论文题目：硼酸锌-线型三嗪杂化成炭剂的合成及其催化成炭阻燃聚丙烯的研究
毕业学生：刘肇闻
指导教师：吴唯
中文摘要：
聚丙烯（PP）具有无毒、力学性能优异和易加工等特性，被广泛应用于建筑、国防军工、农业薄膜等应用领域。然而，在空气中 PP 易燃烧且在燃烧过程中产生大量的熔滴，这影响了它的广泛使用。因此，有必要对 PP 材料阻燃改性。本论文主要做了以下研究工作：
（1）以三聚氯氰（CYC）、乙二胺（EDA）、γ-氨丙基三乙氧基硅烷（KH550）和硼酸锌（ZB）等为原料，合成了一种不易迁移和与聚合物相容性好的硼酸锌-线型三嗪杂化成炭剂（MCA-K-ZB）。经实验得到了最优合成条件：CYC、EDA 和 KH550 的摩尔比为 1:1:1 时，将 CYC 和 EDA 在 0℃下和碱液反应 3h，再升温至 45℃，与 EDA 和碱液继续反应 3h，可得到中间体产物；最后，将中间体和经 KH550 改性后的 ZB 在 95℃ 下继续反应 6h。利用傅里叶红外和碳谱固体核磁共振等分析手段证明了 MCA-K-ZB 的化学结构；热重分析（TGA）表明 MCA-K-ZB 具有优异的热稳定性和成炭性能。
（2）基于 MCA-K-ZB 优异的成炭性能和热稳定性，通过熔融共混法制备了以MCA-K-ZB 为成炭剂和聚磷酸铵（APP）为酸源的膨胀阻燃 PP 材料。燃烧实验表明：加入 25wt% APP/MCA-K-ZB（3/1，w/w）可使得 PP 的极限氧指数（LOI）值达到 32.7%，达到 UL-94 V-0 等级；PP/APP/MCA-K-ZB 的热释放速率峰值和生烟速率峰值分别为136kW/m2 和 0.0187m2/s，相比于纯 PP 分别下降了 85.6%和 77.0%。TGA 结果表明:APP/MCA-K-ZB 体系之间存在明显的协同效应，可以促进 PP 材料发生成炭反应。机理研究表明：燃烧过程中 APP/MCA-K-ZB 可以促进石墨化结构残炭的形成和保留更多的阻燃元素在凝聚相中，从而比APP/MCA-K/ZB 体系有更好的阻燃效果。
（3）利用具有高热稳定性的 4A 沸石与 IFR（APP/MCA-K-ZB）协同阻燃 PP，研究了它的质量百分比对 PP/IFR 阻燃性能和热稳定性能的影响。燃烧测试表明：当IFR/Zeolite 的总添加量为 22wt%，用 1wt%的 4A 沸石替代等质量的 IFR 时，阻燃 PP 样品的 LOI 值可从 29.5%提升到 33.1%，达到 UL-94 V-0 等级；少量的 4A 沸石就可明显减少 PP/IFR 的热释放速率、总体热释放量和质量损耗速率。阻燃机理研究表明：燃烧过程4A沸石催化PP/IFR发生成炭反应并将凝聚相中部分炭残余从无定形结构转变为石墨化结构，这不仅增加了凝聚相中的炭残余量，而且提高了膨胀炭层的热稳定性和 IFR在 PP 材料中的阻燃效率。
Abstract:
Polypropylene (PP) has been extensively applied in many fields such as building, national defense and agricultural film and other applications owing to its superior mechanical property, ease-processing, low toxic and so on. However, PP is a flammable material with a tendency to melt dripping during combustion. Therefore, it is necessary to modify the
flame-retardant PP material. This dissertation has done the following research work.
(1) Cyanuric cyanide (CYC), ethylene diamine (EDA), zinc borate (ZB), and γ-aminopropyltriethoxysilane (KH550) were selected as raw materials to prepare a zinc borate-linear triazine hybrid charring agent (MCA-K-ZB), which is not easily migrated and precipitated, and has good compatibility with polymers. The optimal synthesis conditions were obtained through experiments: when the molar ratio of CYC/EDA/KH550 was 1:1:1, the intermediate product could be prepared by reacting CYC and EDA with an alkaline solution at 0 ℃ for 3 h, then reacting with EDA and an alkaline solution at 45 ℃ for 3 h. Finally, Intermediate and KH550-modified ZB were further reacted in dioxane, maintaining at 95℃ for 6 h. The chemical structure of MCA-K-ZB were confirmed by Fourier transform infrared spectroscopy and 13C Nuclear magnetic resonance analysis. Thermogravimetric analysis (TGA) showed that MCA-K-ZB displayed outstanding thermal stability and char formation ability.
(2) Based on MCA-K-ZB's excellent char formation ability and high thermal stability, an intumescent flame-retardant PP composite based on MCA-K-ZB (carbon-forming agent) and APP (acid source) was prepared by melt blending. Combustion tests shown that the limiting oxygen index (LOI) of PP/APP/MCA-K-ZB composites consisting of 18.75wt% APP and 6.25wt% MCA-K-ZB was as high as 32.7%, and could reach UL-94 V-0 rating. Meanwhile, the peak heat release rate and peak smoke generation rate of PP/APP/MCA-K-ZB were 136kW/m2 and 0.0187m2/s, respectively, which were 85.6% and 77.0% lower than those of pure PP. TGA shown that there was a synergistic effect between APP and MCA-K-ZB, which could promote the char formation reaction of PP materials. The mechanism research shows that APP/MCA-K-ZB could promote the formation of more graphitized structure char residues and retain more flame-retardant elements in the condensed phase, thus resulting a much better flame retardancy than APP/MCA-K/ZB.
(3) 4A zeolite with high thermal stability was combined with IFR (APP/MCA-K-ZB) to prepare an intumescent flame-retardant PP composite, and the effect of its amount on the flame retardancy and thermal stability of flame-retardant PP composite was studied. The combustion tests showed that when 22 wt.% IFR/Zeolite was added, and the equivalent mass of IFR was replaced by 1wt% 4A zeolite, the LOI value of PP/IFR increased from 29.5% to 33.1%, and passed the UL-94 V-0 rating. Meanwhile, a small amount of 4A zeolite could significantly reduce the heat release rate, total heat release and mass loss rate of PP/IFR composites. The mechanism study showed that 4A zeolite could catalyze the carbon formation reaction in the PP/IFR system during the combustion process, thereby increasing the amount of residual carbon in the condensed phase. Besides, 4A zeolite could transform the amorphous structure to graphitized structure in the char residue, thus improving the thermal stability of char residue and enhancing the flame-retardant efficiency of IFR in PP material.
