抗氧剂168及其国内开发

本文叙述了抗氧剂168的合成方法及其进展,介绍了该抗氧剂的性能特点、亚磷酸酯与受阻酚的协同机理和该机理所支持的一系列含磷复合抗氧剂,并对抗氧剂168的国内开发状况进行了简要分析。     

双功能型羟胺类抗氧剂的进展

抗氧剂是聚合物材料中应用最广泛的助剂之一,羟胺类抗氧剂同时具有捕获自由基和分解氢过氧化物的功能,其作为一种双功能型抗氧剂,在聚合物材料的加工和使用过程中已经得到了应用。简述了羟胺类抗氧剂的结构,详细介绍了羟胺类抗氧剂抗氧化作用的机理,在结构和作用机理的基础上对影响该类抗氧剂抗氧化效率的因素进行分析,着重阐述了次级氮氧自由基、取代基及取代烷基链长度对其抗氧化效率的影响。此外,介绍了常用羟胺类抗氧剂(烷基羟胺类、苄基羟胺类以及环状羟胺类等)的开发应用现状。最后,提出羟胺类抗氧剂未来的发展方向应致力于优化合成工艺,开发多元复配体系和多功能型羟胺类抗氧剂,实现抗氧剂的高效利用。     

亚磷酸酯类抗氧剂及其应用

亚磷酸酯是聚烯烃加工用辅助抗氧剂的主要品种之一,文章综述了亚磷酸酯类抗氧剂的作用机理、结构类型、品种开发及其在聚烯烃稳定化中的应用。     

受阻酚类抗氧剂的研究进展

综述了受阻酚类抗氧剂的研究概况、分类、作用机理、抗氧剂效率的影响因素和着色机理,介绍了几种受阻酚类抗氧剂的典型产品,并预测了受阻酚类抗氧剂的发展趋势。     

非对称型受阻酚类抗氧剂的研究新进展

非对称型受阻酚类抗氧剂以其特殊的结构显著提高了聚合物的抗氧化效率,新型非对称型受阻酚的探索与开发代表了当今世界聚合物抗氧化领域的一大发展趋势。简述了非对称型受阻酚类抗氧剂的结构特性及抗氧化机理,重点介绍了几种典型的半受阻酚类抗氧剂的合成及应用,指出了非对称型受阻酚类抗氧剂的研究方向。     

抗氧剂改性聚苯硫醚纤维抗热氧化性能的研究进展

介绍了聚苯硫醚(PPS)的氧化机理、抗氧剂的抗氧机理,以及抗氧剂在PPS改性中的应用;综述了抗氧剂改性PPS的研究现状,展望了抗氧剂改性PPS的发展前景;提出选用抗氧剂与PPS共混改性原则,将抗氧剂组装到纳米粒子,再复合至PPS材料,协同改善了PPS的热氧化稳定性,是今后的一个研发方向,并应进一步探究抗氧剂的抗氧机理及提升PPS复合材料的综合耐热氧化性能。     

有机磷抗氧剂现状与进展

助剂在塑料生产和加工过程中起着重要的作用,主要包括增塑剂、稳定剂、抗氧剂、阻燃剂、发泡剂等10余种。抗氧剂是能够延缓或阻止氧化或自动氧化过程的物质。按其作用机理,主要分为主抗氧剂和辅助抗氧剂。 目前在塑料加工中使用较多的主要是酚类、亚磷酸酯类和硫酯类抗氧剂。近年来,为适应连续加工成型的需要,耐热性、耐水性优良的亚磷酸酯类抗氧剂已开发成功,它在抗氧剂市场的比重将会上升。     

抗氧剂作用机理及研究进展

介绍高分子有机材料的氧化机理,综述了抗氧剂机理以及研究进展,指出了抗氧剂的发展趋势,强调了应加强抗氧剂的研究。     

聚丙烯抗氧剂作用机理及其研究

介绍了聚丙烯氧化机理,综述了聚丙烯抗氧剂的作用机理以及研究进展,指出了聚丙烯抗氧剂的发展趋势,强调应加强聚丙烯抗氧剂的研究。     

石油基航空润滑油抗氧剂种类和抗氧化机理

添加抗氧剂是减缓航空润滑油氧化变质的有效途径。本文主要介绍了石油基航空润滑油的氧化机理,添加的抗氧剂的主要类型,以及这些抗氧剂的抗氧化机理以及协同作用机理。     

抗氧剂的生产现状及发展趋势

介绍了抗氧剂的分类以及抗氧剂的抗氧机理。论述了结构对抗氧剂的影响,以及不同抗氧剂配合时的相互作用。指出了抗氧剂的发展现状以及发展趋势,强调了抗氧剂研究的重要性。     

Antioxidants in soya oil

Oxidation is a major problem associated with refining, storing and using soya oil. Phenolic antioxidants have been used for several decades to alleviate this problem. The mechanism of oxidation and the action of phenolic antioxidants in inhibiting oxidation in soya oil are reviewed. Specific antioxidant applications discussed are: treatment of crude soya oil with TBHQ antioxidant; TBHQ antioxidant treatment as an alternative to hydrogenation of soya oil; and usage of TBHQ antioxidant in soya oil used in frying system.     

