Thermal decomposition of polyurethane elastomers containing antipyrene

Bechev

Troev

et al. 1986

Self Cite

By means of a combined thermal analysis technique,, the thermal behaviour of rigid polyurethane foams containing additive antipyrenes was studied. The presence of phosphorus-and phosphorus/chlorine-containing antipyrenes based on phosphate and phosphonate and a combination of them led to decreases in the rates of heat and weight loss during heating. More steps of decomposition were formed and the interval of decomposition was widened and shifted to higher temperatures. Some thermal characteristics make it possible to predict the optimum antipyrene compositions and concentrations with minimum time, labour and material consumption under laboratory conditions. Rigid polyurethane foam (RPUF) is an organic material with a high tendency to burn. Its combustibility depends essentially on the thermal stability of the structural chemical bonds and the products of decomposition. As with other types of polyurethanes, its flammability is reduced by the addition of antipyrenes. The problem of selecting optimum antipyrene compositions for polymers is becoming an urgent necessity. It requires the development of laboratory methods which are minimum time-, labour-and material-consuming and can provide maximum insight into the inhibiting effect of antipyrenes, thereby allowing a comparative evaluation of their efficiency. A major shortcoming of the available flammability tests is their failure to meet these requirements. Directly proportional relationships between polymer flammability tests and thermal analysis data have, recently been found [1][2][3][4][5]. Systematic studies [6][7][8][9] in this field, however, are still scarce.The aim of this work was to study the effect of additive antipyrenes with different compositions and structures on the mechanism and kinetics of the total thermal decomposition reactions of RPUF, and the possibility of evaluating their effectiveness as combustion inhibitors.

Section: Resultssupporting

confidence: 62%

Thermal behaviour of rigid polyurethane foams

Bechev

Troev

et al. 1986

Self Cite

Investigations of thermal behaviour and flammability of antipyrene-containing polychloroprene compositions

Karaivanova

1991

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The effects of ammonium salt of sulphaminic acid (AS), introduced as antipyrene in polyehloroprene compositions based on 'Byprene-210' in combination with antimony trioxide (AO) and chloroparaffin (ClaP) are studied by means of a combined dynamic thermal analysis. After successive examination of the obtained thermal and flammability characteristics, it is assumed that AS and AO exhibit additive influence. The optimal range of coneentrations of AS for which it is possible to substitute AO in the investigated polyehloroprene compositions is established.It is known that filled vulcanizates of chloroprene rubber belong to the group of the self-extinguishing compositions. Nevertheless, they should meet a number of additional requirements concerning smoke release, etc.For reducing the flammability of chlorine-containing polymers releasing hydrogen chloride on heating, antimony trioxide (AO) is used as an antipyrene, because the hydrogen chloride/AO system exhibits a synergetic fire-retardation effect [1,2].The use of AO, however, has some disadvantages, such as raising the cost of the compositions, making worse the operational and ecological characteristics. These reasons necessitate the creation of fire-protected polychloroprene compositions (PChC) containing organic antipyrenes, which do not aggravate the operational characteristics and are easy to process and ecologically safe. Such a combination of properties can be found in some nitrogen-sulphur-containing organic compounds [3], having low toxicity both in the process of formation and in the process of exploitation of the polymer compositions. In one of our previous papers [4] we offered investigations on the influence of ammonium salt of sulphaminic acid (AS), obtained by us [5] in combination with AO and chloroparaffin, on the physicomechanical characteristics of PChC on the base of 'Byprene-2IO' produced for conveying belts. It was shown that in concentrations from 3 to 12 wt.% AS does not change the basic strength characteristics of PChC beyond the practical standard, it is easy to dose and ensures good processability. AS was found to possess antipyrene qualities for the investigated compositions. The results obtained did not, however, make clear the mechanism of influence of AS on the processes taking place in the system on heating, i.e. what is the cause for its fire-retarding effect.Valuable information on the total mechanisms of operation of antipyrenes can be obtained by studying the thermal behaviour of the polymer systems in a broad temperature interval. Such investigations are based on the correlations found between some characteristics of flammability, on one hand, and of thermal destruction of polymers, on the other, and they are of great help for marking the effect of the antipyrenes [6,7].The aim of the present work is to study the influence of organic ammonium salt of sulphaminic acid (AS) in combination with AO and chloroparaffin (ChP) on the thermal behaviour and flammability of PChC, produced for conveying belts. ExperimentalThe organic antipyr...

Thermal behaviour of rigid polyurethane foams

Troev

Bechev

et al. 1987

Self Cite

The effects of P-and Cl-containing reactive antipyrenes with different compositions and structures on the mechanism and kinetics of the total thermal decomposition of rigid polyurethane foams, together with the possibility of evaluating their effectiveness as combustion inhibitors, were studied by means of a combined thermal analysis technique. It is shown that dynamic thermal analysis can register the changes resulting in the mechanisms and kinetics of the thermal decompositions of the investigated polyurethanes from comparatively low concentrations and differences in the concentrations and from differences in the chemical compositions and structures of the antipyrenes. The most sensitive characteristics associated with the influence of antipyrenes in this case were the coke residue determined at 850 ~ in an inert medium and the areas of exothermic peaks I and II in the DTA curve in air medium.Because of the increased tendency to burning and the requirements for their combustion stability, the problem of selecting optimum antipyrene compositions [1] for polyurethanes is becoming an urgent necessity. This requires the development of laboratory methods which are minimum time-, labour-and material-consuming and can provide .the maximum insight into the mechanism of the inhibitory effect of antipyrenes [1][2][3][4].Additive antipyrenes are not always efficient enough. The tendency is to search for reactivity modifiers which are introduced into the polymer molecule during synthesis. In the case of polyurethanes, it is the most convenient to introduce them in the polyol component. Systematic investigations on the thermal behaviour of substances of this type are still scarce.The aim of the present work was to study the effects of reactive antipyrenes with different compositions and structures on the mechanism and kinetics of the total John Wiley & Sons, Limited, ChichesterAkad~miai Kiad6, Budapest