【作者】 赵斌；

【导师】 张瑜；

【作者基本信息】 东华大学 ， 材料学， 2008， 硕士

【摘要】 聚对苯二甲酸乙二酯(PET)是一种性能优良的聚合物,作为合成纤维以外,它的应用进一步拓展到各类容器、包装材料、薄膜、胶片、工程塑料等领域。近年来,随着聚酯高速纺丝及纺丝细旦化的发展,以及双向拉伸薄膜生产的不断扩大,对聚酯质量的要求不断提高。齐聚物是聚酯聚合过程及降解过程中生成的聚合度为2到10的副产物,齐聚物的存在对PET的纺丝成形、双向拉伸成膜等均会带来一定的不良影响,从而引起了众多生产厂家及研究单位的关注。本课题建立了超声萃取法作为聚酯齐聚物含量的定性分析方法,为快速定性判断聚酯齐聚物含量的范围提供了依据,并采用索氏萃取法作为聚酯中齐聚物的定量分析方法,通过对影响萃取效果的因素进行研究确定齐聚物完全提取的终点,并以此来计算聚酯中的齐聚物含量。通过薄层色谱法结合色谱柱法分离齐聚物;采用核磁共振谱法、热重分析法对齐聚物结构和性能进行表征。结果显示萃取的齐聚物是线性齐聚物和环状齐聚物的混合体,与文献结论一致。课题采用PTA路线进行PET聚合实验,从聚合工艺角度研究了控制和降低齐聚物生成的方法。采用正交试验法定性分析了在聚合过程中聚合时间、聚合温度、催化剂及稳定剂的选择及用量对聚酯产物中齐聚物含量的影响,并进一步试验分析主要聚合工艺的控制以达到降低聚合产品中齐聚物含量的目的。研究发现在聚合过程中,在保证聚合度的前提下适当减缓反应进程,采用较温和的聚合条件有利于降低产物中的齐聚物含量。课题分析了不同齐聚物含量聚酯的结晶性能,通过齐聚物与聚酯的共混物结晶热力学分析和动力学分析发现齐聚物在聚酯结晶成核和晶粒生长方面都有影响。选择不同齐聚物含量的聚酯进行了拉膜和纺丝实验,研究齐聚物对聚酯后加工性能的影响。发现齐聚物在拉膜过程中会导致高破膜率,影响薄膜产量和质量,在纺丝过程中齐聚物容易导致组件压力上升、喷丝板堵塞、断头飞丝等情况,可纺性受到影响。课题通过在生产线上采样,研究了从熔体输送工艺角度控制和降低齐聚物生成的方法探索。通过对螺杆转速、温度的调整考察熔体输送过程中齐聚物含量的变化。发现熔体输送过程中齐聚物的增加是热降解、热氧化降解和力学降解共同作用的结果。为降低辊面齐聚物对薄膜生产的影响研究了BOPET辊面齐聚物的溶解性能。通过近10种有机溶剂比较,发现四氢呋喃能够快速溶解齐聚物并具有较高挥发性能,适合作为生产中祛除辊上齐聚物的优良易挥发溶剂。更多还原

【Abstract】 Poly(ethylene terephthalate) owns excellent properties and is widely used in textile as well as bottle, package material, film, engineer plastics and so on. Recent years, together with the development of super high speed spinning and bi-oriented film producing, the requests for the PET properties become more and more strictly. Oligomers, which are byproducts during PET polymerization and decomposition, contain polymerization degree from 2 to 10. Their negative influence on PET spinning, film producing and dying properties attracts the attention of PET manufactures and research centers.In this thesis, supersonic extraction was used as the qualitative analysis method for quick estimate the oligomer content of polyester, soxhlet extraction was adopted as the quantitative analysis method for oligomer content. Based on the selecting of extraction technology and confirming of extraction time, the oligomers were completely separated and the content were calculated, TLC and chromatographic column were used to separate the oligomes, NMR and TG were used to analysis the structure and thermal properties of the oligomers. Results show that the extracted oligomers were composed by liner oligomer and circle oligomer.PTA route was adopted in PET polymerization, methods for reducing oligomer content were tested through adjustment of technical reference of polymerization. Orthogonal test was carried out to analyze the influence of time, temperature, catalyst and stabilizer to oligomer content. The results show that based on a reasonable polymerization degree a moderate polymerization environment would benefit for low oligomer content in polyester.Crystallization property was analyzed thermodynamically and kinetically. the results show that oligomers have influence on both the formation of nuclei and the growth of crystallites of PET matrix. Film and spinning were tested on PET with different oligomer contents, the results show that oligomer would cause high film rupture rate and low film property in film drawing and bad spinning ability in spinning.The influence of melt transportation to oligomers was studied. The oligomer contents in different melt temperature and melt keeping time were compared. It shows that the increasing of oligomers in melt transportation was cause by thermal degradation, thermal oxidative degradation and mechanical degradation.According to the needs of fast removing oligomers from roller of BOPET, different solvents were test. Tetrahydrofuran (THF), with its excellent volatility, was proved to be a proper solvent for fast dissolve oligomers on roller surface in production.更多还原