Impact modification of fiber reinforced polypropylene composites with flexible poly(ethylene terephthalate) fibers

Abstract

AbstractPolypropylene (PP) hybrid composites were prepared by the combination of traditional reinforcements (wood, glass, carbon) and poly(ethylene terephthalate) (PET) fibers. Interfacial adhesion was improved by the use of maleated PP (MAPP). The composites contained 20 wt% of the traditional reinforcement and the amount of PET fiber changed from 0 to 40 wt% in them. Tensile and impact testing were complemented by acoustic emission testing and scanning electron microscopy (SEM) to follow deformation and failure processes. The results obtained proved that the impact strength of hybrid PP composites can be improved in the presence of all stiff fibers and not only wood as shown earlier. Approximately the same impact resistance can be achieved in all composites, which depends on the amount of PET fiber used; an impact strength as large as 15 kJ m−2 can be obtained with the approach. The large impact resistance is the result of the local deformation processes initiated by the polymeric fiber. Irrespectively of the strength of interfacial adhesion, the main local process is the debonding and/or pullout of the PET fibers, which facilitates also the plastic deformation of the matrix polymer. Other properties depend on the type of the reinforcement and on interfacial adhesion. The application of carbon fibers results in composites with large stiffness, while at good adhesion the strength of glass fiber reinforced composites is the largest. The proper selection of components, composition and interfacial adhesion allows the adjustment of overall composite properties in a relatively wide range. © 2021 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry.