Abstract It is low cost and feasible to improve the mechanical properties of polyurethane by using the chain extender with hydrogen bonding function to improve the degree of microphase separation. In this article, hydrazine hydrate was used to react with ethylene carbonate and propylene carbonate, respectively, to synthesize diacylhydrazines as the polyurethane chain extender with amide bonds, which were characterized by 1H nuclear magnetic resonance. Polyurethane with different contents of hard segment were prepared from poly-3,3-bis(azidomethyl)oxetane-tetrahydrofuran as the polyol and 4,4′-diphenylmethane diisocyanate as the isocyanate components. Fourier transform infrared spectroscopy showed that with the increase of the hard segment content, the proportion of hydrogen-bonded ordered carbonyl group increased to 94%, proving that diacylhydrazines could improve the degree of ordered hydrogen bonding, which led to clear microphase separation observed by field emission scanning electron microscopy and higher storage modulus of the polyurethane. Differential scanning calorimetry and dynamic mechanical analysis showed that polyurethane with higher hard segment content is likely to exhibit multiple thermal transitions caused by microphase separation. When the hard segment content was 40%, compared with polyurethane with 1,4-butanediol as the chain extender, the tensile strengths of polyurethanes with diacylhydrazines also improved by 30% and 76%, respectively. Graphical abstract As a chain extender with amide bonds, dihydrazide improves the ratio of the ordered hydrogen bond, the degree of microphase separation and mechanical properties of polyurethane elastomer.

中文翻译：

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二酰基肼作为扩链剂对含能聚氨酯弹性体微相分离及性能的影响

摘要 利用具有氢键功能的扩链剂提高微相分离度，提高聚氨酯的力学性能成本低、可行。本文采用水合肼分别与碳酸亚乙酯和碳酸亚丙酯反应，合成了二酰基肼作为具有酰胺键的聚氨酯扩链剂，经1H核磁共振表征。以聚-3,3-双（叠氮甲基）氧杂环丁烷-四氢呋喃为多元醇，4,4'-二苯基甲烷二异氰酸酯为异氰酸酯组分，制备了不同硬链段含量的聚氨酯。傅里叶变换红外光谱表明，随着硬链段含量的增加，氢键有序羰基的比例增加到94%，证明二酰基肼可以提高有序氢键的程度，从而导致场发射扫描电子显微镜观察到清晰的微相分离和更高的聚氨酯储能模量。差示扫描量热法和动态力学分析表明，硬链段含量较高的聚氨酯可能会出现由微相分离引起的多次热转变。当硬链段含量为40%时，与含1,4-丁二醇作为扩链剂的聚氨酯相比，含二酰基肼的聚氨酯的拉伸强度也分别提高了30%和76%。图文摘要二酰肼作为具有酰胺键的扩链剂，提高了聚氨酯弹性体的有序氢键比例、微相分离度和力学性能。