PBO/环氧树脂界面的分子建模与力学性能预测

PBO fiber possesses excellent mechanical properties and thermostability.Due to its complex molecular structure,smooth surface and chemical inertness,the properties of PBO/polymer interphase are different from the other fiber/polymer interphases,which is difficult to be studied by experimental approaches.In this work,the curing process of the polymer matrix near the PBO fiber surface is dynamically simulated using molecular dynamics method.The molecular structures of the PBO fiber and the PBO/polymer interphase with different crosslink densities are obtained.The existence and the width of the interphase are determined according to the profile of the relative atomic concentration.The mechanical properties of the PBO/polymer interphase with different crosslink densities are measured in the simulation of uniaxial tensile tests.It was found that the width of the PBO/polymer interphase with different crosslinking densities is almost constant,which is about 5~6 Angstrom.It is thinner than the other fiber-reinforced composites,such as the carbon fiber reinforced composites.Furthermore,the mechanical properties of the interphase were found to be enhanced as the crosslinking density of the polymer matrix increases,which is qualitatively similar to the other interphases.The mechanical properties of the interphase are improved so much owing to the Van der Waals interaction between the PBO fiber and the polymer matrix,while the effect due to crosslink degree on the mechanical properties is much weaker.