Crystalline Structure and Viscoelastic Behavior in Composites of a Metallocenic Ethylene-1-octene Copolymer and Glass Fiber

Several composites with short glass fiber of a copolymer of ethylene and 1-octene, synthesized with a metallocene catalyst, have been prepared, up to a fiber content of 40 wt.-%. The effect of the fiber on the crystalline structure and on the viscoelastic response are analyzed. The role of glass fiber incorporation on crystallite development is discussed based on real-time variable-temperature WAXS and SAXS experiments. The viscoelastic behavior is considerably modified by incorporation of the glass fiber when compared with the plain copolymer. Thus, both the intensity and location of the γ and β relaxations are dependent on the fiber content. Moreover, the stiffness is considerably increased in the composites, allowing the analysis of the viscoelastic behavior up to temperatures well inside the melting region of the copolymer crystals, and thus enlarging substantially the service temperature of these composites. The β relaxation is assigned to the glass transition temperature, in agreement with the calorimetric results (DSC and MDSC) in these composites.