Boron nitride-polymer composites: Mechanical properties evaluation at various strain ratios

Liquid phase exfoliation method is used to achieve three different sized (L≈0.4, 1, 1.9 μm) hexagonal Boron Nitride (hBN) nanosheets by changing the centrifugation rate. Mechanical properties of polymer composites are evaluated with hBN nanosheets utilized as reinforcement filler in polyvinylchloride (PVC) matrices. In an earlier work, uniaxial drawing (300%) was successfully employed to enhance the strength and modulus of these composites from 65-82 MPa and 1.45-1.8 GPa respectively. Here, we try to elaborate more the effect of uniaxial drawing on polymer nanocomposites (0.2 wt % for all three sizes BN) at various strain ratios (100-500%). The ultimate tensile strength (UTS) and Young's modulus (Y) have experienced maximum increase at 450-500% strain are 3 GPa and 240 MPa respectively. Alignment and improved dispersion of hBN inside are the possible reasons for enhancement in mechanical properties; along with the strain induced delamination achieved with uniaxial drawing. The enhancement in mechanical characteristics of polymer composites is close to the theoretically predicted values of hBN.