介孔FexOy纳米晶@超支化聚磷酰胺纳米杂化材料的可控制备及对聚丙烯协同增强、增韧和阻燃作用研究

Biased on the trends of new energy industry in development for lightweight, energy saving, safety, environmental protection, PP composites are required to satisfy many properties of low density, high strength, excellent toughness, high stability and easy processing. This proposal has designed and fabricated a hierarchically mesoporous FexOy nanocrystals @ hyperbranched poly(phosphamide) (HBPA) hybrid which will be used as PP additive. It is expected that designed compound has several advantages of forming good interfacial interaction with PP, low hydrodynamic volume, and multifunctional properties with reinforcing, toughing, heat resistance and flame retardancy. Mesoporous FexOy nanocrystals will be produced by using mesoporous silica template and hydrothermal method, and then be in situ grafted by HBPA to form hierarchically FexOy@HBPA hybrid with abundant terminal amino groups. We will discuss the effects of micro structural factors (including rigid factor, branching degree and molecular weight of HBPA, crystalline phase, dimension and size of FexOy nanocrystals, interfacial effect and microphase of PP/FexOy@HBPA composites) on the rheological (processing), mechanical, thermal and crystalline properties of PP composites to obtain the reinforcing and toughing mechanisms. We will also investigate the thermal degradation temperature and structure, the crystalline phase and pore size of mesoporous FexOy nanocrystals, the combustion process and residual structure of PP composites to analysis the flame retardant mechanism and the synergistic effects. These may provide a novel idea and experimental foundation for the design and preparation of PP additives with high efficiency and multi-properties.

基于新能源产业轻量化、节能、安全、环保等发展趋势，PP复合材料须满足低密度、强度高、韧性好、阻燃、耐热、易加工等要求，本项目设计合成了与PP相容性好，流体力学体积小，集增强、增韧、耐热与阻燃综合功能的介孔FexOy纳米晶@超支化聚磷酰胺（HBPA）杂化材料为PP助剂以实现PP复合材料的轻量化、高性能和多功能化。采用介孔硅模板和水热法制备系列介孔FexOy纳米晶并经HBPA原位接枝包覆后形成含端氨基的介孔FexOy@HBPA纳米杂化材料，研究HBPA的刚性因子、支化度、分子量及分布，FexOy晶型、形貌和尺寸，PP复合材料的界面和微相结构等对其流变（加工）、力学、热和结晶的影响规律，探索其增强、增韧机理；研究FexOy晶型和介孔结构，HBPA和PP复合材料的断裂能、热解温度、降解产物、燃烧参数、残炭结构等以弄清其阻燃和协同机理，为新型高效、多功能PP助剂的研发与应用提供新的思路和实验基础。

针对常规膨胀型阻燃剂的应用存在添加量高，热稳定性差，与基体相容性差，严重恶化基体力学性能等问题，本项目巧妙地设计了以介孔硅和氧化铁或碳纳米管为核，以三氯氧磷，二氨基化合物、氨基硅烷合成的超支化聚磷酰胺为壳组成的系列不同结构与形貌的，集金属催化和膨胀阻燃优点的杂化纳米粒子，并应用到聚丙烯（PP）及环氧树脂（EP）中取得了较好的阻燃效果及显著的增强增韧效果。具体如下：1）采用一步法合成的含硅烷的超支化聚磷酰胺（HBPPA-Si）与聚磷酸铵（APP）具有极好的阻燃协同作用，25%含量下可使PP复合材料达UL94V-0级，其热释放峰值（PHRR），总热释放量（THR）及总烟释放量（TSP）分别下降72.5%，35.8%和62.7%，且对PP复合材料的力学性能影响不大。2）制备了球型和棒状，不同晶型的系列杂化纳米粒子（HBPPA@FexOy, HBPPA@FexOy@SiO2），这种集金属催化和膨胀阻燃特征的纳米粒子与聚丙烯基体界面相容性较好，但需与HBPPA/APP协同使用，1wt%可显著改善PP复合材料的氧指数并缩短垂直燃烧时间，而棒状纳米粒子更能改善PP的力学性能。3）扩展了合成了HBPPA@CNT, HBPPA@SiO2等核壳纳米粒子及应用在环氧树脂中，发现其2%HBPPA@CNT可提高环氧树脂的阻燃性能（接近V0），且拉伸及冲击强度显著提高，显示出优异的阻燃及增强增韧作用。这些研究成果为获得具有兼有高效阻燃和增强增韧作用的杂化纳米粒子阻燃复合材料的设计与制备提供了重要的理论指导和必要的数据支撑。