Abstract
Brown has shown that low-angle electron diffraction (LAED) may be used to determine fibril diameters D and spacings D//0 of crazes in thin polymer films. He found, however, that the D and D//0 determined for air crazes in polystyrene (PS) thin films were larger by about a factor of 3 than those in PS bulk crazes determined by using small-angle x-ray scattering (SAXS). The authors have repeated Brown's LAED experiments and find that the discrepancy may be caused by an aging effect. The fresh crazes have D and D//0 values from LAED that are comparable to those of bulk PS crazes determined by SAXS. As the craze ages, however, fibrils retract and coalesce in wide regions of the craze, leading eventually to an observable 'skin. ' Aged crazes thus have much larger D and D//0 values than do fresh crazes.