Interaction between water and hydrophilic polymers

Hatakeyama, Hyōe; Hatakeyama, Tatsuko

doi:10.1016/s0040-6031(97)00325-0

Cited by 414 publications

(295 citation statements)

References 56 publications

Supporting

Mentioning

274

Contrasting

Unclassified

Order By: Relevance

“…The activation parameters are reported in Figures 9 and 10. These results are coherent with published data from mechanical and dielectric studies [28][29][30][31]49]. The activation energy of the γ mode increases with the hydration level whereas it decreases for the β mode.…”

Section: Isothermal Dynamic Dielectric Responsesupporting

confidence: 91%

See 1 more Smart Citation

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: Isothermal Dynamic Dielectric Responsesupporting

confidence: 91%

“…Authors differentiate three kind of water in biopolymers: free water, freezing-bound water and non-freezing bound water [11,42,48,49].…”

Section: Thermal Transitionsmentioning

confidence: 99%

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

“…HPMC and PVA are humidity (water) dependant, having various strengths of interaction with water [13]. The mechanical properties such as tensile strength, elongation and tear strength as well as the thermal properties of polymers are drastically affected by polymer's moleculewater interaction [14].…”

Section: Introductionmentioning

confidence: 99%

Thermo-physical characterization of Pharmacoat® 603, Pharmacoat® 615 and Mowiol® 4-98

Perfetti

Alphazan

Wildeboer

et al. 2011

J Therm Anal Calorim

View full text Add to dashboard Cite

Hydroxypropyl methylcellulose (HPMC) and polyvinyl alcohol (PVA) are important polymers in pharmaceutical, food and other industries being largely used as encapsulation agents. The characterization of two reference grades of HPMC (Pharmacoat Ò 603 and Pharmacoat Ò 615) and one reference grade of PVA (Mowiol Ò 4-98), through X-ray diffraction (XRD) and thermogravimetry (TG) is described. Specific analyses were performed by means of dynamic vapour sorption analysis of water adsorption/ desorption from vapours at 10, 25, 40, 55 and 70°C. Guggenheim-Anderson-de Boer (GAB), Brunauer-EmmettTeller (BET), Park and n-layer BET models were successfully used to fit the experimental data. The glass transition temperature as function of water content was measured by means of differential scanning calorimetry (DSC). The experimental data were analysed according to Linear, Gordon-Taylor, Fox and Roos equations. XRD

show abstract

“…(Hatakeyama & Hatakeyama, 1998) The first-order phase transition of water fractions closely associated with the polymer matrix is usually impossible to observe; such fractions are termed non-freezing water and it can directly interact with hydroxyl groups of cellulose. Another fraction of water, freezing bound water, is less closely associated and in contrast, it exhibits melting/crystallisation; it is able to interact with either hydroxyl groups of cellulose or water already absorbed to cellulose.…”

Section: Cellulose Water/moisture Interactionsmentioning

confidence: 99%