Biopolymers

Synthetic polymers are used extensively. Approx. 98 % of the 300 million tons of polymers manufactured each year for packaging, construction, appliances, and other technical goods are made from fossil sources, predominantly crude oil. Combustion (thermal recycling) is a preferred route of disposal, at it removes waste, however, CO₂ emissions arise. Biobased polymers, by contrast, are made from renewable resources. A second class of biopolymers for technical applications is biodegradable, being produced from conventional or renewable feedstock. Common biobased plastics are drop-in materials such as biobased PE, biobased PP, and biobased PET, and frequently used biodegradable plastics are PLA (polylactic acid), TPS (thermoplastic starch), and PHA (polyhydroxyalkanoates). Also, composites can contain natural fibers such as sisal or hemp. Biobased polymer additives, e.g., plasticizers, are also in use. Renewable feedstock reduces the carbon footprint of the plastics produced. Hence, biopolymers can contribute to climate change mitigation. Biodegradable bioplastics avoid accumulation of the material in the environment, which has detrimental effects, e.g., on marine wildlife. The degradation of bioplastics in general does not release pollutants, and mineralization of the polymer yields CO₂ and water in case of hydrogen, carbon, and oxygen compounds. In this chapter, biobased polymers, which have a substitution potential of up to 90 %, are briefly discussed with respect to climate change mitigation.