The isotactic polypropylene (iPP) usually shows a unique parent-daughter lamellae structure in which the parent and daughter lamellae are against each other with a near perpendicular angle (80° or 100°). Inducing a high fraction of oriented cross-hatched structure in iPP during processing is desirable for designing the bi-oriented iPP products. We processed a commercial iPP via tensile-stretching and die-drawing to evaluate the structural evolution of oriented parent-daughter lamellae. It turned out that the die-drawing process had an advantage in attaining a high fraction of oriented cross-hatched structure of iPP, as compared to the free tensile stretching. Besides, the presence of α-nucleating agents affected the formation of oriented parent-daughter lamellae in the die-drawn samples whereas such influence diminished in the free stretched ones. It was found that the confined deformation inside the die led to the well-preserved oriented cross-hatched structure in the die-drawn iPP.

全同立构聚丙烯（i PP）通常显示出独特的母子片状结构，其中母片和子状片以接近垂直的角度（80°或100°）彼此相对。为了设计双向iPP产品，在加工过程中在iPP中诱导很大比例的定向交叉影线结构是理想的。我们通过拉伸和模压加工了商用的i PP ，以评估取向的母女片的结构演变。事实证明，与自由拉伸拉伸相比，冲模工艺在获得高比例的i PP定向交叉影线结构方面具有优势。此外，α的存在-成核剂影响冲模样品中取向的母子薄片的形成，而在自由拉伸的样品中这种影响减小。结果发现，模具内部的有限变形导致在模具拉制的i PP中保留良好的定向交叉影线结构。