Sustainability Loop

What is Sustainability?

Sustainability has many definitions. One way to think of it is “meeting the needs of the present without compromising the ability of future generations to meet their needs.”

This definition was created in: Our Common Future, Report of the World Commission on Environment and Development, World Commission on Environment and Development, 1987. Published as Annex to General Assembly document A/42/427, Development and International Co-operation: Environment August 2, 1987.

 

What is a Polymer?

"Polymer" is the technical term for molecules that make up plastic. Polymers are long chain molecules made of smaller, repeating unit molecules called “monomers”, similar to how beads (monomers) connected together form a necklace (polymer). Naturally occurring polymers include DNA, starch, wood and natural rubber. Synthetic polymers include polyethylene, polypropylene and polystyrene. For more general information about polymers visit the Macrogalleria.

 

What is a sustainable polymer?

A sustainable polymer is a plastic material that addresses the needs of consumers without damaging our environment, health, and economy. The feedstocks for sustainable plastics are renewable, such as plants. The production of sustainable polymers should use less net water and non-renewable energy, emit less greenhouse gases and have a smaller carbon-footprint than their non-sustainable counterparts, while still being economically viable.

 

How are sustainable polymers different from ordinary plastic?

Traditional Polymers:

1. Petroleum or natural gas is converted into chemicals (monomers).
2. The chemicals are made into useful plastic products.
3. The plastic products can be incinerated, recycled or thrown away.

Traditional Polymers

Sustainable Polymers:

1. Carbon dioxide and water are used in photosynthesis to grow plants
2. The plants are harvested and processed to make chemicals (monomers or polymers)

  • The plant material may be fermented to produce monomers (e.g., plant-derived sugar to lactic acid)
  • Chemicals may be extracted from the plant to make monomers (e.g., modified soybean oil used in polyurethane foam) or polymers (e.g natural rubber or polyhydroxyalkanoates)

3. The renewable chemicals are converted to plastic products.
4. Some sustainable polymers can be composted (4a) in addition to being recycle or incinerated to recover their energy content (4b).
5. Composting produces carbon dioxide, water and organic matter (dirt) which is used to regenerate the renewable resource feedstock (plants).

Sustainable Polymers

 

What plants are sustainable polymers made from?

Currently, commercially produced sustainable polymers are made from starch-containing plants like corn or sugarcane and seed oils such as soybean or other vegetable oils. Scientists around the world are studying ways to make polymers from alternate renewable sources such as agricultural waste products like corn stover (leaves and stalks).

 

Are sustainable polymers more environmentally friendly to make?

The goal of sustainable polymers is to reduce the negative impact on the environment while still having a plastic material that serves society’s needs. Thus, the ideal sustainable polymer should be more environmentally friendly to make – meaning less water and non-renewable energy use and less pollution emissions, when compared with the petroleum-based plastics we use currently.

 

What products can be made from sustainable polymers?

Sustainable polymers can be used to make many things. Polylactide, presently derived from corn, is made into plastic cutlery, food containers, fibers for clothing, and even cell phone cases. Modified soybean oil is used right now to make polyurethane foam for products like seating cushions and memory foam pillows. The list of products will continue to grow as more research is done and further sustainable polymers are developed.

 

What are the limitations of sustainable polymers?

Some of the challenges facing sustainable polymers include obtaining the physical properties that rival traditional polymers while remaining cost competitive. Extensive research is currently going on in universities and companies worldwide to improve the properties of sustainable polymers. Influencing the cost of sustainable polymers will depend upon discovering new cost-effective ways of manufacturing the polymers as well as policy changes.

 

Are sustainable polymers edible?

No, sustainable polymers are not edible. Although they are derived from plants, sustainable polymers do not provide any nutritive value and will act like any other plastic when ingested.

 

Are sustainable polymers recyclable?

Some sustainable polymers can be recycled, but they need to be separated from the other recyclable plastic (polyethylene, polyethylene terephthalate) that can require additional equipment and sorting methods. Since sustainable polymers are relatively new compared with traditional plastics, the necessary infrastructure is not currently in place, thus, you can’t put sustainable polymers in the recycling bin just yet.

 

Can I compost sustainable polymers in my backyard?

It depends on the specific type of plastic. Some sustainable polymers are not compostable at all. Of the commercially available compostable plastics, some will break down in your backyard compost, but others will need the high humidity and high temperatures of a commercial composting facility. So it is best to dispose of your compostable plastic at an industrial composting site. For more information about curbside compost pick-up in Minnesota visit Eureka Recycling, or to find an industrial composter near you visit Find A Composter.

 

Will sustainable polymers degrade on the shelf, in a landfill, or outside on the ground?

The sustainable polymers that are compostable are designed to last while you use the product. They will not degrade on a shelf or in your home if used properly. Preliminary tests indicate that sustainable polymers will not biodegrade in a landfill due to insufficient conditions, nor will they contribute significantly to methane emissions. Sustainable polymers will also not degrade outside on the ground, so you should always dispose of your plastic waste correctly.

 

How can I tell if a product is made from sustainable polymers?

Unfortunately, right now it is not easy to tell if a product is made from sustainable polymers. Part of the problem is that there isn’t a universally accepted definition of sustainable with respect to materials. However, there are certifications for compostability and biobased content which can help you to identify which products are truly more environmentally friendly. Some of the trade names of different sustainable and partially sustainable polymers are: Ingeo, Mirel, BiOH, Mater-Bi, Sorona, NatureWorks.

 

What new policies are needed?

Sustainable polymers are relatively new to the consumer market. Therefore, there is much work to be done in terms of developing appropriate policies. Currently, there is inadequate regulation of advertising and labeling of environmentally-friendly products. More policies are needed to prevent “greenwashing” and misleading of consumers. In order to take full-advantage of the properties of compostable polymers, industrial composting should be more accessible to consumers, possibly through the use of curbside compost pick-up. Not only could compostable plastics be diverted from landfills in this way, but also food waste. Finally, progress towards improved sustainable polymers can only result from scientific research and technological innovation which requires public support and a commitment to research and education.