PE,PP晶格内应力和晶胞参数变化的关系

高聚物在纺丝及后拉伸过程中,由于大分子运动缓慢,有相当一部分内应力尚未得到松弛,即被冻结在里面。本文以 PE 和 PP 为对象,采用声速法、TMA 法、密度梯度法、WAXS 法和计算机分峰技术,对这两种纤维进行分析,发现 PE 与 PP 的晶格应变相差很大。主要原因是 PE 的理论模量比 PP 大一个数量级。本文计算了 PP 的晶区模量,并与文献报道的理论模量作比较,发现有两种因素影响结晶尺寸和结晶度。本文得到的结论与文献报道的 PET,PPTA 研究结果极为相似。作者认为:品格内应力存在于各种高分子材料中,它是造成品格应变的主要原因。

RELATIONSHIP BETWEEN INTERNAL STRESS AND UNIT CELL PARAMETERS OF PE AND PP

During spinning and drawing of polymers,a considerable part of stress would not be relaxed,but freezed as internal stress because of the moving tardiness of macromolecules.This paper concerns with polyethylene(PE) and polypropylene (PP). Analyzing them by means of sound speed method,thermomechanical analysor,donsity gradient method and WAXS overlapping crystal peaks separation technique,the authors find that the lattice deformation difference between PE and PP is rather large.The main cause is due to the theoretical modulus of PE being 10 times greater than that of PP.The calculated PP lattice modulus is compared with data reported in references.There are two factors affecting the crystal size and crystallinity. However,the conclusion obtained in this work is quite similar to results of other author's studies on PET and PPTA.Therefore,the authors think that internal stross exists in any polymer which is the main reason to cause lattice deformation.