Padmanathan Hiron Raja, Federico Carlos Eloy, Addiego Frédéric, Rommel Robert, Kotecký Ondřej, Westermann Stephan, Fleming Yves
Department of Materials Research and Technology, Luxembourg Institute of Science and Technology, 5 Avenue des Hauts-Fourneaux, L-4362 Esch-sur-Alzette, Luxembourg.
Department of Physics and Materials Science, University of Luxembourg, 2 Avenue de l'Université, L-4365 Esch-sur-Alzette, Luxembourg.
Polymers (Basel). 2021 Sep 14;13(18):3094. doi: 10.3390/polym13183094.
This work aimed at studying the effect of a silica specific surface area (SSA), as determined by the nitrogen adsorption method, on the viscoelastic and fatigue behaviors of silica-filled styrene-butadiene rubber (SBR) composites. In particular, silica fillers with an SSA of 125 m/g, 165 m/g, and 200 m/g were selected. Micro-computed X-ray tomography (µCT) was utilized to analyze the 3D morphology of the fillers within an SBR matrix prior to mechanical testing. It was found with this technique that the volume density of the agglomerates drastically decreased with decreasing silica SSA, indicating an increase in the silica dispersion state. The viscoelastic behavior was evaluated by dynamic mechanical analysis (DMA) and hysteresis loss experiments. The fatigue behavior was studied by cyclic tensile loading until rupture enabled the generation of Wöhler curves. Digital image correlation (DIC) was used to evaluate the volume strain upon deformation, whereas µCT was used to evaluate the volume fraction of the fatigue-induced cracks. Last, scanning electron microscopy (SEM) was used to characterize, in detail, crack mechanisms. The main results indicate that fatigue life increased with decreasing silica SSA, which was also accompanied by a decrease in hysteresis loss and storage modulus. SEM investigations showed that filler-matrix debonding and filler fracture were the mechanisms at the origin of crack initiation. Both the volume fraction of the cracks obtained by µCT and the volume strain acquired from the DIC increased with increasing SSA of silica. The results are discussed based on the prominent role of the filler network on the viscoelastic and fatigue damage behaviors of SBR composites.
本研究旨在探讨通过氮吸附法测定的二氧化硅比表面积（SSA）对二氧化硅填充丁苯橡胶（SBR）复合材料粘弹性和疲劳行为的影响。具体而言，选用了比表面积分别为125 m²/g、165 m²/g和200 m²/g的二氧化硅填料。在进行力学测试之前，利用微计算机X射线断层扫描（µCT）分析SBR基体中填料的三维形态。通过该技术发现，随着二氧化硅比表面积的减小，团聚体的体积密度急剧下降，这表明二氧化硅的分散状态有所改善。通过动态力学分析（DMA）和滞后损耗实验评估粘弹性行为。通过循环拉伸加载直至断裂来研究疲劳行为，从而生成韦勒曲线。利用数字图像相关技术（DIC）评估变形时的体积应变，而µCT则用于评估疲劳诱导裂纹的体积分数。最后，使用扫描电子显微镜（SEM）详细表征裂纹机制。主要结果表明，随着二氧化硅比表面积的减小，疲劳寿命增加，同时滞后损耗和储能模量也随之降低。SEM研究表明，填料与基体的脱粘和填料断裂是裂纹萌生的机制。通过µCT获得的裂纹体积分数和从DIC获得的体积应变均随二氧化硅比表面积的增加而增大。基于填料网络在SBR复合材料粘弹性和疲劳损伤行为中的重要作用对结果进行了讨论。
