聚磷酸铵/可膨胀石墨阻燃环氧树脂的性能

Properties of Flame Retardant Epoxy Resins Thermosets with Ammonium Polyphosphate and Expandable Graphite Composite

将聚磷酸铵(APP)与可膨胀石墨(EG)进行复配后添加到环氧树脂(EP)中,以间苯二胺(PDA)为固化剂,制备阻燃环氧树脂固化物,通过极限氧指数(LOI)、垂直燃烧(UL-94)和热重分析(TGA)测试研究了材料的阻燃性能、热降解行为,通过锥形量热(CONE)测试研究了材料的燃烧行为,通过扫描电镜(SEM)研究了材料炭层的形貌,同时还研究了APP与EG的不同配比对EP材料阻燃性能的影响。结果表明:当APP与EG的质量比为3∶2、添加量为5%时,阻燃EP材料通过了UL-94 V-0级,LOI值达到了29.0%。TGA测试结果表明:阻燃剂APP及EG的加入明显地改变了材料的热降解行为,促进了环氧树脂材料的提前降解和成炭,降低了材料的热降解速率,材料在700℃时的残炭量由14.6%提高到了29.9%。CONE测试结果表明:阻燃剂的加入明显降低了材料的热释放速率(HRR)和总热释放量(THR)。SEM测试结果表明:阻燃材料燃烧后形成了致密均一的炭层,能很好地阻止氧气和热量进入到材料的内部,同时减少可燃气体的逸出,从而抑制了基体树脂的进一步降解和燃烧,提高了材料的阻燃性能。

Ammonium polyphosphate （APP） combined with expandable graphite （EG） were incorporated into epoxy resins and cured with m-phenylenediamine to prepare flame retardant epoxy resins thermosets. The fire retardaney and thermal degradation behavior of cured EP composite were investigated by limiting oxygen index （LOI） , vertical burning test （UL-94） , thermalgravimetric analysis （TGA） and cone calorimeter （CONE） tests. The morphologies of char residues of cured epoxy resins were measured by scanning electron microscopy （ SEM）. Meanwhile, the effect of the mass ratio of APP and EG on the flame retardancy of EP was also investigated. The results revealed that the materials passed UL-94 V-0 rating and the LOI value reached 29.0% when the loading amount of fire retardant was only 5% with the mass ratio of APP and EG was 3： 2. The results of TGA test showed that the decomposition of epoxy resins matrix was promoted ahead of time by the introduction of flame retardant than that of pure EP, and the degradation rate was decreased, the char yield was enhanced from 14.6% to 29.9% at 700 ~C. The results of CONE test revealed that the heat release rate （HRR） and total heat released （THR） of the material were decreased via the incorporation of flame retardant obviously. The SEM results showed that the morphologies of char residues for the flame retardant EP composite were relatively compact and uniform. This char layer could resist the heat and oxygen transferring into the interior matrix and the release of flammable volatiles, which resulted in suppressing the further combustion and degradation of epoxy resins thermosets, consequently the flame retardancy of EP thermosets was improved.