CHARACTERIZATION OF FINITE LENGTH COMPOSITES .2. MECHANICAL PERFORMANCE OF INJECTION MOLDED COMPOSITES

摘要

An overview is given of the mechanical performance (stiffness, strength, toughness, creep...) of finite fibre length reinforced thermoplastics based on polypropylene and polyamide as the matrices and glass, carbon and Kevlar as the reinforcement. Different degrees of fibre orientation distribution and fibre attrition as produced by classical injection moulding and multiple-live feed moulding were evaluated. It was found that the simple test geometry used (injection moulded plaques) resembled more a complicated structure than a material. The properties measured therefore were more the complex response of a strongly anisotropic structure than simple material properties, Increased alignment of the fibres in a given direction affected all the mechanical properties, but the effect was largest for the tensile stiffness. A higher degree of fibre orientation, was not accompanied by an increase in properties related to failure (ultimate stress, K-IC). The modelling of ultimate stress showed that this could be explained by the more severe fibre attrition which resulted from the forces applied to orient the fibres. [References: 14]