Evaluation of the interfacial properties of polypropylene composite laminates, reinforced with paper sheets

Laminates, composed of different papers and polypropylene (PP), were fabricated by a manual stacking and hot pressing. The laminates were characterized by mechanical testing and the results were compared to glass fiber reinforced PP. Furthermore, a detailed evaluation of the interfacial properties and the paper structures was carried out by means of data modeling via rule of mixtures (ROM), as well as electron microscope (SEM) analysis. For investigating the influence of the laminate's composition on the water adsorption behavior, water diffusion coefficients were determined. As a result, laminates with a tensile modulus up to 6 GPa and a tensile strength of 80 MPa were obtained. The property changes of the papers upon processing were successfully modeled, revealing a significant increase of the paper's mechanical properties after fiber embedding. In general, the obtained results indicate a high potential of paper as a suitable reinforcement material for low to middle strained applications.