Size and Interface Effects on Tensile Strength of Polymers with Nano/Micro Particle Inclusions

Polymers with particle inclusions have wide applications, and the mechanical properties of polymer composites affect their reliability in service. The strength of these composites is dependent on factors such as particle fraction, size, distribution, and interface interaction between the two phases, in addition to the properties of the polymers and particles. The size effect of particles and interface damage play an important role and thus draw considerable attention. In this paper, the size- and interface-dependent strength of polypropylene (PP) with nano/micro silica (SiO₂) particles of different fractions is studied through a combination of tensile experiments on a series of samples and corresponding three-dimensional (3D) finite element modeling. The results indicate that PP with 2% SiO₂ nanoparticles of 50 nm exhibits relatively higher tensile strength, shedding light on the microstructure mechanism where smaller particle sizes lead to better interface bonding. Furthermore, the particle size and interface coupling effect is analyzed based on the size-dependent elastic modulus model and the interface-cohesive model. The simulation demonstrates the local interface damage evolution around a particle of the composites in tension. These findings are beneficial for designing polymer composites with nanoparticle inclusions.