RELAXATIONAL AND VIBRATIONAL DYNAMICS OF POLY(PROPYLENE GLYCOL)

Photon correlation spectroscopy has been used to study structural rela xation dynamics near the glass transition temperature for glass-formin g linear chain molecules differing in the number of repeat units. Comp lementary investigations of the low-frequency vibrational dynamics wer e performed by means of Raman spectroscopy. The systems studied range from the low molecular weight liquid propylene glycol (PG, molecular w eight (MW) = 76) to the polymer, poly(propyleneglycol) (PPG, M-W = 400 0). Differences are observed in terms of the fragility of the systems. The findings are attributed to bonding between the hydroxy endgroups which decrease in density as the MW increases. (C) 1998 Elsevier Scien ce B.V. All rights reserved.