Effects of Temperature on Tensile Strength of Carbon fiber and Carbon/Epoxy Composite Sheets

With the increased use of carbon fiber reinforced polymer (CFRP) composites in civil infrastructure, understanding the fire structural performance of these materials is an important safety issue. In this paper, the effect of temperature on the tensile strength of carbon fibers and carbon/epoxy composite sheets was experimentally determined from 20 degrees C to 500 degrees C. Meanwhile, in order to better understand the strength degradation of carbon fiber-polymer composites at elevated and high temperatures, the tension tests were also performed for pure epoxy resin and CFRP sheets by means of 10 degrees C off-axis at the range of 20-80 degrees C, respectively. The experimental results reveal that the strength decrease of carbon composites under tensile loading at elevated and high temperatures is dependent on both thermal softening of the epoxy polymer matrix and thermally-activated weakening of the fibers. The reduction in strength of carbon fiber is attributed to oxidation of the high strength grapheme layer at the near-surface fiber region.