橡胶硫化促进剂的研究进展

作为橡胶加工成形过程中最重要的步骤之一,橡胶硫化直接影响橡胶制品的性能。与单用硫黄相比,少量的促进剂与硫磺配合可以极大地提高硫化速率,改善硫化胶的性能。但目前橡胶硫化促进剂普遍具有潜在的人类健康和环境风险问题,同时硫化促进效能较低、功能单一。因此,开发无毒、无或少氧化锌、高效、多功能的新型硫化促进剂对橡胶工业具有非常重要的意义。本文首先简要介绍了橡胶硫化促进剂的发展历程,然后综述了近年来新型橡胶硫化促进剂的研究进展(包括离子液体促进剂、新型二硫代氨基甲酸盐类促进剂、稀土促进剂、以及含新型副促进剂的硫化并用体系等),并对橡胶硫化促进机理、新型橡胶硫化促进剂的设计进行了展望。     

异氰酸酯对EPDM橡胶粘接的影响

异氰酸酯对EPDM橡胶粘接的影响;EPDM橡胶;异氰酸酯;粘接     

橡胶硫化促进剂DZ合成工艺探讨

采用两步合成法制备橡胶硫化促进剂ＤＺ（Ｎ，Ｎ－二环己胺－２－苯并噻唑次磺酰胺），控制Ｍ钠盐与氯代二环乙胺的摩尔比为１，选择乙醇作有机溶剂，将缩合反应滴加Ｍ钠盐的温度控制在３０－３５℃，即可制得熔点在９０℃以上，溶程小于１℃，且收率近８０％的高品质ＤＺ产品。     

丁腈橡胶的配位硫化

在丁腈橡胶中引入无机金属盐粒子,通过腈基与金属离子之间的固相配位反应来实现丁腈橡胶的配位硫化,创建了一个完全不同于传统硫磺硫化体系的新型非共价键配位交联的橡胶网络体系.同时制备了具有优异的力学性能的配位硫化橡胶材料,既可以作柔性的橡胶材料使用,也可以作为韧性、脆性的塑料材料使用.本文就影响配位交联反应的两个关键因素(金属盐粉末的粒径和丁腈橡胶的丙烯腈含量)进行了探讨,提出了提高配位硫化效率的办法(结晶水、增塑剂等).     

柠檬酸镧的合成及其对SBR橡胶硫化性能的影响

以氯化镧和柠檬酸为原料,合成柠檬酸镧,探究反应条件对柠檬酸镧产率的影响,得到反应体系p H值4~5之间,柠檬酸与氯化镧的摩尔比1.2∶1,反应体系温度50℃为较优的反应条件。并将合成的柠檬酸镧添加到SBR混炼胶中,研究其对混炼胶的硫化特性和硫化胶物理机械性能的影响;结果表明,添加2.5%的柠檬酸镧可使混炼胶的硫化速率t90达到943 s,比未添加柠檬酸镧的快了31 s,当添加量为7.5%时硫化胶的物理机械性能达到最佳,比未添加相比提高了将近50%。通过红外光谱表征产物结构,并采用硫化仪、万能试验机对混炼胶进行硫化性能及物理机械性能测试,研究结果表明,柠檬酸镧可提高混炼胶的硫化性能、硫化胶物理机械性能及抗硫化还原性。因此,柠檬酸镧可以作为SBR橡胶硫化剂的一种补充。     

金属有机框架衍生非晶态硫化钴及电催化分解水性能

利用含氮配体制备了新型钴基金属有机框架,以其为模板通过改变硫源种类、硫化时间及硫化温度,制备了系列无定型硫化钴样品,结合各种结构表征及电化学性能测试表明:以硫化钠为硫源,控制硫化温度及硫化时间分别为60℃、6 h时,得到的样品在1.0 mol·L~(-1)KOH溶液且电流密度在10 mA·cm~(-2)时,析氢反应和析氧反应的过电位分别为178和246 mV,并表现出优异的耐久性。     

2-巯基苯并噻唑稀土配合物的合成、表征及橡胶硫化促进性能研究

在无水乙醇溶剂中,以稀土氯化物与2-巯基苯并噻唑钠盐反应,合成了8种稀土含硫有机配合物.通过元素分析、红外光谱和热重分析,确定了配合物的组成为RELCl2*RE(OH)3*xH2O(L=2-巯基苯并噻唑, RE= La～Gd, Y, 除Pm外,x=0,2～4 );并对合成的镧配合物进行了橡胶硫化促进性能研究,结果表明,该类配合物具有较好的硫化促进性能和改善硫化胶物理机械性能的特性.     

新型金属-树脂间粘接性单体的合成与应用

甲基丙烯酰氧癸基硫脲嘧啶羧酸酯;粘接性单体;复合树脂;牙用合金;粘接性能     

硫化条件对加氢裂化催化剂金属硫化度的影响

采用高压连续微反装置及X -射线光电子能谱 (ESCA)等仪器 ,考察了不同硫化条件对加氢裂化催化剂中活性组分的存在状态及价态分布的影响。研究表明 :在整个硫化温度区间内 ,2 30℃时催化剂硫化速率较快 ,在此温度下需要恒温硫化 ,较佳恒温时间为 3h ,压力 (>4 5MPa)对催化剂硫化度有一定的影响 ,不同组成的催化剂其硫化性能也不同。在催化剂硫化过程中 ,W5 是硫化过程中的一种中间过渡产物 ,随硫化温度的升高可转化为W4 。     

