Novel castor oil-based waterborne polyurethane (CWPU) sizing coatings prepared by replacing traditional petroleum-based petrochemical products with natural renewable bio-extracts are attracting the attentions in the carbon fibre (CF) reinforced epoxy (EP) composites industries. However, CWPU coatings prepared using only castor oil (CO), diisocyanate, and carboxylate hydrophilic chain extender suffer from poor thermal stability, insufficient mechanical strength and weak adhesion. For enhancing the thermo-mechanical properties of CWPU coatings, as well as the surface wettability and interfacial adhesion to the substrates when serving as fibre sizing coatings and as interphases of the CF/EP composites, a compound cross-linker with tri-acrylate branched and tri-isocyanate chain-endings was synthesized and used to prepare hyperbranched CWPU with CO-acrylate-isocyanate interpenetrating cross-linking networks. CWPU coatings revealed favourable thermodynamic performance achieving a T5% decomposition temperature and toughness of 271.8 °C and 36.2 MJ/m³. CWPU coatings imparted excellent wettability to CF through oxygen-containing polar groups and synergy between covalent/hydrogen bonding, resulting in an increase in fibre surface energy to 61.0 mN/m. Stable and robust interphases were constructed in the CF/EP composites by CWPU coatings through "polar similarity compatibility" and multiple physico-chemical reactions. The flexural modulus, interlaminar shear strength, and interfacial shear strength of CWPU-CF/EP were increased by 54.8 %, 36.6 %, and 58.9 %, respectively, compared with those of the unsized CF/EP composites. The research contributes to the development and industrial production of high-performance, eco-friendly bio-based water soluble organic coatings.

中文翻译：

---

超支化生物基水性浸润剂涂料，用于增强碳纤维的润湿性和纤维/环氧树脂复合材料的界面附着力


通过用天然可再生生物提取物替代传统的石油基石化产品制备的新型蓖麻油基水性聚氨酯 （CWPU） 施胶涂料正在引起碳纤维 （CF） 增强环氧树脂 （EP） 复合材料行业的关注。然而，仅使用蓖麻油 （CO）、二异氰酸酯和羧酸盐亲水扩链剂制备的 CWPU 涂层存在热稳定性差、机械强度不足和附着力弱等问题。为了提高CWPU涂层的热机械性能，以及作为纤维浸润剂涂层和CF/EP复合材料的界面时，表面润湿性和与基材的界面粘附性，合成了一种具有三丙烯酸酯支链末端和三异氰酸酯链端的化合物交联剂，用于制备具有CO-丙烯酸酯-异氰酸酯互穿交联网络的超支化CWPU。CWPU 涂层显示出良好的热力学性能，达到 T5% 分解温度和 271.8 °C 和 36.2 MJ/m³ 的韧性。CWPU 涂层通过含氧极性基团和共价/氢键之间的协同作用赋予 CF 优异的润湿性，导致纤维表面能增加到 61.0 mN/m。通过 CWPU 涂层通过“极性相似相容性”和多种物理化学反应，在 CF/EP 复合材料中构建了稳定而稳健的界面。与未施胶的 CF/EP 复合材料相比，CWPU-CF/EP 的弯曲模量、层间剪切强度和界面剪切强度分别提高了 54.8 %、36.6 % 和 58.9 %。该研究有助于高性能、环保型生物基水溶性有机涂料的开发和工业生产。