Overview

When bio-based resins derived from natural oils (described in Chapter 4) are combined with natural fibers (flax, hemp, jute, cellulose, switch grass, chicken feathers), glass fibers, graphite fibers, and lignin, new low-cost composites are produced that are economical in many high-volume applications. These composites are used in agricultural equipment, automotive sheet molding compounds, civil infrastructures, marine applications, housing, and the construction industry. Examples are given for the synthesis, manufacture, and properties of plant-based resins and glass, flax, lignin, and hemp composites, including sheet molding compound. This chapter deals primarily with highly cross-linked triglyceride-based resins suited for liquid molding applications with fibers to form composites. Linear polymers suited to elastomers, pressure-sensitive adhesives, and coatings requiring molecular weights of the order of 10 ⁶ g/mol, are treated in Chapter 8. Such polymers are made primarily with the individual fatty acids with a preference for high oleic (1 C=C per FA).

Henry Ford made the first auto parts in 1938 from soybean proteins with fiberglass reinforcement, as shown in Figure 5.1. This figure shows Mr. Ford performing an impact test on the hood of his car with the blunt end of an ax. Mr. Ford and Thomas Edison were committed to developing bio-based materials to reduce pollution in their mass production of products. However, global wars intervened and the rise of the petroleum-based plastic industry rapidly replaced the more environmentally friendly materials envisaged by these industrial giants. However, 60 years later with significant improvements in agricultural biotech,...