Molecular Simulation On Microcosmic Interfacial Structure Of CF/PPEK Comosites

Interface which connects the fiber and matrix is very important microcosmic structure, it makes large infection on physics and mechanics properties of composites. Studying in microcosmic structure of interface by traditional experiment methods is very difficult, but molecular simulation has particular advantages, because it can exhibit microcosmic figures to investigators, brings lots convenience. In this paper we will study the interfacial structure of the composite CF/PPEK by molecular simulation.First, we constructed single molecular model of PPEK in vacuum, and a combinative anneal simulation with molecular mechanics (MM) and the molecular dynamics (MD) are applied to optimize the structure, the anneal temperature from 298K to 598K. According to the distribution of the value of bonds, angles and dihedrals at initial 298K, highest 598K and descendent 298K, in addition the change of the energy, we find the dihedrals is primary factor in the frames transformation and result in energy reducing. Then we constructed amorphous cells of PPEK with three-dimensional and two-dimensional period boundary condition (marked matrix model1 and matrix model2), and applied anneal simulation with high temperature and pressure. According to the frames and concentration of the two matrix models after anneal simulation, find matrix model1 is discontinuity and disagree with reality, whereas matrix model2 is reasonable, but its density is too small, so we made modification, and gained more reasonable matrix model.Finally, basing on oxygenated CF (connect with -OH) and unoxygenated CF models, we constructed two interface models of CF/PPEK (marked interface model 1 and interface model2), and applied anneal simulation. According to the structure of the two interface models, find that the attraction force from matrix make large distortion of surface of CF in interface model1, so there is less benzene anear from matrix. We also calculated the interfacial energy of the two interface models, and concluded the combine intensity of the two interface is large, and interface model 2 is larger. Farther to analyze the decomposition of the...