可重复加工型生物基热固性自修复聚氨酯树脂的合成与性能

Thermosetting polyurethane resin has some problems such as non- repeatable processing, which greatly reduces the service life of material and causes waste of resources. In this paper, using hydroxylmethylated lignin (Lig-OH) prepared by hydrothermal method as bio-based soft segment, isophorone diisocyanate (IPDI) as hard segment, trimethylol propane (TMP) as cross-linked chain extender, 4,4 '-diaminodiphenyl disulfide (4-SO) as secondary chain extender, and 4-methylumbellione (4-MU) as bio-based end sealing agent, the biodegradable thermosetting polyurethane resin (LPU) was successfully prepared. Its structure was characterized by Fourier infrared spectroscopy, its self- healing properties were studied by optical microscope and 3D profiler, and its mechanical properties and repeatability were studied by tensile and repeated machining test. The results show that LPU-5 (TMP 18 mmol) has the best mechanical properties, with the tensile strength up to 18.92 MPa, elongation at break up to 709.82%. After total incision repair, the tensile strength and elongation at break can reach 16.90 MPa, 630.32% respectively, and the repair efficiency is up to 89% after full-cut repair. After the spline is completely cut and repaired, the resin can be crushed and reprocessed into a complete polyurethane film, which has excellent repeatability. And it can realize the dual repair function under heating and ultraviolet light, in which LPU-2 can complete the scratch repair at 75 ℃ for 10 min.