Abstract
For the composites of stylene-acrylonitrile copolymer (AS) filled with platelet-shaped reinforcements (mica, glass flake), the critical strain energy release rates, Gc, were determined from the Charpy impact values. The results were compared with those of glass fiber filled AS. The critical strain energy release rate of reinforcements, (Gc) f, calculated by a mixture law, increases with the volume fraction of reinforcements, Vf, and ll2/d of reinforcements. Here l is the flake diameter or the fiber length and d is the flake thickness or the fiber diameter. However, the (Gc) f value for flake composites is about half of that of fiber composites at the equivalent Vf and ll2/d. The results are explained by Cottrell's equation for fiber composites, and by modified Cottrell's equation for composites with rectangular shaped flakes, if the pull-out of the reinforcements for the mode of failure is assumed.
