Construction of transparent PAM/PVA interpenetrating network hydrogel for designing fireproof glass with superior heat insulation and aging resistance

The decorative and fireproof performance degradation of grouting fireproof glass exposed to UV irradiation limits its application in the fire protection of buildings. To solve this issue, a transparent polyacrylamide/polyvinyl alcohol (PAM/PVA) interpenetrating network hydrogel was designed to prepare grouting fireproof glass with enhanced heat insulation and anti-aging properties. The results show that the light transmittance of PAM/PVA interpenetrating network hydrogel decreases with the increased content of PVA, and a proper content of PVA in the PAM/PVA interpenetrating network is beneficial to maintain high optical transparency in the resulting hydrogel. Heat insulation test shows that the PAM/PVA interpenetrating network improves the water-locking ability of the resulting hydrogel, and the fireproof glass containing 3wt% PVA shows the lowest backside temperature of 92.6 °C at 3600 s, which is 51.9 % lower than that of fireproof glass with PAM only. Thermogravimetric (TG) and differential scanning calorimetry (DSC) analysis show that the PAM/PVA interpenetrating network hydrogel improves the thermal stability and charring ability of hydrogel, and the hydrogel containing 3wt% PVA exhibits the best charring effect among the samples, showing the highest residual yield of 39.2% at 800 °C. The analysis of decomposition products and char residues shows that the PAM/PVA interpenetrating network hydrogel can extend the heat absorption process of water evaporation and improve the gas flame retardant efficiency. Accelerated aging test shows that the presence of PVA greatly slows down the blistering and yellowing phenomenon of fireproof glass, thus endowing the fireproof glass with the super durability of fire resistance. Especially, the backside temperature at 3600s and light transmittance of the sample containing 2wt% PVA after 168h aging test only changed 19.2°C and 1.9%, respectively, compared to the those of unaged sample.