Influence of wall number and surface functionalization of carbon nanotubes on their antioxidant behavior in high density polyethylene

Carbon nanotubes (CNTs) are extensively incorporated as reinforcement into polymeric materials due to their extraordinary properties. The antioxidant ability of CNTs in high density polyethylene (HDPE) was studied. Single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), and hydroxylated multi-walled carbon nanotubes (MWCNTs-OH) were involved to investigate the influence of wall number and surface functionalization of CNTs on their antioxidant behavior in HDPE. Based on measurements of the oxidation induction temperature and oxidation induction time of CNT/HDPE composites, it is found that the antioxidant ability of the three kinds of CNTs is in the following order: MWCNTs-OH > MWCNTs > SWCNTs. The antioxidant ability and mechanism of CNTs are further examined by electron spin resonance spectra and Raman spectra. It is observed that the antioxidant behavior of CNTs obeys a free radical scavenging mechanism. The order of the radical scavenging efficiency and the defect concentration for CNTs are in good agreement with that of their antioxidant ability in HDPE. With more walls and surface hydroxyl groups, the CNTs have more structural defects and exhibit higher antioxidant ability. The study raises the possibility that CNTs can improve antioxidant properties as well as mechanical properties of polymer matrix.     

A gas chromatographic method for testing antioxidants

A gas chromatographic method for evaluating the effect of antioxidants is described. Emulsions of linoleic acid both with and without antioxidant are oxidized enzymatically. Concentrations of uncreacted linoleic acid are measured at varying incubation times and various concentrations of both lipoxidase and antioxidant. Two antioxidants have been tested. The method is simple, precise, and reproducible. The inhibition mechanism and experimental conditions are discussed.     

Total Phenolics of Virgin Olive Oils Highly Correlate with the Hydrogen Atom Transfer Mechanism of Antioxidant Capacity

Polar extracts of extra‐virgin olive oils (EVOO) contain a large number of phenolic compounds with antioxidant properties. The antioxidant capacity can be measured by different reaction mechanisms, as the single electron transfer (SET) or the hydrogen atom transfer (HAT). In this work, the total phenolic content (TPC) by the Folin‐Ciocalteu method and its correlation with four antioxidant capacity assays (FRAP, ABTS, DPPH^? and ORAC) were evaluated for EVOO polar extracts. It was observed that the higher the total phenolic compounds in the EVOO extracts, the higher the antioxidant capacities, regardless of the method employed. The reaction mechanism observed for TPC by Folin‐Ciocalteu method and also for FRAP, ABTS and DPPH^? antioxidant capacity assays is a single electron transfer, thus, a high correlation among their results is expected. However, the correlation between TPC and ORAC results was also high and significant, allowing to conclude that EVOO phenolic compounds are able to react by the hydrogen atom transfer mechanism, which indicates that they can act as effective radical chain‐breaking antioxidants. These results suggest that, for the EVOO polar extracts, TPC by Folin‐Ciocalteu and ORAC assays could be sufficient to evaluate their in vitro antioxidant capacity.     

亚磷酸酯类抗氧剂的研究及发展趋势

亚磷酸酯类抗氧剂能够有效地提高塑料制品的加工稳定性、耐热稳定性、色泽改良性和耐候性等性能,是重要的抗氧剂品种.文章分析和讨论了分子结构与抗氧剂作用机理的关系.从研究状况、抗氧特性和应用领域三个方面介绍.r亚磷酸酯类抗氧荆的代表品种,并总结了当前亚磷酸酯类抗氧剂发展的趋势,对中国亚磷酸酯类抗氧剂的发展提出几点建议.     

Some Aspects of Polymer Stabilisation

Abstract

Basic principles of polymer oxidation and the mechanism of action of antioxidants are briefly discussed and applications of different antioxidant functions are outlined. Harnessing the processing operation has contributed to the development of targeted reactive processing methods designed to enhance antioxidant performance and polymer durability.     

Phenothiazine derivatives as new antioxidants for the autoxidation of methyl linoleate and their reaction mechanisms

The effect of new antioxidants, such as phenothiazine derivatives, on the autoxidation of methyl linoleate was evaluated by estimating the induction period using the weighing method. Peroxide values (iodometry and IR), refractive indices, mol wts, and UV and IR spectra were measured to investigate the extent of the autoxidation. The induction period evaluated from the weighing method gives almost the same value as that from the peroxide values. It was shown that some new phenothiazine derivatives are remarkably effective antioxidants, and, besides, the mechanism for the autoxidation of methyl linoleate containing phenothiazine derivatives as antioxidants is probably of the same type as that for the substrate alone. This study also investigated the reaction mechanism of phenothiazine derivative antioxidants by determining the electron spin resonance spectra for the antioxidants in the autoxidation of methyl linoleate. Then, the following mechanism was proposed. That is, within the induction period, these inhibitors hold stable nitroxide radicals (>NO*) in the reaction between the antioxidant amino radical (>N*), produced by the reaction of the antioxidant with ROO* or O₂, and the peroxy radical (ROO*). Besides, the more superior the phenothiazine derivative antioxidant, the more inactive the antioxidant makes oxygen and the peroxy radical for the methyl linoleate autoxidation and also for the antioxidant oxidation. Presented at the 12th World Congress of ISF, Milan, 1974.