Contributions to the molecular origin of the dielectric relaxation processes in polysaccharides – the high temperature range

Influence of hydrogen bonds on glass transition and dielectric relaxations of cellulose

“…Measurements on others polysaccharides as starch and dextran confirm this results [22]. A β wet relaxation mode can be observed in all wet polysaccharides in the room temperature range (0-60°C) [22][23][24][25][26][27]. This mode is not observed anymore after drying the sample [22][23][24][25][26][27].…”

“…The α relaxation mode associated with the dielectric manifestation of glass transition is hidden by this conduction phenomenon. The σ electrical conduction manifestation has been already associated with charge transport [26] or Maxwell-Wagner-Sillars effect [28].…”

“…A β wet relaxation mode can be observed in all wet polysaccharides in the room temperature range (0-60°C) [22][23][24][25][26][27]. This mode is not observed anymore after drying the sample [22][23][24][25][26][27]. The hydration influence of polysaccharides on their dielectric properties can be interpreted by several hypotheses: one the one hand, the OH-groups of glucosidic units form hydrogen bonds with water molecules.…”

“…Dielectric dynamic spectroscopy (DDS) has been already used on polysaccharides like cellulose and its derivatives [22][23][24][25][26][27][28][29]. Four dielectric relaxations modes are usually observed γ, β, β wet and α, in the order of increasing temperatures [22][23][24][25][26][27][28][29].…”

“…Four dielectric relaxations modes are usually observed γ, β, β wet and α, in the order of increasing temperatures [22][23][24][25][26][27][28][29]. The dielectric properties of cellulose have been also investigated by combined DDS/TSC [28].…”