随着植物纤维增强聚烯烃复合材料在建材、室内装饰等应用领域的不断扩大，材料的防火安全性能越来越受到重视。纳米二氧化硅和聚磷酸铵可以产生阻燃协效作用，赋予材料阻燃特性。本项目以稻秸表面通过生物矿化作用形成的纳米二氧化硅为研究对象，深入研究生物质纳米二氧化硅在稻秸表面的分布规律和结构特性，并在此基础上，在稻秸表面构筑生物质纳米二氧化硅与聚磷酸铵的原位聚合反应，阐述生物质纳米二氧化硅/聚磷酸铵原位聚合的反应过程和聚合机制；然后，将原位聚合后的稻秸与高密度聚乙烯进行复合，深入探讨稻秸/聚乙烯复合材料热解燃烧过程中，生物质纳米二氧化硅催化聚磷酸铵的酯化、脱水和交联反应、促进炭层形成的过程，提出生物质纳米二氧化硅/聚磷酸铵的阻燃协效机理。本项目的研究成果充分利用稻秸中的硅资源，使其变废为宝，为植物纤维增强聚烯烃复合材料的阻燃技术提供理论依据和技术支撑。

Flammability is one of the important parameters that often limits the application of plant fiber reinforced thermoplastic composites to constructions and interior decoration. Recently, the synergistic effect between nano-SiO2 and ammonium polyphosphate (APP) in polymer and composites has been extensively investigated, and study has showed that the novel nano-SiO2/APP flame retardant could promote char formation, and improve the thermal stability of the char layer formed during combustion. Bio-nano-SiO2, which is widely distributed in the surface of rice straw through biomineralization, could be also used as a synergistic agent of APP. However, very limited studies have been investigated the formation and contribution of the synergistic effect of bio-nano-SiO2 and APP because of the special distribution and complex structure of bio-nano-SiO2 in the surface of rice straw. This study will be focus on (1) the mechanism of in situ polymerization between bio-nano-SiO2 and APP by studying the distribution and properties of bio-nano-SiO2; (2) the synergistic mechanism of bio-nano-SiO2 and APP in the high-density polyethylene composites reinforced with rice straw through etherification, dehydration and crosslinking reactions catalyzed by bio-nano-SiO2. The conclusions from this study would promote the theory and technology development in the fields of flame retardancy of plant fiber reinforced thermoplastic composites by utilization of silica, which widely existed in rice straw.