LOW-TEMPERATURE DEFORMATION OF FLUORIDE AND OXIDE GLASS-FIBERS BELOW THEIR GLASS-TRANSITION TEMPERATURES

Deformations of some fluoride and oxide glass fibers were measured at temperatures below their glass transition temperatures. Glass fibers w ere wound on a cylinder, kept at low temperatures for various times an d the remaining strains of fibers after the heat treatment were measur ed. It was found that the temperature region in which fluoride grass f ibers are deformed is much lower than that for oxide glass fibers. The deformation mechanisms of each of the glass fibers were analyzed base d on a log-normal distribution model of relaxation times. It was found that the activation energy for low-temperature deformation is much lo wer than that for viscous flow near the glass transition temperature. It was concluded that the deformations of each of the glass fibers are caused by different relaxation mechanisms.