成核剂对PET结晶行为及形态结构影响的研究

成核剂对PET结晶行为及形态结构影响的研究 湖北工业大学 硕士学位论文 成核剂对PET结晶行为及形态结构影响的研究 姓名：胡小明 申请学位级别：硕士 专业：材料学 指导教师：严海彪 20100501 湖 北 工 业 大 学 硕 士 学 位 论 文 摘 要 本文系统地研究了四种成核剂：N-A 、液晶VectraA950 、滑石粉、EBS 对PET 的结晶行为、结晶形态、结晶结构的影响。采用差式扫描量热仪(DSC)研究了PET/ 成核剂复合体系的结晶行为，并用Jeziorny 理论对PET 结晶过程进行了动力学分 析；通过偏光显微镜（POM ）、小角激光散射（Sals）、X 衍射（XRD ）对PET/ 成核剂复合体系的结晶形态和结晶结构进行了研究。 DSC 测试结果表明四种成核剂加入到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/成核剂复合体系的 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/成核剂复合体系进行非等温动力学研究，结果显示随着成核剂的加入， Avrami 常数n 减小，结晶速率常数Zc 增大。可见成核剂的加入有利于PET 的成核， 缩短了PET 的结晶周期，加快了PET 的结晶速率。其中效果最好的是成核剂N-A 。 通过POM对PET/成核剂复合体系结晶形态进行研究，结果表明四种成核剂的 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；采用Sals 法来定量分析四种成核剂的加入对PET 晶体尺寸和结晶诱导时间的影响，发现四种 成核剂都能细化PET 晶体尺寸，同时缩短了PET 的结晶诱导时间，加快了PET 的成 核，促进了PET 的结晶，其中效果最为明显的也是成核剂N-A 。通过XRD对成核剂 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 010、100的平均晶粒尺寸减小了，总结晶度变大了，这也表明成核剂的加入细 化了PET 的晶体尺寸，促进了PET 的结晶。 综合考虑四种成核剂对PET 结晶行为、结晶形态、结晶结构的影响，我们发 现成核效果最好的是成核剂N-A ，其次是滑石粉、液晶材料，最后是EBS 。 关键词：PET ，成核剂，结晶行为，结晶形态，结晶结构 I 湖 北 工 业 大 学 硕 士 学 位 论 文 Abstract In this paper, the effects of four kinds of nucleating agents such as: N-A,LCD VectraA950,talc,EBS on the crystallization behaviors, crystallization morphology and crystallization structure were systematic studied. The crystallization behaviors of PET/nucleating agent blends by Differetical Scanning Calorimetry(DSC), and the kinetics of PET crystallization were analysised by Jeziorny theory; The crystallization morphology and crystallization structure of PET/nucleating agent composites were inverstigated by Polarizing Optical Microscope(POM),Small Angle Laser Scattering(Sals) and X Ray Diffraction(XRD),respectively. According to DSC, the glass trasition temperature and the temperature of cooling crystallization decreased by adding these four nucleating agents, while the heating crystallization temperature and melting temperature were increased; at the same time ,the apparent induction period ,the half time of crystallization,the apparent total time of crystallization of PET/nucleating agents blends were shorter than pure PET;Non-isothermal crystallization kinetics of PET/nucleating agents blends were studied by Jeziorny thory, the results showed that Avrami constant n decreased and the crystallization Z increased with nucleating agents adding.These were indicated that the c added of nucleating agents promoted the nucleating of PET,shorten the crystallization time of PET, among which nucleating agent N-A was the best one. The results of the study on crystallization morphology of PET/nucleating agent composites by POM indicated that four nucleating agents all increased the density of nucleating , lessened the size of crystals, and the crystals were distributed more evenly;The effects of adding four nucleating agents on the crystal size and the induction time of crystallization were quantitative anlysisted by Sals, the results show that these four nucleating agents all can lessened the size of crystals ,shortened the induction time of crystallization of PET,accelerated the nucleation and promoted the crystallization of PET. Nucleating agent N-A was the best of these four. Crystallization structure of PET/nucleating agents composites were analysised by XRD, the results showed that crystal cells were not changed, but the average size of crystals which perpendiculared to the crystal surface 010,100were lessened, while the total degree of crystalinity was largered,which also indicated that it could lessened the size of crystal and promote the crystallization of PET by adding nucleating agents. The effects of four nucleating agents on PET crystallization behaviors, crystallization morphology and crystallization structure were amprehensive considerated, finally we found nucleating agents N-A was the best nucleating agent for crystallization of PET, followed by tacl ,LCD VectraA950 and EBS was the last. Keywords: PET, nucleating agents, crystallization behaviors, crystallization morphology, crystallization structure II