Effect of dispersibility of carbon nanotubes on the hardness and thermal properties of polyphenylene sulphide/carbon nanotube composites obtained using solution mixing and melt blending methods

Polyphenylene sulphide (PPS)/carbon nanotube (CNT) composite materials (combining PPS and multi-walled CNTs modified with carboxyl groups) were blended using two methods: (1) solution mixing with 1-chloronaphthalene and (2) melt blending. The dispersion states of CNTs in PPS prepared by the two methods were evaluated using Raman spectroscopic mapping. The effect of the dispersibility of CNTs on the physical properties of the composite materials was evaluated by measuring their thermal behaviour and Vickers hardness. Raman spectroscopic mapping revealed that the dispersion states of CNTs in composites obtained via the solution mixing method were more uniform than in those obtained via melt blending methods. This improved uniformity in the dispersion states of CNTs in the solution mixing method can be attributed to the prior dispersion of CNTs in the solution. Additionally, thermal properties such as the crystallisation and glass transition temperatures, and mechanical properties such as the Vickers hardness of the solution-mixed composite material were higher than those of the melt-blended composite. These results indicate that the uniform dispersion of CNTs increases the contact area between PPS and CNTs, which causes an increase in the crystallisation temperature and a further hardness effect.