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The effect of hydrogen bond on the thermal and mechanical properties of furan epoxy resins: Molecular dynamics simulation study
Polymer Testing ( IF 5.0 ) Pub Date : 2021-06-23 , DOI: 10.1016/j.polymertesting.2021.107275
Wanying Li , Jiahao Ma , Shinan Wu , Junying Zhang , Jue Cheng

The hydrogen bonds (H-bonds) are employed for the thermal and mechanical property enhancement of epoxy networks; however, the formation and evolution of H-bonds, especially in emerging bio-based furan epoxy, cannot be deeply understood at the atomic level in the traditional experimental method. Herein, molecular dynamic (MD) simulation is employed to clearly investigate the H-bonds, free volume and its distribution, mean square displacement, as well as their further influence on thermomechanical behaviors of selected model epoxy resins. The model epoxy resins composed of 2,5-bis [(2-oxiranylmethoxy)-methyl]-furan (BOF), 1,4-bis [(2-oxiranylmethoxy)-methyl]-benzene (pBOB) and 2.5-bis(2-oxiranylmethoxy)-methyl)-cyclopentadiene (BOC), which were cured by 4,4′-diamino diphenyl methane (DDM), respectively. These three epoxy molecules have very similar structure with the only difference in ring blocks of monomers from furan, benzene to cyclopentadiene. Wherein, BOC is artificially designed to further explore the influence of the oxygen atom of furan rings, with ensuring the consistency with the rotation and planarity of BOF. From contrastive simulation results, BOF-DDM has the highest Young's modulus among all these systems due to the least free volume leading by the maximum H-bonds. However, for DDM crosslinking networks, H-bonds seem to have limited influence on Tg of BOF-DDM, and the effect of molecular weight and steric hindrance on Tg is more decisive, which is different from the most relevant reports on furan-based epoxy. Our study gives the significant insight of H-bonds behavior of furan rings, and it is expected to effectively guide the design of epoxy resins.



中文翻译:

氢键对呋喃环氧树脂热力学性能的影响:分子动力学模拟研究

氢键(H 键)用于增强环氧树脂网络的热性能和机械性能;然而,传统实验方法无法在原子水平上深入理解氢键的形成和演化,尤其是在新兴的生物基呋喃环氧树脂中。在此,分子动力学 (MD) 模拟用于清楚地研究 H 键、自由体积及其分布、均方位移以及它们对所选模型环氧树脂的热机械行为的进一步影响。模型环氧树脂由 2,5-双 [(2-环氧乙烷甲氧基)-甲基]-呋喃 (BOF)、1,4-双 [(2-环氧乙烷甲氧基)-甲基]-苯 (pBOB) 和 2.5-双( 2-环氧乙烷基甲氧基)-甲基)-环戊二烯 (BOC),分别用 4,4'-二氨基二苯基甲烷 (DDM) 固化。这三种环氧分子具有非常相似的结构,唯一的区别是单体的环嵌段,从呋喃、苯到环戊二烯。其中,BOC经过人工设计,进一步探索呋喃环氧原子的影响,保证与BOF旋转和平面度的一致性。从对比模拟结果来看,BOF-DDM 在所有这些系统中具有最高的杨氏模量,这是由于最大 H 键导致的自由体积最小。然而,对于 DDM 交联网络,H 键似乎对 从对比模拟结果来看,BOF-DDM 在所有这些系统中具有最高的杨氏模量,这是由于最大 H 键导致的自由体积最小。然而,对于 DDM 交联网络,H 键似乎对 从对比模拟结果来看,BOF-DDM 在所有这些系统中具有最高的杨氏模量,这是由于最大 H 键导致的自由体积最小。然而,对于 DDM 交联网络,H 键似乎对BOF-DDM 的T g以及分子量和位阻对T g的影响更具有决定性,这与大多数有关呋喃基环氧树脂的报道不同。我们的研究为呋喃环的氢键行为提供了重要见解,有望有效指导环氧树脂的设计。

更新日期:2021-06-25
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