Viscoelastic response of nanocomposite poly(vinyl acetate)-hydroxyapatite with varying particle shape-dynamic strain softening and modulus recovery

摘要

Dynamic-strain softening known as the Payne effect was investigated in the case of poly(vinyl acetate)-hydroxyapatite (PVAc-HA) model nanocomposites in which the nanoparticles served as reversible physical cross-links. HA nanofillers with different particle shape and with size ranging from 5 to 60 nm were used. Filler concentration in PVAc nanocomposites was limited to maximum of 5 vol%. Dynamic-mechanical spectra were recorded as a function of structural variables, strain amplitude, and test temperature using the dynamic-mechanical thermal spectroscopy (DMTS). Additionally, amplitude sweep tests were supplemented by the modulus recovery experiments to provide relaxation time data. Observed phenomena were interpreted using polymer physics approach.