Analysis of thermal properties and rheological behavior of LLDPE/EPDM and LLDPE/EPDM/SRT mixtures

Linear low-density polyethylene (LLDPE) and ethylene-propylene-diene terpolymer (EPDM) blends, with and without scrap rubber tire (SRT), has been prepared in a single-screw extruder with a temperature profile of 180/190/200/200/ 210 degrees C. The thermal behavior of virgin LLDPE and the extrusion products have been characterized by differential scanning calorimeter (DSC), and the theological behavior also has been determined. It was observed that when EPDM is partially replaced by SRT, LLDPE/EPDM/SRT mixtures do not show, at first, an expressive diminution in the crystallization temperature (T-c), crystallinity (%chi), heat of crystallization (Delta H-c) and melting temperature (T-m) values. SRT also does not impose substantial increase in the elastic modulus (G'), viscous modulus (G '') and complex viscosity (eta*) values of LLDPE/EPDM/SRT mixtures. The possible formation of a composite of SRT-EPDM particles is suggested as reason for these results. (C) 2007 Elsevier Ltd. All rights reserved.