Lignin as Green Filler in Polymer Composites: Development Methods, Characteristics, and Potential Applications

Abstract

After cellulose, lignin is the most commonly used natural polymer in green biomaterials. Pulp and paper mills and emerging cellulosic biorefineries are the main sources of technical lignin. However, only 2–5% of lignin has been converted into biomaterials. Making lignin-based polymer biocomposites to replace petroleum-based composites has piqued the interest of many researchers worldwide due to the positive environmental impact of traditional composites over time. In composite development, lignin is being used as a filler in commercial polymers to improve biodegradability and possibly lower production costs. As a natural polymer, lignin may have different properties depending on the isolation method and source, affecting polymer-based composites. The application has been affected by the characteristics of lignin and the uniform distribution of lignin in polymers. The review’s goal was to provide an overview of technical lignin extraction, properties, and its potential appropriate utilization. It was also planned to revisit the lignin-based composites’ preparation procedure as well as their composite characteristics. Solvent casting and extrusion methods are used to fabricate lignin from polymeric matrices such as polypropylene, epoxy, polyvinyl alcohol, polylactic acid, starch, wood fiber, natural rubber, and chitosan. Packaging, biomedical materials, automotive, advanced biocomposites, flame retardant, and other applications for lignin-based composites has existed. As a result, the technology is still being refined to increase the performance of lignin-based biocomposites in several applications. This review could assist explain lignin’s position as a composite additive, which could lead to more efficient processing and application strategies.

Effect of Micro- and Nano-Lignin on the Thermal, Mechanical, and Antioxidant Properties of Biobased PLA–Lignin Composite Films

“…Although lignin is highly resistant to chemical and biological degradation, it is slowly degraded by ligninolytic microbes [ 19 ]. Therefore, the integration of lignin with bio-based polymers can lead to renewable composites with improved properties [ 20 , 21 ].…”

Wind Tunnel Testing and Validation of Helicopter Rotor Blades Using Additive Manufacturing

“…Models created in wood require a high cost for skilled workers, and it takes a long time to make the models. Metals like aluminum were used to prepare the model using CNC machines are high cost and less affordable [10,11].…”

Investigating the Synthesis and Characteristics of UV-Cured Bio-Based Epoxy Vegetable Oil-Lignin Composites Mediated by Structure-Directing Agents

“…On the other hand, DMA results indicate that EpLnK does not act as a reinforcing agent, but the great potential of the LnK and its derivatives in different applications (such as anticorrosive protection, electronics industry, and many others [ 16 , 49 , 50 ]) compensates for this inert behaviour in terms of rigidity and thermo-mechanical resistance. The overall behaviour of the studied ELALO-SDA-EpLnK materials, as well as the shape of the registered curves, with a single maximum associated to the Tg by Tanδ peak, may talk about homogeneous materials, the purpose associated with the SDA addition being thus achieved.…”