结构可控的羧基纤维素/淀粉成炭剂的设计合成及膨胀阻燃环氧树脂机理研究

Reducing the smoke production and heat release of polymer materials significantly contributes to saving the human life and property in the fire. In the primary research of this project, a intumescent flame-retardant epoxy (EP/IFR) system was developed by blending carboxyl cellulose (ORC, the char forming agent) and polyformaldehyde encapsulated ammonium polyphosphate (MFAPP) into EP. The smoke and heat releases of EP/IFR were significantly decreased compared with EP owing to the formation of intumescent char residues with high ducility and high melt strength during the combustion. The aim of this project is to study the flame-retardant mechanism of EP/IFR containing ORC/OST and its meta salts via investigating the impact of char forming agent structure (ORC/OST metal salt) on the flame retardancy: I) the structures of char forming agents are differed by the ORC/OST structures prepared by hydrogen peroxide method. Then ORC/OST metal salt will be synthesized by bonding with metal ions and its intrinsic flame-retardant and thermal properties will be designed by varying the ORC/OST structures and meta salts. II) the variations of the compositions and structures of char residues are studied to illustrate the forming mechanism of intumescent char residues with high ducility and high melt strength. Mostly importance, the reaction mechanism of among ORC/OST, MFAPP and EP during thermal decomposition should be revealed, and responded to the high expand-char ducility of EP/IFR. III) The effects of metal ions on the reaction mechanism of ORC/OST metal salt, MFAPP and EP will be investigated, together with the mechanism of thermal expansion and pyrolysis of EP/IFR. Based on these exploring, a synergistic flame-retardant mechanism is going to be summarized between the intumescent char residue and metal ions. This project will promote a novel method to prepare eco-friendly, simple-preparation and high efficient intumecscent flame retardant, developing a novel flame-retardant technology and motivating by enriching the flame-retardant mechanism.

低烟、低热释放的阻燃高分子材料能减少火灾现场生命和财产损失，项目前期以羧基纤维素(ORC)为成炭剂与低添加量的聚甲醛包覆多聚磷酸铵（MFAPP）阻燃环氧树脂(EP)，形成高塑性炭层，有效解决膨胀炭层破裂问题，降低烟、热释放量。为探明该机制，项目以过氧化氢氧化制备结构可调羧基淀粉(OST)和ORC，拟与金属离子键合制备ORC/OST金属盐，经结构调控以获本征阻燃成炭剂。揭示燃烧过程ORC/OST、MFAPP和EP的反应对EP/IFR热分解成炭历程和炭层膨胀行为转变的机理及高塑性膨胀炭层原因。探明塑性膨胀炭层其阻隔效应的调控技术及对EP阻燃性能影响机制。考察燃烧过程金属离子对本征阻燃成炭剂EP/IFR组分反应的影响机制，研究EP/IFR膨胀行为和热分解机制，探明膨胀阻燃+固相阻燃+金属离子催化协同阻燃EP的机理。项目为合成绿色、高效膨胀阻燃剂提供新方法，推动阻燃新技术发展，完善高分子阻燃理论。

膨胀阻燃剂（IFR）具有优异的阻燃抑烟性能，用于制造膨胀阻燃环氧树脂（IFR-EP）可促进环氧树脂（EP）在电子电子电气、航空航天和化学工业等领域的应用。项目开拓了一种用于提高IFR-EP阻燃抑烟性能的基于羧基纤维素或蔗糖的新型膨胀阻燃体系。采用H 2 O 2氧化再生纤维素(RC)和微晶纤维素（MCC），以羧基纤维素或蔗糖作为生物基新型成炭剂。制备氧化再生纤维素（ORC）及测定其羧基含量，探索羧基含量对IFR-EP体系阻燃抑烟性能的影响规律，阐述IFR-EP体系形成高膨胀不破裂炭层的阻燃机理及演变规律。合成会形成超高膨胀比(41.5 倍)膨胀炭层的IFR-EP（EP/MFAPP/ORC27），其残留量(41.8%)比纯 EP 提高了 9.7 倍，放热率峰值（PHRR）、总热量释放（THR）和烟雾生成率（TSP）分别下降55.6%、61.8%和62.2%。极限氧指数（LOI）达到30.3%，UL-94等级达到V-0，提出“异相成炭剂”的全新概念，为制备高塑性膨胀炭层提供了新方法，发展了膨胀阻燃理论。研究 IFR-EP 复合材料在高温环境下的燃烧过程和分解特征，揭示炭层在高温环境下的演变规律。采用 H2O2 氧化MCC制备氧化微晶纤维素（OMCC），以OMCC作为 IFR-EP（EP/MFAPP(3.75wt.%)/OMCC(5wt.%)）中的成炭剂， 发现UL-94 等级达到 V-0，LOI为 28.6%，且1-3 min 内，基体外部受热软化部分分解，3-5 min 是建立膨胀炭层结构的过程，该阶段上述IFR-EP 复合材料质量损失最大、P 元素损失最多，5 min 以后形成稳定的炭层。研究单糖、二糖、低聚糖对IFR-EP 复合材料阻燃抑烟性能的影响，基于二糖的阻燃性能要优于单糖和低聚糖，选用WS作为成炭剂，阐述WS在IFR-EP（EP/MFAPP(5 wt.%)/WS(5 wt.%)）复合材料中的抑烟机理。上述IFR-EP体系的UL-94达到 V-0评级，LOI值为 27.8%，并且 TSP 值与纯 EP 相较降低了 76%。在 190-220℃，WS 转化为焦糖与MFAPP 结合，MFAPP-WS 的存在有利于 EP 形成更连续、更紧密的炭层，更有效地隔绝热量的传递和可燃气体的扩散，并且炭层形成的尺寸均一的“小气室”会储存燃烧过程中产生的烟雾，为以高膨胀炭层阻隔