Viscoelastic characterization; how to fill experimental gap between solid and liquid techniques
Résumé
Viscoelastic behaviors of polymers from liquid to solid state are investigated with techniques such as dynamic mechanical analysis (DMA) and rheometry. The time-temperature superposition principle permits to build master curves. WLF law can then be identified and implemented in numerical softwares to predict thermomechanical behaviors. Polycarbonate (PC) with a glass transition (Tg) around 150°C is tricky to characterize. DMA is limited as the rigidity drops around Tg and rheometry is delicate as the fluidity is not sufficient under Tg + 40°C. Data are obtained with DMA (tensile loading) for T ≤ Tg and with rheometry (shear loading) for T ≥ Tg +40°C. The aim is to fit them to obtain a master curve and identify a thermo mechanical behavior. The goal is to propose a new procedure combining two experimental techniques totally different and push the limit of their relevance domain.