Drenagem de espumas usadas em incendios classe B : influencia da presença de polimeros redutores de atrito hidrodinamico

AUTOR(ES)
DATA DE PUBLICAÇÃO

1997

RESUMO

Poly(ethylene oxide), PEO, is one of the most efficient drag reducing polymers. Its application in foam jels for fire-fighting can improve and even assure the fighting efficiency. In order to evaluate the viability of the application of PEO in foams of high stability used in class B fires (inflammable liquids), the effect of the polymer on the stability of foams was studied through measurements of the structure lifetime, in process of isothermic drainage. Foams were produced in a thermostated glass column by bubbling an aqueous solution of the generator extract. Solutions of different concentrations of extract and PEO, of different molecular weight, were used. It was observed that PEO has a stabilising effect on the foam in the temperature range studied (25° a 40°C), and that the effect is prone to be minimised in higher temperatures. The stabilisation of the foam was found to be favoured by increasing polymer concentration and molecular weight. The presence of PEO molecules modifies superficial properties of foam films and the film disjoining pressure (electrostatic, molecular and steric forces). Among other factors, mechanical and thermal vibrations and variations in air humidity influenced the drainage process and were controlled. Analyses by X-rays fluorescence and UV-vis and IR spectroscopies revealed that the surfactant present in the extract has fluorinated carbon chain and monoanionic nature (benzenossulfonate group). Solutions of the extract were characterised by viscometry and determination of cmc. From the practical standpoint, the main fact noticed in this study was that the presence of PEO does not cause the roam to become unstable. Interactions between polymer and surfactant molecules probably contribute for the increase in the lifetime observed, by means of factors like sterical repulsions provoked by the molecules of PEO in the foam films.

ASSUNTO(S)

espuma antichama efeito toms interação polímero-surfatante

ACESSO AO ARTIGO

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