【作者】 徐锦龙；

【导师】 李伯耿；

【作者基本信息】 浙江大学 ， 化学工程、聚合反应， 2002， 博士

【摘要】 聚合物／蒙脱土纳米复合被认为是聚合物改性的一种重要方法，本文运用反应性有机插层剂对钠基蒙脱土进行有机化处理，采取原位聚合和熔融混合二种工艺制备出聚对苯二甲酸乙二醇酯(PET)／蒙脱土纳米复合材料，并对其结构和性能进行了系统的研究。本文取得以下重要研究进展： 根据PET分子的结构特点设计了一系列新的反应性蒙脱土插层处理剂SS，分别采用原位聚合和熔融混合方法制备出具备不同结构和性能的PET／蒙脱土纳米复合材料，该方法已经申请中国发明专利。研究表明新的有机处理剂SS系列使蒙脱土与PET材料之间具有非常好的相容性。 研究了蒙脱土有机化处理反应过程，发现有机处理剂分子链上支链数量对插层吸附效果和扩胀蒙脱土晶层间距的能力有不同的影响，带有一个支链的有机处理剂具有最佳的阳离子交换吸附能力，而带有二个支链的有机处理剂则具有最大的膨胀蒙脱土晶层间距的能力。 首次对PET／蒙脱土原位聚合反应过程进行了详细研究，考察了原始蒙脱土的品质、有机土的状态和含量对反应过程的影响，获得了最佳的合成工艺条件和原位聚合反应动力学参数，发现有机蒙脱土SS的加入使酯化和缩聚反应速度加快，表明它对酯化和缩聚反应都具有催化效应，但同时又会对缩聚反应中的气液传质过程产生不良影响，产生这种影响的原因是剥离后的蒙脱土片层对体系中的小分子扩散起阻碍作用。 对二种方法制备的PET／蒙脱土纳米复合材料进行表征研究和比较，通过XRD、TEM、SEM研究了蒙脱土硅酸盐纳米片层在PET基体中的插层／剥离、分散情况；通过XRD、IR研究了纳米粒子对PET分子链结构的影响。首次发现了在原位聚合样品中PET分子链大量采取与常规PET不同的左右式构象，而熔融共混样中PET分子链的构象与常规PET相同(反式)；有机蒙脱土在原位聚合复合材料中能够被很好地剥离、分散，而在熔融共混插层复合材料中的剥离效果不如原位聚合插层理想；双插层过程中有机土的“退化”即层间距收缩的现象提出了新的解释，认为这是在一定温度下有机处理剂分子降解或从蒙脱土晶层表面脱 浙江大学博士学位论文附的结果。 通过DSC、TGA研究、比较了二种复合材料的结晶熔融行为和等温结晶过程并得到了结晶动力学参数。直这辗出飘土片雕浴…愿应 层般淬系史舵袅担感嫁作用兼丕照垦，而更多表现出类似增塑剂的行为，使材料的冷结晶速度有所加快，冷结晶温度向低温区移动，同时使材料的熔体结晶能力下降，结晶度随蒙脱土含量的增加逐渐降低：在熔融插层复合体系中蒙脱土片层则体现出较强的异相成核作用，使冷结晶速度增加更快，冷结晶温度向低温区偏移也更大，熔体结晶能力也大大增强，结晶度上升。有机蒙脱土使PET的结晶过程更加复杂化，而现有的机理难以很好地予以解释，本文提出了表面带有大量活性有机分子短链的蒙脱土片层在体系中具有“模板效应”，这种效应对PET链的成核过程以及晶体生长过程起着特殊的作用。PET／蒙脱上纳米复合材料宏观性能研究表明，少量的有机上使原位聚合插层复合材料的力学性能得到一定的改善，但热变形温度降低：熔融插层复合材料的冲击强度和弯曲强度下降，但弯曲模量和拉伸模量大大上升，热变形温度也得到提高。通过气体透过率的分析研究了纳米片层在气体阻隔性方面所起的作用。直潞到工尘屋随直极上凭Z叨娜土原应累食擂詹 魁县直丈赏翅．gET．雕鸽能尝饿殖研驾缓暴。 研究发现原位聚合插层和熔融插层复合材料的熔体都属于非牛顿流动体系，后者的非牛顿性更强，前者的表观粘度对温度具有很高的敏感性，后者则表现出典型的填充聚合物的流动特性——表观粘度高、切力变稀现象明显，而且在较低有机土含量时就会出现常规填充聚合物在高含量时才会出现的类似固体的屈服行为。 对原位聚合插层复合材料的固相聚合过程和固相缩聚产物的熔融双峰现象进行了研究，结果表明有机蒙脱上的加入同样会影响PET的固相聚合反应，蒙脱上片层对小分子扩散有阻碍作用，使表观缩聚反应速度下降，其影响程度比反应温度要大得多。时间和温度都可以使PET／蒙脱土纳米复合材料的结晶完善程度提高，直至熔融双峰变成单一熔融峰。与常规PET不同的是，当固相缩聚温度接近熔融温度时，PET／蒙脱土纳米复合材料的低温熔融峰温几I与固相缩聚温度T、几c和Xo与反应时间t对数值之间不存在线性关系。更多还原

