Burgo Thiago A L, Batista Bruno C, Galembeck Fernando
Department of Physics, Federal University of Santa Maria, 97105-900 Santa Maria, Rio Grande do Sul, Brazil.
University of Campinas, Institute of Chemistry, Campinas, São Paulo 13083-970, Brazil.
ACS Omega. 2017 Dec 14;2(12):8940-8947. doi: 10.1021/acsomega.7b01010. eCollection 2017 Dec 31.
This work describes the conversion of mechanical energy to electricity, by periodically stretching rubber tubing and allowing it to relax. The rubber surface shows periodic and reversible electrostatic potential variations, in phase with the tubing length. The potential change depends on the elastomer used: silicone loses charge when stretched and becomes strongly negative when relaxed, whereas the stretched natural rubber is positive, becoming negative when relaxed. Every other elastomeric material that was tested also showed periodic potential but followed different patterns. When the motion stops, the potential on the resting samples decreases quickly to zero. The potential oscillation amplitude decreases when the relative humidity decreases from 65 to 27%, but it is negligible when the rubber tubing is previously swollen with water or paraffin oil. Elastomer charging patterns do not present the well-known characteristics of piezo-, flexo-, or triboelectricity, and they are discussed considering rubber rheology, wear, and surface properties, including the possibility of surface piezoelectricity. The following mechanism is suggested: rubber stretching provokes chemical and morphology changes in its surface, followed by a change in the surface concentration of H and OH ions adsorbed along with water. The possibility of the occurrence of similar variations in other systems (both inert and biological) is discussed, together with its implications for energy scavenging from the environment.
这项工作描述了通过周期性拉伸橡胶管并使其松弛，将机械能转化为电能的过程。橡胶表面呈现出与管长同相位的周期性且可逆的静电势变化。电势变化取决于所使用的弹性体：硅橡胶在拉伸时失去电荷，松弛时变为强负电，而拉伸的天然橡胶为正电，松弛时变为负电。测试的其他每一种弹性体材料也都显示出周期性电势，但遵循不同的模式。当运动停止时，静止样品上的电势会迅速降至零。当相对湿度从65%降至27%时，电势振荡幅度减小，但当橡胶管预先用水或石蜡油溶胀时，电势振荡幅度可忽略不计。弹性体充电模式不具备压电、挠曲电或摩擦电的众所周知的特性，并且结合橡胶流变学、磨损和表面性质（包括表面压电性的可能性）对其进行了讨论。提出了以下机制：橡胶拉伸会引发其表面的化学和形态变化，随后吸附的H和OH离子以及水的表面浓度发生变化。讨论了在其他系统（包括惰性系统和生物系统）中发生类似变化的可能性，以及其对从环境中收集能量的影响。
