应力作用下聚乙烯护套材料的表面形貌研究

研究了聚乙烯(PE)护套材料在拉伸应力、紫外光下的老化开裂行为。用光学显微镜观察老化试样被辐照表面并拍照,确定在各应力条件下试样的临界开裂时间,研究了老化裂纹的形态;应用红外分析手段,研究了应力水平对老化开裂的影响,并探讨了PE护套的应力、紫外老化开裂的机理。结果表明:当应力水平由材料拉伸强度的10%增长到30%时,材料的耐应力、紫外老化开裂性能则由原来的80%下降至20%;在无张应力作用时,试样裂纹是无规孔洞结构,而在有张应力作用时,裂纹则是有规律的垂直于应力方向的细长结构;应力作用改变材料取向度,产生应力集中使分子链被抽拔或者断裂,促进分子链的氧化断链,加速材料的老化开裂。     

抗氧剂对聚乙烯光降解膜结构及性能的影响

采用紫外光加速老化的方法研究了抗氧剂1010对聚乙烯(PE)光降解膜的影响,并通过红外光谱、紫外光谱分析和拉伸性能测试对老化前后的薄膜的结构和性能进行了研究。结果表明,抗氧剂1010能抑制PE的光氧化降解,且导致薄膜光降解过程中羰基化合物的生成量和类型减少;添加抗氧剂1010的光降解薄膜降解的诱导期延长,PE光降解膜紫外照射3 d后其断裂伸长保留率小于80 %,而添加0.3 %（质量分数,下同）抗氧剂1010的PE光降解膜照射4~5 d后其断裂伸长保留率小于80 %。     

聚氨酯纤维的紫外老化特性及分析

为了考察聚醚型聚氨酯纤维的紫外老化特性,通过扫描电镜观察、黏数测定、红外光谱、小角X射线散射、动态热力学性能测试和拉伸性能测试对纤维在人工加速紫外老化条件下的表面形貌、化学结构、有序微区结构及力学性能的变化进行了表征。结果表明,在试验设置的紫外老化条件下,聚氨酯纤维在老化初期过程表面形貌无明显变化,后期出现明显刻蚀作用,黏数在老化过程中有一定程度的下降,纤维分子C—N键和少量C—O键发生断裂,硬段结构中氢键化程度先增大后减小,老化初期分子键断裂,提高链流动性,促使纤维分子形成有序微区,老化过程中纤维有序微区结构尺寸先增大后减小,玻璃化转变温度呈先上升后下降的趋势,断裂强力和断裂伸长率随着老化时间的增加而下降。研究结果为制备环境适应性强的聚氨酯纤维提供基础数据。     

聚乙烯醇缩丁醛薄膜老化机理研究

利用红外光谱和力学性能的变化研究了聚乙烯醇缩丁醛薄膜的热老化和紫外光老化机理,结果表明,在热老化及紫外光老化过程中,PVB薄膜的拉伸强度均是先增大然后再减小。这是由于在热老化过程中PVB薄膜发生了增塑剂的损失及PVB分子主链和侧链的断裂,而在紫外光老化过程中,主要是发生PVB分子链之间的交联反应,仅有少量的分子链发生断裂。PVB薄膜的光老化和热老化都是由树脂中存在少量聚醋酸乙烯分解生成的自由基诱导而发生的,添加适量的热稳定剂和紫外吸收剂可以吸收薄膜加工时生成的自由基,从而提高薄膜的稳定性及粘结性能。     

耐紫外高灼热丝阻燃聚丙烯材料制备及性能

采用含溴阻燃剂或氮磷膨胀阻燃剂(IFR)、复合抗氧剂、光稳定剂和紫外线吸收剂制备了一种耐紫外高灼热丝阻燃聚丙烯材料,研究了不同阻燃剂对聚丙烯阻燃性能及紫外老化性能的影响,在优选阻燃剂的基础上,比较了不同抗紫外老化助剂对材料紫外老化性能的影响,最后评价了最优配方体系下材料紫外加速老化后的性能衰减状况。结果表明,相同阻燃剂添加量下无卤IFR更易使材料通过灼热丝起燃温度850℃试验且无火焰产生,UL 94阻燃等级达到V–0级,同时紫外老化后的色差变化较小;自制高成炭无卤阻燃剂IFR–S因较好的成炭作用,达到同样效果,添加量可以降低3份;在相同抗氧剂体系下,含卤阻燃体系紫外加速老化28 d后的色差是无卤膨胀阻燃体系的三倍左右;三嗪类及苯并三氮唑类紫外线吸收剂可以明显改善材料紫外老化时的色变状况,同时降低了聚丙烯的降解程度;通过添加IFR–S、低碱性复合抗氧剂、苯甲酸酯类光稳定剂和苯并三氮唑类紫外线吸收剂制备的阻燃聚丙烯材料经过28 d紫外加速老化,拉伸强度下降1 MPa,缺口冲击强度下降3 J/m,阻燃性能未改变。     

