聚乙烯热老化时的稳定剂消耗

在氧化降解(例如聚合物材料作为地管道绝缘护套使用时)是老化的主要机理的情况下,尽管聚合物材料使用寿命预测这方面已取得显著的成就,但它仍然是个迫切的研究课题。目前,现有商品牌号的聚乙烯,在333～353K温度下,大多数使用寿命可以达到10年,这些材料的使用寿命长仍是试验的主要困难。试验这些材料是在高温下进行,并在分析聚合物的氧化动力学基础上,将在高温下获得的使用特性按阿累尼乌斯定律外推到使用的自然条件。     

PE管材热老化程度的超声非线性表征

以热老化时间不同的聚乙烯(PE)管材为研究对象,分析其力学性能;搭建超声检测装置并采集不同热老化试样的超声信号,通过频谱分析(快速傅里叶变换)获得基波和二次谐波的幅值计算超声非线性系数;建立聚乙烯管材超声非线性系数与力学性能之间的变化关系。结果表明,聚乙烯管材的缺口冲击强度随超声非线性系数的增加逐渐减小。由此,可通过超声非线性系数表征聚乙烯管材的力学性能,进而评价聚乙烯管材的热老化程度。     

废砂/PE废地膜复合材料热老化性能的研究

以聚乙烯(PE)废地膜和工业废砂为原料,制备了不同配比的废砂/PE废地膜复合材料,研究了PE基体和复合材料的热老化规律。研究发现,经80℃人工加速热老化处理后,复合材料的玻璃化转变温度(Tg)随老化时间的增加而降低;一定条件下的热老化有助于加强PE基体和废砂间的界面作用,使复合材料的力学性能先升高后降低;废砂的加入有利于PE废地膜热老化性能的提高。     

复合材料老化方法研究进展

概述了复合材料自然老化及人工气候老化研究方法的进展，介绍了根据老化研究结果确定复合材料使用寿命的方法，并就如何全面地、合理地评价复合材料的使用性能提出了几点建议。     

PE塑料管道的快速裂纹扩展研究现状

对国内外聚乙烯塑料管道系统的快速裂纹扩展(RCP)的研究现状进行了介绍，讲述了RCP的研究方法及国内外相关标准，讨论了各种方法间的联系及影响RCP的因素等。     

聚氧化乙烯的防老化

高分子量的聚氧化乙烯(PEO)作为精细化工成员之一,用于絮凝剂、分散剂、增稠剂等方面时,具有用量少、效果好的特点,故被认为是一种优良的合成水溶性高聚物。但因PEO主链中含有醚键,键能较低,无论是水溶液或干料,在使用、贮存时,无极易降解,从而影响其使用价值。如何找出解决PEO降解的办法,是PEO应用的一大课题。以下就PEO防老化问题作一简述。     

聚乙烯自然和人工气候老化相互关系的探索

本文对聚乙烯以以断裂伸长率保持率为评价指标,建立了该指标在自然和人工气候条件下随紫外光辐照能变化的动力学方程,讨论了两种气候老化的相关性,探索了由人工气候老化试验去预报户外自然气候老化试验时间。     

LLDPE紫外老化

本文为一九八六年在西班牙首都马德里召开的LLDPE在欧州及世界发展前景会议上的论文。文章论述了LLDPE薄膜加入或不加入紫外线稳定剂的老化情况。通过户外曝晒老化试验和用Xenotest-150老化试验箱进行人工老化试验,对纯LLDPE和LDPE以及这两种材料的共混料作了比较并对影响LLDPE薄膜寿命的各种参数,例如薄膜厚度、熔融指数、LLDPE的催化剂残渣含量,共聚单体(丁烯—1,4—甲基戊烯—1,乙烯—1)的性质和室外曝晒老化试验所用的背衬情况进行了研究。     

丁苯橡胶和高压聚乙烯并用的热塑性橡胶的热老化研究

叙述了丁苯橡胶和高压聚乙烯并用的热塑性橡胶的热老化过程,其性能与橡胶相,塑料相及其界面层内作用过程的关系。     

Effect of Phenol-CNSL Formaldehyde Copolymer on Thermal Ageing of Elastomers

Cashew nut shell liquid (CNSL) is a cheap agro-byproduct and renewable resource that consists mainly of substituted phenols. A CNSL-based resin was used in this study to modify the properties of the elastomers, chloroprene, CR and ethylene propylene rubber, EPDM. The resin was a copolymer obtained by condensing a mixture of phenol and CNSL with hexamethylenetetramine. The effect of the resin on the ageing properties of elastomers was studied by following changes in tensile strength, elongation at break, modulus, and tear strength. Comparison of the properties of the aged material containing resin with those of specimens not containing any modifiers shows improved ageing characteristics with respect to tensile strength, modulus, and tear strength.     

