Photo‐aging deterioration of hybrid intumescent flame retarding coatings simultaneously modified by silicon aerogel, β‐cyclodextrin, and nano‐ZnO

Abstract

Photo-aging has been manifested as the main threat to the service performance of organic coatings, but the deterioration of intumescent flame retarding coatings (IFRC) is scarcely reported. Therefore, the finish IFRC is benignly designed by simultaneously incorporating silicon aerogel, β-cyclodextrin, and nano-ZnO, its deterioration mechanism under photo-aging (composed of xenon lamp radiation and water spraying) is quantitatively investigated. The results show that the photo-aging facilitates the declined flame retardancy, as measured by the rising fire growth index from 1.07 to 2.43 kW m À2 Ás À1 and the reduced fire performance index from 0.493 to 0.196 sÁm 2 ÁkW À1 with the flame retardancy index of 0.18 for S 30d , as well as the diminished smoke suppression. Because the cleavage of C═N bonding occurs for the IFRC subjected to photo-aging, presenting the serious yellowing of the IFRC surface with enhanced hydrophilicity. Meanwhile, the light-humidity cycles of photoaging lead to the transformation from glassy residue to crystalline SiP 2 O 7 during firing, presenting the disorder and fluffy char for S 30d . Thirdly, the photo-aging makes the pyrolysis E α of 370 ~320 C drop from 177.9 to 120.2 kJÁmol À1 by the modified Coats-Redfern integral method. It probes the photo-aging deterioration mechanism of organic-inorganic hybrid IFRCs.