Comparative study of fiber reinforced PP composites: Effect of fiber type, coupling and failure mechanisms

Abstract

A polypropylene (PP) homopolymer was reinforced with carbon fiber, glass fiber and wood flour in order to compare their advantages and drawbacks. Interfacial adhesion does not influence stiffness, but it affects strongly other properties, i.e. tensile strength and impact resistance. Several local deformation and failure processes take place simultaneously or consecutively in the composites during deformation. The fracture of wood fibers is the dominating process at good adhesion, while debonding, fiber pullout and fiber fracture occurs in carbon and glass fiber reinforced composites. Some of the local deformation processes do not result in the failure of the composites, while others lead to catastrophic failure. A close correlation was found between the characteristic stress determined by acoustic emission and the mechanical properties of the composites. Composites with advantageous properties, i.e. large stiffness, acceptable impact resistance and price, can be prepared by the proper selection of fiber type, composition and interfacial adhesion.