Effect of aging on internal stress and fatigue fracture of poly(4‐methyl pentene‐1)

摘要

AbstractThe fatigue fracture behaviour of injection‐molded poly(4 methyl pentene‐1) has been investigated. Crack growth rate experiments have been conducted on notched specimens after room temperature aging, after annealing at 175°C, and after prolonged cyclic loading prior to notching. Residual stress profiles have been determined for specimens in each of these states, and the crack growth data have been discussed with reference to differences in residual stresses. Annealing caused the reversal of the sense of the residual stresses, and a significant change in stress distribution was found for specimens freshly removed from prolonged storage at −18°C. Scanning electron microscopy of fracture surfaces revealed fibrillar features essentially similar to those found with other semicrystalline p