Thermooxidative degradation, polymer

Thermal, Thermooxidative, and Photooxidative Degradation. Polymers of a-olefins have at least one tertiary C-H bond in each monomer unit of polymer chains. As a result, these polymers are susceptible to both thermal and thermooxidative degradation. Reactivity in degradation reactions is especially significant in the case of polyolefins with branched alkyl side groups. For example, thermal decomposition of... 

L. Matisova-Rychla and J. Rychly, Inherent relations of chemiluminescence and thermooxidation of polymers, In R.L. Clough, N.C. Billingham and K.T. Gillen (Eds.), Advances in Chemistry, Series 249 Polymer Durability, Degradation, Stabilization and Lifetime Prediction. American Chemical Society, Washington, DC, 1996, p. 175. 

Polymers of a-olefins are susceptible to thermal and thermooxidative degradation. Reactivity in degradation reactions is especially significant in the case of polyolefins with branched alkyl side groups,... 

Antonov, A., Yablokova, M., Costa, L., Balabanovich, A., Levchik, G., and Levchik, S. 2000. The effect of nanometals on the flammability and thermooxidative degradation of polymer materials. Mol. Cryst. Liquid Cryst. 353 203-210. 

From the chemist s point of view, the keto defect sites can be formed during polymer synthesis as a consequence of incomplete monomer alkylation, as well as a result of photo-, electro-, or thermooxidative degradation processes occurring after polymer synthesis. Acting as low-energy trapping sites... 

Weight loss by the thermal degradation or thermooxidative degradation of a polymer itself (as opposed to the volatilization of small molecules which might have been trapped in the polymeric structure) invariably requires the breakage of chemical bonds. Once chemical bonds start to break, reactive chain ends and other free radicals are created, and degradation can proceed either by depolymerization or by random chain scission [11,12]. 

This volume is including information about thermal and thermooxidative degradation of polyolefine nanocomposites, modeling of catalytic complexes in the oxidation reactions, modeling the kinetics of moisture adsorption by natural and synthetic polymers, new trends, achievements and developments on the effects of beam radiation, structural behaviour of composite materials, comparative evaluation of antioxidants properties, synthesis, properties and application of polymeric composites and nanocomposites, photodegradation and light stabilization of polymers, wear resistant composite polymeric materials, some macrokinetic phenomena, transport phenomena in polymer matrix, liquid crystals, flammability of polymeric materials and new flame retardants. 

Kozlov, G. V. Shustov, G. B. Zaikov, G. E. The role of polymer melt structure in the heterochain polyetheis thermooxidative degradation process. Journal of Applied Chemistry, 2002, 75(3). 485 87. 

Kozlov, G. V Zaikov, G. E. The physical significance of reaction rate constant in Euclidean and fractal spaces at polymers thermooxidative degradation consideration. Theoretical Principles of Chemical Technology, 2003, 37(5), 555-557. 

The experimental studies of reactions in polymers confirmed the correctness of the approach [18] as a whole and the Eq. (106) of Chapter 2 and Eq. (6) in particular [19]. The authors [20, 21] elaborated the dimension d determination technique and verified its correctness on the example of two polymers melt polyarylate (PAr) and block-copolymer polyarylat-earylenesulfoxide (PAASO). These polymers polycondensation mode and their main characteristics (glass transition temperature T, mean weight molecular weight M and thermooxidative degradation rate k) are adduced in Table 3. 

From the adduced above values and the Eq. (7) the condition follows. At Tjj the polymer melt transition from liquid with fixed structure (where residual structural ordering is observed [27]) to truly liquid state or structureless liquid is observed [28], Nevertheless, structure absence of melt at is related to supramolecular structure absence, but macro-molecular coil structure in melt remains an important structural factor (as a matter of fact, the only one at T>T ). Thus, a polymer melt structure can be considered as a set of separate clusters (macromolecular coils) large number and an oxidant (for example, oxygen) molecule (atom) trajectory in thermooxidative degradation process on such structure is simulated by... 

From the said above it follows, that for prediction of the rate of chemical reactions at all and thermooxidative degradation in particular it is necessary to be able to predict h value as a function of polymer melt characteristics and for this problem solution in the first place the parameter h physical significance should be elucidated. The authors [32] studied these two questions on the example of thermooxidative degradation of two heterochain polymers—PAr and PAASO. 

For the considered polymers (PAr and PAASO) this distinction can be explained by the following circumstance. As it has been shown in Ref. [51], the thermooxidative degradation activation energy at the same A is higher for PAASO than for PAr because of steric hindrances availability... 

Dolbin, I. V Kozlov, G. V. Mashukov, N. L The fractal model of regimes change for thermooxidative degradation of polymer melts. Successes of Modem Natural Sciences, 2002(4 , 101-102. 

A triazine compound, Ethanox 314, of the following structure by Albemerie Corp. has a moderate molecular weight of 784 and a melting point range of 218-223°C [118]. It is claimed to retard thermooxidative degradation in various polymers and to enhance their light stability. The antioxidant exhibits high resistance to extraction and low volatility ... 

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