【作者】 张天水；

【导师】 李春忠； 张玲；

【作者基本信息】 华东理工大学 ， 材料科学与工程， 2010， 博士

【摘要】 聚合物基纳米复合材料的制备与性能研究是现代高分子材料学关注的重点和热点,具有重要的理论和实际意义。本文从纳米Si02的表面改性入手,制备了PBT/SiO2纳米复合材料,探讨了其非等温结晶动力学；重点研究了PBT/PET/SiO2三元纳米复合材料结构和性能的关系,围绕PBT/PET/纳米颗粒复合材料的结构控制、设计和性能优化进行了较为深入的探索和分析,并扩展到其它多相体系中,获取了很多有价值的信息,为高性能耐热的PBT纳米复合材料的开发和应用奠定了基础,主要结果如下：1.采用简单的两相混合法来处理纳米SiO2,红外和表面羟基度分析表明,偶联剂对纳米SiO2的处理获得了成功,且表面羟基度减少。偶联剂的种类和含量显著影响纳米Si02的分散状态和分散稳定性,在KH550含量为3-8wt%时,在PBT基体中分散的最好,复合材料性能最佳。2.纳米SiO2使PBT纳米复合材料的力学性能显著提高,其中在0.3wt%含量下,与纯PBT相比,拉伸强度提高了9.5%,而弯曲强度提高了15.1%,且冲击强度与纯PBT维持了同等的水平,综合力学性能最佳。热变形温度在3wt%含量下比纯PBT提高25.7℃,提高幅度达16.6%。非等温结晶行为表明,纳米SiO2有很好的异相成核作用,可显著提高PBT的结晶温度。纳米SiO2/PBT复合材料体系非等温结晶过程与莫志深法动力学方程相吻合,而对Ozawa方法处理的动力学方程并不太适合。莫志深模型求得pure-PBT、PBT/SiO2(0.3wt%)和PBT/SiO2(3wt%)纳米复合材料的F(T)大小为PBT/SiO2(0.3wt%)< PBT/SiO2(3wt%)<pure-PBT,说明PBT/SiO2(0.3wt%)纳米复合材料的结晶速率最大。由Kissinger方程得到pure-PBT、PBT/SiO2(0.3wt%)和PBT/SiO2(3wt%)纳米复合材料的AE分别为-235.4kJ/mol,-356.1kJ/mol和-351.1kJ/mol,说明PBT/SiO20.3wt%的结晶扩散活化能最低,结晶最容易进行。3.揭示了PBT/PET/SiO2多元纳米复合材料中纳米SiO2对PBT/PET合金界面酯交换反应及性能的影响规律,为PBT/PET/SiO2纳米复合材料的结构控制、设计和工艺优化提供了理论基础。研究表明,纳米SiO2能均匀地分散在PBT/PET合金基体中。DSC和核磁共振氢谱分析表明纳米SiO2的加入在一定程度上抑制了PBT和PET之间的酯交换反应,并对PBT起到了异相成核的作用。从力学和热性能可以看出,PBT/PET/SiO2多元纳米复合材料表现出了优异的性能,力学性能比PBT／PET合金有提高,尤其是直接添加法制备的PBT/PET/SiO2纳米复合材料的拉伸强度提高了3%,弯曲模量提高了23%,而热变形温度高达187.1℃,比之PBT/PET的热变形温度提高了18℃。4.采用熔融共混法制备了PBT/EPOXY/SiO2和PBT/PET/clay纳米复合材料。EPOXY进一步改善了纳米Si02粒子在基体中分散性,提高了界面粘合力,使得复合材料的拉伸和弯曲强度增大,并显著改善了冲击强度和断裂伸长率,达到了同时增韧增强的目的。红外表明,环氧树脂中的环氧基团分别与纳米SiO2表面羟基和PBT的端羟基发生了反应,EPOXY的加入使得PBT的结晶峰温度降低；对于PBT/PET/clay纳米复合材料,TEM可见,有机改性的蒙脱土30B在PBT／PET基体中的形成了插层甚至剥离结构。在PBT/PET组成为80／20时,MMT的含量为2wt%,其综合力学性能最好,热变形温度最高达184.8℃,比纯的PBT提高了19%。更多还原

