中文摘要：

通过多种表征手段，研究了传统挤出PPR管的多层次结构。结果表明：聚合物熔体在加工过程中受轴向应力，分子链沿轴向取向。PPR中高含量的乙烯链段限制了PP分子链的运动，结晶能力差，其结晶度对冷却速率的变化不敏感。PP管内沿厚度方向的晶体结构几乎一致，以α晶为主。外壁快速喷淋冷却会限制乙烯链段聚集形成橡胶相，因而外壁材料中橡胶相含量少，低温韧性较差。

英文摘要：

Multilayered structure of PPR pipe processed by traditional extrusion was studied by various characterization methods. The result indicated the molecular chains oriented along the axial because polymer melt was under the axial stress in the process of extrusion. Crystallization ability of PP molecular chains was poor because high content of vinyl segment limited the movement of PP molecular chains, so the degree of crystallinity was not sensitive with the changing of cooling rate. Crystal structure in PPR pipe was mainly α crystal and there was almost no difference along the thickness direction. The rubber phase was limited to form because of a quick spray cooling at external wall,so the rubber phase content was less and the toughness of outer material was poor at a low temperature.