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Abstract  

A mathematical model of ignition and burning of organic polymers was used for evaluation and quantification of the tendency of polymers to ignition. The model permits investigation of the influence of one parameter of the polymer on the others. It was found that the model could be used for the verification of the ignitability method developed by Miller et al. [1]. Different steady states of combustion were found when using the model proposed. There is a characteristic steady state for normal flaming combustion, another for non-flaming combustion, and there are also unstable steady states that have no real physical meaning.

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Non-isothermal thermogravimetry of polymer

I. General model involving formal termination of active centres

Journal of Thermal Analysis and Calorimetry
Authors:
J. Rychlý
and
L. Rychlá

A Model of polymer decomposition is proposed which formally involves the termination of active centres. It yields reasonable activation energies for the decompositions of polypropylene, polyethylene, polystyrene and polymethyl methacrylate investigated by non-isothermal thermogravimetry. In the value of a formal reaction orders the model reflects the reaction conditions, such as initial sample weight, atmosphere, ventilation conditions, sample holder nature and shape, etc.

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Nonisothermal thermogravimetry of polymers

V. Bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide)

Journal of Thermal Analysis and Calorimetry
Authors:
J. Líška
,
J. Rychly
, and
E. Borsig

Abstract  

The model of weight loss taking place in each step of a scheme of consecutive reactions was applied to nonisothermal thermogravimetric records of bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide). The release of HBr was found to be faster in air than in nitrogen. A significant reduction in the apparent activation energy of dehydrobromination as compared with decomposition of the nonbrominated polymer was ascribed not only to a reduction in the activation energy of the initiation reaction, but also to an increase in the order of the termination reaction (from 1 for the nonbrominated polymer to 2 for the highly brominated polymer).

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DSC study of the decomposition of azodicarbonamide in different media

I. Decomposition of pure azodicarbonamide; the search for the kinetic model

Journal of Thermal Analysis and Calorimetry
Authors:
L. Rychlá
,
J. Rychlý
,
J. Svoboda
, and
J. Šimonik
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Nonisothermal thermogravimetry of polymers

IV. Polyethylene and ethylene-vinyl acetate copolymers highly loaded with Al(OH)3 and Mg(OH)2

Journal of Thermal Analysis and Calorimetry
Authors:
J. Rychly
,
A. Dalinkevich
,
I. Janigová
, and
L. Rychlá

Abstract  

The decomposition of polyethylene and ethylene-vinyl acetate copolymers in composites with Al(OH)3 and Mg(OH)2 (60% by wt.) has been estimated from the aspect of the extent of synchronization of the two fundamental processes, the release of water and flammable volatiles from a polymer and the effect of this on the resulting polymer flammability. An attempt has been made to implement the peculiarities of decomposition observed for each system to the fire behaviour of these materials.

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A new differential method of evaluating integral thermogravimetric records of the formation of volatile products during the degradation of polypropylene in air is presented. The method, applied to 0–100% conversion of the polymer to volatile products, may distinguish the initial presence of low molecular compounds in the polymer, as well as changes in the mechanism of degradation of the material.

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Abstract  

The application of solution microcalorimetry was demonstrated on two model examples – inhibited oxidation of cumene and radical polymerization of styrene.From the experimental dependences of the rate of heat release on time, the rate constants k 7 of the interaction of an inhibitor with radicals of substrate (RO 2 . or R.) in oxidation or in polymerization were determined for the set of inhibitors of N-aryl N-(2-quinone) amine series. It was shown that these compounds are weak inhibitors of oxidation of cumene and rather efficient inhibitor of polymerization of styrene.

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