On the Temperature Coefficient of Unperturbed Dimensions of Atactic Polystyrene

1966 ◽  
Vol 70 (10) ◽  
pp. 3057-3060 ◽  
Author(s):  
Umberto Bianchi ◽  
Eligio Patrone ◽  
Enrico Pedemonte
Keyword(s):  
Temperature Coefficient ◽  
Unperturbed Dimensions ◽  
Atactic Polystyrene

Stress-Strain Isotherms and Stress-Temperature Coefficients of Poly(Dimethylsiloxane) Networks in Compression

1975 ◽  
Vol 48 (2) ◽  
pp. 176-185 ◽  
Author(s):  
R. Y. S. Chen ◽  
C. U. Yu ◽  
J. E. Mark
Keyword(s):  
Statistical Theory ◽  
Temperature Coefficient ◽  
Polymer Networks ◽  
Temperature Measurements ◽  
Stress Strain ◽  
Unperturbed Dimensions ◽  
Temperature Coefficients ◽  
A Value ◽  
Good Agreement

Abstract Stress-strain isotherms at 30, 45, 60, 75, and 90°C have been determined for compressed, unswollen poly(dimethylsiloxane) networks which had been prepared either in the undiluted state or in solution. For these networks in compression, deviations of the dependence of stress on strain from that predicted by the statistical theory of rubberlike elasticity are much less than is the case for polymer networks in elongation. The present data nonetheless give a value for the temperature coefficient of the unperturbed dimensions of the network chains which is in good agreement with published results on networks of poly(dimethylsiloxane) in elongation. This agreement thus seems to validate the intentional disregard of such deviations in analyses of stress-temperature measurements.

Unperturbed Dimensions of Atactic Poly(phenylacetylene)

2005 ◽  
Vol 70 (11) ◽  
pp. 1787-1798 ◽  
Author(s):  
Dana Rédrová ◽  
Jan Sedláček ◽  
Majda Žigon ◽  
Jiří Vohlídal
Keyword(s):  
Molecular Weight ◽  
Random Coil ◽  
Radius Of Gyration ◽  
Dilute Solution ◽  
Chain Branching ◽  
Unperturbed Dimensions ◽  
Molecular Weight Dependence ◽  
Atactic Polystyrene ◽  
Tetrahydrofuran Solution ◽  
Insight Into

Dilute solution characteristics of atactic (ca. 30% trans) poly(phenylacetylene), PPA, were determined by using the SEC/MALS technique in order to obtain a deeper insight into discrepancy between presumed rigidity of conjugated polyvinylene molecules and their random-coil behavior in solutions resulting from earlier viscometry measurements. PPA was found to exhibit the molecular-weight dependence of the radius of gyration in tetrahydrofuran solution similar to that of atactic polystyrene (saturated analogue of PPA); also unperturbed dimensions of these polymers are almost equal. This rather surprising observation is explained as a consequence of the increased π-π attraction between highly polarizable PPA segments with well-delocalized π-electrons, which compensates the effect of stiffening of these segments due to conjugation. Possible influence of chain branching is also discussed.

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