Understanding Fracture Behavior of Brittle Polymeric Glasses

This presentation attempts to understand the crack growth and propagation in brittle glassy polymers, which, in theory, is amenable to study using Linear Elastic Fracture Mechanics (LEFM). We attempt to explore the basic concepts of fracture mechanics using polymethyl methacrylate, polystyrene, physically aged polylactic acid and polycarbonate. Stress-optical measurements around a deliberately introduced single edged notch during uniaxial deformation allows us to examine the stress intensification around this defect to better understand the role of flaws. While models explaining the mechanics and strength of glassy polymers at a chain-network level have been around for some time [1,2] these pictures are more idealistic, i.e., assumes the absence of flaws. Thus, understanding the role of flaws in mechanical responses will extend our knowledge about mechanical characteristics of these glassy polymers.

 

[1] A phenomenological molecular model for yielding and brittle-ductile transition of polymer glasses. J. Chem. Phys. 2014, 141, 094905 

[2] Crazing and yielding in glassy polymers of high molecular weight. Polymer 2020, 197, 122445.