Mahmoud Farag

By Sherif Mehanny, Lamis Darwish, Hamdy Ibrahim, Mohamed Tarek El-Wakad and Mahmoud Farag

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

By Dina Fouad and Mahmoud Farag

Many of the petroleum-based materials and products are causing problems with sustainability of resources and disposal at the end of their lives. Such problems can be solved if biodegradable materials from renewable resources are used in product design. For a material to be fully biodegradable, all its constituents must be biodegradable and should come from renewable resources if it is to be sustainable. Starch-plant fiber composites satisfy both conditions. In addition to their environmental benefits, materials from renewable resources can also be economically advantageous in certain applications, such as motorcar and packaging industries. This chapter starts with a review of the characteristics of biodegradable materials and uses case studies to illustrate their use in the design of sustainable products. The concept of design for a life (DFL), in which the material used in making a given product that will biodegrade at the end of its useful life, will also be explored.

Part of the book: Design and Manufacturing

By Mohamed H. El-Moayed, Justin Kühn, Sea-Hyun Lee, Mahmoud Farag and Sherif Mehanny

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