A New Approach to the Evaluation of Stabilizer Efficiency Under Photo‐Ageing

Summary: Elastomers are very sensitive to oxidative degradation due to the combined effect of light and oxygen. Hence, we investigate the impact of stabilizers on the evolution of molecular structure of elastomers through photo‐oxidation. While a dual processes is generally reported to describe photo‐oxidation of elastomers (oxidation by‐products formation and crosslinking), the aim of the current study is to provide a complete characterization of the efficiency of additives taking into account the dual processes: chemical changes (formation of photoproducts) and molecular structure changes (crosslinking). This work gives new insights about relationships between chemical changes and physical properties evolution of the material through ageing. We conclude that the two phenomenon are correlated to the primary peroxidation reaction and a dual efficiency does not exist for any additive.

Kinetic curves of carbonylated by‐products formation upon photooxidation of stabilized EPDM films comparing with a unstabilized reference.     

环境水体中亚硝酸根的快速测定方法研究

本文提出了一种测定水体中亚硝酸根的快速方法 ,操作简单 ,最大吸收波长 =5 2 4nm ,摩尔吸光系数 =3 .2 7× 1 0 4 L/mol.cm ,本方法应用于环境水样 (青山湖水样 )中亚硝酸根的测定 ,加标回收率 96.90± 2 .0 7%。     

氯化铵氮含量的快速测定法--返滴定法

介绍了氯化铵中氮含量的一种快速测定方法———返滴定法,通过实践表明:该方法具有经济性、可操作性、广泛的应用性、简捷便利性和较高的准确性。     

化学需氧量快速测定法存在问题的改进

在水质ＣＯＤｃｒ快速测定法中,由于取样量仅２．００ｍＬ,对含较多有机颗粒物的浑浊水样,其取样的均匀性、代表性至关重要,否则会带来很大误差。样品置于水浴超声器中作用５ｍｉｎ是一种理想的均化措施。     

Thermal Ageing of Filled Polymers

The rate of thermal ageing has been found to decrease when a polymer is adsorbed onto a filler. The retardation of this glassy state relaxation has been found to be dependent on the type and amount of filler present. Comparison with values for the glass transition temperature and melt rheology parameters shows that the same factors are determining each of these properties. Each of these properties is determined by the mobility of the polymer molecules and this is restricted by adsorption onto a filler.     

PE废塑料溶剂裂解制备聚乙烯蜡

本文以废旧聚乙烯为原料,在溶剂水的作用下进行裂解制备聚乙烯蜡。实验过程中考察了温度、时间及溶剂加入量对产品性能的影响。结果表明:随裂解温度的升高和反应时间的延长都使得反应体系获得了更高的能量,容易使PE大分子发生断链从而得到低分子量PE,从而使产物收率逐渐降低,粘均分子量减少,熔程也随之下降。溶剂加入量对产品性质也有一定影响。当裂解温度为370℃,反应时间60min,溶剂加入量占原料总质量50%时,得到灰白色的聚乙烯蜡,其熔程在104~110℃之间,酸值为0.0143mg·g-1,粘均分子量为3426.4,且具有较高的热稳定性。通过溶剂裂解制得的聚乙烯蜡具有一定的工业应用前景。     

嵌段聚醚酯弹性纤维的老化及热分解

通过测定以PBT为硬段 ,聚乙二醇 (PEG)和聚丁二醇 (PTMG)为软段的嵌段聚醚酯弹性纤维在老化前后的特性粘数、断裂强度、断裂伸长率和弹性回复率的变化 ,发现添加抗氧剂能明显改善该弹性纤维的抗老化性能并提高纤维的力学性能和回弹性能 ;采用热失重测定了PBT -PTMG2嵌段聚醚酯弹性纤维的热分解性能 ,热分解动力学计算表明其热分解活化能较低 ,为 69.6kJ ,容易热分解 ,热分解为 1级反应     

Mechanical properties of ultrahigh-molecular-weight polyethylene fiber-reinforced PE composites

Three types of high-strength polyethylene (PE) fiber-reinforced composite sheets were made by compression molding at the vicinity of melting point of the fiber. Sheet I was molded from only PE fibers. Sheets II and III were prepared by the compression molding of PE fiber with conventional high- and low-density polyethylene films, respectively. The mechanical properties, thermal behavior, and morphologies of the sheets have been investigated and compared with each other. The tensile strength and elastic modulus of sheet III are 660 MPa and 14 GPa, respectively, which were 60 and 30 times higher than those of typical low-density PE film. Although the elastic modulus of sheet III is 6 GPa less than that of sheet II, the tensile strength of 660 MPa is highest in the three types of sheets prepared in this study. The mechanical properties of sheets II and III were about half of predicted theoretical ones. It was concluded that the interfacial adhesion between PE fiber and PE matrix was an important factor to improve the mechanical properties of this PE sheet. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1431–1439, 1998     

流滴减雾聚乙烯棚膜的新制备方法

研究了涂覆法制备减雾聚乙烯棚膜新方法,在聚乙烯棚膜内层添加一种高碳阳离子表面活性荆,采用具有阴离子特性的涂覆型流滴消雾剂涂覆在该棚膜的内表面,涂覆的棚膜流滴减雾期达18个月以上,达到了流滴消雾功能与棚膜寿命同步。