Lecture

Glass Transition: Theoretical Insights

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In course

MSE-431: Physical chemistry of polymeric materials

The student has a basic understanding of the physical and physicochemical principles which result from the chainlike structure of synthetic macromolecules. The student can predict major characteristics of a polymer from its chemical structure and molecular ...

Description

This lecture delves into the concept of glass transition, explaining the calculation of heat capacity, crystallization, and melting processes using Differential Scanning Calorimetry (DSC). It covers the Newton's law of Viscosity, Elasticity, and the Williams-Landel-Ferry (WLF) Equation. The discussion extends to the Poisson's ratio, viscoelastic behavior, and the effect of molecular weight on the glass transition temperature. Various glass transition theories are explored, including the Free-Volume Theory, Kinetic Theory, and Thermodynamic Theory. The lecture also examines the impact of chemical structure on the glass transition temperature, the behavior of copolymers and mixtures, and the transitions observed by Dynamic Mechanical Analysis (DMA).

Official source

Ontological neighbourhood

Physics

Thermodynamics: Statistical mechanics

Related concepts (32)

Thermal analysis

Thermal analysis is a branch of materials science where the properties of materials are studied as they change with temperature.

Kinetic theory of gases

The kinetic theory of gases is a simple, historically significant classical model of the thermodynamic behavior of gases, with which many principal concepts of thermodynamics were established. The model describes a gas as a large number of identical submicroscopic particles (atoms or molecules), all of which are in constant, rapid, random motion. Their size is assumed to be much smaller than the average distance between the particles. The particles undergo random elastic collisions between themselves and with the enclosing walls of the container.

Thermodynamic system

A thermodynamic system is a body of matter and/or radiation, considered as separate from its surroundings, and studied using the laws of thermodynamics. Thermodynamic systems may be isolated, closed, or open. An isolated system exchanges no matter or energy with its surroundings, whereas a closed system does not exchange matter but may exchange heat and experience and exert forces. An open system can interact with its surroundings by exchanging both matter and energy.

Thermodynamic equilibrium

Thermodynamic equilibrium is an axiomatic concept of thermodynamics. It is an internal state of a single thermodynamic system, or a relation between several thermodynamic systems connected by more or less permeable or impermeable walls. In thermodynamic equilibrium, there are no net macroscopic flows of matter nor of energy within a system or between systems. In a system that is in its own state of internal thermodynamic equilibrium, no macroscopic change occurs.

Differential scanning calorimetry

Differential scanning calorimetry (DSC) is a thermoanalytical technique in which the difference in the amount of heat required to increase the temperature of a sample and reference is measured as a function of temperature. Both the sample and reference are maintained at nearly the same temperature throughout the experiment. Generally, the temperature program for a DSC analysis is designed such that the sample holder temperature increases linearly as a function of time.

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