Effect of the strengthening mechanism of SiO₂ reinforced poly(methyl methacrylate) on ductility performance

Polymethyl methacrylate (PMMA) is characterized by good biocompatibility and mechanical properties, and it is therefore used in applications such as denture substrates and billboards. The use of additives to produce composite materials to enhance mechanical properties is a common way to respond to the needs of diverse application environments. The size, degree of agglomeration, and dispersibility of the filler in the composite are the most crucial parameters determining the composite's properties. In this study, three particle sizes of SiO₂ are used for producing composite materials to investigate how the filler size and distribution effect can help overcome the shortcomings of the lack of ductility in PMMA products. The degree of dispersion is defined statistically as A_0.2, and then, the relationship between A_0.2 and toughening performance is obtained. The mechanical properties of composites with different particle sizes are measured via tensile testing. The micron-sized filler was used at 0.05 vol.%, and the fracture strain was 108% higher than that of the original PMMA. The strengthened ductility effect reduced with an increase in the addition and particle size reduction; the micron particles were reduced to 0.05% particles and well dispersed with A_0.2 = 50%. The particles agglomerated and A_0.2 decreased significantly with an increase in the number of additions and a decrease in particle size. Large aggregates caused brittle damage when A_0.2 is less than 10%. A_0.2 can be used as an indicator to evaluate the properties of additive-reinforced composites.