抗氧剂Irganox1010对聚氨酯弹性体老化性能的影响

通过傅里叶红外变换光谱、热分析与力学性能测试,研究了抗氧剂四(3,5-二叔丁基-4-羟基苯丙酸)季戊四醇酯(Irganox1010)对聚氨酯弹性体老化性能的影响。力学测试结果表明,150℃下老化48h后,未加抗氧剂的聚氨酯弹性体的拉伸强度与老化前相比较下降11.6%,而添加抗氧剂的聚氨酯弹性体的拉伸强度与老化前相比较没有下降。热重分析、差示扫描量热分析和红外光谱分析结果表明,抗氧剂Irganox1010能阻碍聚氨酯分子链的断裂,减缓材料的老化,因此能促进聚氨酯弹性体的抗老化性能。     

高温高湿环境下紫外老化对氨纶结构及性能的影响

使用QUV紫外耐候试验机进行老化实验,研究了高温高湿环境下紫外老化对氨纶力学性能及微观结构的影响,通过傅立叶变换红外光谱(FTIR)、差示扫描量热、X射线衍射及力学性能分析探究氨纶紫外老化规律及机理,结果表明:随老化时间增加,N—H基氢键化程度变大,C—N键断裂,侧链上甲基脱氢变为更加活泼的亚甲基;氨纶热性能不断下降,玻璃化转变温度(Tg)不断升高且微相分离程度变差;结晶度在老化初期变化较小,呈先增后减的趋势,在老化150 h达到峰值。紫外老化后的氨纶,断裂伸长率及断裂强力在老化初期(0~50 h)下降明显,随后缓慢上升,分别在200 h及150 h骤降;老化前后氨纶弹性模量与结晶度变化趋势近似,弹性模量先增后减,在老化100 h达到峰值,300%弹性回复率不断下降。FTIR图谱1 110 cm^-1处显示氨纶老化前后醚基无显著变化,而1 710 cm^-1处样品吸水后产生的C=O基峰及3 317 cm^-1处因紫外光照C—N键断裂而引起的N—H吸收峰明显变弱,证明氨纶紫外老化本质是紫外光解及水解的协同作用,温度起到加速老化作用。     

抗氧剂和光稳定剂对PE-LLD紫外光老化的稳定作用

研究了抗氧剂1010、168与光稳定剂622对线形低密度聚乙烯（PE-LLD）抗紫外光老化性能的影响,并通过拉伸性能测试和凝胶渗透色谱等手段对PE-LLD老化前后的拉伸性能、相对分子质量及其分布进行了研究。结果表明,纯PE-LLD经紫外光老化3 d后,其断裂伸长率保留率就降低到50 %以下;单独添加0.15份抗氧剂1010、168或光稳定剂622,PE-LLD的断裂伸长率保留率分别在紫外光老化7、6和15 d后降低到50 %以下;抗氧剂1010、168与光稳定剂622复配使用时,可显著提高PE-LLD的抗紫外光老化性能,具有明显的协同效应。     

PA6在紫外光老化中的变色与结构变化

通过挤出共混法制备了添加不同耐紫外光助剂的尼龙6(PA6)。考察了PA6试样在紫外光照射192 h后其黄色指数(YI)与红外光谱(FTIR-ATR)谱图的变化;分别研究了单独加入抗氧剂、紫外光吸收剂和紫外光稳定剂的PA6试样在紫外光老化过程中的变色行为;在此基础上,复配与优化了含有抗氧剂、紫外光吸收剂与紫外光稳定剂的耐紫外老化的PA6的稳定体系。结果表明:紫外光吸收剂与紫外光稳定剂能明显地延缓PA6的紫外光老化;由酚类抗氧剂/亚磷酸酯抗氧剂(质量比1/1)、紫外光吸收剂Tinuvin 234和紫外光稳定剂Tinuvin 123组成的稳定体系能产生协同效应,使PA6试样具有最佳的耐紫外老化变色性能。     

