Mechanical spectral hole burning in glassy polymers

Polymeric glasses in deep glassy state exhibit excellent mechanical properties and are commonly used in engineering applications. Linear viscoelastic properties of polymers are well characterized by mechanical and di-electric spectroscopies, whereas methods such as large amplitude oscillatory shear (LAOS) provide material response under large non-linear deformation for polymer solutions and melts. Non-linear dynamics of glassy polymers has seldom been reported and an understanding is important from both fundamental and practical perspectives. In the current work, mechanical spectral hole burning (MSHB), an extension of LAOS methodology, has been applied on two amorphous glassy polymers, poly(methyl methacrylate) (PMMA) and polycarbonate to investigate the non-linear dynamics close to the β transition ^[1]. Results from polycarbonate show a weak hole intensity compared to PMMA thus relating the hole burning event with the dynamic heterogeneity as related to the occurrence of strong β transition.

[1] Mangalara. S and McKenna, G.B. J. Chem. Phys, 152.7[MG1] (2020): 074508.