Weatherability flexural properties of CFRP subjected to accelerated and outdoor exposures

This paper discusses the weatherability flexural properties of CFRP subjected to accelerated and outdoor exposures. We used two classes of specimens. The first class of specimens is three unidirectional CFRP laminates having fiber orientation angles of 0, 45 or 90°. The second class of specimens is made solely of epoxy resin identical in chemical composition to the matrix of the above CFRP laminates. In order to clarify the effects of exposure period on the variation of flexural strength and modulus, matrix volume fraction, thickness and absorption rate of infrared rays, a complex accelerated exposure test was conducted which continued for up to 20 cycles, and a direct outdoor exposure has also been conducted which continued for 4 years. It is shown that both the weatherability flexural strengths can be calculated by the results of epoxy resin and thickness change of CFRP during the exposures. After confirming the agreement of the experimental flexural strength with the calculated value for the CFRP used in this paper, it is also shown that a weatherability outdoor flexural strength at 4 years can be predicted from one at 3 years and the correlation of the acceleration exposure test to the outdoor one is demonstrated.