Strain rate sensitivity of polycarbonate and vinyl ester from dynamic mechanical analysis experiments

Measuring the strain rate sensitivity of materials is desired to improve the design of polymeric parts in automotive and aerospace structures. In this work, we present a technique for determining the mechanical response of polymers at different temperatures and strain rates by converting frequency-domain dynamic mechanical analysis (DMA) data to the time domain. Two polymers of practical interest, vinyl ester and polycarbonate, are examined. The modulus of elasticity in the linear region is measured as a function of the applied strain rate and compared to predictions from the DMA transformation technique. Close agreement between the results obtained from the two techniques is observed over the studied range of strain rates. The transformation technique only relies on the assumptions of the linear theory of viscoelasticity and is expected to be applicable to a wide range of polymers and can also be extended to polymer-matrix composites.