Study of dielectric relaxations in cellulose by combined DDS and TSC

Abstract

In this work, thermally stimulated currents (TSC) analyses combined with dynamic dielectric spectroscopy (DDS) have been applied to the investigation of molecular mobility of cellulose. The correlation between results obtained by both methods allows us to attribute the low temperature DDS relaxation mode to the c-mode resolved in TSC. The values of its activation parameters point out that the chain mobility remains localized. At high temperature, the various dielectric relaxation phenomena are separated by applying a recent analytical protocol. The comparison between the activation enthalpy values obtained by DDS and TSC leads to the assignment of the socalled a-mode to cooperative movements of polymeric sequences. The Arrhenius behavior of a-relaxation time is explained using the strong/fragile pattern. The influence of water content on secondary and primary relaxation modes was examined as well.

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

“…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].…”

“…We have already shown that the fruitful synergy of DDS/TSC combination allows us to investigate the changes within the molecular dynamics of cellulose caused by water influences [28,29]. These results stimulate us to study the issue of cellulose glass transition with different water contents using the classical techniques of DSC.…”

“…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]. In the low temperature range (T < 0°C) where the molecular mobility is localized two modes are extracted; i.e.…”

Toughening mechanisms in cellulose nanopaper: the contribution of amorphous regions

“…Therefore, a dielectric loss peak represents a state when the chain mobility does not match the alternation of the applied electric field. The dielectric properties of cellulose have been extensively investigated (Jafarpour et al 2007;Rachocki et al 2005;Roig et al 2011). The peak of the dielectric loss at low temperature is usually assigned to Fig.…”