High-molecular-weight (HMW) benzoxazines were synthesized by Mannich condensation with various combinations of bisphenols and diamines, and the mechanical and thermal properties of the polybenzoxazines derived from the HMW benzoxazines were measured by tensile tests and thermogravimetric analysis (TGA) to investigate the structure-property relationship. Free-standing precursor films were easily obtained from the solutions of HMW benzoxazines by a cast method on glass plates, and transparent and very tough polybenzoxazine films were obtained by thermally curing the precursor films at a temperature up to 240 °C. The polybenzoxazine films showed higher tensile strength and larger elongation at break than typical polybenzoxazine, i.e., PB-a obtained from low-molecular weight benzoxazine synthesized from bisphenol-A and aniline. In particular, among the HMW polybenzoxazines presented in this work, the PODP-oda film derived from 4,4′-oxydiphenol and 4,4′-oxydianiline showed remarkably good mechanical properties (E = 3.7 GPa, sb = 125 MPa, and eb = 4.5%). Moreover, the PODP-oda film revealed a higher 5 wt% weight loss temperature (Td5 = 332 °C) and char yield at 850 °C (CY850 = 58%) than PB-a (Td5 = 301 °C and CY850 = 42%), as evidenced by TGA, suggesting good thermal stability. High-molecular-weight (HMW) benzoxazines were synthesized by Mannich condensation with various combinations of bisphenols and diamines, and the mechanical and thermal properties of the polybenzoxazines derived from the HMW benzoxazines were measured by tensile tests and thermogravimetric analysis to investigate the structure-property relationship. Among the polybenzoxazines presented in this work, the PODP-oda film derived from 4,4′-oxydiphenol and 4,4′-oxydianiline showed remarkably good mechanical properties (E = 3.7 GPa, sb = 125 MPa, and eb = 4.5%) and thermal stability (Td5 = 332 °C).

中文翻译：

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双酚和二胺的各种组合通过曼尼希缩合合成高分子量苯并恶嗪及其热固性材料

通过曼尼希缩合与双酚和二胺的各种组合合成高分子量 (HMW) 苯并恶嗪，并通过拉伸试验和热重分析 (TGA) 测量衍生自 HMW 苯并恶嗪的聚苯并恶嗪的机械和热性能，以研究结构-性能关系。通过在玻璃板上的浇铸方法，很容易从 HMW 苯并恶嗪的溶液中获得独立的前体膜，通过在高达 240°C 的温度下热固化前体膜，可以获得透明且非常坚韧的聚苯并恶嗪膜。与典型的聚苯并恶嗪相比，聚苯并恶嗪薄膜显示出更高的拉伸强度和更大的断裂伸长率，即由双酚-A 和苯胺合成的低分子量苯并恶嗪获得的 PB-a。特别是，在这项工作中提出的 HMW 聚苯并恶嗪中，衍生自 4,4'-oxydiphenol 和 4,4'-oxydianiline 的 PODP-oda 薄膜显示出非常好的机械性能（E = 3.7 GPa，sb = 125 MPa，和 eb = 4.5% ）。此外，与 PB-a（Td5 = 301°C 和 CY850 = 42）相比，PODP-oda 薄膜在 850°C（CY850 = 58%）下显示出更高的 5 wt% 重量损失温度（Td5 = 332 °C）和炭产率%)，如 TGA 所证明的那样，表明良好的热稳定性。通过曼尼希缩合与双酚和二胺的各种组合合成高分子量 (HMW) 苯并恶嗪，并通过拉伸试验和热重分析测量衍生自 HMW 苯并恶嗪的聚苯并恶嗪的机械和热性能，以研究其结构特性关系。在这项工作中提出的聚苯并恶嗪中，