Polymer-particulate composites with differential interfaces: synthesis, characterization, and mathematical modeling to evaluate interface-yield strength correlations

Polymer particulate composites (PPC) are extensively used in numerous mechanical and aviation applications, which take advantage of their synergistic properties such as superior yield strength. This work combines experimental and theoretical approaches to evaluate yield strength of thermosetting PPC made of pristine p-TiO2 or surface-grafted g-TiO2 nanoparticles and an epoxy thermoset. Accordingly, p-PPC and g-PPC sheets containing different volume fraction (ϕf = 0.0234–0.0936) of p-TiO2 or g-TiO2 nanoparticles exhibit variable yield strength. A mathematical model is used to evaluate the effects of nanoparticles aggregation on the relative yield strength of PPC. The interfacial parameters “B” and “Bagg” give a quantitative measure of the ability of stress dispersion by the agglomerated nanoparticles. The higher “B” and “Bagg” values for g-PPC reveal its greater interfacial strength. The experimental data show good correlation with the theoretical predictions. However, these models truly predict PPC’s yield strength only at low volume fraction (ϕf ≤ 0.09) of filler nanoparticles.