三聚氰胺氰尿酸盐改性PPO/PS复合材料的燃烧性能和流动性能

以无卤阻燃剂三聚氰胺氰尿酸盐(MCA)为改性剂, 采用熔体共混法制备了改性聚苯醚/聚苯乙烯 (PPO/PS)复合材料。通过XRD和SEM对MCA-PPO/PS复合材料的微观结构进行了表征, 重点研究了复合材料的燃烧性能和流动性能。研究发现: 在复合材料的制备和加工过程中MCA的微观结构并没有发生任何变化, 因此复合材料中MCA的阻燃作用不变。MCA在复合材料中分散比较均匀, 无明显团聚现象。与纯PS相比, 质量比为100:100的PPO/PS在燃烧时的氧指数增加5.4%, 热释放速率峰值降低33.1%, 但总烟释放量增加近1.5倍。在PPO/PS中加入MCA后得到的复合材料的阻燃性能随着MCA用量增加而逐渐增强, 发烟量大幅度降低, 同时熔体黏度减小, 流动性增加。在MCA-PPO/PS复合材料中加入5%、 25%和45%质量分数的MCA可分别使复合材料的总烟释放量比PPO/PS降低43.7%、 82.6%和91.6%。PPO/PS的阻燃机制为凝聚相成炭阻燃, 随着MCA用量增加, MCA-PPO/PS复合材料的阻燃机制逐渐转变为气相稀释和对聚合物基体的冷却效应。加入MCA对MCA-PPO/PS复合材料可同时起到阻燃、 抑烟和改善加工流动性的作用。

Combustion behavior and flowability of MCA modified PPO/PS composites

MCA-PPO/PS composites were prepared by melt-compounding PPO/PS and melamine cyanurate(MCA) as a halogen-free flame retardant.The structure of the composites was characterized by XRD and SEM,and their combustion behavior and flowability were investigated.It is discovered that the microstructure of MCA in the composites is the same as that of pure MCA after the sample preparation and processing procedure.Thus the flame retardant effect of MCA remains unchanged.MCA is dispersed evenly in the composites,with no obvious agglomeration.In comparison with that of pure PS,the oxygen index(OI) of PPO/PS with mass ratio of 100∶100 increases by 5.4%,the peak heat release rate(PHRR) decreases by 33.1% and the total smoke release(TSR) increases by almost 1.5 times.With rise of MCA loading,the flame retardancy of the MCA-PPO/PS composite gradually improves,while the total smoke release(TSR) decreases remarkably.Meanwhile,the melt viscosity of the composites decreases and the flowability increases with MCA loading.The addition of 5%,25% and 45% mass fraction of MCA to the MCA-PPO/PS composite can decrease the TSR by 43.7%,82.6%,and 91.6%,respectively.The flame retardant mechanism of PPO/PS is condensed phase charring mechanism.The flame-retarding mechanism of the MCA-PPO/PS composite changes from condensed phase charring mechanism to gas phase diluting and cooling effect of polymer matrix with MCA loading.The addition of MCA can enhance flame retardancy,suppress smoke release and improve melt flowability of the MCA-PPO/PS composite simultaneously.