稀土镝掺杂炭黑填充型粉末NR的硫化特性和硫化机理研究

The curing characteristics and vulcanization mechanism of powdered NR filled by dysprosium-modified carbon black

采用液相化学沉积法和凝聚共沉法制备稀土镝掺杂炭黑填充型粉末NR[P(NR/HAF-Dy)],研究其在氧化锌配合和无氧化锌配合下的硫化特性,并对其硫化机理进行探讨。结果表明,在胶料中添加Dy可以提高胶料交联度,但提高幅度较氧化锌小,说明Dy对硫化反应的活化作用有限,不能代替氧化锌单独作活性剂使用;Dy可以延长焦烧时间,提高硫化速率和交联密度。在对胶料硫化特性和DSC曲线分析的基础上,提出Dy3+-Zn2+双金属活性中心硫化机理模型,认为该活性中心具有较大的位阻效应,延缓了其与S8的反应,并加快了多硫化物的断键速度,从而使P(NR/HAF-Dy)具有较长的t10和较快的硫化速率。

Dysprosium-modified carbon black filled powdered NR[P（NR/HAF-Dy）] was prepared by liquid-phase chemical deposition and coacervation-coprecipitation,and the curing characteristics and vulcanization mechanism of the NR compounds with and without zinc oxide（ZnO） were investigated. The results showed that the cross-linking degree of NR compound was increased by adding Dy, but the degree of increase was less than that of NR compound with ZnO,which meant that Dy gave little contribution to the vulcanization reactivity and could not replace ZnO as the only activator;Dy could extend the scorch time of NR compound and increase the curing rate and cross-linking density. Besides,a vulcanization kinetic model based on Dy^3＋-Zn^2＋ double metal active center was proposed by analyzing the curing characteristics and DSC curve of NR compound. The double metal active center had big steric effect,which would delay its reaction with sulfur ring, stabilize more sulfur atom on the side group and increase the split rate of polysulfide, so P（NR/HAF-Dy） would offer longer scorch time and faster vulcanization rate.