Micromechanics for fiber volume percent (Vf) from 0.0V f to 54.0 Vf were conducted using (3 mm long × 9 μm diameter) high-purity quartz fibers in a visible-light vinyl ester particulate-filled photocure resin. MTS fully articulated four-point bend fixtures were used with a 40 mm test span and 50 × 2 × 2 mm 3 sample dimensions. Specimens were tested following the combined modified ASTM standards for advanced ceramics ASTM-C-1161-94 and polymers ASTM-D-6272-00 for modulus, flexural strength, and yield strength. Experimental data provided reliable statistical support for the dominant fiber contribution expressed through the rule-of-mix-tures theory as a valid representation of micromechanical physics. The rule-of-mixtures micromechanics described by V f could explain 92, 85, and 78% of the variability related to modulus, flexural strength, and yield strength respectively. Statistically significant improvements with fiber addition began at 10.3V, for modulus, 5.4Vf for flexural strength, and 10.3V, for yield strength, p < 0.05. In addition, correlation matrix analysis was performed for all mechanical test data. An increase in Vf correlated significantly with increases in modulus, flexural strength, and yield strength as measured by the four-point beriding test, p < 10-10. All mechanical properties in turn correlated highly significantly with one another, p < 10-9. © 2007 Society of Plastics Engineers.