Biodegradable Polymers

This report discusses issues and markets for biodegradable polymers, as distinguished from bio-based polymers. Biodegradable polymers are part of the larger overall bioplastics market. Bioplastics are polymers that are either bio-based or biodegradable (some materials are both). Not all bio-based products are biodegradable (for example, polyethylene based on ethanol), while some biodegradable products are actually made from petroleum-based products (for example, polycaprolactone).

In 2012, the two most important commercial biodegradable polymers were polylactic acid (PLA) and starch-based polymers, accounting for about 47% and 41%, respectively, of total biodegradable polymer consumption. However, certain grades of PLA are not truly biodegradable and are being used in conventional applications. Other polymers that meet the definition of biodegradable include polyesters such as aliphatic/aromatic copolyesters; poly(epsilon-caprolactone) (also known as polycaprolactone), a biodegradable polymer used primarily in starch-based compositions; and cellulosic derivatives and polyhydroxy-alkanoates.

The following pie chart shows consumption of biodegradable polymers by major region:

The bioplastics industry accounts for only about 1% of the total global plastics market. However, rapid growth has continued to take place in recent years. Industry sources expect that bio-based polymers such as bio-polyethylene will increase at a faster rate than biodegradable polymers because of factors such as

• Drop-in ability and use on systems that have the same processing, service and recycling streams as conventional petrochemical-based polymers
• Bio-based commodity plastics demand where feedstock is available (Asia, Central and South America)
• Continued growth from compostable to durable goods in electronics, auto, household, etc.
• Low carbon footprint and sustainability issues

Currently, biodegradable polymers constitute a larger share of the total bioplastics market and strong growth is forecast. It is expected that bio-based polymers will account for the larger share in the next several years.

Europe continues to be the largest biodegradable polymer–consuming region, with over half of the global total. Legislation is a key market driver and includes a packaging waste directive to set recovery and recycling targets, a number of plastic bag bans, and other collection and waste disposal laws to avoid landfill. Consumer awareness of sustainable plastic solutions and pressure from retailers also contribute to the interest in reduction of greenhouse gas emissions and fossil fuel independence. 

In terms of biodegradable polymer end uses, the food packaging, dishes and cutlery market is the largest end use, as well as the major growth driver. In both North America and Europe, these markets accounted for the largest use, and strong double-digit growth is expected in the next several years. The foam packaging market continues to represent a significant share of the biodegradable polymers market, behind food packaging, dishes and cutlery. This market dominated use during the early years of biodegradable polymer development. Compost bags follow foam packaging in terms of volume use. This market will continue to grow strongly, but relatively less than the leading markets. In North America, compost bag use will depend on future composting infrastructure. Other smaller-volume but fast-growing markets for biodegradable polymers include agriculture and horticulture (mulch films), paper coatings (e.g., to line paper products such as cups), medical uses, and other industrial applications. 

In order for a polymer to be considered compostable, three criteria must be met: biodegradation—it has to break down into carbon dioxide, water and biomass at the same rate as food scraps and yard wastes; disintegration—the plastic must become indistinguishable in the compost (e.g., pass through a 2 mm sieve after 12 weeks); and nontoxicity. Most international standards (such as ASTM D6400) require at least a 90% biodegradation of a product within 180 days, along with other factors, to be called compostable. 

A significant obstacle to the widespread use of biodegradable polymers is the lack of composting infrastructure. In recent years, Western European countries have led the way in developing such an infrastructure. In the United States, cities and local communities have continued to develop ways to make composting more accessible. 

Current production costs for PLA-based polymers are still higher than those for conventional petrochemical-based polymers. However, product improvements and increased R&D have lowered costs and made PLA more feasible in many applications. Also, technological advances have improved bacteria and yeast strains to produce lactic acid feedstock on a larger scale.

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