The reinforcement of polyurethane by mini-sized graphene with superior performances

Graphene filler can improve certain properties of a polymer, but often compromises others, partially because it is difficult to control graphene size and dispersion at high content in polymer matrix. In this work, we present that mini-sized sheet sizes (300 × 400 nm) of graphene microsheets (mG) up to 7 wt% are filled in polyurethane (PU) reaching improved performances including mechanical properties (tensile strength, modulus, shape memory), electrical conductivity, thermal conductivity, thermal stability and flame retardance. The filling of 3 wt% mG in PU involves the enhancements of 81 % tensile strength (41.6 MPa at the elongation at break of 605 %), 126.7 % of modulus, 17 times of thermal conductivity (4.24 W/m·K) and 50℃ of thermal stability over net PU. The extensive characterizations disclose that hydrogen bonds strengthened and microphase separation promoted in the PU composite with the filling of the planar shape, hydrophilic edge and low defects of small graphene microsheets. This investigation presents a great potential of extending polymer materials with the filler of graphene microsheets derived from microcrystalline graphite minerals.