Segmental relaxations and other insights into filler-mediated interactions for carbon black-filled polybutadiene rubber

The role of interaction with filler particles in modifying segmental relaxations of elastomers is still not fully clear. This work examines the glass and melting transition of unvulcanized and vulcanized polybutadiene rubber filled with carbon black. It is found that for uncured rubbers, the calorimetric glass and melting transition temperatures are unaffected by the presence of carbon black, without invoking the concept of restricted chains near filler. In quenched vulcanizates, the increment in segmental relaxation with filler loading is detected, which is attributed to the reduction in chemical crosslink density caused by filler agglomeration. On the other hand, the crystalline part constrains the molecular motion in amorphous regions such that the glass transition temperature is raised when the crystallinity is large. This study reveals that the only effect of carbon black is to influence chemical crosslinks through filler networking and then change in segmental relaxations is detectable.     

顶空气相色谱-质谱联用分析橡胶硫化烟气成分来源

建立顶空气相色谱-质谱(HS-GC/MS)联用分析橡胶(制品)硫化烟气成分的方法。对选定配方原材料及其混炼胶在硫化温度下挥发的烟气成分进行HS-GC/MS测试,确定挥发分成分;通过对定性结果的分析对比,推断硫化烟气各成分的来源。该方法的建立对开发绿色橡胶制品有很好的参考性。     

中国轮胎标签制度实施对合成橡胶的影响

简介全球轮胎标签制度及其实施情况,概述我国轮胎标签制度的最新进展,分析轮胎标签制度对丁苯橡胶、顺丁橡胶、异戊橡胶和丁基橡胶等主要合成橡胶需求的影响。我国乳聚丁苯橡胶和镍系顺丁橡胶等低端胶种产能日渐过剩,市场竞争激烈;为提高轮胎性能和轮胎标签等级,溶聚丁苯橡胶、稀土顺丁橡胶和卤化丁基橡胶等性能优异的胶种需求量将逐步提高。合成橡胶企业应调整产品结构,进行技术升级,并加强与轮胎企业的合作。     

国产天然橡胶在低滚动阻力胎面胶中的应用

研究国产天然橡胶（NR）在低滚动阻力胎面胶中的应用。结果表明：与进口NR（20#标准胶）相比,国产NR的生胶门尼粘度较低,塑性初值和塑性保持率较小,加工性能较好;混炼胶的门尼粘度也较低,硫化返原率稍高;硫化胶的拉断伸长率和撕裂强度稍低,60 ℃时的损耗因子稍大,耐老化性能略差。     

花纹沟深度对轮胎性能的影响

使用相同配方、结构及花纹但花纹沟深度不同的轮胎,通过室内外测试研究轮胎花纹沟深度对轮胎性能的影响。结果表明：减小花纹沟深度可以提高轮胎的干地制动性能、操纵性能和舒适性,降低噪声和滚动阻力,但会降低水滑性能和使用寿命;花纹沟深度对湿地制动性能、湿地操纵性能和湿圆环行驶性能影响较小。     

Elucidation of segmental relaxations of silica-filled cis-polybutadiene rubber composites

There has been a lot of interest in characterizing polymer chain dynamics of rubber compounds because it is thought to underpin the exceptional mechanical properties of composites. We studied the effect of precipitated silica on segmental mobility of cis-polybutadiene rubber by using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). It was found that the calorimetric glass and melting transitions of silica-filled master batch materials were essentially identical to those of the gum rubber, showing no dependence of silica loading and silane treatment. And, we observed in calorimetric measurement a change in the melting transition step for the vulcanizates. The results were correlated to the change of chemical crosslinks caused by various factors filler agglomeration and adsorption effect that tended to decrease chemical crosslink density and silane modification increased it. The DMA results demonstrated that the second peak in loss modulus versus temperature curve for the quenched vulcanizates was assigned to melting peak, and this peak disappeared at a slow cooling rate, which coincided well with DSC results. Moreover, crystalline parts constrained amorphous regions such that the glass transition temperature was raised for the cooled vulcanizates with high chemical crosslinks.     

电子辐射预硫化对填充胶料性能的影响

通过考察填充不同用量炭黑N220的天然橡胶的填料-填料相互作用,研究电子辐射预硫化胶料性能的变化。结果表明,电子辐射预硫化后,胶料的门尼粘度提高,硫化胶的基本物理性能无显著变化,但Payne效应和滞后损失大幅下降,可有效提升填充胶料的动态性能,且随炭黑用量增大,提升效果更明显。     

应用橡胶加工分析仪研究胶料中炭黑聚集情况

应用RPA2000橡胶加工分析仪测试炭黑胶料在一定条件下弹性模量的变化,研究炭黑聚集的过程。结果表明,在没有硫化体系或胶料交联前,炭黑的聚集速度很快,而且是一个持续过程,炭黑的聚集速度随着温度的升高而加快。对于终炼胶,炭黑的聚集在硫化交联之前已经开始;在相同的硫化程度下,低温硫化胶料的Payne效应较高,炭黑聚集程度较大;胶料的门尼粘度越高,炭黑的聚集速度越慢,聚集程度越小。     

应用橡胶加工分析仪研究白炭黑胶料的硅烷化反应和填料聚集

应用RPA2000橡胶加工分析仪测试白炭黑胶料的弹性模量变化,研究加工过程中白炭黑胶料的硅烷化反应及填料聚集情况。结果表明:白炭黑胶料中形成了一定数量的白炭黑-硅烷偶联剂-橡胶化学键,很大程度上遏制了白炭黑在胶料硫化过程中聚集;较高硫化温度虽然对减少白炭黑的聚集有利,但因为交联密度随之降低,导致白炭黑胶料的损耗因子(tanδ)仍增大;开炼机剪切作用在降低白炭黑胶料的门尼粘度同时打断了橡胶大分子链和破坏了白炭黑-硅烷偶联剂-橡胶交联结构,加剧了白炭黑聚集,使得白炭黑胶料的tanδ明显增大。     

炭黑和白炭黑填充硫化胶的湿摩擦差异性分析

研究不同负荷和速度下炭黑和白炭黑填充硫化胶的湿摩擦因数,并对其摩损表面进行了扫描电子显微镜和透射电镜表征。结果表明：炭黑填充硫化胶的湿摩擦因数随着速度的增大呈线性下降,随着负荷的增大略有降低,而白炭黑填充硫化胶的湿摩擦因数随着速度的增大呈非线性下降,随着负荷的增大先迅速下降后缓慢降低;白炭黑填充硫化胶摩擦面橡胶膜较薄,裸露白炭黑粒子,过渡区摩擦力较大,不能忽略;炭黑填充硫化胶表面的橡胶膜厚度较大,表面炭黑粒子被橡胶大分子覆盖,过渡区摩擦力小,可以忽略。