Grinding of Waste Rubber
Powdered rubber has several potential application fields, starting with blending in virgin rubber and thermoplastics and up to incorporation in several civil engineering applications such as in concrete and asphalt. Apart from the molecular weight, the filler concentration and grinding technology also has a crucial role in modifying the properties of the processed composites. The grinding method has a direct impact on the surface properties of the particles and hence the polymer–filler interaction, mixing behavior, curing characteristics, and mechanical properties can be tailored by altering the grinding method. For example, cryogenically ground rubber particles have a smoother surface as compared to grind rubber particles. Hence, powder obtained through ambient grinding offers a better miscibility with the polymer system. Sometimes surface modification is performed on cryogenically ground rubber by a revulcanization method with the addition of sulfur in the system in order to achieve better filler matrix interactions. Each of the processes are distinct to each other and offer several advantages, as well as each of them having several limitations. Thus, the grinding method is selected according to the intended application. Moreover, grinding is the preferred waste recycling route of rubbers due to its eco-friendly nature and reasonably moderate cost.