超高效液相色谱-串联质谱法测定橡胶产品中4种秋兰姆类硫化促进剂含量

建立了橡胶产品中4种秋兰姆类硫化促进剂(二硫化四苄基秋兰姆(TBZTD)、二硫化二甲基二苯基秋兰姆(TMD)、福美双-D12(Thiram D12)、二环戊亚甲基二硫化秋兰姆(DPTD))的超高效液相色谱-串联质谱检测方法。橡胶材料中的硫化促进剂经甲醇超声多次提取,提取液离心过滤后以反相C18色谱柱为分离柱,甲醇和水作为流动相进行洗脱,经超高效液相色谱-串联质谱仪测定,外标法定量。研究了不同色谱条件下目标物质的分离情况和不同提取溶剂对提取净化效率的影响。在最优化条件下,TMD和Thiram D12在0.002~1.000 mg/L浓度范围内线性关系良好,其定量下限分别为0.001 0 mg/L和0.001 2 mg/L;TBZTD在0.100~10.000 mg/L浓度范围内线性关系良好,定量下限为0.100 0 mg/L;DPTD在0.020~10.000 mg/L浓度范围内线性关系良好,定量下限为0.020 0 mg/L。空白样品在不同浓度水平的平均加标回收率为82.7%~98.8%,相对标准偏差(RSD)为4.6%~7.0%。该方法简便、快速、灵敏,可满足橡胶产品中TBZTD,TMD,Thiram D12和DPTD的测试要求。     

聚丙烯／顺丁橡胶动态硫化增韧的研究

研究了在聚丙烯(pp)与顺丁橡胶(BR)共混过程中加入橡胶硫化剂使共混体系中橡胶相动态硫化交联。研究结果表明,采用动态硫化法可提高共混物的冲击强度和拉伸强度。借助于SEM和DMA,证实了动态硫化使PP/BR共混体系具有相界面粘结良好的多相结构,改善了两相相容性。探讨了动态硫化增韧的机理。     

硅橡胶硫化反应场的数值模拟

以化学反应动力学原理为基础,实验确定了硅氢加成反应的动力学模型;引入 了硫化率增量的概念,获得了全量硫化率和硫化率增量的数值计算式;根据统计理 论,获得了起始分子无规分布时的交联结构参数的数值计算式;介绍了非稳态硫化 反应场的有限元模拟步骤。在此基础上,设计了硅橡胶硫化反应过程的有限元模拟 软件;应用该软件,根据输入的初边值条件,可计算任一空间点在任一时刻的交联 反应参数和交联结构参数,进而可预测制品性能、优化反应参数,或优化设计高分 子材料。最后给出了一个典型算例,并实验验证了该模拟理论及算法的合理性。     

Radiation Vulcanization of Magnetorheological Elastomers Based on Silicone Rubber

The fabrication of magnetorheological （MR） elastomers was studied by two vulcanization methods, including heat vulcanization （HV） and radiation vulcanization （RV）, were employed to fabricate MRE samples. The dynamical mechanical properties were characterized by using a dynamic mechanic analyzer. In particular, both the MR effect and its durability were investigated. The experimental results showed that RV samples have large magnetoinduced modulus, large zero-field modulus, and good durability property of MR effect. To explain these results, cubic deformation and plasticizer migration were analyzed. Large magneto-induced modulus of RV sample results from cubic deformation during vulcanization process. And the plasticizer migration results in better durability of MR effect.     

Hydrophilicity Modification of Addition-cured Room Temperature Vulcanization Silicone Rubber

Allyl terminated polyether was used to improve the hydrophilicity of addition-cured room temperature vulcanization silicone rubber. With the increasing of the polyether, both the hydrophilicity and water absorbed of the vulcanizates were increased. The mechanical properties were also improved by adding the polyether. The result showed that 1.5wt% of the polyether provided the silicone rubber with proper hydrophilicity.     

A Novel Approach to Prepare a Gradient Polymer with a Wide Damping Temperature Range by In‐Situ Chemical Modification of Rubber During Vulcanization

Summary: Based on the fact that rubber can be chemically modified by sulfur, and sulfur can diffuse into rubber driven by a concentration gradient and chemical reaction, a new approach for the preparation of a polymer with a gradient from rubbery to glassy phase has been developed using the sulfur‐vulcanization reaction of rubber. The gradient polymer obtained exhibits a wide transition range spanning over 100 °C with a peak half‐width of 69 °C. The mechanism of forming the gradient structure is also discussed.

The gradient polymer exhibits a broad tan δ width from −60 to 76 °C with the peak half‐width spanning about 69 °C, indicating a wide damping temperature range.     

Vulcanization of polypropylene

Dynamic covalent crosslinking of commodity thermoplastics is a desirable target in material development, as it promises to combine the enhanced mechanical properties and thermal/solvent stability of thermosets with reprocessability and plastic flow under certain conditions activating the bond exchange. Many attempts of this development suffer from the same two problems: enhanced cost due to complex and often toxic chemicals, and the effective melt-flow index being too low for practical use. Here we return to the origins of polymer networks, and mimic the vulcanization of natural rubber in the commodity polypropylene using elemental sulfur initiated by peroxide. Forming sulfur bridges allows easy catalyst-free reprocessability based on the disulfide bond exchange. We study a broad range of compositions and reaction conditions, finding optimal balance between the crosslinking and chain scission in the melt compounder, and demonstrating much enhanced characteristics of the resulting materials. We specifically discuss and evaluate the balance between the rubber-elastic network response at high temperatures and the plastic flow enabled by disulfide exchange, responsible for the reprocessing of our vitrimers.