高分子材料的老化表征方法

高分子材料的老化会使其性能降低,从而部分或完全丧失其使用价值,因此对高分子材料的老化与防老化研究已成为高分子科学的重要研究领域。本文从高分子材料老化过程中外观变化、力学性能变化、电性能变化、波普性能变化4个方面综述了高分子材料的老化表征方法,展望了表征高分子材料老化的研究方向。     

高分子材料老化与防老化的研究

高分子材料性能优异,应用领域广泛,在户外工程中市场占有率很高。但由于使用过程中高分子材料受光、湿度和温度等环境因素作用,导致力学性能和外观发生变化。为改善高分子材料的抗老化性能,必须充分认识其老化机理和老化进程,进而有目的地进行防老化改性。综述了近年来高分子材料老化研究的进展,提出了研究中存在的问题和今后研究方向。     

应力作用下高分子材料的老化行为研究

从微观角度综述了应力影响高分子材料老化性能的现象,提出了应力引发材料老化的特殊性,并分析了其产生的原因,总结了应力引发材料老化的机理,讨论了应力与其他因素相结合对材料老化的影响,展望了其研究方向。     

成纤高分子的老化

<正> 一 导言 所谓高分子材料的老化,是指其在外界因素的作用下,使其性能劣化的过程,象轮胎发粘,塑料薄膜的脆损,鱼网和衣料在阳光下的破坏等都是高分子材料老化的结果。     

紫外线吸收剂UV-B合成工艺的研究

介绍了紫外线吸收剂UV-B的合成工艺、特点及其性能。该品种是一个价廉和性能良好的光稳定剂。前言随着高分子材料生产的逐渐发展,为了解决高分子材料的老化问题,必须大力发展各种防老化助剂。     

启事

为加强应用研究报导,《老化通讯》已于1981年起改名为:合成材料《老化与应用》,系由化学工业部合成材料老化研究所负责编辑、出版、发行的内部期刊,供有关高分子材料的研究、生产和使用部门的同志参考,欢迎订阅。本刊主要交流下述内容:(1)评述高分子材料的老化性能;(2)报导高分子材料新型稳定剂的研制及应用和防老化试验研究的经验与成果;(3)推荐老化试验方法、设备及性能测试方法;(4)报导高分子材料应用研究成果及技术经验;     

文摘

高分子添加剂的新动向:高分子材料的光稳定化《化学工业》,1989,40,№8,681～692(日文) 介绍了高分子材料的光老化、光稳定剂的作用和问题。防上老化的做法有:(1)改进树脂的性能;(2)用聚合物复合物     

用红外光谱法研究高分子材料的老化

高分子材料及其制品在制造、贮存和使用过程中,由于受到光热氧等外界因素的作用,引起物质的化学性能和物理性能发生变化,使其在机械、电气等方面的实际使用性能逐渐变劣,以至最后丧失使用价值,这称高分子材料的老化。高分子材料在老化过程发生的化学组成上,结构上的变化概括起来是:低分子烃和其他气体的逸出,氧化产物     

(二)高分子材料的防老化(续)

上一讲介绍了用添加防老剂的办法,来抑制高分子材料的老化。本期谈谈提高高分子材料耐老化性能的若干改性措施。(1)高分子材料改性概述1、改性的重要意义顾名思义,高分子材料的改性,就是用各种方法改变高分子材料的性质,以适应人们的需要。     

浅析常用高分子材料在户外环境下的性能失效特征

高分子材料具有优异的性能和广泛的应用领域,因此在户外的使用率很高。然而,由于光、热、湿度和空气污染等环境因素,高分子材料的性能和外观在使用过程中会发生变化。为了不断提高高分子材料的抗老化性能,有必要了解高分子材料在户外环境下的老化过程。该文主要论述的是应用于户外环境下常用高分子材料的性能和结构的变化。     

Infrared microscopy investigation of oxidation and phase evolution in bitumen modified with polymers

