Viscoelastic Properties of Soft Polymer with Microstructures

Abstract

This research studies the effects of microstructures on overall mechanical properties of materials The pendulum-type viscoelastic spectrometer (PVS) was adopted to measure foams and other microstructured polymer Finite element calculations of microstructured materials with COMSOL were performed and their results are correlated with the Cosserat theory Under the quasi-static assumptions the calculated effective modulus of the foam may exhibit a factor of 10 difference for the Young’s and shear modulus For the bulk modulus the effects of microstructure may reach a three order of magnitude difference Calculated negative Poisson’s ratio of the foam may rapidly disappear in terms of the defined microstructural angles With the angle decreases Poisson’s ratio of the foam reaches a plateau Furthermore the effective elastic constants of the foamed materials increase as their size decrease; consistent with the Cosserat theory In addition the thermoelastic damping measured from the PVS experiment is consistent with the theory in terms of the location of frequency but its damping magnitude is not matched

Date of Award	2015 Sept 24
Original language	English
Supervisor	Yun-Che Wang (Supervisor)