Preparation and property of PVA-based colorful coating composite reinforced with silica aerogel particles filled by high-loaded flame retardant

Hydrophilic mesoporous silica aerogel particles were synthesized via self-assembly of amphiphilic polymer (Ph8-PEG6-PEOS) and its instantaneous hydrolysis and condensation in the alkaline environment. Meanwhile, the capture and encapsulation of flame retardant (IPPP) and oil soluble dyes were successively completed during the two processes above. Observed by thermal field scanning electron microscopy (TFESEM), the average diameter of aerogel particles reached about 10 µm. BET surface area analysis displayed that the existence of oil-phase component (IPPP) can result in the expansion of pore diameter, and promote the evolution of mesopores into macropores. Then, IPPP@SiO₂ aerogel particles were utilized to improve the flame retardancy of polyvinyl alcohol (PVA) coatings implemented onto cotton yarns, by employing developed knife coating procedure in an aqueous suspension. The thermal stabilities and flammability behaviors of the samples were evaluated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), and vertical burning test, respectively. Both thermal decomposition temperature and LOI value of coating composites gradually increased with the increment of IPPP@SiO₂-n (n = 10, 30, 50, 70), attaching to the synchronous advancement in stretching property. Furthermore, coatings were thickened by degrees from 0.4 to 4 mm, based on knife coating in multi-stage layer-by-layer mode, to build an ordered porous structure with the assisted adhesion of PVA. The following sintering preserved the close packing of silica aerogel particles and facilitated the formation of a coherent porous monolithic material with excellent thermal insulation performance.

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