Shigeo Amagi

Influences of inorganic fillers on curing reactions of epoxy resins initiated with a boron trifluoride amine complex

Abstract Inorganic fillers are widely used for epoxy resins to improve mechanical and thermal properties. However, inorganic fillers may unexpectedly affect the curing reactions of such epoxy resins. In our present study, influences of inorganic fillers on the curing reactions of phenol novolac epoxy resin (EPN) initiated with boron trifluoride ethylamine complex (BF3MEA) are detailed. The gel times of epoxy resins containing alumina (Al2O3) fillers were longer than those of corresponding unfilled epoxy resins, indicating that Al2O3 fillers delayed the curing reactions of epoxy resins. Mechanisms were proposed and influences of aluminum hydroxide (Al(OH)3), silica (SiO2), and aluminum fluoride (AlF3) fillers were also described.

The Effect of Time and Temperature on Flexural Creep and Fatigue Strength of a Silica Particle Filled Epoxy Resin

Composite materials that use an epoxy resin as a matrix resins have superior mechanical properties over standard structural materials, but these materials exhibit time and temperature behavior when used for long periods and under high temperatures. This time and temperature behavior has not been fully explained. The purpose of this paper is to further describe this time and temperature behavior, increasing the reliability of this class of composite materials. The time and temperature dependence of flexural strength was examined by creep and fatigue testing. Flexural creep tests were carried out at various temperatures below the glass transition temperature. Flexural fatigue tests were carried out at various stress ratios, temperatures below the glass transition temperature and 2 frequencies. The time-temperature superposition principle held for the flexural creep strength of this material. A method to predict flexural creep strength based on the static strength master curve and the cumulative damage law is proposed. When the fatigue frequency was decreased while temperature and stress ratio are held constant the flexural fatigue strength decreases. The time-temperature superposition principle was also found to hold for the flexural fatigue strength with respect to frequency.

The Effect of Time and Temperature on the Flexural Strength of a Silica Particle Filled Epoxy Resin

Composite materials that use an epoxy as a matrix resins have superior mechanical properties but these materials exhibit time and temperature behavior when used for long periods and under high temperatures. This time and temperature behavior has not been fully explained. The purpose of this paper is to further describe this time and temperature behavior, therefore increasing the reliability of these types of composite materials. The time and temperature dependence of flexural strength was examined by flexural static and fatigue testing. Initially the neat resins viscoelastic mechanical behavior was determined experimentally to be later compared to the composites. Static tests were carried out at various constant deflection rates and temperatures below the glass transition temperature of the epoxy resin. It was shown that the time-temperature superposition principle is applicable for the flexural static strength. Comparison of the neat resin and the composite results show that the neat resin is a major influence on the time and temperature behavior of the composite materials static strength behavior. Fatigue tests were carried out at several stress ratios and various temperatures below the glass transition temperature of the matrix resin. It was shown that the time-temperature superposition principle is applicable for the initial flexural fatigue strength by using the time-temperature behavior of the matrix resin. As temperature and stress ratio increased, the creep influence increased in both the flexural strength and the modulus.