合成橡胶硫化的新途径—辐射硫化

介绍了近期发展起来的橡胶辐射硫化技术的特点，并与传统硫化技术作了比较，简要叙述了辐射硫化的工艺过程。简介了辐射硫化在轮胎，电线电缆，热记忆材料等领域应用的研究进展。     

高温硫化和高耐热性胶料

提高硫化温度可增加橡胶制品的生产效率,但它会影响硫化胶的物理性能。为此,本文推荐ＨＴＳ或ＢＣ１－ＭＸ这两种配合剂。在耐热性胶料中,这两种配合剂可赋予橡胶制品优异的物理性能。     

轮胎胶料的过氧化物硫化

虽然过氧化物作为橡胶的硫化剂已使用了很多年,但迄今为止仍未在轮胎工业中获得普遍的应用。尽管目前已有了大量比５０年前敏感性较高的过氧化物危害小得多的工业化产品,但人们仍拒绝在轮胎中使用过氧化物,其主要原因可能是出于对加工安全性方面的考虑,考虑的其它因素...     

根据硫化和力学性能评价天然橡胶与纤维素Ⅱ共混胶料

在橡胶中使用填料的历史几乎与橡胶本身一样久远。橡胶混炼机械刚问世人们就开始使用研磨的重质碳酸钙、重晶石或陶土等填料来降低产品的成本，并发现在天然橡胶中使用这些填料不会显著降低成品硫化胶的性能。     

天然橡胶硫化动力学研究

采用硫化仪测定了2种不同凝固工艺的天然橡胶（NR）的硫化过程,探讨了制胶工艺、配方和温度对硫化动力学参数的影响。研究结果发现,随着温度的上升,硫化速率常数迅速上升。在纯胶体系中,微生物凝固胶的活化能高于酸凝固胶。当加入炭黑后,酸凝固胶的活化能升高,而微生物凝固胶的活化能下降。     

超声硫化的实验研究

成功地利用超声波对天然橡胶进行了硫化,所得试件展示了与传统硫化方法制得的试件相同的硫化,所得试件展示了与传统硫化方法制得的试件相同的性能。但该工艺表现出许多传统硫化方法所不具备的优点。用滞后能量损失理论及声化学作用,解释了超声硫化的机理。     

天然胶乳橡胶手套硫化问题的探讨

<正>一、引言胶乳硫化能充分改变或改善胶乳胶料性能,通常在胶乳配料时提高温度的情况下进行,硫化后的胶乳称为预硫化胶乳。胶乳硫化一般只适用于天然胶乳,是部分或完     

Radiation vulcanization of natural rubber with polyfunctional monomers

This study presents the effect of the polyfunctional monomers (PFMs) triallylcyanurate (TAC), triallylisocyanurate (TAIC), trimethylolpropane trimethacrylate (TMPT), ethylene glycol dimethacrylate (EDMA) and zinc diacrylate (ZDA) on the mechanical properties of natural rubber (NR) crosslinked by electron beam (EB) processing. Dependence of mechanical properties and crosslink density on irradiation dose was determined from a dose range of 50 to 200 kGy. The control blends, obtained with benzoyl peroxide as curing agent, were prepared by blending on a laboratory roller and the control sample curing was accomplished on hydraulic press at 160 °C. The results showed an increase in mechanical properties and crosslink density due to the introduction of PFMs. Also, based on the comparison between EB irradiation and dibenzoyl peroxide vulcanization efficiency, the experimental results show that EB irradiation gave the best results.     

Long-time sulfenamide-accelerated sulfur vulcanization of natural rubber/chlorobutyl rubber compounds

Sulfenamide-accelerated sulfur vulcanization of natural rubber/chlorobutyl rubber compounds has been investigated at temperatures from 155 to 175°C over 0.1 to 400 min. Continuous measurements in a Cone Rheometer were used to estimate the extent of crosslinking, which was plotted against cure time. On the basis of a kinetic analysis, two first-order vulcanization reactions, crosslinking and degradation, have been evaluated. Over the temperature range studied, there is no significant difference between the values of activation energy for these reactions. The rate of the degradation is slower by a factor of 20 than the rate of crosslinking. The degradation reaction can be limited by increasing the “efficiency” of the vulcanizing system.     

