聚磷酸铵-苯并噁嗪微胶囊的制备及其对环氧树脂燃烧性能影响

以多聚甲醛、丙烯胺、苯酚为原料,通过Mannich反应合成烯丙基型苯并噁嗪单体(Bala),并通过核磁共振氢谱(~1H-NMR)确定了其化学结构.将Bala在聚磷酸铵(APP)原位开环聚合后,制备APP微胶囊(BMAPP).傅里叶变换红外(FTIR)和静态接触角测试表明,Bala在APP表面成功聚合,并有效提高APP的疏水性,与纯APP相比,BMAPP的接触角从10.8°提高到了71.3°.将BMAPP添加到环氧树脂(EP)中,制备EP/BMAPP复合材料.通过热重分析仪(TGA)、垂直燃烧(UL-94)、极限氧指数(LOI)、锥型量热仪(CONE)和动态热机械分析仪(DMA)对EP和EP/BMAPP的热性能以及燃烧性能进行对比分析.结果显示,10%的BMAPP的成炭效果最佳,有良好的阻燃性能,可使EP的LOI值从22.6%提高到33.6%,并通过UL-94 V-0级,600°C下残炭率达26.3%.同时,BMAPP可大幅度降低EP燃烧过程中烟密度和热释放速率,提高EP的玻璃化转变温度(T_g).BMAPP/EP-10%中,PBala和APP协同后使EP热释放速率峰值(PHRR)由1247 kW·m~(-2)降低到434 kW·m~(-2),生烟速率(SPR)降低67%左右,T_g从169°C提高到了173°C.

Preparation of Polybenzoxazine-ammonium Polyphosphate Microcapsules and Their Effects on the Flame Properties of Epoxy Resin

Allyl-containing benzoxazine (Bala) was synthesized via Mannich condensation reaction using paraformaldehyde,allylamine and phenol as raw materials.The chemical structure of Bala was confirmed by 1H nuclear magnetic resonance (1H-NMR).Ammonium polyphosphate (APP) microcapsules modified by polybenzoxazine (BMAPP) were prepared by in situ ring-opening polymerization of Bala on the surfaces of APP.Fourier transform infrared spectroscopy (FTIR) and static contact angle test showed that Bala polymerized successfully,and enhanced effectively the hydrophobicity of APP.The static contact angle of the BMAPP microcapsules increased to 71.3° from 10.8°.EP/BMAPP flame-retardant materials were prepared by adding BMAPP microcapsules into epoxy matrix (EP).Thermal properties and combustion performance of EP and its composites were investigated by thermogravimetric analysis (TGA),vertical combustion test (UL-94),limiting oxygen index (LOI),cone calorimeter (CONE) and dynamic thermal mechanical analysis (DMA).The results showed that BMAPP microcapsules promoted EP to form high-quality char layer on the surface of the composites,which could serve as a good barrier against heat and oxygen diffusion and played a great role in the combustion process.The LOI value of EP increased from 22.6％ to 33.6％,and passed the UL 94 V-0 level with the addition of 10％ BMAPP.Residue char of EP/BMAPP-10％ was as high as 26.3％ at 600 ℃.Meanwhile,the incorporation of BMAPP microcapsules led to a great decrease in smoke production rate and heat release rate of EP during combustion process,along with an increase in glass transition temperature (Tg) and storage modulus of EP.The peak of heat release rate (PHRR) of EP/BMAPP-10％ reduced from 1247 kW·m-2 to 434 kW·m-2 due to the synergistic flame retardant effects of PBala and APP in BMAPP.Smoke production rate of EP/BMAPP-10％ was approximately 67％ lower than that of EP.The Tg of EP/BMAPP-10％ increased from 169 ℃ to 173 ℃ with respect to EP.