ИСТИНА

In the present report, we discuss our results of the theoretical study of processes occurring at the early stages of precursor fibers formation. To understand better the system behavior at scales closer to the real ones, we use a mesoscopic simulation model based on the dynamic density functional theory (DDFT). We have performed a mapping of atomistic structures of PAN, dimetilsulfoxide (DMSO), water and multiwalled carbon nanotrubes (MWCNT) on corresponding coarse-grained representations (linear bead-spring chains, set of beads connected by bonds of high rigidity and spherical particles). All coarse-grained force field parameters have been obtained from auxiliary molecular dynamic simulations simulations and the extended Flory-Huggins theory using the polymer consistent force field (PCFF). Structure properties of PAN spinning solutions containing MWCNT have been studied for different quality of solvent, the filler content, temperatures and shear strain rates. The solvent quality is regulated by DMSO/water ratio. Obtained results clearly show that the distribution of MWCNT in the spinning solution becomes homogeneous with increasing of the water content in the solvent. At the same time, the increase of the water content causes a rise in the number of nuclei of a crystalline phase in a nascent precursor fiber. The size of the appearing structures only weakly depends on temperature in a selected range. Also, we observ that an increase in the affinity of PAN and the filler (with using the surface modification of MWCNT) gives a decreasing size of MWCNT aggregates in the spinning solution. Under influence of the shear flow, at a low water content, we may see a decrease in the average number and size of PAN nuclei, while in the case of a high water content conversely, the size of the nuclei increases by the coalescence of small aggregates.