Vulcanization Characteristics and Dynamic Mechanical Behavior of Natural Rubber Reinforced with Silane Modified Silica
作者:Wunpen Chonkaew、Withawat Minghvanish、Ulchulee Kungliean、Nutthaya Rochanawipart、Witold Brostow
DOI:10.1166/jnn.2011.3563
日期:2011.3.1
Two silane coupling agents were used for hydrolysis-condensation reaction modification of nanosilica surfaces. The surface characteristics were analyzed using Fourier transform infrared spectroscopy (FTIR). The vulcanization kinetics of natural rubber (NR) + silica composites was studied and compared to behavior of the neat NR using differential scanning calorimetry (DSC) in the dynamic scan mode. Dynamic mechanical analysis (DMA) was performed to evaluate the effects of the surface modification. Activation energy E a values for the reaction are obtained. The presence of silica, modified or otherwise, inhibits the vulcanization reaction of NR. The neat silica containing system has the lowest cure rate index and the highest activation energy for the vulcanization reaction. The coupling agent with longer chains causes more swelling and moves the glass transition temperature T g downwards. Below the glass transition region, silica causes a lowering of the dynamic storage modulus G', a result of hindering the cure reaction. Above the glass transition, silica—again modified or otherwise—provides the expected reinforcement effect.
采用两种硅烷偶联剂对纳米二氧化硅表面进行水解缩合反应改性。使用傅里叶变换红外光谱(FTIR)分析表面特征。使用差示扫描量热法 (DSC) 在动态扫描模式下研究了天然橡胶 (NR) + 二氧化硅复合材料的硫化动力学,并与纯 NR 的行为进行了比较。进行动态机械分析(DMA)来评估表面改性的效果。获得反应的活化能E a 值。二氧化硅的存在,无论是改性的还是其他的,都会抑制 NR 的硫化反应。纯二氧化硅体系具有最低的固化速率指数和最高的硫化反应活化能。具有较长链的偶联剂导致更多的溶胀并使玻璃化转变温度T g 下降。在玻璃化转变区域以下,二氧化硅会导致动态储能模量 G' 降低,从而阻碍固化反应。在玻璃化转变温度之上,二氧化硅(再次改性或以其他方式)提供了预期的增强效果。