Chapters authored
High-Content Lignocellulosic Fibers Reinforcing Starch-Based Biodegradable Composites: Properties and Applications
Natural source-based composites became promising substitutes and synthetic petrochemical-based counterparts. So far, thermoplastic starch and lignocellulosic fibers are the most common materials for making such eco-friendly ?green? materials. Low cost, abundance, and renewability are the factors that lead to deploying these two types of materials. In this chapter, we are conducting further analysis for previously published results of six types of high-content natural fiber-reinforced starch-based composites. All composites were prepared by compression molding under pressure from 5 to 20 MPa and temperature from 130 to 160°C. Composites exhibited highest tensile strength and modulus of elasticity at fiber weight content from 50 to 70%, and then mechanical properties deteriorated significantly at 80% fiber content due to the insufficient starch resin. For instance, the tensile strength was boosted up from 2-12 MPa for thermoplastic starch to reach 55, 45, 32, 28, 44, 365 MPa for flax, bagasse, date palm fiber (DPF), banana, bamboo, and hemp composites, when fiber content was increased from 0% to the optimum fiber content (50-70%). Kelly-Tyson (random 2d) was the optimum model to predict random fiber composite. Increasing the fiber content and choosing a fiber with high cellulose content significantly improve the moisture resistance of the composites. Fick’s law of diffusion predicted the water uptake property successfully. The thermal stability of composites was improved with increasing the fiber weight content as well. This is attributed to the high thermal stability of cellulose when compared to starch. Properties exhibited by starch-based high-content natural fiber composite are promising for many industrial and biomedical applications.
Part of the book: Composites from Renewable and Sustainable Materials
Perspective Chapter: Potential of Lignin Valorization with Emphasis on Bioepoxy Production
Lignin is the second most abundant natural polymer after cellulose. It has high molecular weight and poor dispersity, which lowers its compatibility with other polymeric materials. Accordingly, it is hard to integrate lignin into polymer-based applications in its native form. Recently, lignin valorization, which aims to boost lignin value and reactivity with other materials, has captured the interest of many researchers. The volatility of oil and gas prices is one strong incentive for them to consider lignin as a potential replacement for many petroleum-based materials. In this chapter, lignin valorization processes, namely hydrogenolysis, pyrolysis, hydro-thermal liquefaction, and hydro-thermal carbonization, are discussed in brief. The chapter also discusses the synthesis of lignin-based epoxy resin as an already existing example of a lignin-based product.
Part of the book: Lignin