The mechanical properties of low density 2-D planar-random carbon-carb
on composites with densities in the range 0.17-0.40 Mgm(-3) were deter
mined by 3-point bend and tensile testing and correlated with the micr
ostructure. Three-point bend and tensile specimens fractured in a brit
tle manner, with the former failing through a flexural failure for spa
n-to-depth ratios from two to eight. Tensile strength and elastic modu
lus values were lower than the respective flexural values. This was th
ought to be due to the increased volume under stress, and to the deriv
ation of the flexural modulus equation, not taking into account the sh
ear component of the beam deflection, respectively. Mechanical propert
ies were isotropic within the planes, and greater than the respective
out-of-plane values, and mechanical property values increased with an
increasing density. However, there was a decrease in the anisotropy of
mechanical properties with increasing density, which was accounted fo
r by the reduction in microstructural anisotropy, in particular, assoc
iated with the increasing proportion of recycled material.