Fracture mechanics of polymers: plastics and elastomers

In this presentation we examine a unifying framework for fracture of polymers.  The motivation stems from the relatively recent modeling [1,2] of yielding and brittle-ductile transition (BDT) in glassy polymers where chain uncrossability provides chain networking.  The inherent mechanical strength of such polymers at or below BDT may be estimated in terms of the network structure and chain pullout in the glassy state.  Such knowledge enables us to address the question of whether brittle fracture of polymers such as PS and PMMA and crosslinked rubbers could be understood without invoking the Griffith idea that accounts for the fracture strength in terms of critical energy release rate.  Our preliminary results suggest that we can and perhaps should develop a different fracture criterion that also takes the material response into explicit account, which influences the geometric characteristics of intentional precut.

[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.