仪纶共聚酯热降解动力学研究

使用热失重分析法(TGA)研究了聚酰胺酯(仪纶共聚酯)的热降解动力学。结果表明:仪纶共聚酯与常规半消光聚酯(PET)和聚己内酰胺(PA6)相比,其降解行为更接近PA6:在热降解反应初期其降解活化能略低,但在反应后期降解活化能较高;仪纶共聚酯中少量聚酰胺组分的引入,很大程度上改变了聚酯的分子结构,导致其降解机理与PET差异较大,表现为单核粒子随机成核机理。     

稳定剂在聚酯生产中的应用

概述了热稳定剂和抗氧剂在聚酯生产中的应用发展,说明各种稳定剂、抗氧剂之间具有协同效应,同时在生产中使用稳定剂和催化剂组成催化稳定体系。     

环氧树脂降解与稳定化研究进展

介绍了环氧树脂的降解机理,综述了国内外近来对环氧树脂光氧化、热降解的研究进展以及通过在环氧树脂中添加光稳定剂和抗氧剂等提高环氧树脂耐候性的技术进展,并介绍了几种新型光稳定剂在环氧涂料和灌封料中的应用。     

涂料的光老化与光稳定剂

分析了涂料成膜物光降解机理。介绍了丙烯酸酯类、苯乙烯类、芳香族聚酯、芳香族聚氨酯等几种主要涂料成膜物光降解行为及其降解产物,并根据成膜物的降解行为介绍了紫外光屏蔽剂、紫外光吸收剂、自由基清除剂、酚类抗氧剂等光稳定剂。     

受阻胺光稳定剂和抗氧剂并用对聚合物紫外光稳定性的影响

阐述了受阻胺稳定剂(HALS)和抗氧剂的分类和作用机理,重点介绍了受阻胺类光稳定剂和抗氧剂并用对聚合物紫外光降解中的影响。当受阻胺类光稳定剂和抗氧剂并用时,既有协同效应,又有对抗效应,也有加和效应。这依赖于受阻胺类光稳定剂和抗氧剂的种类。同时介绍受阻胺光稳定剂发展的趋势。     

聚氨酯材料的老化降解与稳定化研究进展

介绍了聚氨酯的降解与稳定化机理，综述了用于聚氨酯的紫外线吸收剂、抗氧剂、光稳定剂的一些品种。讨论了紫外线吸收剂(UV-571，UV-328)、抗氧剂(Irganox 1010、Irganox1135、Irganox3125)，受阻胺(HALS)(UV-770，UV-765)等稳定剂对聚氨酯材料的光氧、热老化的影响，结果表明，同时使用上述3类稳定剂可得到较好的效果     

稳定剂对聚对苯二甲酸乙二醇酯扩链及黏弹性的影响

通过监测聚对苯二甲酸乙二醇酯(PET)扩链反应过程中的转矩变化,并结合动态流变测试,研究了三种受阻酚类抗氧剂对PET扩链反应及抑制热降解的影响规律。分析了受阻酚分子结构对PET热稳定的作用机制。结果表明,采用低分子量的抗氧剂3114对PET的热稳定效果最好。与未添加抗氧剂相比,抗氧剂3114加入使得PET扩链反应中最大转矩提高123. 2%,最终转矩提高48. 4%。热加工历程后的PET黏度比未加抗氧剂的提高145. 5%(ω=0. 1 rad/s)。     

聚合物稳定化助剂技术进展

回顾了最近10a国内外聚合物降解与稳定化理论的研究进展,指出稳定化助剂的技术发展趋势,介绍了热稳定剂、抗氧剂和光稳定剂品种的开发动向。     

关于PVC降解与稳定的研究(续)

三、PVC稳定的机理 在已认识PVC降解机理及其影响因素的基础上,使我们认识到PVC的稳定性是可以通过某些措施得到改进的,其中包括添加某些化学助剂于聚合反应过程及其加工过程而获得改进,这种改进PVC稳定性的助剂称为稳定剂,其中包括热稳定剂、光稳定剂、抗氧剂及润滑剂等。现就树脂加工过程中所使用的不同性质的助剂,对于改进PVC     

提高聚酰胺纤维稳定性的途径及机理

从提高聚酰胺纤维的稳定性出发 ,论述其在光、热、氧、杂质等作用下易发生降解的机理和改进聚酰胺的光、热、氧稳定性的方法及作用原理 ,并对不同的改性方法 (如添加抗氧剂、有机热稳定剂、表面改性剂、液态低聚物共混、接枝改性等 )及应用进行了比较。     

抗氧剂和光稳定剂在粉末涂料中的应用探讨

系统介绍了光稳定剂和抗氧剂的种类,分别研究了抗氧剂、光稳定剂以及两者并用在粉末涂料中应用,并阐述了两者在抑制或延缓涂膜的光/热氧化速度所发挥的作用机制。     

医用聚氯乙烯耐辐照改性研究进展

综述了热稳定剂、抗氧剂和光稳定剂改性聚氯乙烯（PVC）的耐辐照机理,以及不同助剂组合添加产生的协同效应。对近年来有关PVC材料耐辐照改性方面的研究进展进行了总结,并对耐辐照PVC材料的发展前景进行了展望。     

