Tannic acid (TA) is a bio-based high-molecular-weight organic molecule. Although biologically sourced, TA is a pollutant in industrial wastewater streams, and there is desire to find applications in which to downcycle this molecule. Many flame retardants (FRs) used in epoxy are synthesized from petroleum-based monomers. Various bio-based modifiers have been developed, but increasing the flame retardancy of the system without trade-offs with other properties has proved challenging. In this work, TA is incorporated into the thermoset. The molecular behavior of the system was dependent on the TA loading, with low concentrations causing the molecule to be surface-functionalized, while at higher concentrations the molecule was cross-linked into the network. The material was further characterized for its cross-link density, thermal stability, mechanical and thermomechanical properties and FR ability. In this work, TA was found to work well as an intumescent agent but did not reduce the heat release rate. The results of this study suggest that the external (hydrophilic surface-phenol groups) and internal (d-glucose and attached phenyl groups) structural regions of the TA molecule impact the FR ability of the molecule in epoxy separately. Maintaining the structural integrity of both regions is critical to the synergistic FR behavior of the molecule.

中文翻译：

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基于单宁酸的预聚物体系，可增强环氧热固性材料的膨胀

单宁酸（TA）是一种基于生物的高分子量有机分子。尽管TA是生物来源的，但它却是工业废水中的污染物，因此人们希望找到可将该分子进行下循环的应用。环氧中使用的许多阻燃剂（FRs）是由石油基单体合成的。已经开发了多种生物基改性剂，但是在不牺牲其他性能的前提下提高系统的阻燃性已被证明具有挑战性。在这项工作中，TA被并入了热固性塑料。系统的分子行为取决于TA的负载量，低浓度会导致分子被表面官能化，而高浓度会导致分子交联到网络中。该材料的交联密度，热稳定性，机械和热机械性能以及阻燃能力。在这项工作中，发现TA可以很好地用作膨胀剂，但不会降低放热率。这项研究的结果表明，外部（亲水性表面酚基团）和内部（亲水性酚基团）TA分子的d-葡萄糖和连接的苯基）结构区分别影响该分子在环氧树脂中的FR能力。维持两个区域的结构完整性对于分子的协同FR行为至关重要。