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当硫黄硫化NR胶料暴露于热老化环境中时,物理性能和使用性能发生了重大变化。这些变化与原有交联结构的改变直接相关。如通常在硫化载重轮胎和工程机械轮胎时遇到的过硫化过程中所看到的,分解反应往往占主导地位,而且交联密度和物理性能下降。该过程导致高生热,最终影响了轮胎的主要性能,如耐屈挠、耐切割和抗崩花掉块性能。因此,轮胎工业不断努力改进耐切割和抗崩花掉块性能,同时保持高水平的产品质量和使用性能。橡胶工业通过改变填料、优化硫化体系或改变聚合物品种及其并用比,研制一些配方来改善轮胎耐切割和抗崩花掉块性能,但要以牺牲滞后、生热和屈挠性能为代价。本文概括介绍一些实用方法,重点介绍一种使用对芳香聚酰胺(Twaron和Technora)短纤维改善耐切割和抗崩花掉块性能的方法。业已证实,在典型载重轮胎或工程机械轮胎胎面胶中添加1~3份对芳香聚酰胺可显著改善滞后和生热,从而降低滚动阻力。轮胎试验数据表明,轮胎使用性能获得显著改善,耐久性能提高18%~22%,生热和滚动阻力分别降低10%和12%~24%。
When sulfur vulcanized NR compounds are exposed to heat aging environments, significant changes have taken place in physical properties and service properties. These changes are directly related to changes in the original cross-linked structure. As is commonly seen during the over-vulcanization encountered in the vulcanization of truck tires and construction machinery tires, the decomposition reaction tends to dominate and the crosslink density and physical properties decrease. This process leads to high heat build-up, ultimately affecting the main properties of the tire such as flex resistance, cut resistance and chipping resistance. As a result, the tire industry is continually striving to improve the resistance to cutting and chipping off, while maintaining a high level of product quality and serviceability. The rubber industry has developed some formulations to improve the tire’s cut and chipping resistance at the expense of hysteresis, heat build-up and flexing properties by changing the filler, optimizing the cure system or changing the polymer species and their combination ratios. This article provides an overview of some practical methods, highlighting a method for improving the resistance to chipping and chipping off using aromatic polyamide (Twaron and Technora) staple fibers. It has been confirmed that the addition of 1 to 3 parts of para-aramid to a typical truck tire or construction machinery tire tread rubber can significantly improve hysteresis and heat generation, thereby reducing rolling resistance. Tire test data show that tire performance has been significantly improved, durability increased by 18% to 22%, heat and rolling resistance decreased by 10% and 12% to 24%.