PTMG-TMP混合扩链交联对聚氨酯树脂力学性能的影响

在常压、惰性气体保护下，利用二步法合成甲苯-2，4-二异氰酸酯（TDI）-聚丙二醇（PPG）预聚体，再用少量聚四氢呋喃醚二醇（PTMG）与三羟甲基丙烷（TMP）进行混合扩链交联，制备聚氨酯树脂（PU）固化产物并进行性能研究。采用FTIR对预聚体以及固化产物的分子结构进行表征，用万能试验机测试PU的力学性能。研究结果表明，少量PTMG的加入能降低反应的活性并改善PU固化产物的韧性。当TDI-PPG预聚体中-NCO的质量分数为24.0wt%、扩链交联剂中PTMG的含量为5wt%、异氰酸酯指数（R）介于1.01~1.05之间时，PU固化产物具有良好的力学性能，拉伸强度达到87.4 MPa，弯曲强度达到104~106 MPa，拉伸模量达到3.51~3.60 GPa，弯曲模量达到3.20~3.28 GPa，断裂伸长率达到4.45%~4.83%。

Effect of mixed chain crosslinking of PTMG-TMP on mechanical properties of polyurethane

Toluene-2,4-diisocyanate-poly propylene glycol (TDI-PPG) prepolymer was synthesized by two-step method with the protection of argon under normal pressure. A small amount of polytetrahydrofuran ether diol (PTMG) and trimethylolpropane (TMP) as chain cross-linker, were mixed with the TDI-PPG prepolymer to prepare a polyurethane resin casting. FTIR was used to analyze the molecular structure of theTDI-PPG prepolymer and the cured products. The mechanical properties of the polyurethane resin castings were tested by the universal testing machine. The results show that the addition of PTMG reduces the activity of the reaction while improves the toughness of PU cured product. When the mass fraction of -NCO in TDI-PPG prepolymer is 24.0wt%, the content of PTMG in chain extension crosslinker is 5wt%, and the isocyanate index (R) ranges from 1.01 to 1.05, the tensile strength is 87.4 MPa, the flexural strength is 104 MPa to 106 MPa, the modulus is 3.51 GPa to 3.60 GPa, the elongation at break is 4.45% to 4.83%