Session D40 - Poster Session I.
POSTER session, Monday afternoon, March 12
Exhibit Hall, Washington State Convention Center
Previous work in our group suggests that, in craze nucleation, only when a nanovoid grows to a critical size can it serve as a nucleus for stable craze growth. However, what factors influence this nanovoid growth process remains unclear. A new technique, synchronized stress-PALS test, has been established to study the change in size and intensity of nanovoids when polymer glasses are under stress. A series of glassy copolymers based on poly (ethylene terephthalate) (PET) and poly (1,4-cyclohexylenedimethylene terephthalate) (PCT) were investigated by synchronized stress-PALS at different stress levels. The results suggest that both stress level and chain mobility of the polymers influence nanovoid growth. Based on these experimental results, a craze nucleation model has been proposed. This model, based on thermodynamic and kinetic analysis, show that the craze nucleation process is determined by the modulus, surface energy and chain mobility of polymer glasses.