This paper reports on the adhesion characteristics between microspheres and rubber surfaces. Silica, polystyrene, and poly(methyl methacrylate) microspheres were deposited on cis-1,4-polybutadiene (BR) films. A BR meniscus formed on the sphere surfaces when the film thickness was less than the diameters of the spheres. Additionally, the attractive forces acting on the spheres in the direction of the BR films were examined via atomic force microscopy. Sedimentation of the spheres occurred for films with thicknesses much greater than the diameters of the microspheres in all systems. Interestingly, this wetting process occurred even in the silica/BR system, despite the incompatibility of these materials. The driving force for meniscus formation is the difference between the surface free energy of BR (γ BR) and that of the spheres (γ sphere). For all systems, γ BR is lower than γ sphere, i.e., the BR surface is more stable than those of the spheres, and thus a meniscus forms to stabilize the system. Once a meniscus formed, a downward force acted on the spheres to embed them into the BR film. Sedimentation eventually ceased when the angle between the tangential line of the sphere and the rubber surface became equal to the equilibrium contact angle determined by Young’s equation. Interestingly, the sedimentation behavior was nearly identical for spheres with various surface free energy values except in terms of their final positions. The same sedimentation phenomena were studied with crosslinked BR films. In contrast to the experiments performed using various types of spheres, the sedimentation behavior varied with different rubber characteristics. The results of these studies indicate that the sedimentation behavior mainly depends on the physical properties of the rubbers used, although the physical properties of the spheres are in determining their final depth.

中文翻译：

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微球与橡胶表面之间粘附并伴有弯月面形成和沉降的研究

本文报道了微球与橡胶表面之间的粘附特性。二氧化硅，聚苯乙烯和聚（甲基丙烯酸甲酯）微球沉积在顺式1,4-聚丁二烯（BR）膜上。当膜厚度小于球的直径时，在球表面上形成BR弯月面。另外，通过原子力显微镜检查了沿BR膜的方向作用在球体上的吸引力。对于厚度大于所有系统中微球直径的薄膜，发生了球的沉淀。有趣的是，尽管这些材料不兼容，但即使在二氧化硅/ BR体系中也发生了这种润湿过程。弯月面形成的驱动力是BR（γBR）的表面自由能与球体（γ球体）的表面自由能之差。对于所有系统，γBR均低于γ球，即，BR表面比球表面更稳定，因此会形成弯月面以稳定系统。一旦弯液面形成，向下的力作用在球体上，将其嵌入BR膜中。当球体切线与橡胶表面之间的夹角等于由杨氏方程确定的平衡接触角时，沉淀最终停止。有趣的是，对于具有各种表面自由能值的球，除了其最终位置以外，其沉降行为几乎相同。用交联的BR膜研究了相同的沉积现象。与使用各种类型的球体进行的实验相反，沉降行为随橡胶特性的不同而变化。这些研究的结果表明，尽管球体的物理性能决定了其最终深度，但其沉降行为主要取决于所用橡胶的物理性能。