EG与APP协同阻燃硬质聚氨酯泡沫塑料燃烧及热降解机理研究

将可膨胀石墨（EG）与聚磷酸铵（APP）复合用于阻燃硬质聚氨酯泡沫（RPUF），采用极限氧指数及锥形量热仪研究了EG/APP对RPUF燃烧性能的影响；通过扫描电镜、热失重分析及X射线光电子能谱表征了RPUF/EG/APP残炭的微观形貌、热降解行为及化学组成. 结果表明，添加质量分数20%、质量比为7:3的EG/APP阻燃RPUF的协同效果最好，氧指数可达36.0%，热释放速率最小，有一定的抑制产烟和CO释放的作用. 在阻燃RPUF燃烧过程中，EG热解残炭虽松散，但燃烧初期抑制烟气效果突出；APP残炭连续致密，但热稳定性不足，且易于生烟；而RPUF/EG/APP残炭隔热效果显著、抑制烟气效果较好. 其作用机理与多磷酸渗入EG残炭，增加了炭层的耐热性及炭层表面N/C、P/C元素摩尔比的增加有关. 

Combustion and Thermal Degradation Mechanism of Rigid Polyurethane Foams Modified with Expandable Graphite and Ammonium Polyphosphate

Expandable graphite (EG) and ammonium polyphosphate (APP) were used to improve flame retardancy of rigid polyurethane foams (RPUF). The combustion behaviour of RPUF/EG/APP was investigated by limiting oxygen index (LOI) and cone calorimeter test. The thermal degradation behaviour,the composition and micro-morphology of char were surveyed by TG, X ray photoelectron spectroscopy and scanning electron microscope, respectively.The results show that the optimum ratio of EG and APP is 7:3 and synergistic effect of EG and APP for RPUF is excellent when the addition level of EG/APP is 20%, the LOI reached to 36.0% and the heat release is minimum. In the combustion process of flame retardant RPUF, the smoke and CO suppressant effect of RPUF/EG is outstanding at prophase in spite of loose char layer, the char layer of RPUF/APP is continuous and dense but its thermal stability is insufficient and produced more smoke, and the char layer of RPUF/EG/APP has obviously effect on the insulation heat and has better effect on the inhibition of smoke and CO production. The mechanism of RPUF/EG/APP is related to the increase of thermal oxidation resistance and ratios of N/C and P/C on char surface when polyphosphoric acid permeated EG char layer.