旋转挤出加工中聚丙烯管内β成核剂的自组装成纤及诱导形成偏离轴向杂化串晶的研究

Based on supramolecular scientific principles, fiber forming technology of β nucleating agent and rotation extrusion are introduced into polypropylene (PP) pipe processing to overcome the shortcomings of the conventional PP pipe extrusion technologies. Self-assembly of β nucleating agent in the PP pipe will be controlled, by adjusting the β nucleating agent concentration and the melt extrusion temperature, to form the fibrous nucleating agent; with the self-designed rotation extrusion equipment, the hoop movement will be superimposed on the axial movement through the rotation of the mandrel and the die to have the alignment of the fibrous nucleating agent deviate from the axial direction, and the temperature field will be controlled by cooling the inner and outer walls to regulate epitaxial growth of polymer on the surface of the nucleating agent so as to form the hybrid shish-kebab morphology of β crystal deviated from the axial direction. The impact of its alignment, aspect ratio and content on the strength and toughness of PP pipe will be studied, as well as the relative mechanism. As a result, PP pipe with excellent hoop strength and impact strength will be prepared and new technologies and theories of preparing PP pipes with high performances will be developed. This is an innovative study on fundamental scientific studies on structure and performance regulation of polymer materials, therefore very important to both academic study and practical applications.

本项目针对目前常规方法挤出加工聚丙烯管（PP）存在抗冲击强度差、环向强度低的不足，借鉴超分子科学原理，将β成核剂自成纤技术及旋转挤出方法引入PP管制造领域，通过调节β成核剂的浓度和熔融挤出温度控制其在PP熔体中的自组装行为，形成纤维状结构，研究其成核效应，利用自行设计的旋转挤出设备，通过芯棒和口模的旋转，在轴向运动上叠加旋转运动，控制纤维状成核剂偏离轴向排列，通过内外壁双冷实现挤管过程中温度场的控制，调控PP在纤维成核剂表面附生生长，形成偏离轴向排列的β型杂化串晶，建立其调控机理，考察偏离轴向β型杂化串晶结构的排列方式、长径比、含量与PP管环向强度、冲击强度的关系，深入研究其增强增韧作用，制备兼具高环向强度和优异抗冲击韧性的PP管，建立基于晶体结构调控的PP管旋转挤出加工新理论新技术，为推动国民经济支柱产业的发展提供关键技术，具有十分重要的理论和实际意义。

聚丙烯（PP）管综合性能优良的，广泛应用于城市给排水输送等领域，但常规方法挤出加工PP管存在抗冲击强度差、环向强度低的不足，限制了其发展。本项目将芳酰胺类β成核剂自成纤技术引入PP 管旋转挤出领域，形成偏离轴向β型杂化串晶，解决了PP管加工过程中自增强串晶与自增韧β晶不易共存的难题，同时提高了PP管的环向强度与冲击韧性，深入研究相关科学问题，为全面解决PP管的高性能化问题提供新途径，达到预期目标：(1) 选择含氢键的芳酰胺类β成核剂，通过调控成核剂浓度、熔融加工温度等控制其自组装行为，阐明纤维状成核剂形成条件，建立纤维状β成核剂长径比及含量的调控机理；（2）研究了纤维状β成核剂的成核作用及β型杂化串晶的形成机理，揭示了β型杂化串晶结构，建立了β型杂化串晶增强PP的模型。（3）研究了不同旋转挤出模式下聚合物熔体的螺旋流动，建立了旋转挤出过程中增强相偏离轴向排列的理论模型，为旋转挤出制备高性能PP管提供理论基础。（4）通过自组装β成核剂和PP管的旋转挤出加工耦合，研究含自组装β 晶成核剂的PP管内偏离轴向β 型杂化串晶结构的形成和演变，研究了β型杂化串晶的排列、含量、长径比等，与PP管环向强度、冲击强度的关系，将结构与物理性能结合起来，研究其增强增韧机理，优化加工条件，制备了高强高韧PP管，建立了基于晶体结构调控的PP 管旋转挤出加工新理论新技术。（5）发表SCI论文17篇，授权中国发明专利2项。培养博士研究生4 人，硕士研究生3人。