Anisotropic-isotropic transition of solutions of cellulose derivatives: a DSC study. [Differential scanning calorimetry]
Cellulose acetate (CA)/trifluoroacetic acid (TFA), cellulose triacetate (CTA)/trifluoroacetic acid, and hydroxypropylcellulose (HPC)/water solutions are able to develop liquid crystalline (cholesteric) order above a certain polymer concentration C/sup **/. When the polymer concentration C is smaller than C/sup **/, no peak is recorded on a DSC trace upon heating. When C>C/sup **/, a well-defined peak for CA/TFA appears at a temperature T/sub t/. This peak is attributed to the anisotropic-isotropic phase transition. The origin and nature of this peak are discussed in the light of available theories. A T/sub t/-C phase diagram is plotted. For CTA/TFA solutions, one or two peaks arise, depending onpolymer concentration. The peak at the higher temperature is attributed to the anisotropic-isotropic transition, and the peak at the lower temperature to the destruction of a ''gel-like'' phase. HPC/water solutions have a very different behavior. Upon heating, they are transformed into a turbid phase regardless of the concentration. 22 references, 11 figures, 1 table.
- Research Organization:
- Ecole Nationale Superieure des Mines de Paris, Centre de Mise en Frome des Materiaux, Valbonne, France
- OSTI ID:
- 7138802
- Report Number(s):
- CONF-8205234-Vol.1
- Journal Information:
- J. Appl. Polym. Sci.: Appl. Polym. Symp.; (United States), Journal Name: J. Appl. Polym. Sci.: Appl. Polym. Symp.; (United States); ISSN JPSSD
- Country of Publication:
- United States
- Language:
- English
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ANISOTROPY
CALORIMETRY
CARBOHYDRATES
CELLULOSE
CELLULOSE ESTERS
CRYSTALS
DIAGRAMS
ENTHALPY
ESTERS
FLUIDS
ISOTROPY
KINETICS
LIQUID CRYSTALS
LIQUIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
POLYSACCHARIDES
QUANTITY RATIO
SACCHARIDES
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES