A new Schiff base flame retardant monomer with nitro group (NO₂), 5-((4-nitrobenzylidene) amino) isophthalic acid (NBA) was firstly synthesized to prepare fire-safety PET copolyester (NBA_nPET). The group of NO₂ passivated the cross-linking reactivity of Schiff Base by affecting the formation of the intermediate states of the cross-linking reaction and further to improve the cross-linking temperature of NBA_nPET to the temperature range (347–372 °C) from that of (250–348 °C), which showed better machinability in a broad processing temperature zone. In additional findings, the new synthesized NBA Schiff Base helped to shorten the time of polycondensation of PET with the advantage to save 58% of the reaction time by its acid structure. And the group of NO₂ enhanced the thermal stability of NBA_nPETs, which improved its residue char in high temperature to enhance its flame retardancy. NBA₁₀PET with NBA (7.9 mol%) processed LOI of 32% and V-0 of UL-94 without drip. The analysis of mechanism showed that the group of NO₂ in NBA did not decompose into the gas phase and NBA performed the mechanism of condensed phase during combustion of Schiff Base modified PET. The newly prepared NBA_nPET with these better properties could possess wider application prospects.

首先合成了一种新型的具有硝基（NO ₂），5-（（4-硝基苄叉基）氨基）间苯二甲酸（NBA）的席夫碱阻燃单体，以制备防火PET共聚聚酯（NBA _n PET）。NO ₂基团通过影响交联反应中间态的形成而钝化席夫碱的交联反应性，并进一步提高NBA _n的交联温度PET的温度范围为（250-348°C）的温度范围（347–372°C），在较宽的加工温度范围内均显示出更好的可加工性。在其他发现中，新合成的NBA Schiff碱有助于缩短PET的缩聚时间，其酸结构可节省58％的反应时间。NO ₂组增强了NBA _n PET的热稳定性，改善了其在高温下的残炭，从而提高了其阻燃性。NBA （7.9 mol％）的NBA ₁₀ PET处理的LOI为32％，UL-94的V-0无滴落。机理分析表明，NO ₂基团NBA中Schiff Base改性的PET在燃烧过程中没有分解成气相，并且NBA发生了冷凝相的机理。这些性能更好的新制备的NBA _n PET可能具有更广阔的应用前景。