Scientific Study

The pine nut industry generates a high amount of residues, currently under-valorized in most cases as energy production through incineration. A more effective end-of-life option involves using pine nut shells in polymeric composites, since they represent a source of valuable compounds, such as polysaccharides, lignin, and polyphenols. In the current study, composites were prepared by melt blending pine nut shells with polypropylene and low-density polyethylene. In particular, the composites were loaded with up to 10% and 30% by weight of pine nut shells with respect to polypropylene and polyethylene, respectively. To improve the compatibilization with the hydrophobic matrices, the natural filler was functionalized with stearic acid and added as a compatibilizer. The filler was characterized in terms of chemical composition, antioxidant capability, thermogravimetric analysis, and infrared spectroscopy. Thermal and mechanical properties of the final materials were evaluated through differential scanning calorimetry and tensile testing. Some composites were subjected to accelerated UV aging to assess the antioxidant effect of the biowaste loaded. This approach has a high potential as to what concerns the reduction of plastics use, limiting the use of fossil-derived polyolefins, improving their durability with natural fillers while maintaining their thermal and mechanical properties, and avoiding waste dumping.

https://doi.org/10.1016/j.polymer.2026.129698