Accelerated thermo-oxidative aging for carbon fiber reinforced polycyanate under high pressure atmosphere

Abstract

The aim of this study is to accelerate thermo-oxidative aging in carbon fiber reinforced plastics (CFRP) submitted to high temperature atmospheric pressure. In this study, long-term thermo-oxidative aging test was conducted to examine the effect of high pressure atmospheric environment on the weight and mechanical properties of CFRP to accelerate the rate of thermo-oxidative degradation. The effect of thermo-oxidative environment under high atmospheric pressure on the change in weight, strength, and shrinkage behavior of a CFRP with polycyanate (FSD-M-08178) was investigated. The aging test was conducted at 180 °C up to 8,000 h under atmospheric pressure and the test result was used as a reference data. Other aging tests were also conducted under elevated pressure conditions (0.3 and 0.5 MPa) at the same exposure temperature up to 2,000 h and the test results were treated as the accelerated aging test data. Unidirectional laminates [0]8 and [90]8 for tensile specimens and angle ply laminates [±45]2S for off-axis tensile specimens were aged in oven, and then mechanical tests were carried out on them. The results indicated that elevated pressure would cause faster and larger weight gain in earlier aging period. The outcomes of these experiments were changes in weight, strength, and local shrinkage deformation were changed quickly under elevated atmospheric pressure environment. Same micro damage onset and extension irrespective of pressure during thermo-oxidative aging and subsequent loading test were observed. The test results indicate that the change in weight, strength, and local shrinkage deformation could be accelerated by elevated pressure without change in thermo-oxidative degradation mechanism. Therefore, the elevated pressure testing would be a better method to accelerate thermo-oxidative degradation. On the other hand, the change in strength under elevated pressure conditions is faster than local shrinkage deformation. Equivalent acceleration rate of degradation could not be obtained.