ON THE DYNAMIC MECHANICAL-BEHAVIOR OF POLY(ETHYL METHACRYLATE) REINFORCED WITH KEVLAR FIBERS

The dynamic mechanical relaxation spectra of a series of composites with a matrix of poly (ethyl methacrylate) reinforced with continuous Kevlar fibers present several characteristics that have been proposed in the literature regarding polymer composites as a proof of the existence of an interphase between the polymeric matrix and the filler with mechanical properties different from both: The alpha-relaxation, associated with the glass transition of the matrix, is shifted in the temperature axis, and a peak appears in the tan delta vs. temperature plot, which was not present either in the matrix or in the fiber relaxation spectra. Nevertheless, a simple block model which does not include the existence of such an interphase is able to reproduce not only the dependence of the loss tangent and storage modulus with the fiber content, but also the shift of the alpha-relaxation and the presence of the new alpha' peak in the composites.