STRUCTURAL REARRANGEMENTS IN CRAZED POLYM ERS INDUCED BY SUBLIMATION DRYING

The freeze-dried (by sublimation drying) solvent-crazed PET and PC sam ples showed 1.5 - 3 times greater dispersity than the samples obtained by conventional drying. At a fixed length of solvent-crazed samples, their specific inner surface Si was found to be controlled by the surf ace energy gamma at the polymer-environment interface so that S-i gamm a = const. This relationship was valid when one liquid environment is replaced by another as well as when the frozen liquid environment is s ublimated from the crazes in PET, In the case of the removal of liquid environment from the craze structure in PC, a decrease in S-i was sho wn to be associated with the breakdown of some craze fibril rather tha n with coagulation of craze fibrils during the attainment of coagulati on equilibrium in quasicolloidal structure of the crazes, as was obser ved in solvent-crazed PET samples. The effect of annealing of the solv ent-crazed samples before and after sublimation drying on the stabilit y of microporous crazed structures was considered.