【作者】 周政；

【导师】 王贵宾；

【作者基本信息】 吉林大学 ， 高分子化学与物理， 2012， 博士

【摘要】 聚醚醚酮是一种高性能特种工程塑料，它具有的多项优异性能使其在军工、航空航天、石油化工、生物医疗等领域有着广泛和极有潜力的应用，但是，聚醚醚酮也存在着老化降解、交联等问题。本论文主要研究聚醚醚酮在熔融状态下的降解交联行为及稳定性的改善。首先，为了研究聚醚醚酮树脂熔融阶段的降解机理，我们合成出聚醚醚酮齐聚物作为聚醚醚酮树脂的模型化合物，这种模型化合物具有与聚醚醚酮相似的结构和更好的溶解性，并且结构精确，纯度很高。通过研究这个模型化合物的降解过程，我们总结出了模型化合物的降解交联机理，进而推断出聚醚醚酮树脂在熔融阶段发生的降解交联行为。然后，我们尝试通过添加抗氧剂的方法来提高聚醚醚酮树脂的熔融稳定性。我们优选了三种分属不同类别的抗氧剂及其复配抗氧剂与聚醚醚酮树脂熔融共混，然后分别考察了这些抗氧剂对聚醚醚酮的熔融稳定性、热分解温度及机械性能的影响，最终，研究优化出添加抗氧剂的聚醚醚酮树脂配方，获得了熔融稳定性良好的聚醚醚酮树脂。进一步，我们又通过非等温热力学模型和追踪聚醚醚酮体系中自由基的方法，研究了抗氧剂对聚醚醚酮的作用，并推断其作用机理。更多还原

【Abstract】 The widespread use of synthetic polymers has revolutionized the manufacturingindustry. Poly (ether ether ketone), a type of thermoplastic resin, is widely usedespecially in aerospace, automotive and health care applications due to the excellentchemical resistance, superior mechanical properties, tribological properties and highservice temperature. However, like other commercial plastics, PEEK will experiencesome types of degradation or cross-linking in the process of extrusion and injectionmolding due to the higher processing temperature which is almost paralleled with its’melting point (around340oC). The degradation will lead to a decline in PEEKproperties, such as embrittlement and difficulty in molding.Little work has been carried out on elucidating the reactions taking place in themelt of PEEK because the determination methods of the degradation are limited. Themethod that tracks the small organic molecules in the gas upon decomposition todeduce the degradation mechanisms is not suitable for the melting PEEK becausethere are nearly no organic molecules released into the gas phase when PEEK ismelted at the temperature lower than450oC. Some methods, like FTIR and13C NMRmeasurements, are not efficiently to investigate the degradation mechanisms preciselysince the chemical changes in the melting PEEK are not as visible as the changeshappened at the higher temperature (over450oC). The excellent solvent resistance ofPEEK is another important factor which brings embarrassment to the analysis ofPEEK because the difficulty to find a fine solvent to dissolve the polymer well thatmany measurements which are normally considered to be proven technique to studythe chemical structure are limited. In this work, the stability of melting PEEK was evaluated by rheological testand thermogravimentric analysis. Dimeric model compound of PEEK have beensynthesized successfully and tested in the conditions paralleled with PEEK to studythe reactions which occurred in the melt. Mass spectrum (MS), FTIR and1H NMRmeasurements were used to observe the changes of chemical structures of thecompounds. By the analysis on the structure changes of model compound, a possiblemechanism of degradation and crosslink of melting PEEK was proposed.The Rheological study of PEEK indicated the melting viscosity of PEEK wouldincrease with the prolongation of the melting time, and the reason was normallyconsidered that some types of crosslink occurred between polymer chains. Tospeculate the reactions which occurred in the melting PEEK accurately, a novelmethod and design of experiment was introduced. The model compound, dimericPEEK, was synthesized and treated at the similar experiment condition paralleled withpolymer PEEK. The model compounds before and after degradation were analyzed bymass spectrum,1H NMR and FTIR to reveal the changes of molecular structurecaused by the heating treatment. The results showed that not only crosslink but alsografting reaction happened during the degradation. When the molecule was heatedabove the melt point, the ether bonds and the end carbonyl groups were more unstablethan the other chemical bonds and easily generate radicals which then grafted to theadjacent molecular on the ortho position of carbonyl or combined with anotherradicals. Meanwhile, a little of crosslink reaction occurred between the molecularchains, causing the increase of viscosity and molecular weight. Finally, a possiblegrafting and crosslink mechanisms of polymer PEEK was proposed.Three types of antioxidants were used to intend to improve the stability of poly(ether ether ketone)(PEEK). To evaluate the effect of the antioxidants on theproperties of PEEK and the stabilization mechanism, some characterization methodswere carried out, such as rheometer, TGA, universal tester and electron spinresonance (ESR). The results indicated that the efficiency of the phosphorousantioxidant (DS9228) in improving the melting stability of PEEK was better than thatof the phenolic antioxidant (3114) and HP136, and the melting stability of PEEK sample containing0.07wt%DS9228was the best among all samples Additionally, noobvious changes could be observed in mechanical properties of PEEK containingantioxidants compared to virgin PEEK.In this dissertation, TG and differential thermogravimetry (DTG) measurementsof Poly (aryl ether ketone) containing naphthalene moieties were reported. Thethermal degradation temperature and the kinetics of polymer were studied throughnonisothermal in Air conditionsElectron spin resonance (ESR) is an effective measurement to observe thestructure and the number of free radicals, which provide a route to study the effect ofthe free radicals on polymer processed at high temperature. the efficiency ofantioxidants for PEEK was evaluated by ESR and the stabilization mechanism ofantioxidants on PEEK resin was discussed.更多还原