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采用两步投料法,将氧化石墨烯(GO)与4,4′-二苯基甲烷二异氰酸酯(MDI)充分反应后、再加入聚醚多元醇和三羟甲基丙烷原位聚合制备聚氨酯(PU)/GO纳米复合材料。用广角x衍射、拉伸仪、热失重分析仪和扫描电子显微镜等研究了GO含量对PU/GO复合材料弹性模量、拉伸强度、断裂伸长率和热稳定性能的影响。研究发现当GO含量为0.2%时,GO在PU基体内分散均匀未出现团聚现象;当GO含量增加时,出现GO团聚体,且随着GO含量增加而增加。GO团聚现象对PU/GO复合材料的力学性能和热稳定性提高具有不利的影响。未出现GO团聚体的PU/0.2%GO复合材料具有最佳力学性能和热稳定性。用连二亚硫酸钠、氢氧化钠水溶液就地还原制备还原PU/GO纳米复合材料(PU/rGO),研究GO还原对复合材料力学性能和热稳定性的影响。结果发现,GO在PU基体内可以实现一定程度的就地还原,还原后复合材料的力学性能有所下降,但热稳定性能有所提高。
The two-step feeding method was used to react GO and 4,4’-diphenylmethane diisocyanate (MDI) sufficiently, and then in-situ polymerization of polyether polyol and trimethylolpropane to prepare polyurethane (PU ) / GO nanocomposites. The effect of GO content on the elastic modulus, tensile strength, elongation at break and thermal stability of PU / GO composites was investigated by means of wide angle X-ray diffraction, tensile tester, thermogravimetry and scanning electron microscopy. The results showed that when the content of GO was 0.2%, no agglomeration of GO occurred in the PU matrix. When the content of GO was increased, GO aggregates appeared and increased with the increase of GO content. GO agglomeration has an adverse effect on the mechanical properties and thermal stability of PU / GO composites. The PU / 0.2% GO composites without GO aggregates have the best mechanical properties and thermal stability. The reduction PU / GO nanocomposites (PU / rGO) were prepared by in situ reduction with sodium dithionite and sodium hydroxide aqueous solution, and the effect of GO reduction on the mechanical properties and thermal stability of the composites was studied. The results showed that GO could be partially reduced in situ in the PU matrix, the mechanical properties of the composites decreased after reduction, but the thermal stability was improved.