The search of alternative reinforcement materials in polymer composites has gained interest due to economic and ecological reasons. Lignocellulosic plant fibers are characterized by suitable mechanical properties and could potentially replace traditional synthetic reinforcements, such as glass fibers, in several applications. The natural quality variation of natural fibers led to the approach of using processed plant fibers, such as pulp and paper fibers, for composite production. Paper shows only moderate variations in mechanical properties within one paper type enabling the production of composite parts with high reproducibility.
In this work, laminates fabricated from paper layers and thermoplastic films were produced by hand-stacking and compression molding. Different paper types and matrix materials were used and the influence of the composite structure on the mechanical and physical properties was examined. Mechanical characterization was carried out by tensile, flexural and impact testing. The physical properties were characterized by density measurements and water uptake tests. Furthermore, the composites porosity was determined by TGA and the influence of paper content on the crystallinity of the polymer phase was examined by DSC measurements. Information about environmental influences on the durability of the paper laminates were obtained by application-orientated testing series. Thus, the impact of water uptake on the mechanical properties was determined. In order to obtain information about the composites structure and buildup, various microscopic analyses were carried out. The general structure was examined by stereo microscopy, while the crystallinity of the polymer phase was observed by polarized light microscopy. Further microscopical analyses were carried out by SEM and AFM/Raman spectroscopy. By optimizing the composite production process followed by detailed material characterization, laminates with high mechanical properties and good reproducibility were obtained.