Abstract
The percolation model is used to interpret the brittle‐ductile transition of HDPE/CaCO3 blends. The percolation threshold (θsc) for HDPE/CaCO3 blends is found to be 0.52, which is equal to π/6. The critical exponent (g) is found to be 0.83 for HDPE/CaCO3 blends. The toughening efficiency of blends which have monodisperse, highly asymmetrical particles, strong interphase adhesion and high matrix toughness is greater. The brittle‐ductile transition in polymer blends seems to be a universal percolation phenomenon.