【作者】 冯凯；

【导师】 严海彪；

【作者基本信息】 湖北工业大学 ， 材料学， 2011， 硕士

【摘要】 本文系统地研究了三种分子量的聚乙二醇(PEG),分别为PEG4000、PEG6000和PEG8000对PET的结晶行为、结晶形态、结晶结构的影响,并同时研究玻璃纤维(GF)对PET的力学性能和结晶行为的影响。采用差式扫描量热仪(DSC)研究了PET/PEG复合体系和PET/GF复合体系的结晶行为,并用Jeziorny理论对复合体系的结晶过程进行了动力学分析;通过偏光显微镜(POM)研究了PET/PEG复合体系的结晶形态,通过X衍射(XRD)对PET/PEG复合体系和PET/GF复合体系的结晶结构进行了研究。对于PET/PEG复合体系,三种分子量的PEG加入到PET熔体中,均使得PET的玻璃化温度和冷结晶温度降低,而热结晶温度和熔融温度升高;同时PET/PEG复合体系的表观诱导期、半结晶时间、表观总结晶时间都比纯PET的短;通过Jeziorny理论对PET/PEG复合体系进行非等温动力学研究,结果显示随着PEG的加入,Avrami常数n减小,结晶速率常数Z c增大。可见PEG的加入提高了PET分子链段运动能力,同时由于其与PET相容性的局限性,起到了成核的作用,缩短了PET的结晶周期,加快了PET的结晶速率,其中效果最好的是PEG8000添加量为10wt%时的PET/PEG复合体系。通过POM对PET/PEG复合体系结晶形态进行研究,结果表明PEG的加入,均使得PET的成核密度增大,晶体尺寸变小,晶体分布更加均匀;通过XRD对PEG加入后的复合体系的结晶结构进行分析,发现晶胞并无变化,但是垂直于晶面[110]、[100]的平均晶粒尺寸减小了,[010]晶面的平均晶粒尺寸变化不大,总结晶度变大了,这也表明PEG的加入细化了抑制了[110]、[100]晶面的晶体生长,促进了PET的结晶。同时对PET/GF复合体系的力学性能和结晶行为进行了研究,结果表明将经硅烷偶联剂KH550处理后的玻璃纤维(GF)添加到PET中,提高了PET的拉伸强度和冲击强度,其中玻纤添加量为30wt%时,复合体系的力学性能提高最大。DSC结果表明玻纤在PET中起到了成核作用,提高了PET的热结晶能力,但由于其阻碍了PET分子链段运动,故使得PET的冷结晶能力减弱。XRD结果表明玻纤对PET的晶胞无影响,但能提高PET的结晶度,同时使得垂直于[010]、[110]和[100]晶面的平均晶粒尺寸明显减小,细化了晶体尺寸。更多还原

【Abstract】 In this paper,the effects of three kinds of molecular weight Polyethylene glycol(PEG) such as:PEG4000, PEG6000 and PEG8000 on the crystallization behaviors, crystallization morphology and crystallization structure of PET were systematically studied, and the effects of glass fiber on the mechanical properties and crystallization behavior of PET were studied too. The crystallization behaviors of PET/PEG composites and PET/GF composites were studied by Differential Scanning Calorimetry (DSC), and the kinetics of PET crystallization were analysed by Jeziorny theory; the crystallization morphology were investigated by Polarizing Optical Microscope (POM), and the crystallization structure were investigated by X Ray Diffraction (XRD).For PET/PEG composites, PEG with three kinds of molecular weight joining in PET melt, all made the glass transition temperature and cold crystallization temperature of PET reduced, the crystallization temperature and melting temperature of PET increased, at the same time, the apparent induction period, the half time of crystallization, the apparent total time of crystallization of PET/PEG blends were shorter than pure PET. Non-isothermal crystallization kinetics of PET/PEG blends were studied by Jeziorny theory, the results showed that Avrami constant n decreased and the crystallization Zc increased with PEG adding. That was to say the adding of PEG improved the moving of the link segments of PET molecule, because of the limitations of the compatibility of PET and PEG, PEG played the role of nucleation and shorten the crystallization cycle, speeding up the crystallization rate of PET. When PEG8000 were added for 10wt%, the effect was the best. The results of the study on crystallization morphology of PET/PEG composites by POM indicated that PEG increased the density of nucleating, lessened the size of crystals, and the crystals were distributed more evenly. Crystallization structure of PET/PEG composites were analysed by XRD, the results showed that crystal cells were not changed, but the average size of crystals which were perpendicular to the crystal surface [110] and [100] were lessened, and the average size of crystals which were perpendicular to the crystal surface [010] were not changed, while the total degree of crystallization was increased, which also indicated that it could lessened the size of crystal and promote the crystallization of PET by adding PEG.The mechanical properties and crystallization behaviors of PET/GF composites were studied at the same time, and the results show that the adding of GF which the surface was treated with KH550 improve the tensile strength and impact strength of PET, and when the additive quantity is 30wt%, the effect is the best. The results of DSC show that GF plays a role as nucleation, improved the heat crystallization ability, but it make the cold crystallization ability decreased because it hold up the moving of link segments of PET molecule. The XRD results show that when added GF in PET, the crystal cells of PET were not changed, but the average size of crystals which were perpendicular to the crystal surface [010], [110] and [100] were lessened, and the total degree of crystallization was increased.更多还原