Preparation and characterization of PVA-H18 gel foam for preventing spontaneous combustion of coal based on interfacial self-assembly

Abstract

In order to improve the stability time and foaming ratio of gel foam, and change the traditional preparation method of gel foam. In this paper, using super-hydrophobic nanoparticles, PVA, sodium tetraborate and sodium bicarbonate as the main raw materials, based on the self-assembly effect of super-hydrophobic nanoparticles and hydrophilic macromolecules, a high-foaming gel foam (PGF) without foaming agent was prepared. Through the test, the foaming volume of the 100 ml PGF can reach 329 ml without adding foaming agent, which is 1.4 times of the traditional gel foam (TGF) and 1.2 times of the viscous foam (VF). Even without foaming agent, the PGF has a half-life of more than 13 days and can retain water for more than 15 h at 100 °C. Response surface analysis showed that the foaming performance of the PGF was affected by nanoparticles, sodium tetraborate and sodium bicarbonate, among which the content of nanoparticles was the main factor. At the same time, sodium tetraborate and sodium bicarbonate also significantly affect the water retention performance of PGF. Fire prevention experiments show that the gel foam prepared by this method also has excellent fire prevention ability, which can effectively inhibit the consumption of hydroxyl group and the generation of methyl and methylene group in the process of coal oxidation. Moreover, it can still play an inhibiting ability at a high temperature of 400 °C, and can effectively prevent the recurrence of coal fire after extinguishing. The development of PGF provides a new method for the preparation of gel foam in the future. At the same time, the application of foaming agent is avoided, which reduces the pollution of surfactant to the environment.