利用静电吸附构建生物基核壳阻燃剂用于阻燃改性牛皮纸

Construction of Biobased Core-shell Flame Retardant by Electrostatic Adsorption for the Flame Retardant Modification of Kraft Paper

为了改善聚磷酸铵(APP)使基材表面变色和力学性能降低的缺点,同时符合阻燃剂的绿色发展趋势,制备了一种核壳结构的生物基阻燃剂(APP@EP)。采用植酸钠(PA-Na)和蛋清蛋白(EWP)作为壳体材料,在水溶液中通过静电吸附作用将其逐层沉积在APP表面。通过涂布工艺将APP@EP应用于牛皮纸,并对阻燃牛皮纸的阻燃性能和力学性能进行了研究。热重(TG)分析表明,APP@EP在高温下的热稳定性显著增强,700℃时残炭量达到56.7%。APP@EP阻燃改性牛皮纸的极限氧指数值(LOI)从19.8%提高到45.2%,炭化长度从210 mm降低到41 mm。与APP阻燃改性牛皮纸相比,APP@EP阻燃改性牛皮纸的热释放速率峰值(PHRR)和总热释放量(THR)分别降低了35.91%和44.98%,抗张指数提高了24.92%。对残炭的进一步研究表明,APP@EP阻燃改性牛皮纸经过燃烧后,形成了完整致密的含有P-O-P和P-O-C结构的炭层,并且其石墨化程度较高。

Aiming at improving the disadvantages of ammonium polyphosphate(APP) that caused surface discoloration and lower mechanical properties of the substrate, and meeting the green development requirement simultaneously, a biobased flame retardant(APP@EP) with core-shell structure was fabricated. Sodium phytate(PA-Na) and egg white protein(EWP) were used as shell materials, which were deposited on the surface of APP layer by layer through electrostatic adsorption in aqueous solution. Then APP@EP was applied to kraft paper through the coating process, and the flame resistance and mechanical properties of flame retardant kraft papers were investigated. Thermal gravimetric(TG) analysis indicated that the thermal stability of APP@EP was improved significantly at high temperature, and the residual mass reached 56.7% at 700 ℃. The limiting oxygen index(LOI) value of APP@EP treated kraft paper was increased from 19.8% to 45.2%, and the char length was decreased from 210 mm to 41 mm. Compared with APP treated kraft paper, the peak of heat release rate(PHRR) and total heat release(THR) of APP@EP treated kraft paper decreased by 35.91% and 44.98%, and the tensile index increased by 24.92%. Further analysis of residues demonstrated that after the combustion of APP@EP treated kraft paper, a complete and dense carbon layer containing P-O-P and P-O-C structures was formed with higher degree of graphitization.