Mechanisms of Fatigue Damage and Fracture in Semi-Crystalline Polymers.
Abstract
Fatigue crack profiles and fracture surfaces of poly(vinylidene fluoride) (PVDF), nylon 66 (N66), and poly acetal (PA) were studied to ascertain the mechanisms of cyclic damage and fatigue crack propagation in semi-crystalline polymers. Crack tip damage is believed to begin as small trans-spherulitic and interspherulitic tensile crazes. However, compressive yielding within the reverse plastic zone at the crack tip crushes and elongates the spherulities in the direction of crack growth. Consequently, the microstructure of the polymer in advance of the crack front is very different from the original morphology of the spherulitic bulk material as evidenced by the resulting fracture surface appearance. When the test temperature is below the glass transition temperature, however, plastic deformation is limited, and fatigue fracture occurs before significant disruption of the spherulitic structure. In this case, the fracture surface morphology reflects the original microstructure of the bulk polymer. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 30, 1981
- Accession Number
- ADA096068
Entities
People
- John A. Mason
- Philip E. Bretz
- Richard W. Hertzberg
Organizations
- Lehigh University