An experimental investigation has been conducted to evaluate the use of recycled rubbers in blends for the development of new thermoplastic elastomers (TPE) and rubber-toughened plastics. The recycled rubbers were obtained from various commercial sources and included representatives from the EPDM, SBR, and NR/SBR blend families, as well as a range of particle sizes. A series of five different virgin polypropylenes (PP) were used as the plastic phase, representing a range of molecular weights and suppliers. Blends were prepared in a Haake Buechler batch mixer over a broad range of constituent fractions. Compatibilization and reactive blending techniques were used to improve the quality of the scrap rubber/plastic blends with respect to both mechanical and rheological properties. Results indicate that these blending techniques are required to obtain acceptable mechanical strength in the resultant materials. Additional parameters that significantly enhanced properties included elevating the blending temperature, reducing rubber particle size, and increasing PP molecular weight. This later conclusion was attributed to a lower degree of crystallinity in the PP phase that contributes to better blending between the phases.

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