Improvement of Mechanical Properties of Acrylic Resin Adding Filler Particles

Objective: Previous studies showed that biaxial flexural strength (BFS) of PMMA did not improve by simply adding filler particles to the PMMA powder. This study was designed to improve the mechanical properties of PMMA by incorporating different types of silica filler particles into MMA and polymerising it, in order to achieve an even distribution of particulates in the polymer. Methods: Impregnated PMMA-Silica 1w%, silanated Laponite 1w% & Silanated silica filler particles 1w% and 10w% were mixed with MMA using ultrasonication for 15min. Bezoyl peroxide 70%, 2 w% as a heat cure initiator and N, N dimethyl–p-toluidine 3 w% as chemical initiator were added to the mixture and stirred for 15min, purred inside the mold, packed and cured for 24h at room temperature and then for 2 hours at 95Cº in the form of 12mm diameter and 2 mm thick discs. MMA itself was processed under the same condition as a control. All the samples, discs, were stored in water for 48 hours at 37ºC before BFS. A ONE-WAY ANOVA analysis and TUKEY'S comparison were carried out to determine significance using MINITAB (p<0.05). Results: BFS of the polymerized MMA was 119±10 MPa. Incorporating Impregnated PMMA-Silica and silanated Laponite 1w% into MMA decreased the BFS of the resin to 100± 28 and 113± 20 MPa respectively. The differences were not statistically significant. Adding Silanated silica filler particles 1w% to the resin had no effect on its BFS while incorporating of 10w% improved the strength of the resin up to 149±20 MPa. The difference was statically significant. Conclusion: Even distribution of some surface modified particles within the resin matrix can improve the BFS of PMMA.