中文摘要：

将具有封闭空心结构的酚醛微球（HPMs）引入到聚丙烯／膨胀阻燃剂（PP／IFR）体系，燃烧时一方面依托PP／IFR形成膨胀多孔炭，另一方面通过HPMs形成空心炭微球，嵌入到前面多孔炭的骨架中，形成具有多层次孔的炭结构，从而调控膨胀炭层，进而调节材料的阻燃性能．通过极限氧指数（LOI）、垂直燃烧（UL-94）等研究了材料的阻燃性能；通过热失重分析（TGA）测试其热稳定性；采用红外热成像仪监测燃烧过程材料的表面温度，用扫描电镜（SEM）观察IFR、HPMs在基体中的分散行为及炭层结构．结果表明，少量HPMs在聚合物中分散得比较均匀．HPMs调控了膨胀炭层，使PP／IFR形成了表层炭致密，内层具有多层次孔的炭结构．这种优质的炭结构可以使样品表面温度迅速降低，从而有效提高PP／IFR体系的阻燃效率，使得PP在添加18wt％IFR和1wt％HPMs就可以通过UL-94V0级别．

英文摘要：

Hollow phenolic microspheres （HPMs） with closed hollow structure were introduced into polypropylene/intumescent flame retardant （PP/IFR） composites. On the one hand,induced by IFR in PP, intumescent char was formed; on the other hand, hollow carbon microsphere was formed from HPMs during combustion,and it would be embedded in the backbone of the intumescent char layer. Thus a hierarchically porous char was constructed to regulate the intumescent char layer and to improve the flame retardancy of PP/ IFR composites. The flame retardant properties of PP/IFR composites were measured by using the limiting oxygen index （LOI） and vertical burning （UL-94）. The thermal degradation behaviors were tested by thermal gravimetric analysis （TGA）. The surface temperature was detected by Infrared Thermal Imager during the test of UL-94. The dispersion behaviors of IFR and HPMs and char morphology were observed by scanning electron microscopy （ SEM）. The results showed that no more than 1 wt% HPMs was dispersed uniformly into PP. The PP composites passed UL-94 V0 test at total addition of 18 wt% IFR and 1 wt% HPMs,while the samples containing 20 wt% IFR or HPMs could not be classified in UL-94 test. This indicated good synergistic effect between IFR and HPMs in PP composites. Observing from the photos after burning, a few char residues were formed for PP/IFR and PP/HPMs but the char volume for PP/IFR/HPMs was increased evidently. TGA results showed that char residues for PP/IFR/HPMs were more than that for other samples. Moreover, HPMs modified the intumescent char morphology well. It caused a dense surface of the char and induced the inside char to form hierarchical porous structure. The intumescent char layer with high quality decreased the superficial temperature quickly, prevented fuel and heat transfer from outside to inside, causing the flame extinguished. It was because of the improved char quantity, modified char quality and hierarchically porous char,which resulted in the increased flame retardant