ABS改性及其耐候性能研究

把TiO2、ZnO纳米粒子和有机抗氧剂加入到ABS中,制备其改性材料,进行紫外光老化和热氧老化试验,测定了老化前后ABS改性材料的力学性能。结果表明,ABS/TiO2(25nm)比ABS/TiO2(60nm)复合体系的抗紫外老化性能好;ZnO/TiO2/ABS复合体系有较好的抗紫外老化性能,但韧性有所下降;无机纳米粒子和有机抗氧剂配合使用时,ABS的抗热氧老化性能提高,说明两者有协同作用。     

Enhanced UV resistance of solar cooling high density polyethylene/titanium dioxide composites for long outdoor life via synergy effect of UV absorber and antioxidant

In this study, the ultraviolet (UV) resistance of high‐density polyethylene (HDPE)/titanium dioxide (TiO₂) composites was investigated. It is widely known that UV absorber could efficiently improve the UV resistance of the composites, and prevent the composites from being damaged by UV light. However, a small percentage of UV light still exist that may cause damage to material only with the assistance of UV absorber. Therefore, antioxidant was used in combination with UV absorber to further improve the UV resistance of the materials. Herein, three kinds of main antioxidants were used in combination with one kind of auxiliary antioxidant, and simultaneously UV absorber was added into the matrix material to enhance the UV resistance of the HDPE/TiO₂ composites. It was found that antioxidant could prevent the break of the molecular chains during preparation processing and reduce the rate of the photo‐oxygen degradation during UV irradiation. As the aging time increases, the crystallinity of the composites increased, but the control HDPE increased the most. The reflectance of the composites without antioxidant showed a slight decrease after UV irradiation, whereas the reflectance of the composites containing antioxidant still maintained the same level after UV irradiation. With the enhancement of the aging resistance of HDPE/TiO₂ composites, the general characters were highlighted without sacrificing the excellent solar reflectivity and great cooling performance. Besides, with the addition of antioxidant and UV absorber, excellent mechanical properties of the composites can be also achieved after UV irradiation. J. VINYL ADDIT. TECHNOL., 25:303–309, 2019. © 2019 Society of Plastics Engineers     

中型散装容器专用树脂的性能

研究了中型散装容器专用树脂高密度聚乙烯QHB07的基本物性、耐紫外光老化性能、耐环境应力开裂（ESCR）性能和流变行为。结果表明：QHB07的200℃氧化诱导期超过100min;经过500h紫外光老化试验后,断裂伸长率基本无变化;ESCR可达5000h;具有良好的加工性能,能够满足生产厂家的要求。     

耐候性聚氨酯用稳定剂

介绍了聚氨酯的稳定化机理,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、Irganox 1135、Irganox3125),受阻胺(HALS)(UV-770、UV-765)等稳定剂对聚氨酯光氧老化的影响,结果表明,同时使用上述3类稳定剂可得到较好的效果。     

抗紫外光环氧树脂的研究进展

综述了国内外的抗紫外环氧树脂的研究进展：研究结果表明,添加紫外线吸收剂和抗氧剂后可明显提高环氧树脂的光稳定性,并使之可用于LED,此外,稳定剂配合使用时效果更好。     

Degradation assessment of LDPE multilayer films used as a greenhouse cover: Natural and artificial aging impacts

