掺杂铝溶胶改性可膨胀石墨(EG)对半硬质聚氨酯泡沫(SRPUF)阻燃性能的影响

Effect of Alumina-sol Modified Expandable Graphite on Flame Retardation of Semi-rigid Polyurethane Form

先使用铝溶胶对可膨胀石墨(EG)进行改性,然后用一步法制备纯半硬质聚氨酯泡沫(SRPUF)、掺杂未改性EG的SRPUF和掺杂改性EG的SRPUF。使用傅立叶红外光谱仪(FT-IR)和透射电子显微镜(TEM)表征了铝溶胶改性的EG,结果表明:铝溶胶包覆已经在EG表面。用材料拉伸试验机和氧指数测试仪测试泡沫的拉伸性能和阻燃性能,确定了EG的用量为12%、掺杂改性EG的SRPUF的力学性能优于掺杂未改性EG的SRPUF。使用氧指数测试仪和水平垂直燃烧测定仪测试三种SRPUF的阻燃性能,结果表明:掺杂铝溶胶改性EG的SRPUF阻燃性能最好,极限氧指数为27.6%,水平燃烧等级达到HF-1级。使用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)分析了阻燃机理,结果表明:EG表面的γ-Al OOH以脱水、晶型转变和释放不燃气体的三种形式提高了阻燃效果,同时起粘结蠕虫石墨的作用。

Expandable graphite（EG） was modified by using alumina-sol（Al-sol）, then the semi-rigid polyurethane foam（SRPUF）, EG doped SRPUF and Al-sol modified EG doped SRPUF were prepared respectively by one step method. The prepared Al-sol modified EG was characterized by means of Fourier transform infrared spectroscopy（FT-IR） and transmission electron microscope（TEM）. The tensile property and flame retardance of the prepared foams were examined with tensile testing machine and oxygen index tester respectively. The results show that the surface of EG was coated with the Al-sol after modification; For the same doping amount of 12%（mass fraction）, the mechanical property of the SRPUF doped with Al-sol modified EG was better than that with the plain EG; Among others, the flame retardance of the SRPUF doped with Al-sol modified EG is the best with limiting oxygen index of 27.6% and horizontal burning level of grade HF-1. The SRPUFs before and after burnt were examined by means of XRD, SEM and TEM, it follows that the enhancement of flame resistance of the SRPUF doped with Al-sol modified EG may be ascribed to the following facts, i.e. the release of crystal water, crystal-phase transformation and the release of non-flammable gas of the Al-sol on the top surface of EG, besides, the Al-sol can also play important role as binding agent for fixing the worms-like graphite.