香草醛衍生含磷席夫碱的合成及与DOPO协效阻燃环氧树脂

Application of Vanillin-Derived Phosphorus-Containing Schiff Base/DOPO Compounding Flame Retardants in Epoxy Resins

本文以苯基磷酰二氯、香草醛和4-氨基苯酚为主要原料,合成了一种含磷席夫碱阻燃剂(PH-VAN-AP),并采用红外光谱、核磁共振氢谱和核磁共振磷谱证明其结构符合预期。将DOPO与PH-VAN-AP作为复配阻燃剂PH/DOPO加入环氧树脂(EP)中,通过垂直燃烧(UL-94)、极限氧指数(LOI)和锥形量热测试(CCT)对其阻燃性能进行了表征,并利用热失重和差示扫描量热分析了环氧树脂的热稳定性、热降解过程及玻璃化转变温度(T_(g))。结果表明,PH/DOPO兼有气相和凝聚相2种阻燃机理,能有效提高EP的燃烧性能。具体而言,当仅添加PH/DOPO至体系的3%(质量分数)时,顺利通过了UL-94测试并达到V-0等级,其LOI由24.7%提高至34.8%。此外,峰值热释放速率(PHRR)和总热释放(THR)分别降低了257 kW/m^(2)和8 MJ/m^(2),材料的残留量提高了6.8%。添加3%的PH/DOPO,环氧树脂的Tg由149.5℃降至148.1℃,变化不大,表明PH-VAN-AP一定程度上改善了由于DOPO加入EP后导致T_(g)下降的问题。

A phosphorus-containing Schiff base flame retardant(PH-VAN-AP)was synthesized using phenylphosphoryl dichloride,vanillin,and 4-aminophenol as main raw materials,and its structure was proved to be as expected through FT-IR,1H-NMR and 31P-NMR.DOPO and PH-VAN-AP were incorporated into epoxy resin(EP)as compound flame retardant PH/DOPO,and their flame retardant properties were characterized by vertical burning(UL-94),limiting oxygen index(LOI)and cone calorimetry test(CCT),and the thermal stability,thermal degradation process of the epoxy resin were analyzed by thermogravimetric(TG)and differential thermal scanning calorimetry(DSC)and glass transition temperature(T_(g)).The experimental results show that PH/DOPO shows both gas-phase and condensed-phase flame retardant mechanisms,which can effectively improve the combustion performance of EP.Specifically,when only 3%of PH/DOPO was added to the system,it successfully passes the UL-94 test and reaches the V-0 rating,and its LOI increases from 24.7%to 34.8%.In addition,the peak heat release rate(PHRR)and total heat release(THR)are reduced by 257 kW/m^(2) and 8 MJ/m^(2),respectively,and the residual is improved by 6.8%.With the addition of 3%PH/DOPO,the T_(g) of the epoxy resin decreases from 149.5℃to 148.1℃with little change,indicating that PH-VAN-AP can improve the T_(g) decrease due to the addition of DOPO into EP to some extent.