Simulating the crystal growth of PPS using molecular dynamic
Topic(s) : Material science
Co-authors :
Hironobu OMICHI (JAPAN), Ryo HIGUCHI (JAPAN), Yutaka OYA (JAPAN), Jun KOYANAGI (JAPAN), Tomohiro YOKOZEKI (JAPAN), Takahira AOKI (JAPAN)Abstract :
In recent years, carbon fiber-reinforced thermoplastics (CFRTP) have attracted the attention of many worldwide, including the aerospace and automobile industries. Since thermoplastic resin contains a mixture of crystalline and amorphous portions, the degree of crystallinity varies depending on molding conditions such as pressure and cooling rate, affecting material properties. This could be explained by the chain-folding of polymers, the principal mode of crystallization in this situation. These chain-folded lamellae are the main building blocks of polymeric materials, with their spatial distribution dominating all physicochemical properties of the materials. Therefore, crystal structures and crystallization mechanisms are the central subjects in the science and technology of polymers.
Previous studies show that various experimental methods such as TEM and AFM successfully obtained information on polymer crystallization at the nanoscale. However, t the same could not be said at the atomic scale. This has resulted in computer simulation becoming an attractive methodology to study scientific problems such as polymer crystallization, as it is a powerful tool for obtaining detailed information at the molecular level. Over the last few decades, Molecular Dynamics (MD) and Monte Carlo simulations have improved the understanding of polymer crystallization. Most of these simulation models used united-atom models or coarse-grained models to reduce the number of atoms and the computing costs by simplifying the chemical details of a repeated unit. In comparison, the all-atom models require more computing resources but are more suitable for studying crystalline structures and mechanical responses.
MD simulations of polymers are generally conducted on commodity plastics such as polyethylene. On the other hand, the actual resins used in composite materials are super engineering plastics such as PPS (polyphenylene sulfide) and PEEK (polyether ether ketone), polymers that have never been conducted on before. Therefore, we analyzed a single PPS chain using all-atom MD simulations. We calculate the equations of motion for each atom and molecule sequentially to track changes in the motion of all particles over time, focusing on when the chain-folding process begins, and how the cooling rate and degree of polymerization affect the chain-folding process. We are also going to be looking into how multiple PPS chains will affect the crystallization process and will be searching for the perfect range of cooling rate and degree of polymerization for crystallization, while also deepening our knowledge on the effect a carbon fiber and its surface treatment will have on the chain folding process.
Previous studies show that various experimental methods such as TEM and AFM successfully obtained information on polymer crystallization at the nanoscale. However, t the same could not be said at the atomic scale. This has resulted in computer simulation becoming an attractive methodology to study scientific problems such as polymer crystallization, as it is a powerful tool for obtaining detailed information at the molecular level. Over the last few decades, Molecular Dynamics (MD) and Monte Carlo simulations have improved the understanding of polymer crystallization. Most of these simulation models used united-atom models or coarse-grained models to reduce the number of atoms and the computing costs by simplifying the chemical details of a repeated unit. In comparison, the all-atom models require more computing resources but are more suitable for studying crystalline structures and mechanical responses.
MD simulations of polymers are generally conducted on commodity plastics such as polyethylene. On the other hand, the actual resins used in composite materials are super engineering plastics such as PPS (polyphenylene sulfide) and PEEK (polyether ether ketone), polymers that have never been conducted on before. Therefore, we analyzed a single PPS chain using all-atom MD simulations. We calculate the equations of motion for each atom and molecule sequentially to track changes in the motion of all particles over time, focusing on when the chain-folding process begins, and how the cooling rate and degree of polymerization affect the chain-folding process. We are also going to be looking into how multiple PPS chains will affect the crystallization process and will be searching for the perfect range of cooling rate and degree of polymerization for crystallization, while also deepening our knowledge on the effect a carbon fiber and its surface treatment will have on the chain folding process.