In situ exfoliation of graphite in solid phase for fabrication of graphene/polyamide-6 composites

In this study, we reported a new in situ method to prepare the polyamide-6 (PA6)/graphene nanoplates by solid state shear milling. The PA6/graphene nanoplates compounding powder was prepared with the addition of 10 wt% of graphite. During the milling process, graphite was in situ exfoliated into few-layer graphene sheets in the PA6 matrix in solid phase. Using this compounding powder, the PA6/graphene composites were fabricated with different contents of graphene by melting dilution process. The number of graphene layers was 4-6 which was confirmed by high-resolution Transmission electron microscopy and Atomic Force Microscope. The exfoliation process of graphite was also demonstrated by Scanning electron microscopy observation. Both Raman and X-ray diffraction proved that the thickness of graphite was reduced significantly. The thermal conductivity of the composites with 5.0 wt% of graphene loading was increased by 85% and the yield strength was also appreciably enhanced. The results showed that solid phase in situ exfoliation method paves a new way to prepare graphene-based polymer composites on a large-scale with high performance.