两种不同化学组成的超支化聚氨酯改性环氧树脂

Epoxy Resins Modified by Hyperbranched Polyurethanes with Different Composition

利用芳香族二元异氰酸酯和脂肪族二元异氰酸酯分别与二乙醇胺反应,设计合成了不同化学组成的超支化聚氨酯,考察了其对环氧树脂的改性作用.运用核磁共振、傅里叶红外光谱(FTIR)、扫描电子显微镜(SEM)、弯曲、拉伸、冲击强度、储能模量、示差扫描量热法(DSC)以及热失重(TGA)等对超支化聚氨酯的结构及其性能进行了证实和表征,并发现基于芳香族超支化聚氨酯改性的环氧树脂共混体系表现出均相结构,而脂肪族超支化聚氨酯和环氧树脂共混后却形成了非均相体系.均相的共混体系证明超支化聚合物自身能够有效地改善环氧树脂的力学性能和热学性能.

Hyperbranched polyurethane（HBPU）, with highly branched three-dimensional topological structures and outstanding mechanical properties, have recently received increasing attention in the modification of epoxy resins. Herein, HBPUs with different composition were synthesized and added into epoxy resins. Homogenous blending system and heterogeneous blending system were obtained by incorporating different HBPUs. The effect of micro-phase separation on toughening epoxy resins was removed by the homogeneous system, which proves the HBPU modifying epoxy resins. Aromatic hyperbranched polyurethane（M-HBPU） and aliphatic hyperbranched polyurethane（H-HBPU） were prepared through the reaction of diethanolamine with aromatic diisocyanate（MDI） and aliphatic diisocyanate（HDI） respectively, and the obtained polymers were added into epoxy resin as modifiers to make samples for test. The structures of the M-HBPU and H-HBPU were confirmed by Fourier transform infrared spectroscopy（FTIR） and nuclear magnetic resonance spectroscopy（NMR）. The micro-phase structures were studied by scanning electronic microscopy（SEM） and the images showed that the blending of M-HBPU and epoxy resin was homogeneous after curing, while the blending of H-HBPU and epoxy resin was phase-separated. The mechanical properties, including flexural strength, impact strength, tensile strength and storage modulus, of the modified epoxy resins were improved after the treatment with both M-HBPU and H-HBPU. There was an optimal amount of the hyperbranched polyurethanes in the modified epoxy resin system. Meanwhile, differential scanning calorimetry（DSC） and thermal gravimetric analysis（TGA） results revealed that the thermal performance of epoxy resins per-treated with the M-HBPU was enhanced markedly, as compared with the pure epoxy resins. The homogeneous phase system of epoxy resins was obtained successfully after the modification with M-HBPU. All these results indicated that the mechanical properties and thermal performances of the modified epoxy resin could be improved directly by M-HBPU without the effect of micro-phase separation.