1 Rationale & Drivers – the Value Proposition
New environmental regulations, societal concerns, and a growing environmental awareness throughout the world have triggered the search for new products and processes that are compatible with the environment. Sustainability, Industrial ecology, ecoefficiency, and green chemistry are the new principles that are guiding the development of the next generation of products and processes. Thus, new products have to be designed and engineered from “conception to reincarnation” incorporating a holistic “life cycle thinking approach.”
The ecological impact of raw material resources used in the manufacture of a product and the ultimate fate (disposal) of the product when it enters the waste stream has to be factored into the design of the product. The use of annually renewable resources and the biodegradability or recyclability of the product is becoming an important design criterion. This has opened up new market opportunities for developing biodegradable and biobased products as the next generation of sustainable materials that meets ecological and economic requirements -- ecoefficient products. The attached figure captures this new paradigm showing the shift from the traditional materials like cotton, fur, silk, etc., to the synthetics S curve with the discovery of cheap oil, coupled to ease of manufacture, low labor input and excellent functionality. Now, the materials technology is at a new paradigm driven by environmental and sustainability considerations as discussed earlier.
The United States government has enacted legislation requiring the federal government to purchase biobased products -- Farm Security and Rural Investment Act of 2002 (P.L. 107-171, 2002). The U.S. Department of Agriculture (USDA) is developing guidelines to designate biobased products that can be procured by Federal agencies.
2 Bioplastics encompasses two separate but interlinked concepts:
biobased plastics representing the “beginning of life” of the plastic
- Origins of the carbon feedstock/resource
- Plant-biomass feedstock vs petro-fossil feedstock
biodegradable-compostable plastic representing the “end-of-life”.
- Zero waste solutions – food and bio waste diversion from landfill
- Useful in plasticulture – soil biodegradability
- Marine biodegradable ?? Issues
- Misleading and false claims – additives (oxo, organic, enzyme) added to PE, PP, PS, PET make it completely biodegradable. Not all biobased plastics are biodegradable-compostable; end-of-life is recycling
3 Bio-Based Materials and Plastics
- Represents the “beginning of life” of the product and uses plant-biomass (new carbon) vs petro-fossil (old carbon) feedstock/resources
- Replaces petro-fossil carbon in the product with biobased carbon
- The value proposition arises from removing carbon present as CO2 in the environment and incorporating it into a polymer molecule via plant-biomass photosynthesis in a short time scale of one (agricultural crops, algae) to 10 years (short rotation wood and tree plantations) in harmony with Nature’s biological carbon cycle.
- Plastics made from petro/fossil resources (like Oil, Coal, Natural gas) which are formed from plant biomass over millions of years and so cannot be credited with any CO2 removal from the environment even over a 100 year time scale ( the time period used in measuring global warming potential, GWP100).
4 Biodegradable Materials
- Microorganisms utilize carbon substrates as “food” to extract chemical energy for their life processes. They do so by transporting to the C-substrate inside their cells and:
- Under aerobic conditions, the carbon is biologically oxidized to CO2 releasing energy that is harnessed by the microorganisms for its life processes. Under anaerobic conditions, CO2+CH4 are produced.
- Thus, a measure of the rate and amount of CO2 or CO2+CH4 evolved as a function of total carbon input to the process is a direct measure of the amount of carbon substrate being utilized by the microorganism (percent biodegradation)
- Using biodegradability as an end-of-life option to remove single use short life disposable plastics/products from the environmental compartment completely and in a safe and efficacious manner via microbial assimilation (microbial food chain)