Configurational Thermodynamic Properties of Amorphous Polymers and Polymer Melts. II. Theoretical Considerations

1975 ◽  
Vol 8 (2) ◽  
pp. 211-218 ◽  
Author(s):  
Olagoke Olabisi ◽  
Robert Simha
Keyword(s):  
Thermodynamic Properties ◽  
Polymer Melts ◽  
Amorphous Polymers ◽  
Theoretical Considerations

Thermoelasticity and Stress Induced Crystallization of EPDM Elastomers

1971 ◽  
Vol 44 (4) ◽  
pp. 1093-1108 ◽  
Author(s):  
U. Flisi ◽  
A. Valvassori ◽  
G. Novajra
Keyword(s):  
Thermodynamic Properties ◽  
Composition Range ◽  
Amorphous Polymers ◽  
Microstructural Parameter ◽  
Sequence Distribution ◽  
Monomer Sequence ◽  
Stretching Ratio ◽  
Narrow Composition Range ◽  
Stress Induced Crystallization ◽  
Induced Crystallization

Abstract The thermoelastic behavior of various EPDM rubbers has been investigated by performing stress-temperature measurements at different stretching ratios in order to determine their thermodynamic properties and the occurrence of stress induced crystallization. A broad range of terpolymer compositions was investigated and the regularity of monomer sequence distribution was also taken into account. It has been found that statistical terpolymers, like the commercial ones, are generally amorphous and hardly crystallize under stretching for propylene contents higher than 40% by weight. Below this level it is possible to obtain, in a narrow composition range, amorphous polymers that can crystallize under stretching, provided that their monomer sequence distribution is regular enough. The influence of this microstructural parameter has been studied by testing a 3/1 ethylene/propylene model copolymer, obtained by hydrogenation of a sample of poly-3-methyloctenamer. Studying the influence of stretching ratio on crystallization temperature of standard EPDM rubbers, it has been noticed that crystallization occurs at low elongation, which might be related to the presence of “nuclei” in the undeformed state.

Models of Thermodynamic Properties of Prominences

1979 ◽  
Vol 44 ◽  
pp. 349-355
Author(s):  
R.W. Milkey
Keyword(s):  
Thermodynamic Properties ◽  
Mass Transport ◽  
Emission Spectrum ◽  
Thermodynamic Parameters ◽  
Working Group ◽  
Physical Processes ◽  
Theoretical Concepts ◽  
Group 3 ◽  
Observational Techniques

The focus of discussion in Working Group 3 was on the Thermodynamic Properties as determined spectroscopically, including the observational techniques and the theoretical modeling of physical processes responsible for the emission spectrum. Recent advances in observational techniques and theoretical concepts make this discussion particularly timely. It is wise to remember that the determination of thermodynamic parameters is not an end in itself and that these are interesting chiefly for what they can tell us about the energetics and mass transport in prominences.

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