Alkyl hypophosphate flame retardants have aroused intense research interests in flame retardancy of polymers owing to the combined effect of gas phase and condensed phase. In this work, aluminum diisobutyl hypophosphate (APBA) was incorporated into polyethylene glycol terephthalate (PET) to investigate its flame retardant effect and mechanism. PET achieved a V-2 level in UL-94, with a low LOI of 21.2%. In contrast, PET/APBA-15% composites showed a 51% increase of LOI value and a V-0 level, accompanied with the significant reduction of melt droplets. Gas phase analysis by Py-GC/MS and TG-FTIR indicated that the phosphorous free radicals and nonflammable gases were generated during the cracking of APBA, resulting in the radical quenching and dilution of combustible gas. Condensed phase analysis by SEM, Raman, and XPS results revealed that APBA could effectively facilitate the formation of dense char layers consisting of aluminophosphate and graphitic structures due to the interaction with PET matrix. The compact barrier layer could insulate heat and inhibit the volatilization of combustible materials, leading to improved flame retardant properties. Furthermore, the introduction of APBA increased the melt viscosity of PET/APBA composites according to rheological analysis, which further promoted the formation of a char barrier layer to further enhance the flame retardant properties.

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二异丁基连二磷酸铝在聚对苯二甲酸乙二醇酯中的作用及其阻燃机理

烷基连二磷酸酯阻燃剂由于气相和凝聚相的共同作用，引起了聚合物阻燃领域的广泛研究兴趣。本工作将二异丁基连二磷酸铝（APBA）掺入聚对苯二甲酸乙二醇酯（PET）中，研究其阻燃效果和机理。PET 在 UL-94 中达到 V-2 级别，LOI 低至 21.2%。相比之下，PET/APBA-15% 复合材料的 LOI 值提高了 51%，达到 V-0 水平，同时熔滴显着减少。Py-GC/MS和TG-FTIR气相分析表明APBA裂解过程中产生磷自由基和不燃气体，导致自由基猝灭和可燃气体稀释。SEM、拉曼和 XPS 的凝聚相分析结果表明，由于与 PET 基质的相互作用，APBA 可以有效促进由铝磷酸盐和石墨结构组成的致密炭层的形成。致密的阻隔层可以隔热并抑制可燃物质的挥发，从而提高阻燃性能。此外，根据流变分析，APBA的引入增加了PET/APBA复合材料的熔体粘度，这进一步促进了防炭层的形成，从而进一步增强了阻燃性能。