THE EFFECT OF NANOCALCITE-MODIFIED EPOXY RESINS ON THE MECHANICAL PROPERTIES AND TENSILE FATIGUE PERFORMANCE OF GLASS REINFORCED COMPOSITES

摘要

The effect of nanocalcite-modified epoxy matrix resins on the mechanical properties and tensile fatigue performance of glass-reinforced composites was examined. Glass fabric reinforced composite laminates were created using an industry-standard epoxy matrix as a control material and 3M Matrix Resin 8835 (MR 8835), an epoxy resin having a high loading of surface-functionalized nanoscale calcite particles. Incorporation of a high loading of calcite nano-scale particles lead to improvements in composite compression strength and through-thickness properties. The tensile static and stress-controlled fatigue behavior of the MR 8835-based laminates were examined in both the resin-dominated ±45° and the fiber-dominated 0° directions. Static tensile modulus and strength were higher for the nanocalcite-modified laminates for both orientations. Stress-life curves, cyclic stress-strain loops, and reduction of stiffness during cycling data were obtained from fatigue testing. Fatigue performance in the ±45° orientation was dramatically improved for nanocalcite-modified laminates relative to the standard laminate. Fatigue life was improved up to 65 times over the control material and resistance to increasing mean strain (ratcheting) was much greater for the MR 8835-based composite. Additionally, retention of laminate stiffness was greatly improved. The 0° tensile fatigue performance was also dramatically improved, with fatigue life improvements of greater than 10 times the life of the control material. Laminate stiffness was greatly increased over the entire life for all stress levels tested. Peak strain levels were significantly lower than for the control material at comparable stress levels.