Study of the relationship between thermal insulation behavior and microstructure of a fire‐resistant gel containing silica during heating

Abstract

SummaryAdding a transparent gel containing silica between 2 sheets of glass could improve the fire resistance of laminated glazing by its thermal intumescent behavior at high temperature. In this study, a custom fire test shows that the glazing reaches the highest thermal insulation rating of 40 minutes when the molar ratio of SiO 2 and Na 2 O in the gel is 4.0, but above this ratio, the thermal insulation rating of the glazing decreases with the increasing silica content. Thermal and scanning electron microscopic analyses have been used to investigate the thermal behavior and microstructure of the residual layer, respectively. The results indicate that, although the high silica content is responsible for the high amount of residue that is essential in the formation of a pro-

Synthesis and characterization of cross‐linked poly(sodium acrylate)/sodium silicate hydrogels

“…This fact suggests that the fire‐retardant operation of a laminar pane consists of several stages in which different mechanisms take place: at the first stage, heat is absorbed to approximately 120°C, what is characterized by a linear rapid increase in temperature; at the second stage, water evaporates quickly from gel at about 120–220°C, which is the first insulation barrier that discharges significant amounts of heat; at the third stage, depending on the viscosity and other properties of gel, evaporation of water can be slowed down and can occur up to 500°C; at the fourth stage, a silicate insulation layer, constituting a hard and opaque pumice which is the second and the ultimate insulating barrier, is created. Depending on its porosity, the temperature increase on the outer side of the sample may vary . …”

Effect of Composition on the Physicochemical Properties of Cross-Linked Poly(sodium acrylate)/Sodium Silicate Hydrogels

“…The thickness of the gel layer may also have an impact on fire insulation time. The thicker it is, the longer this time will be [15,35,36].…”

“…Zhang et al [13,14] investigated hydrogel polyacrylamide-based fire-retardant layers with the addition of salts such as magnesium chloride and potassium aluminum sulfate, which had a similar effect to the hexamethoxymethyl melamine ether. Liu et al [15,16] tested water glass systems with a molar modulus of 4.0 with the addition of glycerol and silica, where the gelling agent was ammonia, and the resulting glass packet was heated at 80 • C for 1 h to gel. A similar polymerization method was described already in 2000 by Sugiura K. et al [17].…”