Effect of short glass fiber/filler particle proportion on flexural and diametral tensile strength of a novel fiber-reinforced composite

Abstract

Purpose: To evaluate the effect of glass fiber/filler particles proportion on flexural strength and diametral tensile strength of an experimental fiber-reinforced composite. Methods: Four experimental groups (N = 10) were created using an experimental short fiberreinforced composite, having as a factor under study the glass fiber (F) and filler particle (P) proportion: F22.5/P55 with 22.5 wt% of fiber and 55 wt% of filler particles; F25/P52.5 with 25 wt% of fiber and 52.5 wt% of filler particles; F27.5/P50 with 27.5 wt% of fiber and 50 wt% of filler particles; F30/P47.5 with 30 wt% of fiber and 47.5 wt% of filler particles. The experimental composite was made up by a methacrylate-based resin (50% Bis-GMA and 50% TEGDMA). Specimens were prepared for Flexural Strength (FS) (25 mm ? 2 mm ? 2 mm) and for Diametral Tensile Strength (DTS) (3 ? 6 Ø mm) and tested at 0.5 mm/min in a universal testing machine. Results: The results (in MPa) showed significance (different superscript letters mean statistical significant difference) for FS (p < 0.009) and DTS ( p < 0.001) - FS results: F22.5/P55:217.24 ? 20.64^B; F25/P52.5: 245.77 ? 26.80^AB; F27.5/P50: 246.88 ? 32.28^AB; F30/P47.5:259.91 ? 26.01^A. DTS results: F22.5/P55: 21.82 ? 4.42^B; F25/P52.5: 22.00 ? 7.40^B; F27.5/P50:18.63 ? 4.41^B; F30/P47.5: 31.05 ? 2.97^A. In SEM analysis, areas without fiber reinforcement demonstrated to be more prone to the presence of bubbles and crack development. The group F30/P47.5 showed areas with a great quantity of fibers without empty spaces for crack propagation. Conclusion: Increasing fiber content results in higher flexural and diametral tensile strength of an experimental composite reinforced with glass fibers.