In polymer-based thermal conductive composites, the dispersion state of fillers affects the properties of the final materials. Generally speaking, the preparation methods of composites include solution method, melting method or reverse filling method, among which the solution method and melting method are the most widely used. However, in the current research, the dispersion and efficiency of fillers are difficult to meet the application requirements.
Professor Bai Shu of Peking University combined the respective advantages of solution method and melting method, in which the viscosity of the system in the solution method was low, which was beneficial to the dispersion of fillers, and the shear force in the fusion method was strong. Therefore, the team used nylon 6 as the matrix. Graphene nanoparticles were used as thermal conductive fillers. Nylon 6 / graphene nanoparticles were prepared with formic acid as solvent, and then extruders were used to further shear to promote the dispersion of graphene nanoparticles. The preparation process is as follows:
From the CT photos of the composites, it can be seen that the dispersion of graphene nanoparticles after two-step processing is very uniform (as shown in the figure below, the dispersion state of a), is better than that of one-step method (figure b).
Then the thermal conductivity of the composites was studied respectively. the results showed that the thermal conductivity of the composites (the content of graphene nanoparticles was 20 wt%) reached 3.55 W / MK, which was 11.7 times higher than that of pure nylon 6 and higher than that of one-step method (2.0 W/mK).
Composites Part A 126 (2019) 105578Back