The Effect of Ultrafine Ground Tire Rubber Concentration on the Rheology, Dynamic Mechanical and Physical Properties of Injection Molded Elastomers

Recycling of thermoset elastomers involves more difficult processes compared to recycling of thermoplastics. Thermoset elastomers can be recycled by preparation of crumb rubber by grinding. This powdered rubber can then be mixed in compounds with thermoplastics, in asphalt, or incorporated into recycled rubber/virgin rubber compounds. In recycled rubber/virgin rubber compounds the material offers both environmental benefits and reduced compound costs. For certain applications, it is useful to process the compounds by injection molding. This work investigates the effects of ultrafine ground tire rubber and its content on the rheology, and mechanical properties (dynamic mechanical and physical) of injection molded elastomers. The data from capillary rheometry was compared with the standard viscosity models to investigate the effect of recycled rubber on flowability of the recycled rubber/virgin rubber compounds. Compounds prepared with diffe rent loadings of recycled rubber were injection molded using different molding conditions and the flow length and weld strength (DuPont flow mold) were compared. The effect of curing time and temperature on tensile strength, elongation and dynamic mechanical properties was also studied.