Du Yonggang,Wang Yiming,Yu Yueru,Shi Gonghui,Zhou Shuai,Liu Mei,Ren Shitong,Jia Xiangxiang,Zhao Ge
In this work, the bio-based epoxy nanocomposites (GER/DOPO-POSS) were prepared, and AE-POSS was synthesized and used as compatibilizer for GER/DOPO-POSS nanocomposites. The effects of AE-POSS content on mechanical properties, thermal stability, compatibility and flame retardancy of GER/DOPO-POSS nanocomposites were discussed. The results showed that the addition of AE-POSS significantly improved the dispersity of DOPO-POSS in gallic epoxy matrix. AE-POSS can improve both the thermal stability and flame retardancy of GER/DOPO-POSS nanocomposites. When 6.0 wt % AE-POSS was added in GER/DOPO-POSS, the limiting oxygen index of it was 25.6%, and the initial thermal degradation temperature of it was 36 °C higher than that without AE-POSS. Graphic abstract
Du Yonggang,Shi Gonghui,Wang Jiaming,Wang Yiming,Wang Xuhua,Wang Liwei,Yang Jinhui,Ren Shitong
The bio-based epoxy nanocomposite (GAER/DOPO-POSS) was prepared from gallic epoxy resin (GAER) and polyhedral oligomeric silsesquioxane (which containing 9,10-dihydrogen-9-oxo-10-phosphorus-phenanthrene-10-oxide groups, called DOPO-POSS). The polyhedral oligomeric silsesquioxane containing epoxy groups (E-POSS) was grafted onto aminated graphene oxide (E-GO), then the novel POSS-E-GO was obtained. The POSS-E-GO was used as modifier for GAER/DOPO-POSS nanocomposite. The influences of POSS-E-GO content on mechanical properties, dynamic mechanical properties and thermal stability of GAER/DOPO-POSS nanocomposites were determined. The experimental results show that POSS-E-GO can significantly improve the toughness of the GAER/DOPO-POSS nanocomposite. When 0.5wt% POSS-E-GO was added in GAER/DOPO-POSS nanocomposite, the impact strength of the nanocomposite was 4.74 kJ/m 2 higher than that in the absence of POSS-E-GO, meantime the initial thermal degradation temperature was 277 °C.
The cage and ladder structured phosphorus-containing polyhedral oligomeric silsesquioxanes (DOPO-POSS) have been synthesized through the hydrolytic condensation of 9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide (DOPO)-vinyl triethoxysilane (VTES). The unique ladder and cage–ladder structured components in DOPO-POSS endowed it with good solubility in vinyl epoxy resin (VE), and it was used with tetrabutyl titanate (TBT) to construct a phosphorus-silicon-titanium synergy system for the flame retardation of VE. Thermal stabilities, mechanical properties, and flame retardancy of the resultant VE composites were investigated by thermal gravimetric analysis (TGA), dynamic mechanical analysis (DMA), three-point bending tests, limiting oxygen index (LOI) measurement, and cone calorimetry. The experimental results showed that with the addition of only 4 wt% DOPO-POSS and 0.5 wt% TBT, the limiting oxygen index value (LOI) increased from 19.5 of pure VE to 24.2. With the addition of DOPO-POSS and TBT, the peak heat release rate (PHRR), total heat release (THR), smoke production rate (SPR), and total smoke production (TSP) were decreased significantly compared to VE-0. In addition, the VE composites showed improved thermal stabilities and mechanical properties comparable to that of the VE-0. The investigations on pyrolysis volatiles of cured VE further revealed that DOPO-POSS and TBT exerted flame retardant effects in gas phase. The results of char residue of the VE composites by SEM and XPS showed that TBT and DOPO-POSS can accelerate the char formation during the combustion, forming an interior char layer with the honeycomb cavity structure and dense exterior char layer, making the char strong with the formation of Si-O-Ti and Ti-O-P structures.Keywords:vinyl epoxy resin;flame retardant;thermal stability;mechanical properties
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