Preparation and properties of reduced graphene oxide/polyurethane flexible composites
In order to construct thermoplastic polyurethane(TPU)based flexible circuits using fused deposition modeling(FDM)3D printing technology.TPU as flexible matrix and industrial grade graphene oxide(GO)as conductive filler were applied to prepare flexible conductive filament used for FDM 3D printing.In order to improve the conductivity of GO,reduced graphene oxide(RGO)was prepared by thermal reduction of GO at high temperature.The RGO/TPU flexible conductive composites were prepared by solvent blending method.The influences of RGO content on the conductivity,mechanical properties,force sensitivity perfor-mance,and thermal properties of the RGO/TPU flexible composites were explored.The research results indicate that when the content of RGO is about 12 wt%,the electrical performance of the composite is significantly improved,which is approaching the resistance range of semiconductor materials.RGO can significantly increase the tensile modulus of TPU flexible composite.When the content of RGO reaches 12 wt%,the tensile modulus is about 56.36 MPa,which is nearly 16 times that of pure TPU.But with the increase of RGO content,the elongation at break and breaking strength of the flexible composite decrease significantly.When the strain is 130%,the resistance change rates of filaments with 10 wt%and 12 wt%RGO are only 53.5%and 48.4%,respectively,and the sensitivity coefficients are only 0.41 and 0.38.The addition of RGO can increase the crystallization temperature of the RGO/TPU flexible composite significantly.However,the RGO with excessive content(≥8 wt%)can lead to a decrease in crystallization temperature.