Investigating molecular origins of mechanical stress during deformation of polymer glasses: in-situ birefringence measurements

In absence of microscopic experimental tools to investigate molecular deformation due to macroscopic deformation of glassy polymers, we monitor in real time the emergence of birefringence at different temperatures during ongoing uniaxial tensile deformation, stress relaxation and creep. By comparing the stress-optical behavior among PS, PMMA and bisphenol A PC where the optical anisotropy arises from either side group (PS) or backbone (PMMA and PC), we can learn about the intermolecular and intramolecular contributions to mechanical stress and obtain more insights into the stress-optical relationship identified in the mechanical deformation of these glassy polymers.