Mechanical modeling of the transcrystalline interphase behavior in commingled PBT/Glass fiber composites

In a previous work, a mechanical model was proposed to predict the reinforc ement of amorphous polymers by particulates as well as by unidirectional fi bers over wide ranges of volume fractions of fillers and temperatures (or f requencies). This model is based on both the definition of a representative morphological pattern (RMP), accounting for the presence of fiber clusters , and a quantitative morphology analysis, based on the percolation concept. In this work, such an approach is extended to describe the viscoelastic pr operties of a semicrystalline polymer, poly(butylene terephthalate), commin gled with 30 and 50 vol % of unidirectional glass fibers. It is found that aggregates constituted by both fiber clusters and a transcrystalline region (TCR) can act as the continuous phase. Based on the use of a mechanical mo del in a reverse mode, the actual viscoelastic behavior of this TCR is extr acted and compared to that displayed by the unfilled polymer. (C) 2000 John Wiley & Sons, Inc.