Preparation and Mechanical Characterization of Creep-less FRP Using T_g-less Epoxy Resin

Abstract

Continuous carbon fiber-reinforced T_g-less epoxy resin was produced and evaluated to create a creep-less composite material usable in continuously loaded structural parts. The T_g-less epoxy resin was obtained through the anionic curing of ordinary epoxy resin with an alkaline salt of carboxylic acid. In the viscoelastic behavior of the cured T_g-less epoxy resin, the storage modulus did not drop and the resin remained in a glassy state even at elevated temperatures, such as 300ºC. Additionally, the loss tangent was low at all testing temperature ranges. This indicates that stress relaxation hardly occurred; thus this resin may enable the creation of a creep-less composite material. The brittleness of the cured T_g-less epoxy resin was successfully overcome through modification with nano-rubber particles. Finally, creep tests were conducted using a three-point bending mode for carbon fiber-reinforced composite materials using modified and unmodified T_g-less epoxy resins as the matrices. As a result, in the case of T_g-less epoxy resin containing 16 wt% of nano-rubber particles, the creep strain rate became almost zero after a testing time of over 50 h.