Bokobza Liliane
Independent Researcher, 194-196 Boulevard Bineau, 92200 Neuilly-Sur-Seine, France.
Polymers (Basel). 2023 Jun 30;15(13):2900. doi: 10.3390/polym15132900.
The reinforcement of elastomers is essential in the rubber industry in order to obtain the properties required for commercial applications. The addition of active fillers in an elastomer usually leads to an improvement in the mechanical properties such as the elastic modulus and the rupture properties. Filled rubbers are also characterized by two specific behaviors related to energy dissipation known as the Payne and the Mullins effects. The Payne effect is related to non-linear viscoelastic behavior of the storage modulus while the Mullins or stress-softening effect is characterized by a lowering in the stress when the vulcanizate is extended a second time. Both effects are shown to strongly depend on the interfacial adhesion and filler dispersion. The basic mechanisms of reinforcement are first discussed in the case of conventional rubber composites filled with carbon black or silica usually present in the host matrix in the form of aggregates and agglomerates. The use of nanoscale fillers with isotropic or anisotropic morphologies is expected to yield much more improvement than that imparted by micron-scale fillers owing to the very large polymer-filler interface. This work reports some results obtained with three types of nanoparticles that can reinforce rubbery matrices: spherical, rod-shaped and layered fillers. Each type of particle is shown to impart to the host medium a specific reinforcement on account of its own structure and geometry. The novelty of this work is to emphasize the particular mechanical behavior of some systems filled with nanospherical particles such as in situ silica-filled poly(dimethylsiloxane) networks that display a strong polymer-filler interface and whose mechanical response is typical of double network elastomers. Additionally, the potential of carbon dots as a reinforcing filler for elastomeric materials is highlighted. Different results are reported on the reinforcement imparted by carbon nanotubes and graphenic materials that is far below their expected capability despite the development of various techniques intended to reduce particle aggregation and improve interfacial bonding with the host matrix.
在橡胶工业中，为了获得商业应用所需的性能，弹性体的增强至关重要。在弹性体中添加活性填料通常会使诸如弹性模量和断裂性能等机械性能得到改善。填充橡胶还具有与能量耗散相关的两种特定行为，即佩恩效应和穆林斯效应。佩恩效应与储能模量的非线性粘弹性行为有关，而穆林斯效应或应力软化效应的特征是，当硫化胶再次拉伸时应力降低。这两种效应都强烈依赖于界面粘附和填料分散。首先讨论传统橡胶复合材料（通常以聚集体和团聚体形式存在于主体基质中的炭黑或二氧化硅填充）的增强基本机制。由于聚合物 - 填料界面非常大，使用具有各向同性或各向异性形态的纳米级填料有望比微米级填料带来更多的性能提升。这项工作报道了用三种可增强橡胶基体的纳米颗粒获得的一些结果：球形、棒状和层状填料。由于其自身的结构和几何形状，每种颗粒都显示出能赋予主体介质特定的增强效果。这项工作的新颖之处在于强调了一些填充纳米球形颗粒的体系的特殊力学行为，例如原位二氧化硅填充的聚（二甲基硅氧烷）网络，其显示出很强的聚合物 - 填料界面，并且其力学响应是典型的双网络弹性体。此外，还强调了碳点作为弹性体材料增强填料的潜力。尽管开发了各种旨在减少颗粒团聚并改善与主体基质界面结合的技术，但关于碳纳米管和石墨烯材料的增强效果报道的不同结果远低于其预期能力。
