An exploratory investigation of viscoelastic nanoindentation on polyvinyl acetate

Scope and Method of Study. Nanoindentation load-displacement data of polyvinyl acetate (PVAc) was obtained at different temperatures ranging from ∼20°C to 42°C using two novel equipments, Hysitron Triboindenter and Interfacial Force Microscopy (IFM). Load-displacement data was analyzed using viscoelastic contact theory and JKR contact mechanics theory.;Findings and Conclusions. Load-displacement data obtained by Hysitron Triboindenter was analyzed using viscoelastic theory and shear creep compliance curves were obtained at different temperatures. Load-displacement data obtained by IFM was analyzed using viscoelastic theory and JKR contact mechanics theory and shear creep compliance curves were obtained at different temperatures. Small drift rate in load-displacement data obtained by Hysitron Triboindenter resulted in big error in shear creep compliance curves so that master shear creep compliance curve could not be formed. Glass transition temperature of PVAc was found at ∼34°C using shear creep compliance curves and it showed that glass transition temperature of PVAc is not unique. Adhesion forces between PVAc and tip was observed by IFM and invalidity of JKR method for PVAc was shown.