多金属氧酸盐离子液体催化膨胀阻燃体系高效阻燃机理研究

Introducing catalyst or synergist into intumescent flame retardant (IFR) system is one simple, convenient and effective way to improve its flame retardant efficiency. In this work, polyoxometalates-based ionic liquid (PIL) is used as a catalyst in a traditional IFR system. The compatibility and matchable quality between flame retardants and matrix can be modified; the charring and flame retardant efficiency of material can be improved; and the combination properties of composites can be mediated because of the variety of topological structure, tunability of size, participatory of multielement for PIL. The effects of PIL on the charring speed and residue are studied by comparing the calculated (cal.) and experimental (exp.) curves based on their percentages in their system obtained from thermogravimetric analysis. The relationships between the components, structure, content, anion, cation of PIL and the flame retardant properties are investigated, respectively. The whole process of cross-linking, charing, expanding, and anti-flaming will be explored. The roles of in-organic construct block, organic structure and morphology of PIL played in the flame retardant efficiency will be discovered. Based on the above results, the process of charring catalyzed by PIL and synergistic mechanism in flame retardant materials will be clarified, which is important for revealing the objective laws governing the flame retardant efficiency. This work will provide a novel thought for designing and preparing of polymer composites with high efficiency in synergistic intumescent flame retardant system, and it will also broaden the application of PIL catalyst in flame retardant field.

引入催化剂或协同剂是提高膨胀阻燃剂效率的一条简便有效的途径。申请者提出将多金属氧酸盐离子液体（PIL）作为催化剂引入到传统的膨胀阻燃材料中，利用PIL拓扑结构的多样性、尺寸的可调变性和多元素的参与性调控其催化活性，调节其与阻燃剂和基体的匹配性和相容性，提高成炭和阻燃效率，进而调和阻燃材料的综合性能。通过阻燃剂体系在热失重过程中各组分质重损失的计算结果与实际测试结果的对比，探索PIL对膨胀阻燃剂体系成炭速度和成炭量的影响；分别研究PIL的组成、结构、添加量以及其阴离子和阳离子在聚合物交联成炭和膨胀阻燃过程中的作用，揭示无机构筑单元和有机基团及PIL的结构和形态对阻燃效率的贡献；全面分析各种途径得到的数据，阐明催化成炭和协同阻燃机理，这对于揭示高效阻燃体系的内在规律具有重要意义。本课题的研究结果将为高效阻燃材料的设计和制备提供一种新的思路，同时也拓宽了PIL类催化剂在阻燃领域的应用。

本项目通过改变阴离子与阳离子的结构，制备了一系列不同结构的多金属氧酸盐(PILs)；将这些PILs分别与膨胀型阻燃剂（IFR）复合，构建高效协同阻燃体系，用于提升聚丙烯（PP）的阻燃效率。系统研究了阴离子和阳离子对阻燃性能的影响，阐明了阻燃机理，揭示了阴阳离子结构和性能对阻燃效率的贡献。得到的主要结论如下：阴离子中磷钼酸和钴钨酸在聚丙烯中的协同效果最好，分别添加0.5wt%磷钼酸咪唑盐/14.5wt%IFR或1wt%钴钨酸咪唑盐/16wt%IFR，可以使PP通过UL-94V0测试，若不添加PILs则需要25wt%IFR才能使PP通过UL-94V0测试，说明PILs大幅提升了APP/PER的阻燃效率。磷钼酸盐有颜色，而钴钨酸则基本无色，说明杂原子可以调节PILs的物性，使其颜色变浅； 阳离子中咪唑、三聚氰胺的作用比较好，但是当咪唑的取代基中烷基链过长时，反而会引起阻燃效率降低；此外当阳离子为金属离子钠和锌时，催化阻燃效果也比较优异。然而当将多金属氧酸阴离子插到粘土层间或负载到聚磷腈微球上时，由于催化活性点被覆盖，反而协同作用较差。总而言之，阴阳离子均对阻燃性能产生较大影响，其中阴离子主要起催化作用，阳离子主要调控阴离子的催化作用，两者形成的多金属氧酸盐可以调节膨胀阻燃聚丙烯的成炭过程，进而改变了炭的多孔结构和完整性，从而能够发挥更好的阻隔作用，因而提升了阻燃效率；在整个过程中，形成的炭的化学结构并无不同，只是调控了膨胀发泡的过程，避免了缺陷的产生。