Effect of Physical Surface Treatment of Carbon Fiber on Fracture Toughness and Bending Properties for CFRP

CFRP(Carbon Fiber Reinforced Plastics) is applied for many parts in aerospace vehicle and automobiles. The strength is already improved by chemical fiber treatment. In this study, the improvement of physical surface treatment to mechanical properties is focused. Three kinds of grain-degrees of sand papers are used for physical surface treatment to plain woven carbon cloth. The rubber particle modification method is also used for examining the improvement of strength. DCB(Double Cantilever Beam) test and static bending test are conducted. The relationships between fracture toughness, bending strength and rubber content, grain degree are examined. The relationships between crack propagation length and grain degree is also examined. The observation of carbon fiber is also conducted using SEM (Scanning Electron Microscope). As a result, it is understood that the rubber modification and physical surface treatment is effective for the strength of CFRP. The effect at tensile and compressive side to the strength is examined in detail.