Viscoelastic characteristics of short fiber reinforced polybutylene terephthalate

The mechanical characteristics of short-fiber-reinforced thermoplastics should be evaluated based on viscoelastic theory because of the time and temperature dependent characteristics of the matrix resin. In this study, the viscoelastic characteristics of short-fiber-reinforced polybutylene terephthalate, PBT composite, are evaluated by material testing and micromechanics model. Firstly, tensile tests are carried out PBT composite with three fiber volume ratios under various temperature and strain rate conditions. The results show that the viscoelastic characteristics of the PBT composites can be obtained by the time-temperature superposition principle using shift factor of the PBT resin. Next, the Eshelby model combined with the Mori–Tanaka theory is used to predict to the viscoelastic characteristics of the PBT composites based on the measurement of fiber length and fiber orientation angle. The predicted viscoelastic characteristics of the PBT composites are in good agreement with the tensile test.