The Computer Simulation Of PP/PA6 Blending System

Since the beginning of the 21 st century,computer simulation has been widely used as an important method and means in the research,design and development of materials,and it has greatly promoted the development of materials related fields.In order to study the compatibility of PP and PA6 from molecular level,the PP / PA6 blends was simulated by MD molecular dynamics method at room temperature(25?).In addition,the DPD dissipative particle dynamics method was used to simulate PP / PA6 / PP-b-PA6 ternary blends,and the related mesomorphic information was obtained.The effective convergence of MD and DPD has opened up a new way for polymer blending study.Firstly,the PP / PA6 blends was simulated by MD method.At the normal temperature and normal pressure,the mixture of 80PP/20PA6,60PP/40PA6,50PP/50PA6,40PP/60PA6 and 20PP/80PA6 were studied by microscopic simulation.Contrast the Flory-Huggins interaction parameters and C-C atom pairs radial distribution function.The results showed that the concentration ofwere bigger than,indicated that these blending systems were incompatible.Contrast the(PP-PA6)and(PP-PA6)C-C atoms radial distribution function,it is found that PP and PA6 are difficult to be compatible with the above five proportions.The effect of temperature change on the compatibility of PP and PA6 was studied by MD simulation.The PP/PA6 blends were calculated by Blend module of Material Studio software.The compatibility of PP and PA6 was predicted,and then the five The ratio of Flory-Huggins interaction with PP/PA6 varies with temperature changes.The results showed that the PP and PA6 mixtures at room temperature are compatible only when the content of PP(or PA6)is very low,and the temperature of the system can decrease the Flory-Huggins interaction parameter and promote the system compatibility.In addition,MD simulation also studied the effect of temperature on the mean square end of PP and PA6 molecular chains and the energy of the system.Using DPD to simulate PP/PA6 blends.The mesoscopic appearance of PP/PA6 at 90/10,80/20,70/30,60/40,50/50,40/60,30/70 and 10/90 was calculated and the PP/PA6 mesoscopic morphology was a spherical droplet structure in the 90/10,80/20 and 10/90 mixed models,and the bundle structure was distributed in the 70/30 and 30/70 mixing models,at 60/40 and 40/60 the mixed model was a layered structure distribution and a double continuous structure distribution in 50/50 binary blend.The particle size distribution of PP/PA6 particles along the X-axis is studied,the aggregation of the particles can be investigated by the density spectra of particles.To study the end-to-end distance of PP/PA6 blends,it was founded that the size of PP and PA6 was proportional to its corresponding content,which was due to the increase of some components to leave more free extension space,Which is conducive to the diffusion of molecular chains and solution entanglement.In order to verify whether the DPD simulation parameters are appropriate,the phase diagram of the DPD simulation is compared with the SEM image of the relevant literature,and it was founded that the two have high similarity.By analyzing the evolution of PP/PA6 blends by intercepting the phase diagram of different time steps,it was founded that the time steps required to achieve the equilibrium of different mixing ratio systems are different.In this paper,the influence of temperature change on PP/PA6 mixed system was simulated.It was found that the temperature change had some influence on the mesoscopic appearance of the mixed system.Secondly,the temperature increased the diffusion coefficient of the beads and the root mean square distance.The effect of shear stress on the blending of PP/PA6 was studied.The simulation results showed that the effect of the smaller shear rate on the mesoscopic morphology was negligible.When the shear rate continues to increase,the mesoscopic appearance will follow the shear rate Directional orientation and change,and eventually the formation of tubular beam gel structure,from the relevant literature also found that the blending system under the shear force gradually into tubular beam structure.Finally,the end-to-end distance and the diffusion coefficient of the beads of the system were increased by the DPD simulation,which indicates that the increase of the shear force was beneficial to the fragmentation and migration of the aggregates.Study on PP/PA6/PP-b-PA6 ternary blending system which containing block copolymer compatibility by DPD simulation.Firstly,the meso-isometric and interfacial tension of the binary mixture system with the same PP/PA6 mixing ratio and the compatibilizer-containing ternary blends were compared.It was found that the interface of the ternary blends appeared in the rugged protrusions,and Ternary system interface tension is less than the binary system,indicating that the addition of compatibilizer does play a role in promoting PP/PA6 compatibility.Secondly,the effects of PP-b-PA6 addition and chain length on the PP/PA6 mixed effect were investigated.It was found that adding a small amount of PP-b-PA6 could reduce the interfacial tension of the system and improve the compatibility of PP-PA6 rear interface tension due to PP,PA6 phase "swelling" and increase,which was not conducive to system compatibility.Finally,the interfacial properties of compatibilism ternary mixed system were investigated,and the influence of compatibilizer addition on interface thickness was investigated.