反应挤出阴离子聚合尼龙6纤维增强复合材料的制备及原位成纤机理研究

Due to the distinguishing feature of polyamide (PA6) prepared by anionic polymerization via reaction extrusion and in situ microfibrillar composite, it is very valuable to prepare and study the in situ fibrillation mechanism of PA6 fiber reinforced composites prepared by reactive extrusion. In this research, a melting mixiture of ε-caprolactam, PS and PS-co-TMI is added into a two-screw extruder, and then the anionic polymerization of ε-caprolactam is initiated to prepare PS/PA6 blends. Based on the analysis of the mechanism of anionic polymerization and the graft polymerization of PA6 onto PS-co-TMI, a controlled polymerization will be realized in the reaction extrusion. The morphology evolution of the PS/PA6 blends during reaction extrusion is anaylsized. Then, the mechanism of controlled morphology in the reactive extrusion is illustrated via the investigation of the effect of processing conditions, thermodynamic and hydrodynamic characterization on the morphology developing. Based on the illustrations mentioned above, structure controllable PS/PA6 composites with dispersed PA6 fibers could be prepared. The relationship between morphology characterizations and the physical and processability properties of the PA6 fiber reinforced composites are studied. Then, the in situ fibrillation mechanism and relationship between structure and mechanical properties of PS/PA6 composites are illustrated. At last, a new strategy for the preparation of PA6 fiber reinforced composites with designed structure and properties via anionic polymerization by reactive extrusion is established.

基于反应挤出阴离子聚合尼龙6（Polyamide 6，PA6）的工艺特点及原位微纤增强复合材料的突出优势，本项目选用己内酰胺、苯乙烯及苯乙烯-3-异丙烯基-二甲基苄基-异氰酸酯共聚物（PS-co-TMI）混合熔体为原料，首先通过反应挤出阴离子聚合制备PS/PA6合金，揭示反应挤出阴离子聚合反应及PS-co-TMI阴离子接枝反应机理，制备反应可控的PS/PA6合金。分析合金形貌结构演变过程，明确挤出加工条件、热力学及动力学等因素与形貌结构演变之间的关系，揭示反应挤出阴离子聚合PS/PA6合金形貌结构调控机理。制备PS为连续相、纤维状PA6为分散相的PS/PA6复合材料，研究其微观形貌结构，阐明PA6分散相的原位成纤机制；制备结构可控的PA6纤维增强复合材料。表征其力学、热及加工性能，研究复合材料结构与性能之间的关系，最终建立结构与性能可控的PA6纤维增强复合材料的反应挤出阴离子聚合制备方法。

原位微纤增强复合材料的制备成本低且工艺绿色环保、纤维分布更加均匀、纤维本身机械性能优异、界面脱粘问题减少，近年来一直是国内、国外高分子共混领域的研究热点。本项目基于反应挤出己内酰胺阴离子开环聚合，以苯乙烯和己内酰胺为主要原料、双螺杆挤出机为反应容器，通过反应挤出制备了尼龙6/聚苯乙烯（PA6/PS）不相容原位合金，研究了聚合反应及合金形貌结构演变机理，并对PA6/PS原位合金的微观结构、结晶性能、热稳定性能及力学性能进行表征和分析，同时深入探索了PA6/PS原位合金结构与性能之间的关系，最终通过反应挤出原位阴离子聚合制备了结构与性能可控的PA6原位微纤增强PS合金。.首先，本项目以己内酰胺和苯乙烯为原料，通过反应挤出阴离子聚合制备了PA6/PS原位合金。使用SEM观察了经过四氢呋喃刻蚀的PA6/PS原位合金的脆断面，发现当PS含量高于30 wt%时，合金形貌由PS分散相/PA6基体转变为PA6分散相/PS基体，出现了在传统熔融共混体系中少见的、低PS含量就能发生相反转的反应诱导相分离现象，本项目对反应诱导相分离产生相反转的机理进行了深入探讨。.其次，本项目基于反应挤出阴离子聚合过程中的反应诱导相分离，以己内酰胺和苯乙烯为原料，调控合金中PS的含量分别为30~45wt%及50wt%，通过反应挤出阴离子分别制备了以纤维状或微球状PA6为分散相，PS为连续相的PA6/PS原位合金，除去合金中的PS连续相，制备了PA6微纤及PA6微球；研究了合金组成与PA6微纤、微球结构之间的关系。.最后，本项目基于对反应挤出阴离子聚合制备了以PA6连续微纤为分散增强相的PA6/PS原位微纤复合材料，并对复合材料的结晶、热稳定性及力学性能进行了分析表征合金进行了表征，最终建立了原位微纤增强复合材料结构与性能可控的制备方法。.本项目揭示了挤出机中己内酰胺原位聚合共混物的结构与性能的调控机制，本项目建立的PA6微球、PA6连续微纤以及PA6/PS原位微纤增强复合材料的可控制备方法，能为聚合物微球、聚合物连续微纤以及原位微纤增强复合材料的连续可控制备提供很好的借鉴价值。