Unfolding behavior of self-folded boron nitride nanosheets inducing ductility of cementitious composites

JL Liu and N Hu and CL Chow and D Lau, APPLIED SURFACE SCIENCE, 599, 153818 (2022).

DOI: 10.1016/j.apsusc.2022.153818

A classical molecular dynamics simulation is adopted to study unfolding behavior of self-folded boron nitride nanosheets (BNNSs) in the cementitious composite. The simulation results show that unfoldings of the self-folded BNNSs initiate at the interface between the interlayers of the self-folded BNNSs because this interface is weaker than the BNNS- tobermorite interface under individual tensile and shear deformation. The interfacial microstructure shows that the ends of the self-folded BNNSs are embedded into the rugged surfaces of tobermorite, which exhibits a mechanical interlocking effect on the BNNSs-tobermorite interface. Furthermore, the existence of the hydrogen bonds at the BNNS- tobermorite interface yield a robust interfacial interaction between BNNSs and tobermorite. The critical peeling forces required to peel the adhesion between BNNS and tobermorite and between interlayers of self- folded BNNSs are obtained from a continuum model, which gives insights into the unfolding initiation of the self-folded BNNSs. The progressive peeling at the BNNS-tobermorite interface allows the self-folded BNNSs to maintain mechanical reinforcement in tobermorite under a large deformation at the atomistic scale. The atomistic scale reinforcement of the self-folded BNNSs in the deformation capacity and mechanical properties of cementitious composites significantly improves the ductility of cementitious composites.

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