Crazing and Fracture in Polymers

Abstract

The discussion on the fracture of solid materials, both metals and polymers, customarily begins with a presentation of the stress-strain behavior and of how various conditions such as temperature and strain-rate affect the mechanisms of deformation and fracture. This article describes crazing and fracture in polymeric materials, with a review of the behavior of the elastic modulus as a function of temperature or time parameters, emphasizing the importance of the viscoelastic nature of their deformation and fracture. The discussion covers the behavior of polymers under stress, provides information on ductile and brittle behaviors, and describes craze initiation in polymers and crack formation and fracture by crazing. Macroscopic permanent deformation of polymeric materials caused by shear-yielding and crazing, which eventually can result in fracture and failure, is also covered.

Strength Assessment of PET Composite Prosthetic Sockets

“…In the monolithic HDPE and PP samples, a classic cup–cone type ductile failure [ 33 , 34 ] was observed (as shown in Figure 8 d,e). This occurred when the material was stretched within its gauge section during the tensile loading process.…”

“…Upon closer inspection of the HDPE sample in Figure 9 d, it can be seen that there were crazing and recoiled failed fibrils after the tensile failure. On the other hand, the PP sample failed surface had a peak and valley, indicating that the final failure was due to microvoid coalescence [ 33 , 34 ].…”

“…These crazes are small, localised, plastically deformed zones with dense fibrils separated by microvoids. Upon closer inspection of the HDPE sample in Figure 9d, it can be seen In the monolithic HDPE and PP samples, a classic cup-cone type ductile failure [33,34] was observed (as shown in Figure 8d,e). This occurred when the material was stretched within its gauge section during the tensile loading process.…”