具有自由基淬灭功能大分子膨胀型阻燃剂的合成及其阻燃聚丙烯的作用机理

Synthesis of a novel macromolecular charring agent with free-radical quenching capability and its mechanism in flame-retarding polypropylene

针对传统小分子膨胀型阻燃剂(IFR)易迁移、易吸湿、热稳定性差、阻燃效率低、与基体相容性差及功能单一等缺点,本论文通过分子设计,合成了一种新型具有自由基淬灭功能的大分子膨胀型阻燃剂(HAPN),并将其与聚磷酸铵(APP)复配阻燃聚丙烯(PP),研究HAPN与APP的质量比对PP阻燃性能的影响,并探讨了HAPN与APP协同阻燃PP的作用机理。结果表明:当阻燃剂总用量为25.0%(质量百分比),且HAPN与APP质量比为1:1时,PP的极限氧指数(LOI)从18.0%提高到29.5%,仅燃烧了35 s就发生自熄,并且垂直燃烧测试通过了UL-94 V-0级。其可能的阻燃机理是:HAPN与APP可在聚合物凝聚相中快速形成致密的膨胀炭层,有效阻隔可燃气体、氧气及热量的传输;同时受阻胺基团的自由基淬灭作用可抑制凝聚相中PP的降解,并阻断气相中的自由基链式反应,加速火焰的熄灭。

A novel macromolecular intumescent flame retardant containing hindered amine structure(HAPN)was synthesized and used to blend with ammonium polyphosphate(APP)to flame-retard polypropylene(PP).The results revealed that when the total amount of the flame retardant was25.0wt%and the mass ratio of HAPN and APP was1:1,the limiting oxygen index(LOI)of PP composite was improved from18.0%to29.5%,and a UL-94V-0rating was achieved.The possible flame retardant mechanism was that,on one hand,HAPN and APP could suppress the heat and mass transfer between the gas phase and condensed phase by forming compact intumescent char layer;on the other hand,the free-radical quenching capability of the hindered amine could extinguish the flame by inhibiting the degradation of PP in the condensed phase and blocking the radical chain reaction in the gas phase.