【Abstract】 Preparation of polymer/montmorillonite nanoconposites considered to be kinds of important method of polymer modification. Na-montmorillonite(Na-MMT) was modified with organic reagents that have reactive end-groups with them and organo-montmorillonite was obtained. Poly(ethylene terephthalate)(PET)/montmorillonite nanocomposite was prepared by two methods of intercalated polymerization and melt intercalation. Structure and properties of different intercalation hybrids were systemically studied. The following important research and develops were achieved:A series of new organic agents (SS) , which have reactive end-groups with them and especially suit to PET, were prepared and used for organic treatment of Na-MMT . Different structure and properties of PET/montmorillonite nanocomposites were obtained by intercalated polymerization and melt intercalation. The results indicate that there are the very good compatibility between montmorillonite and PET. Also corresponding method and technology was applied for a China Patent.The process of preparation of organo-montmorillonite was studied. The number of branch chains that link to SS organic reagents chain has different influences to the ability of absorption and expanding the interlayer distances of montmorillonites. The SS organic reagent with one branch chain has the best ability of ion exchange reaction and that with two branch chains has the best ability of expanding the interlayer distances of montmorillonite.It was first reported on study of in-situ polymerization process of PET/ montmorillonite nanocomposites. The effect of quality of original montmorillonite, morphology and content of organo-montmorillonite on in-situ polymerization process was studied. The best process conditions for in-situ polymerization and reaction kinetics parameters are given. The addition of organo-montmorillonite increased the esterification rate and the polycondensation rate of PET polymerization, but also decreased the mass transfer rate of polycondensation due to barrier property of montmorillonite flakes to small molecules of reaction system. It was shown thatorgano-montmorillonite can catalyze both esterification and the polycondensation reactions.Characterization of PET/montmorillonite nanocomposites prepared by both intercalated polymerization and melt intercalation were studied. The intercalate, exfoliate and dispersing status actions of montmorillonite in PET phase were investigated by XRD, TEM and SEM. The effect of montmorillonite flakes on structure of PET molecule chains was studied by XRD and ER. In in-situ polymerization prepared nanocomposites PET molecule chains mostly take right-and left conformations, while in melt intercalation prepared nanocomposites they take trans conformations, and similar to the pure PET they mostly take trans conformations. Organo-MMT in the nanocomposite was exfoliated and dispersed better by in-situ polymerization process than by melt intercalative. The "retrogression" phenomenon, which concerned with the action of shrinking the interlayer distance of MMT was newly explained as the result of decomposition or desorption of organic agents from MMT layers.The thermal property and isothermal crystallization kinetics of nanocomposites were investigated by DSC and TGA. It was shown that montmorillonite did not act as a nucleating agent abviously in PET crystallization processes for the in-situ polymerization prepared nanocomposite, but more behaved as a plasticizing agent. The crystallization rate of nanocomposite was increased. While the crystallization temperature lowered. Hence, the ability of melt crystallization decreased. Montmorillonite acted as a very good nucleating agent in PET crystallization processes of melt intercalation nanocomposite. The presences of organo-montmorillonite complicated the crystallization processes of PET. The org-modified agent took part in polycondensation of PET in polymerization process. The author suggested a "patter plate effect" theory, which considered that the special structure of O-MMT inter更多还原