Degradation reaction mechanisms

The rate equations for the degradation reaction mechanism shown in Equations (i) to (iii) are as follows (1) ... 

TG-FTIR has become a quite popular, versatile, cost-effective and informative instrument for modern polymer analysts concerned with compositional analysis and degradation/ reaction mechanism studies. The growth rate of TG/FTIR instrumentation currently exceeds that of TG-MS. 

Degradation Reaction Mechanisms. A detailed discussion of a large number of reactions believed to take part in the thermo-oxidative degradation of PE at the tesq>eratures and oxygen concentrations encountered is given in ref. 2. In the following, only some main lines will be reviewed. 

This contribution presents the degradation reaction mechanisms and processes of lubricants and the factors influencing them. In addition, mechanisms by which antioxidants inhibit lubricant oxidation with respect to specific industrial and engine oil applications are suggested. 

By the use of certain additives which divert or moderate the degradation reaction. A wide range of antioxidants and stabilisers function by this mechanism (see Chapter 7). 

Richards et al.23-24 proposed that the alkaline degradation reaction proceeds via a slow, rate-determining SJCB mechanism, where the substitution at the C-l of the D-glucose moiety by oxyanions derived from l -OH or 3 -OH resulted in 1- or 3-O-P-D-glucopyranosyl-D-fructose (see Fig. 4) the mechanism implies that T - time thyl sucrose is degraded via 3 -displacement and 3 -(3-methylsucrose via the 1 -displacement. The 1- or 3-<3-[3-D-glucopyranosyl-D-fructose intermediates are then... 

A general reaction mechanism for the grafting of MA onto EPM is given in Figure 13.3 [15,16]. Free-radical grafting of MA starts with the decomposition of the radical initiator, usually a peroxide [15,18]. The peroxide decomposes at elevated temperamres into the corresponding oxy radicals, which may further degrade to alkyl radicals and ketones. These oxy and alkyl radicals abstract... 

Kinetic Model Development Our kinetic model for the degradation of polypropylene Q.) is based upon the following reaction mechanism ... 

Another interesting example of the fission of non-activated C—C bond with the liberation of carbon dioxide is the decarboxylation of oxalate. The enzymes related to degradation of oxalate have a number of potential apphcations especially in relation to diagnosis and human health. Also, the reaction mechanism of this enzyme is interesting. It requires metal ions to activate the substrate and this might give some hints to develop decarboxylation reactions of other types of compounds. In this way, the future extension is expected in this area. 

It is generally accepted that oxo-Mn (V) is the catalytieally aetive speeies however, the reaction mechanism is currently under intensive debate sinee it strongly depends on the oxygen donor and the reaction conditions (6). On the other hand, low catalytic productivities are obtained due to oxidative degradation of the salen hgand (7). 

Another reaction mechanism that occurs in some chain-growth polymers is solvolysis. In this type of reaction, a species reacts with a C-X bond, where X represents a halogen, and breaks it. Specifically, this becomes important when describing the degradation of polyvinyl chloride. Acidic species act to remove the chlorine atom, forming hydrochloric acid. 

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