Energetic and entropic elasticity of nonisothermal flowing polymers: Experiment, theory, and simulation

• Published in: Journal of rheology (New York : 1978) Vol. 52; no. 1; pp. 105 - 140
• Main Authors: Ionescu, T. C., Edwards, B. J., Keffer, D. J., Mavrantzas, V. G.
• Format: Journal Article
• Language: English
• Published: Melville, NY Society of Rheology 01.01.2008
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Rheology and viscoelasticity; Energetic elasticity; Nonisothermal flows; Entropic elasticity; Monte Carlo simulation; Molten state; Molecular physics; Flow(fluid); Non isothermal condition; Experimental study; Statistical mechanics; Modeling
• ISSN: 0148-6055; 1520-8516
• DOI: 10.1122/1.2798235

The thermodynamical aspects of polymeric liquids subjected to nonisothermal flow are examined from the complementary perspectives of theory, experiment, and simulation. In particular, attention is paid to the energetic effects, in addition to the entropic ones, that occur under conditions of extreme deformation. Comparisons of experimental measurements of the temperature rise generated under elongational flow at high strain rates with macroscopic finite element simulations offer clear evidence of the persistence and importance of energetic effects under severe deformation. The performance of various forms of the temperature equation are evaluated with regard to experiment, and it is concluded that the standard form of this evolution equation, arising from the concept of purely entropic elasticity, is inadequate for describing nonisothermal flow processes of polymeric liquids under high deformation. Complete temperature equations, in the sense that they possess a direct and explicit dependence on the energetics of the microstructure of the material, provide excellent agreement with experimental data.