Preparação e uso de agente compatibilizante na mistura da borracha EPDM contendo resíduo EPDM-r.

Abstract

This thesis aimed to recover rubber residue containing carbon black EPDM (EPDM-r) and for this purpose, modified EPDM with 2-mercaptoethanol (EPDMAT) as compatibilizing agent was used. In this study we evaluated the effect of the amount of compatibilizing agent (EPDMAT) 3,5,7 and 10 phr in the blend EPDM / EPDM-r / EPDMAT in two cure systems: sulfur and dicumyl peroxide. To evaluate the effect of EPDMAT and cure system studies were performed on the rheological and mechanical properties of tensile bond strength, creep and tear, crosslinking density and morphology of the blends EPDM / EPDM-r / EPDMAT. The results indicated a great content in 5phr EPDMAT to be used, and that the addition of 10 phr EPDMAT reduces the mechanical properties due to the saturation of charge-polymer interface. Regarding the effect of cure system, the mixtures cured with peroxide had lower values of maximum torque and crosslinking density than the mixtures cured with sulfur, however, the mechanical properties of these compositions showed higher values than the mixtures containing sulfur. This behavior was attributed to the nature of the bonds formed by the peroxide cure system which promotes linkages (-CC-) between the polymer chains that are stronger and more stable than those formed by the system with sulfur (-Sx-C-C -). In relation to the processing of the blends using the Rubber Processing Analyzer (RPA), it was found that the addition of EPDMAT did not change the complex modulus, elastic and viscous, and the viscosity of the mixtures. Among the mixtures with residue content (EPDMr) ranging from 0 to 80 phr, the best properties were found for mixture containing 80 phr of EPDM-r and 5 phr EPDMAT. This result indicates that the interfacial action of the compatibilizer is more efficient for higher load levels (above 60 phr). The morphologies of mixtures obtained by scanning electron micrograph indicated that the addition of 5 phr EPDMAT increases the dispersion of the EPDM-r residue, especially the concentrations of 60 and 80 phr, both studied curing systems.