Increase in traffic volume has led to a wider use of Polymer modified Bitumens (PmB’s) in road construction. Although the mechanical properties of such materials have been widely studied, their change with time in service, also called ageing, is yet to be fully understood.One of the most important issues is to identify the process involved: is PmB ageing a consequence of bitumen ageing, polymer ageing or both at the same time? Moreover, most PmB’s feature a two-phase structure made of polymer rich areas along with polymer poor regions, depending on the bitumen chemistry, the polymer nature and content. It is therefore important to take this peculiar structure into consideration when trying to sort out the respective effect on ageing of the polymer and the bitumen. Infrared microscopy allows characterizing separately different phases in heterogeneous products; therefore it is appropriate for PmB’s.In this paper, PmB’s were studied in their original state and after conventional tests claimed to simulate the ageing during the mixing process and several years of road service (RTFOT + PAV). The PmB’s included plastomers and elastomers, some of them being in situ crosslinked. Infrared microscopy was used to determine for each phase the polymer rate and functional indices characterizing the bitumen such as aromaticity, aliphaticity and condensation, and also to map the polymer distribution in the PmB.The characterization of PmB in their original state points out which species of the bitumen are involved in the polymer swelling and the effect of the polymer nature. The characterization of the same PmB’s after the RTFOT + PAV ageing shows how the bitumen species responsible for the swelling evolve during ageing. In addition, kinetic studies were performed using an heating cell fitted to the IR microscope. They confirmed the tendencies obtained with the conventional ageing tests.These studies come to the conclusion of an interdependence of the ageing of the different constitutive phases in a PmB and of chemical exchanges between them. They make clear the micro-morphological modification induced by ageing in a PmB. They finally help to better understand the effect of a crosslinking on the PmB microstructure and its ageing mechanism.     

高分子材料的老化研究进展

介绍了有关高分子材料在环境因素作用下老化研究的历史,综述了橡胶、塑料及胶粘剂的环境老化行为、国内外研究的发展及现状,展望了高分子材料老化的研究动向和发展趋势.     

Synthesis of Polymer-Metal Complexes and Their Effects on Dielectric Properties and Ageing and UV Resistance of SBR Vulcanizates

Metal free and some metal-perylene polymers as well as some metal phthalocyanine polymers were incorporated into butadiene styrene rubber (SBR) compounds as coloring agents. Ageing and UV resistance of the vulcanizates obtained were studied in terms of the mechanical properties. The dielectric properties of the vulcanizates were also discussed. The results obtained revealed that cobalt perylene and cobalt phthalocyanine polymers showed superior performance in SBR vulcanizates against thermal ageing and UV radiation. The optimum concentration of cobalt phthalocyanine polymer was found to be 1 phr (parts per hundred parts of rubber).     

聚合物等离子体表面改性时效性的研究进展

介绍了聚合物等离子体表面改性过程中的时效性现象,并从时效性产生的原因、影响因素以及解决办法等3方面综述了聚合物等离子体表面处理时效性的研究进展,对等离子体表面改性技术时效性的研究方向做了展望。     

Jute fiber reinforced polypropylene produced by continuous extrusion compounding,part 1: Processing and ageing properties

This article addresses the processing and ageing properties of jute fiber reinforced polypropylene (PP) composites. The composite has been manufactured by a continuous extrusion process and results in free flowing composite granules, comprising up to 50 weight percent (wt %) jute fiber in PP. These granules have similar shape and diameter as commercially available PP granules. Rheological analysis shows that viscosity of the compounds follows the same shear rate dependency as PP and is on the same level as glass‐PP compounds. The mechanical properties show very little variation and exhibit strength and stiffness values at the upper range of competing natural fiber reinforced compounds for injection molding. The mechanical performance reduces gradually upon prolonged thermal loading and immersion in water. The low water diffusion coefficient of the 50 wt % jute‐PP composites indicates that the fibers are not forming a continuous network throughout the polymer. The jute fibers exhibit a stabilizing effect against ultra violet irradiation (UV) on PP polymer and, as a consequence, the mechanical properties of jute‐PP composites hardly decrease during an accelerated UV ageing test. Bacteria, fungi, and garden mold grow easily on the compound material, but only have a limited effect on mechanical properties. The resistance to growth of bacteria on the materials surface can be increased using a biostabilizer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

