A synergy study of zinc borate in halloysite nanotube reinforced, siloxane epoxy base intumescent fire resistive coatings

Abstract

This study focuses the combined effects of halloysite nanotubes and zinc borate in siloxane epoxy base intumescent formulation when used with traditional intumescent ingredients e. g. ammonium polyphosphate, melamine and expandable graphite. Zinc borate was substituted in halloysite nanotube reinforced siloxane epoxy base intumesce fire retardant coatings and their effects on char morphology, char expansion, fire performance and thermal stability were characterized through field emission scanning electron microscopy, bunsen burner fire test and thermogravimetric analysis. During intumescent reaction, polydimethylsiloxane form char residue containing silica on the material surface and zinc borate, an inorganic flame retardant, releases boron oxide (B 2 O 3 ) which effectively contribute to the char formation. Present study suggests that the existing synergism between polydimethylsiloxane and zinc borate is the result of chemical reaction via forming cross-linking B-O-Si structure. At the same time, alumina-siloxane film develops over the external layer of char due to release of alumina from halloysite nanotubes. Consequently, silicon, aluminum and boron elements together contribute to the integrity of char residue layer with better quality, achieving obviously improved flame retardancy compared to previous fire retardant systems.Keywords: Intumescent fire retardant coatings / polydimethylsiloxane / zinc borate / halloysite nanotubes / synergism Schlü sselwö rter: Intumeszente feuerfeste Beschichtungen / Polydimethylsiloxan / Zinkborat / Halloysit-Nanorö hren / Synergie

Thermal insulation performance and char formation and degradation mechanisms of boron-containing hydrocarbon intumescent coatings

“…Besides, the presence of BA was reported to reduce the characteristic viscosity drop of the coating during softening, and therefore plays a crucial role in the expansion process, acting both as an intumescent additive and a char reinforcer [30]. BA was also found to have significant effects on the adhesion strength of the char to the steel substrate [8] and to increase the residual weight of the char [31], while ZB affected the char formation [5] and flame retardant properties of the coating [32] and contributed with synergistic effects on thermal degradation [8][9][10]33] and smoke suppression [34,35]. Published studies on APB-containing intumescent coatings, however, are rare.…”

“…However, industrial-scale fire testing is costly and time-consuming. Meanwhile, due to an uncontrolled flame temperature or a limited heating power, most of the laboratory-scale testing equipment, such as gas burners [2,[8][9][10], radiators [3,11], and electrically heated ovens [12], cannot follow the required temperature-time curve defined in the standard (some exceptions are Morys et al [13], who developed a modified bench-scale muffle furnace following the DIN EN 1363-1 standard, and Gardelle et al [14], with a combination of J o u r n a l P r e -p r o o f 3 a laboratory-scale furnace and gas burners, simulated the UL1709 heating curve). Recently, Zeng et al [5] presented a laboratory-scale, electrically-heated oven that does follow the UL1709 fire curve, and allows formation of chars with properties similar to those produced in industrial-scale experiments.…”

Tensile properties and fire residue morphology of flame-retarded-polypropylene composites

“…It is extensively believed that the fire residue morphology of specimens after combustion or burning is closely related to the flame-retardant behavior and mechanisms besides the fire behavior. 16,18,29 The LOI is one of the important parameters for characterizing the flame-retardant properties of polymer materials. Table 1 lists the LOI of the neat PP and the three PP composites.…”

Synergistic Flame Retardant Effect of Organic Phosphorus–Nitrogen and Inorganic Boron Flame Retardant on Polyethylene

“…ZB decomposes to form zinc oxide and boron oxide . Boron oxide is softened by heat at high temperatures to form a boron‐containing coating, which suppress the release of flammable volatiles and prevent heat exchange . The synergistic effect of ZB on the efficiency of flame retardant was improved through incorporating it into other flame retardants as a synergist via physically mixing .…”