Oxidation and stabilization of hydrocarbon polymers: Relationships,new aspects and unsolved problems

Oxidation processes involved in processing, atmospheric ageing and the pre-burning stages of hydrocarbon polymers are outlined. Open problems based on up-to-date knowledge of the mechanisms of oxidation and stabilization processes are considered. Stabilizers used to assist processing and long-term stability are transformed during their service-time. Some of the products thus formed, as well as the products of polymer oxidation, should be considered as inherent impurities of polymers and play an active role in the degradation. Because of safety consideration, some of the products have to be protected also against catastrophic oxidation, i.e. burning. Significant changes in the mechanisms of degradation take place in the pre-burning step in the phases of high temperature oxidation and oxidative pyrolysis. Fuller understanding of the mutual relationships in the mixtures of antioxidants and/or light stabilizers with flame-retardants in lacking.     

Study of polyethylene photodegradation in formulations with a system of interacting photostabilizers and antioxidants

The accelerated UV photodegradation process of low-density polyethylene films, formulated with two photostabilizers and two antioxidants, was studied to evaluate the effect of different combinations of UV stabilizers and antioxidants on the overall photodegradation process. An experimental design, consisting of 33 formulations with different additive ratios and a blank, was used to evaluate the performance of the four mixed additives. From each formulation, 200 micron-thick films were produced by the extrusion-blowing process. Samples from these films were submitted to accelerated UV aging, and the polymer degradation was measured by carbonyl group evolution, molecular weight distribution changes, and maximum elongation loss. The effect of the additive combination on the different degradation reactions is discussed qualitatively by using “relative variables” and a triangular diagram. © 1996 John Wiley & Sons, Inc.     

小本体聚丙烯稳定化研究

选用国产抗氧剂和光稳定剂,对小本体聚丙烯树脂进行了稳定化试验。通过加工稳定性,热老化和户外曝露等多项试验考核,证实所推荐的稳定化配方能够有效地抑制小本体聚丙烯树脂在加工过程中产生的热氧降解,也在不同程度上延长了它们的热氧化寿命和耐候寿命。     

硬脂酸稀土和硬脂酸钙对PVC热稳定特性的比较研究

为有助于加深对稀土热稳定剂的认识,尝试以CaSt2为参照,并以LaSt3为代表,比较研究了硬脂酸稀土对PVC的热稳定特性,并探讨了有关的原理。结果表明:(1)硬脂酸稀土的热稳定特性与CaSt2相似;(2)LaSt3/ZnSt2和环氧大豆油(ESO)的并用效果与CaSt2/ZnSt2相当,但与季戊四醇(PET)和二苯甲酰甲烷(DBM)的并用效果与CaSt2/ZnSt2相比略有逊色;(3)LaSt3/ZnSt2和PET、DBM的并用效果不如CaSt2/ZnSt2的原因可能在于,与Ca2 相比,La3 能更强烈地与Zn2 竞争和PET和DBM形成配合物,从而使后两者的作用更不能得到充分发挥。     

聚酯热氧化降解的速度和机理

本文推导了求PET热氧化降解速度常数的公式。采用热重法、粘度法和羧端基法,对不同催化稳定体系的PET,求出了热氧化降解速度常数。根据实验结果,讨论了热氧化降解机理。     

抗氧剂、光稳定剂在聚碳酸酯和改性材料中的应用技术

简单介绍了抗氧剂和光稳定剂作用、功能和类别.列举了不同抗氧剂、光稳定剂条件下聚碳酸酯和ABS改性合金材料热老化试验的数据:亚磷酸酯抗氧剂和受阻酚抗氧剂的配合体系,可以有效保护聚碳酸酯的相对黏度和色泽,提高PC/ABS合金拉伸强度和缺口冲击强度;使用紫外线吸收剂可以有效地延缓聚碳酸酯变黄并适当保持强度;经试验或实际应用确...     

Effects of a mixture of stabilizers on the structure and mechanical properties of polyethylene during reprocessing

The properties of two polyethylenes [a high‐density polyethylene (HDPE) and a low‐density polyethylene (LDPE)] were studied after several extrusion cycles. To reduce the degradation effects during the reprocessing, a mixture of two stabilizers was added to the formulations. The predominant degradation mechanism was chain scission for the HDPE and chain branching and crosslinking for the LDPE. For both polyethylenes the FTIR spectra exhibited a growth in the number of carbonyl groups as a function of the number of extrusion cycles. Their tensile properties were degraded with the reprocessing but both polyethylenes maintained their nearly constant thermal behavior and crystallinity. The addition of a primary phenolic antioxidant and a secondary phosphite antioxidant preserved the melt behavior of virgin materials after the reprocessing and reduced the degradation effects. From the tensile tests, the efficiency of the antioxidants in the LDPE was very high and, after the reprocessing, the material retained the mechanical properties of virgin LDPE. The efficiency of the antioxidants for the HDPE was not significant. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3910–3916, 2004