An improved crack-bridging model for rigid particle-polymer composites

Abstract

The incorporation of rigid particles is a promising design strategy to enhance the fracture toughness of polymeric materials. Quantitatively evaluating the toughening effect of particles is crucial for thoroughly exploring the full potential of such a strategy. In this paper, an improved crack-bridging model is proposed to correlate the fracture toughness of rigid microparticle-reinforced polymer composites with their microstructure. The critical stress intensity factor (SIF) is used to describe the fracture toughness of composites. The critical SIF values of composites rely on the critical SIF of the polymer matrix and the SIF induced by the bridging particles. The discrete bridging forces induced by particles are treated as the continuous bridging stresses. The bridging-SIF is determined by the integration of bridging stress. Theoretical predictions revealed that increasing the particle volume fraction and the particle-matrix interfacial strength can effectively improve the fracture toughness of polymeric materials. For the polymer reinforced with micron-sized particles, the fracture toughness increases with increased particle size. The theoretical results predicted by our model agree well with the experimental data. Our results help to elucidate the dependence of the fracture toughness of particle-polymer composites on their microstructure and therefore are useful for the design and optimization of advanced composite materials.