Toughening thermo‐setting resins with both high impact strength and tensile strength is a challenging issue. In this study, a novel cross‐linked polyurethane nano spheres for toughening epoxy resin were prepared by self‐emulsification method with hexamethylene diisocyanate trimer (HDI trimer) and diethylene triamine (DETA) as the crosslinkers. The structure, morphology and particle size of cross‐linked polyurethane nano spheres were investigated by infrared spectroscopy, laser particle size analyzer and scanning electron microscopy. Results showed that the prepared cross‐linked polyurethane nano spheres showed spherical shape and had the size in the range from 40 to 258 nm. The application of cross‐linked polyurethane nano spheres in toughing epoxy resin was investigated. The results showed that cross‐linked polyurethane nano spheres can be uniformly dispersed in epoxy resin and no obvious aggregation phenomenon was observed. And the tensile strength and impact strength of epoxy resin can be increased simultaneously when the cross‐linked polyurethane nano spheres were used in toughening epoxy resin. With the increase of the amount of polyurethane nano spheres in epoxy resin, both the tensile strength and impact strength of epoxy resin had the trend of first increase and then decrease. The amount of HDI trimer in the microspheres had a great impact on their toughening effect on epoxy resin. When the cross‐linked polyurethane nano spheres contained HDI trimer content of 12 wt% and the amount of the nano spheres in epoxy resin was 8 wt%, the impact strength of the epoxy resin can reach as high as 23 kJ/m2, which was 4.33 times that of pristine epoxy resin. And the tensile strength of toughened epoxy resin was 50.7 MPa, which was at same level of that of pristine epoxy resin. The results of this study indicate that the cross‐linked polyurethane nano spheres have a great potential in toughening thermo setting resins, such as epoxy resin.

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聚氨酯基交联纳米球及其在环氧树脂增韧中的应用

增韧具有高冲击强度和拉伸强度的热固性树脂是一个具有挑战性的问题。本研究以六亚甲基二异氰酸酯三聚体（HDI三聚体）和二乙烯三胺（DETA）为交联剂，采用自乳化法制备了一种新型交联聚氨酯纳米球，用于增韧环氧树脂。通过红外光谱、激光粒度分析仪和扫描电子显微镜研究了交联聚氨酯纳米球的结构、形貌和粒径。结果表明，所制备的交联聚氨酯纳米球呈球形，尺寸在40~258 nm之间。研究了交联聚氨酯纳米球在增韧环氧树脂中的应用。结果表明，交联聚氨酯纳米球能够均匀分散在环氧树脂中，没有观察到明显的聚集现象。将交联聚氨酯纳米球用于增韧环氧树脂可以同时提高环氧树脂的拉伸强度和冲击强度。随着环氧树脂中聚氨酯纳米球用量的增加，环氧树脂的拉伸强度和冲击强度均呈现先增大后减小的趋势。微球中HDI三聚体的含量对其对环氧树脂的增韧效果影响很大。当交联聚氨酯纳米球中HDI三聚体含量为12 wt%、纳米球在环氧树脂中的含量为8 wt%时，环氧树脂的冲击强度可高达23 kJ/m2，是原始环氧树脂的4.33倍。增韧环氧树脂的拉伸强度为50.7 MPa，与原始环氧树脂处于同一水平。这项研究的结果表明，交联聚氨酯纳米球在增韧热固性树脂（例如环氧树脂）方面具有巨大的潜力。