The thermal expansion of carbon-fibre reinforced plastics

The thermal expansion characteristics of a series of carbon-fibre fabric reinforced plastic laminates over the approximate temperature range 90 K to 440 K have been determined. The reinforcements included Morganite Type II fibres in a plain weave and a two-by-two twill weave and Courtaulds Grafil E/XAS fibres in a two-by-two twill weave, a five-shaft satin weave and in an unwoven unidirectional disposition. The results show that the ratio of fibre tow densities in the principal fibre directions, the crimp in the reinforcing fibres and the laminate stacking sequence all influence the magnitudes and temperature dependences of the linear thermal expansion coefficients, as well as the detailed manner in which the dimensions respond to changes of temperature. Volume shrinkage effects resulting from temperature cycling are also reported. The linear thermal expansion coefficients of Courtaulds Grafil E/XAS carbon fibres in directions parallel, ^f , and perpendicular, _¶ ^f , to the fibre axis have been estimated as ^f =–2.6× 10^–7 K^–1 and ^f =2.6×10^–5 K^–1.