Viscoelastic behaviour of glass beads reinforced poly(butylene terephthalate): experimental and theoretical approaches

The dynamic mechanical behaviour of a series of poly(butylene terephthalate )/glass beads composites was studied as a function of filler ratio, filler size and surface treatment. Samples were subjected to compression-tension t esting within a temperature range from -150 degrees C to 150 degrees C. The real part (E') of the dynamic modulus and the loss tangent (tan delta) wer e studied around beta and alpha relaxations. It was observed that the magni tude of these relaxations decreased as the glass beads ratio increased. A s imilar decrease was observed at constant tiller ratio with improving filler -matrix adhesion by a coupling agent. All these results might be due both t o the matrix substitution by fillers and to the reducing of polymer chains molecular mobility in the vicinity of the interface. Using Hashin's corresp ondence principle, the viscoelastic behaviour of such composites was descri bed by self-consistent models in the neighbourhood of the cu relaxation and compared to experimental data.