Effects of different fibers on the properties of short-fiber-reinforced polypropylene composites

The aim of this paper is to give a comprehensive overview of the effects of different fiber types on the properties (flexural/tensile strength and modulus, notched and unnotched impact resistance, heat deflection temperature, density) of injection molded short fiber-reinforced polypropylene composites. The fiber length in the composite materials was analyzed, too. The influence of a coupling agent on the fiber/matrix interaction respectively the composite performance was investigated. Different sizings are compared for most fiber types. All fibers were characterized by contact angle measurements and their respective surface energies were calculated. Most fiber types used show a reinforcing effect in accordance to the respective fiber properties. Comparison of different sizings and the use of a coupling agent show that fiber/matrix interaction has a significant impact on composite properties. A slight increase of the final fiber length can be achieved by using initially longer fibers. However, the results of this study indicate that a certain amount of adhesion is required for improving composite performance by increased fiber length.