NIMTE OpenIR  > 硕/博士论文成果
Thesis Advisor崔平
Degree Grantor中国科学院研究生院
Place of Conferral宁波
Degree Discipline其它专业
KeywordPet/二氧化硅纳米复合材料 界面结构 机理 结构性能关系
Abstract聚合物基无机纳米复合材料是高分子材料领域研究的热点之一,引起了学术界和 工业界的广泛关注。本课题组在前期的工作中已经制备了性能优异的PET/二氧化硅纳米复合材料。然而,PET/二氧化硅纳米复合材料的微观结构、界面结构形成机理及材料的结构与性能的关系等基础问题并未得到很好地解决。开展这方面工作对设计、制备出性能优异的新型纳米复合材料有着重要的指导作用。 基于上述问题,本文研究了PET/二氧化硅纳米复合材料的界面结构及其形成机 制,进而探讨其在高性能材料设计中的应用研究。具体包括以下几个部分: 采用傅立叶变换红外光谱(FTIR)、X 射线光电子能谱(XPS)、固体核磁共振(NMR)、差示扫描量热仪(DSC)以及热重分析(TGA)等方法对PET/二氧化硅纳米复合材料的界面结构进行表征,发现PET 分子链与二氧化硅之间以化学键相连。其中在固体核磁共振测试中,PET-grafted-SiO2 的谱图中Q3 峰消失,直接证实了PET 分子链与二氧化硅间存在共价键结合,表明部分PET 分子链成功地接枝到二氧化硅表面。进一步研究表明PET 分子链不仅在二氧化硅表面发生了接枝反应,而且与纳米二氧化硅粒子间形成了微交联结构。基于对PET/二氧化硅纳米复合材料的界面结构的研究,提出了PET-grafted-SiO2 的结构示意图。 利用GPC 对材料的分子量及分子量分布进行测试,发现在纯PET、未接枝PET 和接枝PET 中接枝PET 分子量最小、分子量分布最宽,且在其GPC 曲线中出现了双峰,分析PET/二氧化硅纳米复合材料原位聚合中的四种反应类型发现此双峰对应于两种反应类型。此外,建立了PET 分子链与纳米二氧化硅粒子间相互作用模型,可以定性地解释在动态流变测试中储能模量、损耗模量和复数粘度的变化趋势。 对PET/二氧化硅纳米复合材料的缩聚过程进行研究,提出了PET/二氧化硅纳米 复合材料界面结构形成的机制,即PET 的单体先在二氧化硅表面接枝,且随着反应的进行,接枝PET 与纳米二氧化硅粒子形成微交联结构。正是由于这种微交联结构使得接枝PET 的缩聚过程偏离了线性关系。采用固相缩聚方法使PET/二氧化硅纳米复合材料的分子量进一步提高,对其结构研究表明PET 分子链与二氧化硅表面的交联结构进一步形成。 基于PET/二氧化硅纳米复合材料的界面结构研究的基础上,设计并合成了两种纳 米复合材料,即聚对苯二甲酸乙二醇酯/凹凸棒纳米复合材料、聚对苯二甲酸丁二醇酯/二氧化硅纳米复合材料,研究发现纳米粒子的添加可以提高聚合物基体的热力学性能,对其微结构研究表明PET/二氧化硅纳米复合材料的界面键合在聚酯基无机纳米复合材料中具有一定的普适性。
Other AbstractThe study of polymer/inorganic nanocomposites is of great interest to both academy and industry because they exhibit significantly improved properties in comparison with conventional materials. In our previous work, PET/silica nanocomposites were prepared by in situ polymerization. The thermal and mechanical properties of the nanocomposites were greatly improved. However, the interface structure and the relationship between structure and properties are not well understood. Understanding of these can help us to design high performance materials. In this thesis, we have investigated the interface structure of the PET/silica nanocomposites and its application in high performance materials. The main contents in the thesis are as follows: The interface structure of poly(ethylene terephthalate) (PET)/silica nanocomposites were characterized by Fourier transform infrared (FTIR), X-ray photoelectron spectra (XPS), solid-state nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The decrease of intensity of the Q3 peak in solid-state NMR measurement is the direct evidence for the covalent attachment of PET chains to the silica surface, indicating that some PET chains have been grafted onto silica surface. Further study reveals that PET chains form lightly crosslinking structures duringthe polycondensation. A schematic diagram of the structure of PET-grafted-silica nanocomposites is given. The molecular weight and the molecular weight distribution were determined by gel permeation chromatography (GPC). The results show that grafted PET chains have a lower molecular weight and broader distribution. In addition, bimodal distributions are observed in the GPC trace of grafted PET, which correspond to two reaction modes in the polymerization process of PET/silica nanocomposites. Furthermore, a model described the interaction between PET chains and silica is developed, which could qualitatively explain the observed dynamic rheological responses. The kinetics of polycondensation of PET/silica nanocomposites prepared by in situ polymerization was investigated by GPC. The mechanism of such a graft reaction is revealed, which can be described as following: During the esterification process, the monomers of PET react with the silanol groups on the surface, and then PET chains grow on the nanoparticle surface. At a certain time, some grafted PET chains react with each other, which leads to the interparticle or intraparticle chains to crosslink lightly. The kinetic plot for grafted PET shows a deviation from a linear correspondence due to the formation of lightly crosslinking structures. Higher molecular weight of the PET/silica nanocomposites has been reached by solid-state polymerization. The structure of the obtained nanocomposites is investigated and the results show that the lightly crosslinking structures further forms. Based on the discussion about the interface structure of PET/silica nanocomposites, we designed and prepared two different polyester/inorganic nanocomposites, i.e. PET/attapulgite nanocomposites and poly(butylene terephthalate)/silica nanocomposites. Compared with these polyester matrixes, the nanocomposites exhibit significant improvements in thermal and mechanical properties. The structure of these polyester/inorganic nanocomposites is also investigated and the results show that the polyester chains are grafted onto inorganic nanoparticles through chemical bonding, indicating that the interface structure of PET/silica nanocomposites is a universal structure in the polyester/inorganic nanocomposites.
Document Type学位论文
Recommended Citation
GB/T 7714
姚霞银. 聚酯基无机纳米复合材料界面结构表征设计及应用研究[D]. 宁波. 中国科学院研究生院,2007.
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