The Degradation of Long-Chain Molecules

Simha, R., On the degradation of long chain molecules. Journal of Polymer Science, 10(5), pp. 499-502 (1953). 

Key contributions to the general theory of the degradation of long chain molecules. 

Jellinek, H. H., White, G. The degradation of long-chain molecules by ultrasonic waves. 1. 

Mark, H., Simha, R., Degradation of long chain molecules, Transactions of the Faraday Society, 35, pp. 611-618 (1940). 

The oxidation of long-chain fatty acids is known as p-oxidation as it is the second carbon atom from the carboxyl end that is attacked in the process. In summary, the molecules of long-chain fatty acyl-CoA are shortened by the step-wise removal of two-carbon fragments to form acetyl-CoA, which is oxidised by the Krebs cycle. Since virtually all naturally occurring fatty acids have an even number of carbon atoms, P-oxidation results in then-complete degradation to acetyl-CoA (Appendix 7.2). 

The reason why the viscosity falls is the effect of the solvent on the molecules of nitrocotton which tends to degrade the chains. The shortening of the molecular chains is relatively more marked in the case of long chains, i.e. with nitrocellulose... 

The change in sample size has been shown to influence product ratios, fractional conversions, and rates of pyrolysis for several polymers [14]. However, the dependence of pyrolysis results on sample size does not have only a negative impact on data reproducibility. This effect may reveal mechanistic features of the pyrolysis process, such as secondary reactions that occur during the residence time of primary products in the melt and diffusion-restriction of the interaction of long-chain radicals, when the thickness of the degrading film is comparable with the diameter of the hydrodynamic volume of the polymer molecules. 

Prekopa, A. (1953). Investigation of the degradation process of long chain molecules using probabilistic methods, MTA Aik. Mat. Int. KozL, 2, 103-23 (in Hungarian). 

The rate expressions and values, mechanisms, and the activation energies for the condensation reactions forming polymers are similar to those of small molecule reactions. Reaction rate increases with temperature in accordance with the Arrhenius equation. Average DP also increases as the reaction temperature increases to the ceiling temperature where polymer degradation occurs. Long chains are only formed at the conclusion of classical polycondensation processes. 

It is very interesting to observe the influence of aldehydes on nitrocellulose solutions. This has been done by Kozlov and Bedushevskaya [66]. This effect is most complicated, since in accordance with the said authors two processes were occurring simultaneously the formation of cross links which produced an increase of viscosity, and a degradation of the long-chain molecules which reduced the viscosity. 

Some new extractants were not soluble in alkanes thus, a long-chain alcohol like n-octanol had to be selected. The degradation of the diglycolamide TODGA was similar for n-octanol and dodecane solutions (182,183). With polyaromatic nitrogen donors like the /Pr-BTP molecule, a similar hydrolysis effect was measured in pure w-octanol and alkane-octanol (70-30% in volume) (244). 

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