The engineering properties of polypropylene hybrid composites reinforced with lignin and zeolite

This study investigated the synergistic effect of lignin and natural zeolite on the technological properties of the hybrid composites. The hybrid composite samples were produced using a polypropylene matrix (PP), lignin, and zeolite through extrusion and injection molding processes. Lignin content of the samples varied between 0 and 15 wt%, while zeolite content was constant by 10 wt% The chemical and thermal properties of the hybrid composites were characterized using Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and X-ray Diffraction (XRD). Mechanical properties namely tensile, flexural, impact strength as well as water absorption rates were evaluated. Additionally, surface characterization was performed using Scanning Electron Microscopy (SEM). The incorporation of lignin (5 wt%) and zeolite enhanced the thermal stability and led to a slight increase in the crystallinity of the hybrid composites. A significant enhancement in mechanical properties and water resistance was observed with 5 wt% of lignin. However, lignin content above 5 % led to poor dispersion, resulting in deteriorated composite properties. XRD results further confirmed that lignin and zeolite influence the crystal structure of the PP matrix. At lower lignin concentrations, improved dispersion demonstrated the synergistic effect of lignin and zeolite, suggesting the potential of these hybrid blends for applications in the green bio-composites market.