From strong to fragile glass formers: secondary relaxation in polyalcohols.
We have studied details of the molecular origin of slow secondary relaxation near T(g) in a series of neat polyalcohols by means of dielectric spectroscopy and (2)H NMR. From glycerol to threitol, xylitol, and sorbitol the appearance of the secondary relaxation changes gradually from a wing-type scenario to a pronounced beta peak. It is found that in sorbitol the dynamics of the whole molecule contributes equally to the beta process, while in glycerol the hydrogen bond forming OH groups remain rather rigid compared to the hydrogens bonded to the carbon skeleton.
Döss
A
A
Institut für Physikalische Chemie, Johannes Gutenberg-Universität, 55099 Mainz, Germany.
Paluch
M
M
Sillescu
H
H
Hinze
G
G
D005898:Glass / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013012:Sorbitol / Q000737:chemistry; D013057:Spectrum Analysis; D013402:Sugar Alcohols / Q000737:chemistry*; D014993:Xylitol / Q000737:chemistry
D013402:Sugar Alcohols; D013012:Sorbitol; C003460:threitol; D014993:Xylitol