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The variational principle, which allows the deduction of the basic equation system of continuum mechanics from the local form of Gyarmati’s integral principle is presented in this paper. Following the approach of irreversible thermodynamics, the principle the kinetic energy is described like the fundamental equation of thermodynamics as the internal energy change, namely intensive quantity multiplied by the changing of extensive quantity. As the internal energy is objective so that is an independent quantity from the coordinate system, this description to the internal energy can be done. However, the kinetic energy is coordinate-dependent quantity. To resolve this contradiction the stress tensor can be divided into elastic and dissipative stress components by using the laws of thermodynamics.

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Abstract  

Contributions of modern, temperature-modulated calorimetry are qualitatively and quantitatively discussed. The limitations are summarized, and it is shown that their understanding leads to new advances in instrumentation and measurement. The new thermal analysis experiments allow to separate reversing from irreversible processes. This opens the irreversible states and transitions to a description in terms of equilibrium and irreversible thermodynamics. Amorphous systems can be treated frommacroscopic to nanometer sizes with weak to strong coupling between neighboring phases. Semicrystalline, macromolecular systems are understood on the basis of modulated calorimetry as globally metastable, micro-to-nanophase-separated systems with locally reversible transitions.

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Modulated differential scanning calorimetry in the glass transition region

II. The mathematical treatment of the kinetics of the glass transition

Journal of Thermal Analysis and Calorimetry
Authors: B. Wunderlich, A. Boller, I. Okazaki, and S. Kreitmeier

Temperature-modulated differential scanning calorimetry (TMDSC) is based on heat flow and represents a linear system for the measurement of heat capacity. As long as the measurements are carried out close to steady state and only a negligible temperature gradient exists within the sample, quantitative data can be gathered as a function of modulation frequency. Applied to the glass transition, such measurements permit the determination the kinetic parameters of the material. Based on either the hole theory of liquids or irreversible thermodynamics, the necessary equations are derived to describe the apparent heat capacity as a function of frequency.

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This review traces the development of thermal analysis over the last 40 years as it was experienced and contributed to by the author. The article touches upon the beginning of calorimetry and thermal analysis of polymers, the development of differential scanning calorimetry (DSC), single run DSC and other special instrumentations, up to the recent addition of modulation to calorimetry. Many new words and phrases have been introduced to the field by the author and his students, leaving a trail of the varied interests one can have over 40 years. It began with “cold crystallization” and most recently the term “oriented, intermediate phase” was coined, creating in-between: “extended chain crystals,” the “irreversible thermodynamics of melting of polymer crystals,” “dynamic differential thermal analysis” (DDTA), “the rule of constant increase ofC p per mobile bead within a molecule at the glass transition temperature,” “superheating of polymer crystals,” “melting kinetics,” “crystallization during polymerization,” the “chain-folding principle, “molecular nucleation,” “rigid amorphous phase,” a “system of classifying molecules,” “macroconformations,” “amorphous defects,” “rules for the entropy of fusion based on molecular shape and flexibility,” “single-molecule single-crystals,” “a system of classifying phases and mesophases,” and “condis phase.”

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Abstract  

This review traces the development of thermal analysis over the last 50 years as it was experienced and contributed to by the author. The article touches upon the beginning of calorimetry and thermal analysis of polymers, the development of differential scanning calorimetry (DSC), single-run DSC, and other special instrumentations, up to the recent addition of modulation to calorimetry and superfast calorimetry. Many new words and phrases have been introduced to the field by the author and his students, leaving a trail of the varied interests over 50 years. It began with cold crystallization and more recently the terms oriented, intermediate phase, glass transitions of crystals, and decoupled chain segments were coined. In-between the following phenomena were named and studied: extended-chain crystals, irreversible thermodynamics of melting of polymer crystals, zero-entropy-production melting, dynamic differential thermal analysis (DDTA), the rule of constant increase of C p per mobile bead within a molecule at the glass transition temperature, superheating of polymer crystals, melting kinetics, crystallization during polymerization, chin-folding principle, molecular nucleation, rigid amorphous phase, system of classifying molecules, macroconformations, amorphous defects, rules for the entropy of fusion based on molecular shape and flexibility, single-molecule single-crystals, systems for classifying phases and mesophases including condis phases, and the globally metastable semicrystalline polymers with reversible, local subsystems.

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thermodynamics” (1971) up to the recent books by, e.g., C. Truesdell, S. Bharatha “Concepts and Logic of Classical Thermodynamics as a Theory of Heat Engines” (1988); D. Jou, J. Casas-Vazques and G. Lebon “Extended Irreversible Thermodynamics” (1993); R. F

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be negative, as the entropy generation rate can only be positive. The former then reflects directly the rate of entropy generation, which according to irreversible thermodynamics is the driving force for the process. The higher the entropy generation

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, impossibility limits of science and science of limits Vintage New York . 25. Šesták , J , Chvoj , Z 2002 Irreversible thermodynamics and true thermal dynamics in view of

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documented by proper thermal analysis at its zero-entropy-production limit as described by irreversible thermodynamics. Equilibrium thermodynamics, which describes the equilibrium zero-entropy-production process on melting, does not apply to the

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