Reuse of materials is a significant global goal that contributes to sustainable development. Polymer-specific plastic identification from the waste stream is examined in this study to achieve environmentally optimistic reuse of plastic material in secondary applications. Two diverse waste streams, 86.11 kg of construction and demolition waste (CDW) plastic and 57.74 kg of mechanically sorted plastic, were analyzed by using a handheld tool whose identification technology was based on the near-infrared spectrum. The study indicates a significant effect of human and single fraction on manual separation. The polymer composition in the plastic waste stream varied depending on the source, but the most common plastic grades, polypropylene (PP) and polyethylene (PE), were represented in every waste stream. The waste stream also included unidentified and unfavorable wastes, which indicates that identification of the plastic fractions is needed and more studies should be done in this field in the future.

In this research, lignin and modified lignin were used as a biobased additive in the manufacturing of biocomposites. The biocomposites were produced from polylactic acid (PLA) and wood. Lignin used in this study was recovered both from spruce and from construction and demolition waste (CDW) by extracting it with a deep eutectic solvent (DES), and part of the recovered lignin was modified in esterification with maleic anhydride. The implementation of lignins on biobased composites in filament extrusion was tested and the influence of lignin on the composite manufacturing process and mechanical characteristics of the produced biocomposites was evaluated and discussed. The results showed that lignin compounds can be used as a part of biocomposites based on PLA and wood material, because the lowest tensile strength was achieved with samples which did not contain any commercial coupling agent compounds. Lignin was found to act in the biocomposites more as a coupling agent than as a lubricant, and the coupling agent strength effect of esterified lignin was comparable to the commercial coupling agent used in these experiments. The best specific tensile strength of filaments achieved in this study were 7.68 and 7.71 MPa for materials that included commercial coupling agent and esterified lignin, respectively.

Wood modification, of which thermal modification is one of the best-known methods, offers possible improvement in wood properties without imposing undue strain on the environment. This study investigates improvement of the properties of heat-treated solid wood. Scots pine (Pinus sylvestris) was modified in two stages: impregnation with modifiers followed by heat treatment at different temperatures. The impregnation was done with water glass, melamine, silicone, and tall oil. The heat treatment was performed at the temperatures of 180°C and 212°C for three hours. The modified samples were analyzed using performance indicators and scanning electron microscope micrographs. The mechanical and physical properties were determined with water absorption, swelling, bending strength, and impact strength tests. All the modifiers penetrated better into sapwood than hardwood; however, there were significant differences in the impregnation behavior of the modifiers. As regards the effect of heat treatment, generally the moisture properties were improved and mechanical strengths impaired with increasing treatment temperature. In contrast to previous studies, the bending strength increased after melamine impregnation and mild heat treatment. It is concluded that the properties of impregnated wood can be enhanced by moderate heat treatment.

Novel mechanical pre-treatment methods for effective indium recovery from end-of-life liquid-crystal display panels

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