聚氨酯对环氧树脂增韧性能研究

Study on toughening properties of polyurethane for epoxy resin

利用甲苯二异氰酸酯(TDI)和聚丙二醇(PPG)合成不同结构的端—NCO聚氨酯(PU)预聚体,然后由聚氨酯预聚体与环氧树脂进行接枝反应,制备聚氨酯改性环氧树脂。研究了聚氨酯预聚体结构和用量对改性环氧树脂力学性能的影响规律。结果表明,当聚醚多元醇选用PPG1000,且TDI∶PPG=2∶1时,制得的聚氨酯预聚体对环氧树脂的增韧效果最好,当ω(PU预聚体)=10%时,改性环氧树脂的应变和拉伸强度分别达到84. 7%和27. 1 MPa,是改性前的30. 47倍和3. 04倍。通过扫描电镜对聚氨酯的增韧机理进行了研究,发现改性前环氧树脂为脆性断裂,聚氨酯改性后的环氧树脂断裂时银纹明显增多,为韧性断裂。

-NCO polyurethane prepolymer(NCOPU)with different structures was synthesized by using toluene diisocyanate(TDI)and polypropyl glycol(PPG).Then polyurethane modified epoxy resin was prepared by graft copolymerization of polyurethane prepolymer with epoxy resin.The influence of the structure and amount of polyurethane prepolymer on the mechanical properties of the modified epoxy resin was studied.The results showed that the toughening effect of polyurethane on epoxy resin was the best when the molecular weight of PPG 1000 and TDI∶PPG=2∶1.Besides,whenω(NCOPU)=10%,the strain and the tensile strength of the modified epoxy resin were respectively 84.7%and 27.1 MPa,30.47 times and 3.04 times of unmodified epoxy resin.The toughening mechanism of polyurethane was studied by scanning electron microscope.It was found that the epoxy resin was brittle fracture before modification,and the crazing of polyurethane modified epoxy resin increased obviously,which was ductile fracture.