【Abstract】 The study on the structure and properties of Polymer nanocomposites is the focal point and hotspot in the modern polymer materials; it is of great significance in science and practice. This thesis starts from the surface treatment of inorganic particles and the preparation of PBT/SiO2 nanocomposites. The relationship between the structure and properties of the PBT/PET/SiO2 ternary nanocomposites was studied systematically. Deep investigation and analysis on the control and design of structure and performance optimization of the nanocomposites were carried out and applied to other systems. A lot of valuable information was obtained that can act as theoretical basis for development of PBT nanocomposites with high mechanical and thermal properties. The main works and conclusions were listed as following:1. SiO2 nanoparticles were treated with siliane coupling agent by simple two phase blending method. Surfaces of SiO2 nanoparticle were successfully coated by silane coupling agent with analysis of FTIR and the surface oxhydryl degree. The results indicated that the dispersion of SiO2 was strongly affected by the kinds and the concentration of siliane coupling agent. SiO2 nanoparticles could be well dispersed in PBT matrix when the concentration of KH560 is 3-8%wt.2. The mechanical properties of the PBT/SiO2 nanocomposites were obviously enhanced. Compared with the pure PBT, the tensile and flexible strength of nanocomposite with 0.3wt% SiO2 were enhanced 9.5% and 15.1% respectively without losing the impact strength. The thermal deformation temperature increased 25.7℃when 3wt% SiO2 nanoparticles were added. The DSC results showed that crystallization peak temperature for the nanocomposites increased distinctly in comparison to that of pure PBT, which indicated that addition of SiO2 nanoparticles had heterogeneous nucleating effect on PBT. The Ozawa model failed to describe the non-isothermal crystallization of PBT nanocomposites, while Mo model is suitable. The crystallization active energies of pure PBT and nanocomposites with 0.3wt% and 3.0wt% SiO2 determined by Kissinger model were -235.35kJ/mol,-356.14kJ/mol and-351.18kJ/mol respectively.3. The effect of SiO2 nanoparticles on the phase morphology, transesterification between PBT and PET and mechanical properties of the PBT/PET/SiO2 nanocomposites prepared by two methods were studied, which made a theoretical basis for the control and design of structure and performance optimization of the nanocomposites. SiO2 nanoparticles dispersed well in the PBT/PET matrix. DSC and HNMR results showed that the addition of SiO2 nanoparticles restrained the transesterification between PBT and PET to some degree., which is because that SiO2 nanoparticles can react with the end groups of polyesters especially when they exist at the interface of PBE and PET phases. PBT/PET/SiO2 nanocomposites exhibited higher properties than those of PBT/PET blend. For PBT/PET/SiO2 nanocomposite prepared by one-step method, the tensile strength, flexural modulus and HDT were enhanced by 3%, 23% and 18℃respectively.4. PBT/EPOXY/SiO2 and PBT/PET/clay ternary nanocomposites were prepared by melt blending in a twin-screw extruder. The effect of epoxy on phase morphology and mechanical properties of PBT/SiO2 nanocomposites was investigated. FTIR rusult showed that the epoxy groups of the epoxy resin react with the hydroxyl groups of the SiO2 surfaces and PBT chains. Addition of epoxy improved the dispersion SiO2 nanoparticles and interfacial adhesion between the SiO2 nanoparticles and PBT matrix, which resulted in not only the enhancement of the tensile and flexural properties, but also improvement of impact strength and elongation, with a good balance of stiffness and toughness. For PBT/PET/clay nanocomposites, an inserted and exfoliated structure was observed by TEM. When the PBT/PET composition is 80/20wt and the MMT content is 2wt%, overall mechanical properties is optimum, and the thermal deformation temperature reached 184.8℃.更多还原