Biodegradable polymers are bio-based or synthetic polymers that decompose to carbon dioxide, water, and humus in industrial or municipal composting facilities. A few (but not all) of these polymers decompose in backyard compost bins or in soil, fresh water, or salt water. 

Biodegradable polymers are a subset of the larger bioplastics sector. Bioplastics are polymers that are bio-based (derived from plant feedstocks), biodegradable (compostable), or both. Conventional thermoplastics are neither bio-based nor biodegradable. In the figure below, the materials in the three shaded boxes are bioplastics; the materials in the two right-hand boxes are biodegradable polymers.

Double-Digit Demand

The current market for biodegradable polymers is small, but demand is growing at double-digit rates. In 2015, according to our IHS Chemical analysis, world consumption of biodegradable polymers amounted to 410,000 metric tons, substantially less than half of 1% of global demand for conventional thermoplastics. Polylactic acid (PLA) was the largest volume biodegradable polymer, accounting for more than 40% of consumption. Starch-based polymers (including starch-copolyester blends) accounted for a similar but slightly smaller share. Polybutylene adipate terephthalate (PBAT, a copolyester), polyhydroxyalkanoates (PHAs), polybutylene succinate (PBS), polycaprolactone (PCL), and polyglycolic acid (PGA) made up the remainder.

Disposable applications dominated biodegradable polymer demand in 2015. Food packaging, disposable dishes and cutlery, and shopping bags accounted for 44% of world consumption. Other important end uses included compost bags, foam packaging (including packing peanuts), and agricultural mulch films. Paper coatings are a relatively small but promising end use; other applications range from hydraulic fracturing (fracking) fluids to biomedical devices (resorbable sutures, orthopedic stents).

Regulation is an important demand driver. For example, a ban on free non-biodegradable plastic shopping bags has led to increased consumption of compostable bags in China. Corporate and consumer interest in environment-friendly products also supports demand growth, creating a market for products like biodegradable coffee pods and organic yogurt in compostable containers. The carbon footprint (cradle-to-plant-gate CO₂ emissions per kilogram of polymer) of bio-based biodegradable polymers like PLA and PHA is smaller than that of fossil fuel-based polymers. And biodegradable polymer packaging reinforces the brand message of all-natural and socially conscious products.

Finally, specific performance attributes can also drive demand for biodegradable polymers. A case in point: PLA is the material of choice for 3-D printing filament because of its low melting point, narrow melt window, and low thermal shrinkage.

Expanding Capacity

The expanding market has encouraged established producers to expand capacity and new players to enter the industry. NatureWorks, the world’s largest PLA manufacturer, plans to build a world-scale PLA production unit in Thailand. Corbion, the world’s largest producer of lactic acid, intends to begin commercial production of PLA. BASF and Novamont have expanded copolyester production capacity; MHG inaugurated a new PHA plant. Startup companies like Newlight Technologies and Mango Materials are developing new technologies for PHA production.

Strategic issues for biodegradable polymers include:

• Cost competitiveness: Biodegradable polymers are generally more expensive than fossil fuel-based polymers like polyethylene, polystyrene, and polyethylene terephthalate (PET). Increases in production scale and improvements in process technology are expected to reduce the price differential. 
• Certification: The development of international standards for compostability such as ASTM D6400 and EN 13432 has benefitted producers, processors, and consumers of biodegradable polymers, but “greenwashing” remains a concern.
• Composting infrastructure: The lack of composting infrastructure in many regions is a significant obstacle to the widespread use of biodegradable polymers. 
• Regulations: Legislation that requires the use of biodegradable compost bags or bans the distribution of non-biodegradable plastic products supports demand growth for biodegradable polymers.

This article was authored by Marifaith Hackett, senior manager at IHS Chemical; she can be reached atMarifaith.Hackett@ihs.com.

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