甲基丙烯酸全氟烷基代乙酯对天然橡胶乳液辐射改性研究

天然橡胶的性能与其组成中的C C双键有密切关系,由于C C双键的存在,为天然橡胶的改性提供了便利,大多数天然橡胶的改性方法,如氯化、氢氯化、环化、环氧化、接枝共聚等皆是建立在这一思路基础上的.White等[1]认为接枝天然橡胶的目的是提高天然橡胶的机械强度,赋予特殊的功能.作     

高硅ZSM—5沸石填充硅橡胶膜的醇—水渗透蒸发分离性质

高硅ZSM－5沸石填充疏水性硅橡胶蓦地低浓度醇－水体度醇－水体的渗透蒸发性质的研究有明，提高沸石硅铝比，增加填充量以及进行酸处理皆有利于改善膜对醇－水的分离系数和通量。料液的成，浓度以及温度对膜的分离性质也有显著影响。     

气相色谱-质谱联用法测定橡胶制品中多环芳烃（蒽）含量不确定度评定

目的对气相色谱-质谱联用仪法测定橡胶制品中多环芳烃（蒽）含量不确定度进行评定,确定影响不确定度的关键因素。方法依据《ZEK01.4-2008 GS认证过程中PAHs的测试和验证》,使用气相色谱-质谱联用仪法测定橡胶制品中多环芳烃（蒽）含量,并对结果的不确定度进行评定,分析影响测量不确定度的各个因素,对各个分量进行计算和合成。结果扩展不确定度U=5.7 mg/kg,置信概率95%。结论该实验的不确定度主要影响因素是曲线校准。     

Enhanced Physical and Mechanical Properties of Nitrile-Butadiene Rubber Composites with N-Cetylpyridinium Bromide-Carbon Black

The physical and mechanical properties of nitrile–butadiene rubber (NBR) composites with N-cetylpyridinium bromide-carbon black (CPB-CB) were investigated. Addition of 5 parts per hundred rubber (phr) of CPB-CB into NBR improved the tensile strength by 124%, vulcanization rate by 41%, shore hardness by 15%, and decreased the volumetric wear by 7% compared to those of the base rubber-CB composite.     

Blending of Natural Rubber/Recycled Ethylene-Propylene-diene Rubber: Promoting the Interfacial Adhesion Between Phases by Natural Rubber Latex

This article deals with blends based on natural rubber (NR) and recycled ethylene-propylene-diene rubber (R-EPDM). Natural rubber latex (NRL) was introduced into the blends to enhance interfacial adhesion between NR and R-EPDM. A new route of compounding was also suggested. The blends were prepared by mixing R-EPDM and other additives in NRL before blending with natural rubber on a two-roll mill. By applying this method, the homogeneity of the blends and cross-linking distribution are significantly improved. The blends exhibited superior state of cure, swelling resistance, mechanical properties and dynamic mechanical properties. The degree of entanglement between NR and R-EPDM also increased after NRL modification.     

干摩擦条件下天然橡胶／钢的磨损机理研究

采用FALEX试验机考察了20^#钢／天然橡胶在干摩擦条件下的磨损机理。用扫描电子显微镜分析了20^#钢和橡胶磨损表面形貌。用X射线光电子能谱仪分析了金属和橡胶磨损表面元素的含量及化学状态,用镜面全反射傅立叶红外光谱仪分析了橡胶磨损表面官能团的变化。结果表明,20^#钢／天然橡胶摩擦副发生了粘着磨损,其磨损机制为：金属及金属氧化物与天然橡胶分子自由基在摩擦表面发生反应;在亚表层以金属与大分子自由基的反应为主,主要产物为含有Fe-C的金属－聚合物;金属本身发生氧化,主要产物为Fe2O3,FeO和Fe3O4,而在亚表层的主要产物以FeO为主,表面膜可能通过化学键、静电作用力和分子间的范德华力与金属基体相结合。     

磺化丁基橡胶离聚体在混合溶剂中的聚集行为

用顺磁共振（ESR）谱和粘度法考察了磺化丁基橡胶离聚体在二甲苯／正己醇混合溶剂中的聚集行为．ESR谱表明离聚体的离子基团发生聚集，其聚集程度受极性共溶剂（正己醇）的影响．粘度考察表明，在不同的浓度时离子基团有不同的聚集形式，低浓度时以分子内聚集为主，高浓度时以分子间聚集为主．离聚体的聚集度（DA）与浓度（c）的关系可用经验式DA＝Aexp（kc2）表示，其中A、k为常数．k值反映聚集度受浓度影响的程度，醇含量增大时k值减小，这是因为醇对离子的溶剂化作用导致离子聚集的倾向减小．     

溶胶-凝胶法原位生成SiO2改性硅基耐烧蚀材料

建立了在硅基耐烧蚀材料中用溶胶-凝胶法原位生成SiO2的方法.首先将硅橡胶、气相白炭黑、纤维等原料混炼硫化制备出硫化胶.然后将硫化胶依次浸入四氢呋喃、原硅酸乙酯和正丁基胺水溶液中进行预溶胀处理、物理扩散和化学反应,得到原位生成SiO2.SEM照片显示,在硅基耐烧蚀材料中原位生成的SiO2颗粒呈球形,粒径在40~60 nm,但分布不均匀,在硫化胶表层存在富集现象.实验结果表明,原位生成SiO2平均含量增加,硅基耐烧蚀材料的抗拉强度增加,线烧蚀率下降;含13.7%原位生成SiO2硅基耐烧蚀材料抗拉强度为5.82 MPa,线烧蚀率为0.071 mm/s.     

Dynamic Mechanical Properties of Aged Filled Rubbers

Abstract

It is well known that the macromolecular structure and the microstructure of the fillers play an important role in the mechanical properties of filled rubbers. This paper focuses on the dependence of the complex modulus of aged natural rubber vulcanizates on the filler network and polymer structure. Dynamic mechanical analysis (DMA) at 30°C, 50°C, and 70°C on the aged rubbers with/without prestrain showed the Payne effect, i.e., a storage modulus drop with increasing amplitude, and the appearance of a loss tangent maximum at strain of about a few percent. The storage modulus increased with the aging time at 70°C, 24 < 72 < 240 hr, in the case of nonprestrain. When the prestrain was applied, strain‐induced crystallization was generated that enhanced the storage modulus. As time passed, the prestrain relaxed and the crystalline structures began to disappear. After 72 hr, the crystalline structures had almost disappeared, and they had only a weak effect. Consequently, there existed a higher modulus for an aging time of 24 hr than 72 hr at testing temperatures of 30°C and 50°C. It was concluded that the storage modulus was determined by the postvulcanization, strain‐induced crystallization, aging, and relaxing time.     

橡胶弹性支座动态承载特性及其影响因素分析

基于复刚度理论,采用正交实验法,对风力发电机橡胶弹性支座进行动态性能实验,研究载荷频率、载荷幅值、预载荷诸因素对弹性支座动态性能的影响规律. 实验结果表明,橡胶材料的动态性能与载荷频率和幅值具有显著的相关性. 频率增加,橡胶弹性元件的弹性刚度和阻尼因子明显增大;幅值增加,弹性刚度减小,阻尼因子却逐渐增大. 对实验数据进行方差分析,表明载荷频率对动态性能的影响最大,其次是载荷幅值,预加载因素影响非常有限.