Molecular interpretation of the main relaxations found in dielectric spectra of cellulose – experimental arguments

Einfeldt, Jürgen; Meißner, Dana; Kwasniewski, Albert

doi:10.1023/b:cell.0000025404.61412.d6

Cited by 47 publications

(52 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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].…”

Section: Introductionsupporting

confidence: 72%

“…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.…”

Section: Introductionmentioning

confidence: 96%

“…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].…”

Section: Introductionmentioning

confidence: 99%

“…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].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

Roig¹,

Dantras²,

Dandurand³

et al. 2011

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

The molecular dynamic in hydrated cellulose has been investigated by a combination of thermal analyses and dielectric spectroscopy. Differential Scanning Calorimetry (DSC) shows the dependence upon hydration of the glass transition temperature T g . A physical ageing phenomenon has been observed. At the molecular scale, bound water is hydrogen bonded to polar sites of cellulose macromolecules. At the macroscopic scale, water molecules play the role of a plasticizer for cellulose lowering its T g . Dynamic Dielectric Spectroscopy (DDS) combined with Thermostimulated Currents (TSC) have allowed us to follow more localized molecular mobility. The β relaxation mode is characterized by activation entropies that vanish for higher water contents indicating molecular mobility localization. It is plasticized by water like the glass transition. This analogy is explained by a common origin of both mechanisms: the mobility of the cellulose backbone. The evolution of the γ mode upon hydration follows an anti-compensation law. Water acts as an anti-plasticizer in a hydrogen bonded network.

show abstract

Section: Introductionsupporting

confidence: 72%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Roig¹,

Dantras²,

Dandurand³

et al. 2011

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

show abstract

“…These two relaxation modes have been resolved experimentally in a series of elementary thermograms revealing the existence of a discrete distribution of relaxation times. According to the literature, the c relaxation mode of cellulose has been attributed to molecular mobility of Roig et al 2011a) and the b relaxation mode of cellulose to molecular mobility of glycosidic rings thanks to b 1-4 glycosidic bonds (Saad et al 1996;Saad and Furuhata 1997;Einfeldt et al 2000aEinfeldt et al , b, 2001Einfeldt et al , 2003Einfeldt et al , 2004Einfeldt and Kwasniewski 2002;Meissner et al 2000;Jafarpour et al 2007Jafarpour et al , 2009). Lignin has also been studied by TSC in the low temperature range.…”

Section: Resultsmentioning

confidence: 99%

Dielectric and mechanical properties of various species of Madagascan woods

et al. 2017

View full text Add to dashboard Cite

OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. Any correspondence concerning this service should be sent to the repository administrator: staff-oatao@listes-diff.inp-toulouse.fr Abstract The low-temperature molecular mobility of three different wood species was analyzed, with the two major constituents-cellulose and lignin-as reference. Mechanical and dielectric dynamic techniques were used. In order to observe the fine structure of the broad relaxation modes of wood, a very low-frequency analysis was carried out by thermostimulated current technique. Low-temperature relaxations of rosewood were assigned to low-temperature relaxations of cellulose. There was no dielectric response of lignin in rosewood. Contrarily, both cellulose and lignin responses were distinguished in ebony and varongy. Thermostimulated currents analyses exhibit the specific behavior of lignin in the various wood species. Moreover, the relaxation mode of cellulose observed at lower temperature remains localized in rosewood, while it tends to delocalize in varongy and ebony. The nature and intensity of physical interactions that induce variation of phase miscibility might be responsible for the observed differences. Even at the scale of the c relaxation, physical interactions modify molecular mobility.

show abstract

Dielectric spectroscopy and relaxation phenomena of moistened and dry polysaccharides

Shinouda

Moteleb

2005

J of Applied Polymer Sci

View full text Add to dashboard Cite

ABSTRACT:The effect of hydration on the dielectric constant and loss factor tan ␦ of viscose hydrocellulose, hydroxypropyl cellulose, and dextran was studied in a wide range of temperatures and frequencies. The results obtained reveal that (1) whereas hydration shows little effect on the variation with temperature of both and tan ␦ of hydrocellulose, the presence of adsorbed water significantly modifies the dielectric behavior of the other two samples; (2) only one relaxation denoted as ␥-process is observed in the case of hydrocellulose sample irrespective of its moisture content; (3) two absorption peaks are recorded with moistened hydroxypropyl cellulose and dextran specimens, one below room temperature denoted as ␤-process and a dispersion loss at high temperature; and (4) after drying of these samples, the dispersion loss peak disappears, the ␤-peak diminishes, and the ␥-peak, which is hidden behind the sizable ␤-peak, is observed and that, although with increasing frequency, the former peak disappears, the intensity of the latter one increases. The analysis of these results in view of the chemical and the fine structure of the test samples as well as the calculated activation energy indicates that the ␥-and ␤-relaxations recorded are of different natures. The satisfactory interpretation given clarifies to a great extent the contradictions reported in the literature concerning the relaxation phenomena in polysaccharides.

show abstract

Molecular interpretation of the main relaxations found in dielectric spectra of cellulose – experimental arguments

Cited by 47 publications

References 30 publications

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

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

Dielectric and mechanical properties of various species of Madagascan woods

Dielectric spectroscopy and relaxation phenomena of moistened and dry polysaccharides

Contact Info

Product

Resources

About