Effect of vulcanization temperature and vulcanization systems on the structure and properties of natural rubber vulcanizates

The effect of vulcanization temperature (150°–180°C) on the structure and technical properties of gum natural rubber vulcanizates with four different 2-(morpholinodithio)-benzothiazole: sulphur ratios (A, 0.6:2.4; B, 1.5:1.5; C, 2.4:0.6; D, 3.0:0.0) at the respective optimum cure times has been determined. The influence of cure temperature on (a) the chemical crosslink density; (b) the distribution of crosslink types; (c) the extent of sulphidic main chain modifications and (d) the zinc sulphide formation was investigated. Results show that elevated cure temperatures produce a network with lower crosslink density, in particular a lower polysulphidic crosslink density. The formation of intramolecular sulphidic groups and zinc sulphide increase with increasing cure temperatures. The possibility of chain scission during vulcanization, as examined by a quantitative analysis of the sol—gel data, was found to be negligible. The network results have been correlated with the technical properties.     

蛋白质对天然橡胶硫化动力学的影响

选用与天然胶乳中的d球朊结构类似的牛白蛋白,将其加入到经Alcalase蛋白酶处理得到的低蛋白天然橡胶中,通过硫化仪法研究了蛋白质对胶料硫化动力学的影响。结果表明：各胶样的硫化反应可按一级反应处理;在相同温度条件下,随着蛋白质用量的增加,焦烧时间（t10）和正硫化时间（t90）缩短,硫化反应速率提高,说明牛白蛋白能够提高天然橡胶的硫化速度;硫化速率随着温度的升高而显著提高,且都能很好地符合阿伦尼乌斯方程;反应活化能随着蛋白质用量的增加而提高。     

硫化体系对天然橡胶性能的影响

采用常规硫化体系(CV)、半有效硫化体系(SEV)和有效硫化体系(EV)制备了不同的NR(天然橡胶)硫化胶。着重探讨了不同硫化胶的微观形貌、200%定伸强度、撕裂强度、拉伸强度、断裂伸长率和交联密度。研究结果表明:SEV硫化胶的微观形貌相对较好,填料能均匀分散在基体中;在其他条件保持不变的前提下,当w(NOBS)=w(硫)=2.0%(相对于NR质量而言)时,相应的未老化SEV硫化胶的撕裂强度(78 kN/m)相对最大;SEV硫化胶的交联密度大于CV硫化胶和EV硫化胶,并且适当增加交联密度能有效提高其综合性能,从而为开发新一代轮胎等复合材料奠定了基础。     

Radiation vulcanization of natural rubber latex with polyfunctional monomers

Natural rubber latex was irradiated with γ-rays from Co-60 in the presence of polyfunctional monomers to accelerate crosslinking of rubber molecules. Hydrophobic monomers were more effective in accelerating the vulcanization than were hydrophilic monomers. This was ascribed to high solubility of hydrophobic monomers in rubber particles. Among the hydrophobic monomers, neopentylglycol dimethacrylate (NPG) exhibited the highest efficiency in accelerating the vulcanization. Advantages of using NPG are (1) high colloidal stability of the irradiated latex and (2) high thermal stability of dried rubber film.     

Structural characterization of vulcanizates. Part IX. Comparison of the vulcanization of natural rubber and cis-trans-isomerized natural rubber with sulfenamide-accelerated sulfur and dicumyl peroxide vulcanization systems

Large variations in the microstructure of 1,4-polyisoprenes, from ca. 100% cis-trialkylethylene groups, as in natural rubber (NR), to ca. 40% cis- and 60% trans-trialkylethylene groups, as in an equilibrium-isomerized NR, have little influence on the overall chemistry of vulcanization of the polyisoprenes by a N-cyclohexylbenzothiazole-2-sulfenamide-accelerated sulfur system or by a dicumyl peroxide system. The peroxide crosslinks the equilibrium-isomerized NR more efficiently than it crosslinks NR; this is attributed to the sulfur dioxide, which is used to isomerize the NR, scavenging some of the nonrubber constituents in the NR, which are known to compete with the rubber hydrocarbon for reaction with free radicals from the peroxide. By comparison with NR vulcanizates, the corresponding equilibrium-isomerized NR vulcanizates have higher values of the C₂ term of the Mooney-Rivlin stress–strain equation and higher χ (polymer–swelling liquid interaction parameter) values of the Flory-Huggins equation.