May 2004

Biodegradable Plastics Make Progress

With concern for landfill volumes on the rise, more attention is being focused on the development of biodegradable varieties of materials that have traditionally been difficult to accommodate in landfills. Some of the toughest materials to dispose of are also among the most plentiful.

Biodegradable plastics have been around for nearly 20 years, and standards for their definitions and testing – developed through eight years of research by the American Society for Testing and Materials (ASTM) – have been in place since 1999.

According to the ASTM, “biodegradable plastics are a degradable plastic in which the degradation results from the action of naturally occurring microorganisms such as bacteria, fungi and algae.” Not coincidentally, these are the same forces that make composting possible.

Packaging products made from these biodegradable polymers are becoming a more widely accepted alternative to traditional plastics in such applications as consumer package goods, the fast food industry, agriculture and containers for a variety of commonly used products. Eventually, that will mean good news for landfills.

To understand biodegradable plastics, a basic understanding of “traditional” plastics is essential. This understanding of traditional plastics should include what they are made of, how they are produced and why they pose a concern for the environment. Briefly, all traditional plastics are made from non-renewable raw materials – resources including petroleum products that will eventually become exhausted.

Mike Corwin, marketing manager for BASF North America explains, “Chemically, there are two ways to arrive at biodegradability. The first approach is through renewable resources – organic in nature – such as cornstarch. The second involves synthetic, co-polyester technologies based on petroleum products,” he said.

Polymers found in nature are known as biopolymers. Starches, proteins and peptides form the chemical basis for biopolymers and when blended with other compounds, exhibit many of the desirable characteristics of traditional plastics. When blended with other compounds, biopolymers can be injection molded or processed into a wide variety of products.

BASF’s biodegradable plastic is a synthetic material marketed under the brand name Ecoflex.® The formability and strength of this biopolymer is ideal for use in the manufacture of biodegradable bags for example. Bags for such applications as grocery and garbage bags that would otherwise be landfilled. It’s a plastic, but bacteria and fungi reduce it to water, carbon dioxide and biomass almost as quickly as they would potato peelings.

While biodegradable plastics offer considerable promise, it may take some time before the benefits of these materials are felt. At present, the percentage of biodegradable plastics in current solid waste streams is very small. The continued development of more applications for biodegradables will likely change that.

“There’s the whole issue of cost-effectiveness as well,” adds Mike Corwin of BASF. “Right now, the production for traditional polyester products is roughly 700,000,000 lbs. per year. In contrast, biodegradable volumes account for only 20,000,000 lbs. At that rate, the industry just can’t realize the economies of scale afforded by more traditional products, so biodegradables will continue to be more expensive to produce. Eventually, when more markets for biodegradables are developed and production increases, prices will come down. Getting to that point is the difficult part,” he observed.

While biodegradable packaging represents only a small portion of the total North American solid waste stream at present, refinements in formulation will invariably lead to expanded applications and improved cost effectiveness in the future.