废旧聚丙烯β-晶增韧与刚性粒子增强协同机理研究

The high value-added recycling of recycled polypropylene (RPP) has much benefit on energy saving and environmental protection, and it is significant in the sustainable development of human society and national economy. However, the traditional toughening of elastomer or reinforcement of rigid particles can hardly achieve balance between stiffness and toughness of RPP. On the basis of this challenge, the main purpose of this project is to prepare filled RPP with balanceable stiffness and toughness, and to study the synergistic mechanism between reinforcement and toughening. Accordingly, β-nucleated RPP and rigid particles with supported β-nucleating agent will be prepared, and then filled RPP containing high β-phase content will be obtained through regulating and controlling the β-phase content of RPP and the nucleating efficiency of rigid particles. Therefore, filled RPP with balanceable stiffness and toughness will be prepared by the effective synergy between the reinforcement of rigid particles and the toughening of β-phase. Furthermore, the internal relationship among rigid particles, β-phase content and mechanical properties of RPP will be demonstrated through the systematic study on the influence rules of molecular chain structure and the heterogeneous nucleation effect of rigid particles on the β-nucleation of RPP, as well as the effect of rigid particles and β-phase content on the mechanical properties of RPP. Meanwhile, it is expected to reveal the synergistic mechanism between reinforcement and toughening, combining with the analysis of the interface structure between rigid particles and RPP. This project aims at obtaining filled RPP with high mechanical properties as good as polypropylene (PP), hence providing scientific basis to the high value-added recycling of RPP.

废旧聚丙烯（RPP）的高附加值再资源化有利于节能环保，对人类社会和国民经济可持续发展具有重要意义。针对传统弹性体增韧或刚性粒子增强RPP存在刚性和韧性难以平衡的问题，本项目致力于刚韧平衡填充RPP的制备及其增强增韧协同机理探究。为此，拟制备β-成核RPP和负载β-成核剂刚性粒子，调控RPP中β-晶含量和刚性粒子的β-成核效率，获得高β-晶含量填充RPP。刚性粒子具有增强作用，β-晶具有增韧效果，使增强和增韧作用协同化，从而制得刚韧平衡填充RPP。通过系统研究分子链结构和刚性粒子具有异相成核作用对RPP中β-成核作用的影响规律，以及刚性粒子和β-晶含量对RPP力学性能的影响，阐明刚性粒子、β-晶含量和力学性能之间内在关系，再结合刚性粒子与RPP间界面结构分析，揭示填充RPP的增强增韧协同机理。本项目的开展旨在获得力学性能达到PP新料水平的填充RPP，为RPP的高附加值再生利用提供科学依据。

聚丙烯（PP）作为五大通用塑料之一，广泛应用于各个领域，从而产生大量废旧聚丙烯（RPP）。为了人类社会的可持续发展，PP等塑料废弃物的高附加值利用受到各国的高度重视。针对传统弹性体增韧或刚性粒子增强RPP存在刚性和韧性难以平衡的问题，本项目通过RPP的β-晶化形成高韧性β-成核RPP替代弹性体增韧，避免弹性体增韧带来的刚性降低；再通过无机刚性粒子提高RPP刚性，从而制得高刚高韧RPP。（1）获得了不同β-成核剂对具有不同化学组分RPP结晶行为和β-成核作用的影响规律，为制备β-晶含量可控的RPP提供了理论依据。（2）基本掌握了β-成核剂、硅灰石和负载β-成核剂硅灰石对RPP结晶行为和β-晶含量的影响规律。通过调控β-成核剂的种类和用量，以及具有不同异相成核作用无机粒子的填充量，能够制得β-晶含量高于80%的填充RPP复合材料。（3）基本明确了β-成核剂和具有不同异相成核作用硅灰石对RPP力学性能的影响规律，也揭示了RPP增强增韧协同机理。通过结合硅灰石对RPP的增强作用和β-晶的增韧效果，获得了刚韧平衡填充RPP复合材料。