ISSN:
0022-3832
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Measurements are reported for the reversible changes in force with temperature at constant length of wet and dry viscose rayon and wet ramie. It was found that the force was a reversible function of the temperature although the components of its thermodynamic equivalent, the product of modulus and coefficient, are very time dependent. The entropies of stretching obtained as the negative slopes of the force-temperature curves are interpreted in terms of the mechanisms of reversible stretching. Completely dry rayon is glasslike and shows no slippage of chains but only deformation of valence bonds and angles on reversible stretching. Wet rayons exhibit a rubberlike slippage of chains above 50°C. but below this temperature chain movement is restricted. This inhibition of the chains produces at low temperatures a yield point in the wet stress-strain curves and poor work recovery. Sodium hydroxide, although speeding up stress relaxation, has no effect on the reversible stretching of the amorphous wet cellulose. In room air, the entropy of stretching is opposite to that of completly dry rayon even up to 92°C. Wet ramie appears to be in the glassy state like the completely dry rayon.
Additional Material:
11 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1954.120147603
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