受阻胺类橡胶防老剂研究进展及发展趋势

从橡胶的老化机理出发介绍受阻胺类橡胶防老剂的防老化作用机理,以合成受阻胺类橡胶防老剂基础原料(萘胺和萘酚、苯胺、对取代基苯胺、二苯胺、对苯二胺、对氨基二苯胺)的不同把防老剂分为六类,详细介绍了一些代表性防老剂,并在此基础上总结出以各原料为基础合成防老剂的常用路线。最后指出受阻胺类橡胶防老剂的发展趋势。     

聚合物抗氧剂技术进展

抗氧剂是重要的聚合物稳定化助剂，文章全面而系统地综述了聚合物抗氧剂工业的理论研究进展和技术开发趋势，进而归纳了近十年来国内外抗氧剂品种的主要结构和应用特征，旨在推动国内抗氧剂工业的技术进步。     

Antioxidative effect of Ajowan in a model system

Model conditions were utilized to test the antioxidative activity of a methanolic extract of ajowan (Carum coptimum) (MEA). MEA was less effective than butylated hydroxytoluene in protecting against oxidation of emulsified linoleic acid measured by coupled oxidation of linoleic acid-β-carotene, conjugated diene values, and the thiobarbituric acid values. Ajowan may have potential as a source of natural antioxidant.     

抗氧剂的研究现状和发展趋势

综述了抗氧剂的研究近况,即高相对分子质量化、多功能化和反应性化是目前抗氧剂研究的发展方向和研究热点,在进行抗氧剂研发时也要注意分子结构的合理化,同时,生物基抗氧剂也是值得关注的发展方向。此外,还介绍了一些新型抗氧剂的合成方法。     

Significance of dietary antioxidants for health

Since evidence became available that free radicals were involved in mechanisms for the development of major diseases, including cardiovascular disease and cancer, there has been considerable research into the properties of natural dietary antioxidants. However, it has become clear that dietary antioxidants can only have beneficial effects in vivo by radical scavenging or effects on redox potential if they are present in tissues or bodily fluids at sufficient concentrations. For many dietary components, absorption is limited or metabolism into derivatives reduces the antioxidant capacity. For many dietary phytochemicals, direct antioxidant effects may be less important for health than other effects including effects on cell signalling or gene expression in vivo.     

天然抗氧化剂——茶多酚的应用

介绍茶多酚在国内外食品工业、医药保健、日用化学品等方面的应用现状,展望了茶多酚在国际市场上的广阔前景。     

橡胶防老剂合成技术进展

我国是全球橡胶防老剂主要生产国和消费国，但是落后的工艺技术和日趋严格的环境保护法出台给我国橡胶防老剂业发展带来较大压力，开发新型工艺及清洁工艺成为我国橡胶防老剂未来发展重点。本文介绍了国内主要的橡胶防老剂如防老剂4020、40201NA、RD、3100、MMB、FAO-7和烃化聚酚等合成技术进展。     

High-temperature stabilization of polypropylene using hindered phenol–thioester stabilizer combinations,Part 1: Optimization and efficacy via nondust blends

The thermal degradation of unstabilized polypropylene has been investigated under long-term processing (twin extruder) and thermal aging at 150°C, with additive concentration studies on combinations of an established hindered phenolic antioxidant (pentaerythritol tetrakis (3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate) [S1010] and two popular thioesters (distearyl-3,3′-thiodipropionate [DSTDP] and didodecyl-3,3′-thiodipropionate [DLTDP]) using melt flow rate, carbonyl index and powder diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) (FTIR), and differential scanning calorimetry (DSC) (oxidation induction time [OIT]) and ultimate embrittlement time (Fracture) on injection-molded test pieces. It was found that 20:80 phenol:thioester ratios provided the best long-term thermal stability (LTTS); however, this was the reverse for processing stabilization (80:20), underlining the antioxidant nature of the two stabilizers (long term vs. melt). Melt preblending of the stabilizers (to form a no-dust blend) gave rise to improved LTTS. DRIFTS FTIR indicated that there was an improvement in preblending the additives, which removed any volatile impurities. Increased additive dispersion and localized potential efficacy in the stabilization cycle is important, as well as possible improved addition of the additives to the extruder rather than fine powder. The data are discussed in relation to the long-term stabilization of polypropylene in high-temperature applications such as under the bonnet of automobiles where minimizing stabilizer losses and maximizing synergy are important.     

硫代受阻酚类抗氧剂

主要介绍了硫代受阻酚类抗氧剂的作用机理和现阶段典型产品的应用发展情况,最后介绍了高分子量硫代酚类抗氧剂。     

Wood Flour and Polypropylene or High Density Polyethylene Composites: Influence of Maleated Polypropylene Concentration and Extrusion Temperature on Properties

Abstract

The effects of the concentration of a maleated polypropylene additive (0 to 5 percent by weight) and of extrusion blending temperature (190°C to 250°C) on the mechanical properties of extruded and injection-molded polypropylene-wood flour composites were investigated. The effects of maleated polypropylene additive on similarly processed polypropylene-wood flour and high density polyethylene-wood flour composites were also compared. Both the additive and the high extrusion temperature led to some wood degradation and to a less polar wood surface. The additive led to greater reinforcement of the composites, as indicated by moderate but useful increases in heat deflection temperature, strength, and modulus. The major portion of those improvements was achieved by adding 1 to 2 percent additive. However, both the additive and the high extrusion temperature decreased impact resistance, presumably as a consequence of increased reinforcement by the filler particles and wood degradation. Heat deflection temperature, strength, and modulus of the polypropylene-wood flour system were marginally better than that of the high density polyethylene-wood flour system; impact resistance was marginally poorer.