Interlaminar mode I- and II-fracture energy measurements (in terms of the strain energy release rate) were carried out with different laminates of a glass fiber/thermoplastic PA 12- and aramid fiber/PA 12-composite system. Specimens were prepared from fiber bundles interspersed with polymer powder and a polymer sheath around them. The results, obtained from two different test procedures and data reduction methods, reflect a good interlaminar fracture toughness of the different laminates. This can be attributed to the large damage zone size due to the tough matrix and a big amount of fiber bridging, which is highlighted by micrographs achieved with SEM-analysis.
