A significant change is occurring in the global polymer industries. Development of a new generation of bio-based polymers, polymers derived from renewable resources, is progressing rapidly. Complementing historical biopolymers such as natural rubber and cellulosics, these new bioplastics include a growing number of commercial successes, including polylactides and polyhydroxyalkanoates. Many more bioplastics are on the near horizon, made possible by rapid advances in biotechnology. The molecular specificity of biochemical transformations is ideally suited for producing high purity monomers needed for making high molecular weight polymer molecules. Some of the newest developments involve the creation of well-established polymers (polyethylene, polybutlylene, poly(ethylene terephthalate)) via new biochemical pathways that start with renewable, rather than fossil, resources. This article highlights some recent advances in bio-based polymers. Specifically, this review includes topics ranging from novel biopolymer synthesis, new bio-based nanocomposites, novel processing, and holistic assessments of sustainability through quantitative life-cycle analysis. It is demonstrated that greener plastic materials can be produced through ecologically responsible conversion of renewable resources using industrial biotechnology and enhanced by nanotechnology. This emerging approach represents a triple technological convergence that promises to significantly alter the value chains of the global plastics industries.

Starch is an abundant, biodegradable, renewable, and low-cost commodity that has been explored as a replacement for petroleum-based plastics. By itself, starch is a poor replacement for plastics because of its moisture sensitivity and brittle properties. Using starch as a fermentation feedstock, various promising biodegradable plastic products have been developed that rival petroleum-based plastics and are poised to enter the marketplace or are already in production. Other starch-based plastics are blends with other compatible resins or are based on chemical treatments that improve the functional properties of various products. While these approaches are very promising, there are efforts under way to develop viable products from starch by using different processing technologies and by combining starch with other materials to make functional composites. This article focuses on different technologies for making starch-based foam materials and the use of reinforcing fibers and nanoparticles for making composites that can substitute for some petroleum-based foam products.

In recent years, bio-based products have been of great interest since sustainable development policies have tended to expand with decreasing reserves of fossil fuels and growing concerns for the environment. Consequently, biodegradable and renewable polymers have been the topic of significant research. These polymers can mainly be classified as agro-polymers (starch, chitosan) and biopolyesters (polyhydroxyalkanoates, poly(lactic acid)). Unfortunately, for certain applications, these bio-based polymers cannot be fully competitive with conventional thermoplastics since some of their properties are too weak. Therefore, to extend the range of their applications, current bio-based polymers have to be reformulated. Some of the most promising are nano-biocomposites, where nano-sized fillers are dispersed into a biopolymer matrix, which could yield a range of improved properties (stiffness, permeability). This article reports the most recent developments in renewable nano-biocomposites based on the use of nanoclay fillers.

There are a large number of natural fibers that have the potential to replace synthetic fibers made from glass, carbon, and polymers as the reinforcing phase in composites. Interest in these fibers has increased, as they offer a sustainable, readily available, high specific modulus option. The high modulus of cellulose crystals makes them attractive as a reinforcing phase in composites. These cellulose crystals are the key structural component in natural fibers, but the complex microstructure of the fiber means that the full value of the cellulose crystal modulus cannot be utilized. Moreover, the surface of natural fibers can have varying chemistry depending on the pretreatment of the fiber and the degree to which lignin and other hydrophobic materials are removed from the fiber. In addition, cellulose swells in contact with water, and this can degrade the properties of the fiber and composite. A better understanding of the surface properties and techniques to control the composite interface are required if natural fibers are to fulfill their potential.

Bio-based plastics, in which the fossil carbon is replaced by bio/renewable-based carbon, offer the intrinsic value proposition of a reduced carbon footprint and are in complete harmony with the rates and time scale of the biological carbon cycle. Identification and quantification of bio-based content is based on the radioactive C-14 signature associated with (new) biocarbon. Using experimentally determined biocarbon content values, one can calculate the intrinsic CO2 emissions reduction achieved by substituting petrocarbon with biocarbon—the material carbon footprint value proposition. The process carbon footprint arising from the conversion of feedstock to final product is computed using life-cycle assessment methodology. Biodegradability in conjunction with selected disposal systems such as composting and anaerobic digestion offers an end-of-life solution to completely remove the plastic substrate from the environment. Not all bio-based polymer materials are biodegradable, and not all biodegradable polymers are bio-based. Most importantly, complete biodegradability (complete utilization of the polymer by the microorganisms present in the disposal environment) is necessary as per ASTM and ISO standards, otherwise there could be serious health and environmental consequences.