Rabinowitch model

Equation (5.50) is usually called the Rabinowitch model (Rabinowitch, 1937). Although in the particular selected example there is only one chemical rate constant, in the general case Eq. (5.50) must be written for every reaction step. This means that the faster chemical steps will be more affected by diffusional resistances than the slower chemical reactions. 

As it turned out, the Emerson and Rabinowitch models were both partly correct and partly incorrect. 

A modified kinetic model based on the Rabinowitch [144] approach, taking into account the diffusion phenomena including the molecular diffusion processes and molecular size distribution, has been found to describe the conversion profile of Zn-catalyzed dicyanate cure for the entire range [98]. The average dif-fusivity decreased by several orders of magnitude during cure. The Rabinowitch model explains the diffusional limitations in reactions of small molecules as... 

In his rejection of the Emerson model, Rabinowitch went on to say The difficulty of the phosphate storage theory appears most clearly when one considers the fact that, in weak light, eight or ten quanta of light are sufficient to reduce one molecule of carbon dioxide. If each quantum should produce one molecule of high-energy phosphate, the accumulated energy would be only 80-100 kcal per Einstein—while photosynthesis requires at least 112 kcal per mole, and probably more, because of losses in irreversible partial reactions (Vol. 1, p. 228). 

E. Rabinowitch, Tram. Faraday Soc.j 33, 1225 (1937), appears to have been the first to use this lattice model to compute collision frequencies in solution. 

A description of a bond thermolysis in solution requires at least two elementary steps. This is due to the fact that the immediate product of the bond cleavage step is a pair of radicals which are initially restricted to remain as neighbors by the surrounding solvent molecules. We follow Rabinowitch and Wood and term this reactive species the cage pair intermediate . Scheme 1 depicts a simple chemical model for this kinetic sequence. Subsequent to the... 

Chemical models that incorporate both chemically controlled and diffusion-controlled stages of cure have been described (Chern and Poehlein 1987 Matsuoka et al. 1989 Wisanrakkit and GiUham 1990a,b Stutz et al. 1993 Deng and Martin 1994). See Prime (1997) for a general overview. The most common approach is to employ the Rabinowitch (1937) model for small-molecule reactions, where the timescale for the overall reaction can be modeled as the sum of the time for diffusion of reactants plus the time for chemical reaction... 

The cage picture was introduced in papers by (a) E. Rabinowitch [18,c] and (b) E. Rabinowitch and W.C. Wood [18,d]. In the second of these papers it was shown that the situation could be simulated by a mechanical model (see Ref. [18,e] and below). [Author I have regularly shown the behaviour of such a model when lecturing to undergraduates.)... 

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