Yeh Cheng-Yang, Kuo Cheng-Yu, Li Kuan-Hung, Tsiang Raymond Chien-Chao, Chang Jen-Ray
Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 62102, Taiwan.
ACS Omega. 2021 Jan 15;6(4):2800-2812. doi: 10.1021/acsomega.0c05133. eCollection 2021 Feb 2.
The coupling agent TESPT (bis-[3-(triethoxysilyl)propyl] tetrasulfide) was modified by substituting polyisoprenyl (PI) carbanions for the ethoxyl groups on silicon for increasing the interaction of rubber with its fillers. The modification was carried out by the reaction of TESPT with polyisoprenyllithium, which had been previously prepared by anionic polymerization of isoprene using butyllithium. The success of the substitution was confirmed by Fourier-transform infrared spectroscopy, and the molecular weight of the modified TESPT (PI-TESPT) was determined from gel permeation chromatography measurements. The effects of tethered PI, as well as of its chain length, on the mechanical and dynamic properties of rubber compounds were examined using a universal testing machine and dynamic mechanical analysis (DMA). In rubber sample preparation, the amount of PI-TESPT (PI of 2900 g/mol) used in rubber compounding is equal to that of the reference sample with TESPT ( ). For samples, the amounts of PI-TESPT (PI of 5500 g/mol) and PI-TESPT (PI of 13,700 g/mol) used were calculated as molar ethoxyl groups which are nearly equivalent to those of PI-TESPT. At the same wt % (parts per hundred, phr) of elemental sulfur in rubber compounds, despite the order of cross-linking density being (sample prepared with TESPT) > > > , the exhibited tensile strength is of the order of > > ≈ . The better mechanical properties of , as opposed to those of , could be attributed to the extra reinforcement from the PI-rubber chain linkage and better silica dispersion, as suggested by the mixing torque and Payne effect (Δ') measurements. While the dynamic properties of are inferior to those of , these properties can be improved by adding more elemental sulfur to increase the cross-linking density.
通过用聚异戊二烯（PI）碳阴离子取代硅上的乙氧基来改性偶联剂TESPT（双-[3-(三乙氧基甲硅烷基)丙基]四硫化物），以增强橡胶与填料之间的相互作用。改性是通过TESPT与聚异戊二烯锂反应进行的，聚异戊二烯锂是先前用丁基锂引发异戊二烯阴离子聚合制备的。取代反应的成功通过傅里叶变换红外光谱得以证实，改性后的TESPT（PI-TESPT）的分子量通过凝胶渗透色谱测量来确定。使用万能试验机和动态力学分析（DMA）研究了键合PI及其链长对橡胶复合材料力学和动态性能的影响。在橡胶样品制备中，橡胶配方中使用的PI-TESPT（PI为2900 g/mol）的量与使用TESPT的参比样品的量相等。对于其他样品，所使用的PI-TESPT（PI为5500 g/mol）和PI-TESPT（PI为13700 g/mol）的量按照与PI-TESPT几乎等效的乙氧基摩尔数来计算。在橡胶复合材料中元素硫的重量百分比（每百份，phr）相同时，尽管交联密度顺序为（用TESPT制备的样品）＞＞＞，但所表现出的拉伸强度顺序为＞＞≈。与相比，更好的力学性能可归因于PI-橡胶链连接带来的额外增强作用以及更好的二氧化硅分散性，这由混炼扭矩和佩恩效应（Δ'）测量结果表明。虽然的动态性能不如，但通过添加更多元素硫以增加交联密度可以改善这些性能。
