Oligomeric mechanism of film boiling elimination (EFB effect) during metal quenching in solutions of polyisobutylene in mineral oil

The results of a study of the cooling and rheological properties of solutions of oligomers and polymers polyisobutylene (PIB) in mineral oil are presented onwards. The concentration of PIB additives ranged from 0.25% by weight to 20.0% by weight while molecular mass (Mm) ranged from 4,0•102 m.u. to 6,0•104 m.u. It was established that in oligomeric PIB solutions with Mm from 0,68•103 to 1,0•104 there was a range of optimal concentrations in which there is a sharp reduction in the duration or complete elimination of film boiling (EFB effect) observed. In isoviscous solutions of PIB oligomers, an extreme dependence of the Inconel 600 thermal probe (TP) maximum cooling rate on Mm is observed, which is explained by the indirect influence of the geometric sizes of PIB macromolecules on the ratio of the density of the initial and critical heat fluxes caused by the first and second boiling crisis. A mechanism is proposed for the formation of an oligomeric heat-insulating film in the wall layer, which is responsible for the destruction of the vapor film (VF) and the transition to bubble boiling.