Physical transformations kinetics

A physical explosion can arise when a substance whilst being compressed undergoes a rapid physical transformation. At the same time, the potential energy of the substance is rapidly transformed into kinetic energy, and its temperature rises rapidly, resulting in the production of a shockwave in the surrounding medium. 

The basis of the application of group theory to the classification of the normal vibrations of a molecule lies in the fact that the potential and kinetic energies of a molecule are invariant to symmetry operations. A symmetry operation is a physical transformation of the molecule, such as reflection in a mirror plane of symmetry or rotation through 120° about... 

The term dynamics is derived from the word dynamis, the Greek word for force. In physics, dynamics is the study of forces and the changes caused by them. The field of mechanics uses this word in particular when dealing with the motion of bodies and the reasons why they move. This term is then expanded to other areas and is reflected in such expressions as hydrodynamics, thermodynamics, or electrodynamics. When we discuss the field of matter dynamics we will generally be talking about transformations of substances and the forces driving them. States of equilibrium (treated in the field of statics, also called chemical thermodynamics ) will be covered in addition to the temporal course of transformations (kinetics) or the effects of electrical fields (electrochemistry). 

Raman fibre optics has been used to study the emulsion homopolymerisations of styrene and n-butyl acrylate (35). An IR spectroscopic technique for the examination of radical copolymerisations of acryl and vinyl monomers was developed. A comparative study of the copolymerisation of model monomer pairs was made using monofunctional and polyfunctional compounds. The data established the role of structural-physical transformations, involved in the formation of crosslinked polymers, on the copolymerisation kinetics and on the nonuniformity of distribution of crosslinks in the copolymers formed (151). Raman fibre optics of polymerisation of acrylic terpolymers was also used to monitor as well as an on-line measurement of morphology/composition (66). The high temperature (330 °C) cure reaction of 4-phenoxy-4 -phenyl-ethynylbenzophenone was monitored using a modulated fibre optic FT-Raman spectrometer (80). 

In order to exert full control over the progress of a chemical reaction or physical transformation, the fluid dynamic environment must be sufficiently intense so as to ensure that the mixing and heat transfer rates are faster than the intrinsic chemical kinetics. This concept is shown schematically in Figure 5.12, which illustrates the progress of a reaction represented simply as A + B C, with the reactants A and B travelling in plug flow along a tubular reactor. When the interdiffusion of... 

The kinetics of diffusion-controlled phase transformations has long been a focus of research and it is vital information for industrial practice as well as being a fascinating theme in fundamental physical metallurgy. An early overview of the subject is by Aaronson et ai (1978). 

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