This article focuses on the assessment and understanding of the mechanism of natural and artificial aging processes of a triple‐layer film made of low‐density polyethylene (LDPE) used as greenhouse cover. The film material contains color dye and ultraviolet–A (UV–A) and infrared (IR) stabilizers and antioxidant. The combined effect of temperature variations and UV–A radiations, of the natural and artificial aging, on the physical properties (free surface energy and yellow color measurements), mechanical behavior (tensile tests), thermal stability (TGA and DSC analysis), and structural stability (FTIR analysis) was investigated. The natural aging was conducted on a greenhouse, located in northern Algeria, over a period of 7 months. However, the artificial aging was performed at four different agricultural greenhouse simulating conditions of temperature and UV–A radiation (namely, at 40°C, 40°C with UV–A, 50°C, and 50°C with UV–A) for periods of aging up to 5486 h (7.6 months). The results revealed that, the maximum loss of the yellow color additives occurs at 2981 h under the natural aging process and at 2440, 1096, 1340, and 121 h under the four artificial aging conditions, respectively. There was an observed increase in the films free surface energy and a significant degradation in the mechanical properties with aging time. This can be correlated with the film material structural changes. The natural aging of the film in North Africa is almost equivalent to artificial aging at 40°C. The concurrent effect of temperature and UV–A radiations induced polymer chains scission leading to faster degradation in the film material and consequently a reduction in its durability and service lifetime. The results show also that the measured parameters are directly related to the limit of use criterion for evaluating the lifespan of agricultural greenhouse LDPE covers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Oxidation behavior of isoprene polymers and butadiene polymers

The oxidation behavior of cis-1,4-polyisoprene, emulsion polyisoprene, emulsion isoprene/styrene copolymers, and emulsion butadiene/styrene copolymers by heat aging or ultraviolet irradiation has been investigated from the change of gel fraction and molecular weight distribution. It was determined that the oxidation behavior of both isoprene and butadiene polymers is strongly dependent on the composition of the polymers as well as on the microstructure of the polymers. In the case of oxidation by heat aging, the probability ratio of chain scission to crosslinking of both isoprene and butadiene copolymers increases gradually with increasing styrene fraction. In the case of oxidation by ultraviolet irradiation, isoprene copolymers show a remarkable increase in the probability ratio of chain scission to crosslinking, whereas butadiene copolymers show substantially no change with increase in styrene fraction. It was also demonstrated that both isoprene and butadiene polymers show a greater tendency for crosslinking with oxidation by ultraviolet irradiation than with oxidation by heat aging.     

加速紫外老化对聚乙烯薄膜力学性能的影响

介绍了聚乙烯(PE)薄膜老化机理,并对PE薄膜进行了人工加速紫外光老化试验。分析了老化时间对PE薄膜力学性能的影响。结果表明:紫外光的照射使PE的化学键发生交联和断裂反应,其中断裂反应占主导,使聚合物分子量减小,物理性能下降;PE薄膜的拉伸强度、断裂伸长率和弹性模量随老化时间的延长而降低;PE薄膜抵抗破坏的能力在老化60 h以上会急剧下降,而此时弹性模量的变化趋势变得平缓,断裂伸长率与老化时间近似成线性关系递减。     

荧光增白剂在昆虫病毒领域的新用途

近年来发现荧光增白剂在生物防治研究中能提高昆虫病毒防紫外线的能力和昆虫病毒杀虫能力,并能加快病毒致死昆虫的速度。详细介绍作为昆虫病毒的紫外线保护剂和昆虫病毒杀虫剂的增效剂的荧光增白剂种类和性质。并对国内外该课题的研究现状进行了简要概括,提出了我国荧光增白剂的研究和生产单位在这项边缘学科的研究工作中应承担的课题。     

高密度聚乙烯管材光氧老化性能及寿命预测

采用荧光紫外灯人工加速老化方法模拟自然太阳光对高密度聚乙烯(PE-HD)管材和热熔接头的光氧老化,在不同温度下(50、60、70℃),使用UVA-340型标准荧光紫外灯管在光照和冷凝2种循环模式下模拟老化,并利用傅里叶变换红外光谱仪(FTIR)对老化后的管材和接头试样进行了分析表征,通过差示扫描量热仪(DSC)测量了管...     

地木耳活性成分的提取及其护肤功效研究

为探索天然植物提取物美容护肤的功效,研究了地木耳Nostoc commune Vauch.（普通念珠藻）醇提物和水提物的抗氧化、保湿和防晒效果。结果表明,地木耳提取物对羟自由基（·OH）和过氧化氢（H2O2）具有良好的清除能力,且失水率低、紫外线吸收能力强,具有良好的抗氧化、保湿和紫外线防护效果。不同品系地木耳的提取物在抗氧化、保湿和抗紫外线效果上无显著性差异,醇提物的效果略优于水提物。