高分子材料的老化及防老化研究

介绍了环境因素如温度、湿度、氧气、光、化学介质、微生物等对高分子材料老化的影响机理,在此基础上,提出了高分子材料的防老化方法。     

Composites of ethylene‐vinyl acetate copolymers with modified magnesium hydroxide–thermo‐oxidative ageing

Flame retardant composites must perform their protective roles permanently, also under conditions of intermittent or long‐term exposure to sunlight, moisture or increased temperature. The aim of our work was characterization of the thermo‐oxidative ageing (90 °C) and the changes in flammability of ethylene‐vinyl acetate copolymer composites with 40 and 60 wt.% of magnesium hydroxide. The neat polymer and its composites were investigated for their thermal (DSC) and structural (FTIR) characteristics as well as their density, melt flow index, tensile properties and combustibility during ageing test. As FTIR results identified the different carbonyl groups in copolymer were created, the highest oxidation intensity was observed for neat copolymer. That process was accompanied by the scission of the polymer macromolecules, especially for first 700 h of thermal ageing. Thermo‐oxidative ageing resulted also in the reduction of flammability of the test materials. The highest reduction was observed for neat polymer. The changes in some properties as analysed both for the copolymer and for its composites after over 700 h of ageing were indicative for initiation of cross‐linking of copolymer molecules after that time. Copyright © 2014 John Wiley & Sons, Ltd.     

Degradation of rubber to metals bonds during its cathodic delamination, validation of an artificial ageing test

Rubber-metal assemblies used for submarine applications are often associated to cathodic protection which can lead to cathodic disbonding of the polymer/metal interface.The degradation mechanisms of polychloroprene/epoxy adhesive/copper-aluminium substrate systems associated to an accelerated ageing test are compared to the degradations resulting from natural ageing conditions in the Mediterranean sea. From destructives tests, a kinetic in four steps is identified for both ageing conditions. This kinetic is confirmed by Electrochemical Impedance Spectroscopy data during ageing. In order to further identify the failure mode, the disbonded surfaces on polymer and steel sides are analyzed using SEM and FTIR. Both ageing conditions present the same type of degradation which validates the fact that the accelerated ageing protocol reproduces the natural conditions. The chemical transformations in delaminated epoxy are very similar to the chemical transformation in epoxy coatings under high energy electron-beam irradiation. However, bidendate metal carboxylates rather than carboxylic acid chain ends are the main oxidation products due to the alkaline environment at the coating-metal interface. It was shown that the metal/polymer interface is not destroyed by an alkaline attack but by a strongly oxidative attack caused by the intermediates of the oxygen reduction.     

Degradation and Stabilization of Polypentenamer

Abstract

The ageing of polypentenamers has been studied. The roles of molecular mass, of catalist used for the polymer preparation, and of antioxidants are discussed. The results of polymer ageing in the presence of various phenolic and amine-type stabilizers are described.     

Characterization of Boundary Phenomena Using Broadband Dielectric Spectroscopy

Applicability of low-frequency dielectric methods of investigation of solid inhomogeneous structures are presented. The methods prove to be very useful for determination of physical properties of both inhomogeneous one-component and multi-component systems including systems arising as a result of adsorption of gases and liquids onto solid surfaces. It is also possible to study adhesion of composite components using the dielectric methods. The methods are particularly useful for investigations of ageing phenomena of polymer composites. The dielectric properties of two polycrystalline low-molecular weight organic compounds are presented as an example of investigations of one-component inhomogeneous structures.