Abstract
This study pointed out the direction of science technology, small, and molecular dynamics was one of the good methods to research small scale world. We introduce the developments of small scale to help us to solve engineering problems that can make us have simple directions and ideas. This study introduced the features and applications of polypropylene simply. There were easy words for related researches about molecular dynamics、polypropylene、solution properties、diffusion properties. In chapter 3, we showed study methods and potential functions including a simulation flow chat、initial methods、algorithm、calculation method of force、periodic boundary condition and potential parameter of alkane series and polypropylene. Molecular dynamics simulation was used to measure end-to-end distance、radius of gyration and diffusion coefficient of polypropylene solution. The chain length and concentration were control variances to discuss simulation results. Because the change for diffusion substance was small, the diffusion coefficient changed little with weight percent concentration, too. The diffusion coefficient decreased with increasing chain length, because the raising size of polypropylene hindered substance moving. Key Word：Molecular Dynamics、Polypropylene、Diffusion Coefficient