MORPHOLOGICAL INVESTIGATIONS OF INJECTION MOLDED FIBER-REINFORCED THERMOPLASTIC POLYMERS

Fibres affect the matrix morphology in fibre-reinforced composites. Especially in semi-crystalline melts the fibres can act as nucleation rods causing a structure known as transcrystallinity. Transcrystalline structures are also found in injection moulded parts. They affect the structure of fracture surfaces especially in the case of long fibre-reinforced polymers with good fibre/matrix adhesion. Transcrystalline structures are usually generated and investigated in a microscope with a hot stage. For injection moulded parts this is an inadequate method. The morphological results presented here were obtained from plasma-etched inner surfaces and thin sections by means of light and contrast interference microscopy accompanied by scanning electron microscopy of fracture surfaces. Plasma etching is a well suited preparation technique to reveal both morphological superstructures and damage such as voids, debonding and fibre cracks in composites.