Abstract Molecular designing flexibility offered by benzoxazine chemistry, has been utilized to synthesize side-chain benzoxazine functionalized resins, in one-step approach via reaction of polyethylenimine (PEI) and guaiacol. The functionalization of polyethylenimine bearing amine functionalities, with benzoxazine groups as side-chains, is expected to confer a densely cross-linked network in the resulting thermoset. In the present work, guaiacol has been chosen as bio-based phenol, and polyethylenimine enriched with primary, secondary, tertiary amine groups, has been employed as an amine co-reactant. The reactants stoichiometry (phenol: amine: paraformaldehyde) has been varied from 2:1:4 to 20:1:40 molar ratio, resulting in a series of side-chain type guaiacol based benzoxazine-functionalized polyethylenimine resins (G-pei), which differ in percentage of oxazine functionalization. All the resins prepared have been characterized using FTIR, 1H, 13C NMR spectroscopies, and the evolution of oxazine functionalization in the resins has been monitored via 1H NMR spectroscopy. The polymerization behaviour in resins has been evidenced using non-isothermal DSC studies, which reveals that G-pei resins exhibit peak polymerization temperature (Tpeak) below 200°C. Temperature sweep rheological experiments have been performed to obtain flow behaviour and processing window of the developed resins, where an evident reduction in the viscosity of resins has been observed around 100°C, thereby making it an appropriate temperature for processing. The influence of polar groups on the surface property of thermosets has been investigated by performing contact angle measurements, which reveals the hydrophilic nature of prepared thermosets. Thermal degradation behaviour of the multifarious bio-based thermosets, has been studied using thermogravimetric analysis, where maximum degradation temperature (Tmax) for the cured specimens has been found to be above 300°C, with a high char yield (30 to 50%). The influence of dense network on the glass transition temperature of thermosets, has been additionally studied by DSC experiments. The adhesive performance of side-chain type benzoxazine-functionalized polyethylenimine resins, enriched with oxazine functionalities as well as polar groups, has been evaluated by lap shear strength values, which have been observed in the range of 22 to 49 Kg/cm2.

中文翻译：

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调整基于愈创木酚和聚乙烯亚胺的多种苯并恶嗪树脂的结构和性能

摘要 苯并恶嗪化学提供的分子设计灵活性已被用于通过聚乙烯亚胺 (PEI) 和愈创木酚反应一步法合成侧链苯并恶嗪官能化树脂。带有胺官能团的聚乙烯亚胺的官能化，以苯并恶嗪基团作为侧链，有望在所得热固性塑料中赋予密集的交联网络。在目前的工作中，愈创木酚被选为生物基苯酚，富含伯、仲、叔胺基团的聚乙烯亚胺被用作胺共反应物。反应物的化学计量（苯酚：胺：多聚甲醛）从 2:1:4 到 20:1:40 的摩尔比变化，产生了一系列侧链型愈创木酚基苯并恶嗪官能化聚乙烯亚胺树脂（G-pei），它们的不同之处在于恶嗪官能化的百分比。所有制备的树脂均已使用 FTIR、1H、13C NMR 光谱进行表征，并且树脂中恶嗪官能化的演变已通过 1H NMR 光谱进行监测。使用非等温 DSC 研究证实了树脂中的聚合行为，这表明 G-pei 树脂的聚合峰值温度 (Tpeak) 低于 200°C。已经进行了温度扫描流变实验以获得所开发树脂的流动行为和加工窗口，其中在 100°C 左右观察到树脂的粘度明显降低，从而使其成为加工的合适温度。通过进行接触角测量研究了极性基团对热固性塑料表面性质的影响，这揭示了制备的热固性塑料的亲水性。已经使用热重分析研究了多种生物基热固性塑料的热降解行为，发现固化样品的最大降解温度 (Tmax) 高于 300°C，并具有高炭产率（30% 至 50%） . 密集网络对热固性材料的玻璃化转变温度的影响，已通过 DSC 实验进行了额外研究。富含恶嗪官能团和极性基团的侧链型苯并恶嗪官能化聚乙烯亚胺树脂的粘合性能已通过搭接剪切强度值进行评估，观察到的范围为 22 至 49 Kg/cm2。已经使用热重分析进行了研究，发现固化样品的最大降解温度 (Tmax) 高于 300°C，并具有高焦化率（30% 至 50%）。密集网络对热固性材料的玻璃化转变温度的影响，已通过 DSC 实验进行了额外研究。富含恶嗪官能团和极性基团的侧链型苯并恶嗪官能化聚乙烯亚胺树脂的粘合性能已通过搭接剪切强度值进行评估，观察到的范围为 22 至 49 Kg/cm2。已经使用热重分析进行了研究，发现固化样品的最大降解温度 (Tmax) 高于 300°C，并具有高焦化率（30% 至 50%）。密集网络对热固性材料的玻璃化转变温度的影响，已通过 DSC 实验进行了额外研究。富含恶嗪官能团和极性基团的侧链型苯并恶嗪官能化聚乙烯亚胺树脂的粘合性能已通过搭接剪切强度值进行评估，观察到的范围为 22 至 49 Kg/cm2。已经通过 DSC 实验进行了额外的研究。富含恶嗪官能团和极性基团的侧链型苯并恶嗪官能化聚乙烯亚胺树脂的粘合性能已通过搭接剪切强度值进行评估，观察到的范围为 22 至 49 Kg/cm2。已经通过 DSC 实验进行了额外的研究。富含恶嗪官能团和极性基团的侧链型苯并恶嗪官能化聚乙烯亚胺树脂的粘合性能已通过搭接剪切强度值进行评估，观察到的范围为 22 至 49 Kg/cm2。