸，无定形散射逐渐集中在赤道上。超过平台应力区的起始点，这种非晶散射突然消失，同时发生结晶成一个短暂的六方相。当这种六方相出现时，它迅速转变为正交相，从而使薄膜表现出更高的平台应力。与此相反，表现出较低的平台应力的膜表现出温和的转变，并在拉伸的后期阶段的六方相的复苏。这些结果表明，“缠结相分离”的过程中进行的熔融拉伸的EST-PE。(c)2006爱思唯尔有限公司保留所有权利。
The relationship between entanglement characteristics and transient crystallization during drawing from ultra-high molecular weight polyethylene (UHMW-PE) melts is discussed, based on a combination of in situ X-ray measurement and stress profile analysis. Films having different entanglement characteristics were prepared by solution blending of higher and lower MW samples having a viscosity average MW of 1.07 x 10(7) (higher) and 1.73 x 10(6) (lower), followed by compression molding at 180 degrees C. Stress profiles recorded at 155 degrees C above the melting temperature of 135 degrees C exhibited a plateau stress region, whose stress level was lower for the film prepared with more of the lower MW component. With drawing, an amorphous scattering gradually concentrated on the equator. Beyond the beginning point of the plateau stress region, such amorphous scattering abruptly disappeared and crystallization into a transient hexagonal phase occurred simultaneously. As soon as this hexagonal phase appeared, it rapidly transformed into an orthorhombic phase for the film exhibiting higher plateau stress. In contrast, the film exhibiting lower plateau stress exhibited a gentle transformation and a resurgence of the hexagonal phase in the later stage of drawing. These results demonstrate that "entanglement phase separation" proceeds during melt-drawing of UHMW-PE. (c) 2006 Elsevier Ltd. All rights reserved.