Preparation and characterization of polypropylene composites reinforced by functional ZnO/lignin hybrid materials

Abstract The aim of this study was to obtain polypropylene composites filled with a ZnO/lignin hybrid filler and to examine their chemical and mechanical properties. Inorganic-organic hybrid materials were obtained using an environmentally-friendly, low-cost mechanical method. The use of an inorganic component mainly influenced the improvement of thermal properties, in turn, the use of lignin was mainly supported by its low price as well as unique properties. The effectiveness of ZnO/lignin materials production was confirmed using Fourier transform infrared spectroscopy and, indirectly, by colorimetric analysis. In addition, the thermal stability and porous structure analyses were also carried out. Polymer composites containing 3 wt% of each filler were subjected to wide angle X-ray diffraction tests and differential scanning calorimetry studies to define their supermolecular structure as well as thermal properties. Polarized light microscopy was performed to assess the influence of fillers on the crystallization of polypropylene. Tensile tests provided information regarding the mechanical properties of produced materials. The presence of hybrid fillers influences the nucleation activity and it was responsible for an increased crystallinity degree of composite samples. It was also established that introduction of ZnO and hybrid fillers with high amount of ZnO into the polypropylene matrix resulted in a significant increase of density of the formed nuclei.