Biaxial orientation of polypropylene by hydrostatic solid state extrusion. Part I: Orientation mechanism and structural hierarchy
Biaxial orientation of polypropylene by hydrostatic solid state extrusion. Part I: Orientation mechanism and structural hierarchy
复制标题
通过静压固态挤出对聚丙烯进行双轴取向。
DOI：
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发表时间：
1986
期刊：
影响因子：
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通讯作者：
E. Baer
中科院分区：
文献类型：
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作者：
S. Pan;H. R. Brown;A. Hiltner;E. Baer
分析了取向聚丙烯在双轴取向下的固态挤压结构。利用光学显微镜（OM）、小角x射线散射（SAXS）和广角x射线散射（WAXS）研究了取向过程中球晶、片层和大分子水平的结构变化。结果表明：聚丙烯球晶经过双轴仿射逐步变形，均匀变形成圆盘状；在这一球晶扁平化过程中，片层向平面方向旋转发生在片层破裂之前，其轴向拉伸比约为1.5。在大分子水平上，晶体c轴与片层破裂同时在平面内取向，而晶体b*轴逐渐向平面垂直取向。非晶链在变形平面上也优先取向。提出了一个层次模型来说明扁平球粒的取向性质。
The structure which results from solid state extrusion using biaxial orientation is analyzed for oriented polypropylene. Structural changes on the spherulitic, lamellar, and macromolecular level during orientation are investigated using optical microscopy (OM), small angle X-ray scattering (SAXS), and wide angle X-ray scattering (WAXS). The results show that polypropylene spherulites undergo stepwise biaxial affine deformation and deform homogeneously into a disc-like morphology. During this spherulitic flattening process, lamellar rotation into the planar direction occurs prior to lamellar break-up at a baxial draw ratio of about 1.5. On the macromolecular level, the crystalline c-axis orients in the plane concurrently with the lamellar break-up, while the crystalline b*-axis gradually orients normal to the plane. Amorphous chains are also oriented preferentially in the plane of deformation. A hierarchical model is proposed to illustrate the nature of the orientation in the flattened spherulites.