These days everyone seems to be getting on the “environmental bandwagon.” People talk about hybrid cars, electric vehicles, biodiesel, renewable resources, and the list goes on. An interesting question is how sustainable are the polymers you use or make? A simple question but there are no simple answers. So how do you evaluate sustainability? Life Cycle Assessment (LCA) and the application of Green Design principles are powerful tools in sustainability evaluations.
LCA is a systematic set of procedures for compiling and examining the inputs and outputs of materials, energy and the associated environmental impacts directly attributable to the functioning of a product or service system throughout its life cycle. The most common versions of LCA are a cradle-to-grave and cradle-to-factory gate evaluations. The former addresses all phases of LCA while the latter addresses from the raw material phase to the product leaving the factory site phases. It seems that for cosmetic ingredients the cradle-to-factory gate LCA is more applicable since the use of the material on the human body should not pose environmental threat. The figure below shows the stages of LCA and the place of Green Chemistry and Green Engineering in the overall scheme:
LCA has been documented by the International Standardization Organization (ISO) in the following standards:
- ISO 14040: 1997-Principles and Framework
- ISO 1441: 1998-Goal and Scope Definition and Inventory Analysis
- ISO 14042: 2003-Life Cycle Impact Assessment
- ISO 14043: 2003-Interpretation
Green Design consisting of Green Chemistry and Green Engineering addresses similar issues as LCA with special focus on environmental impact of industrial production. Green Chemistry is the design of chemical products and processes that reduce or eliminate the generation of harmful and toxic wastes threatening humans and the environment. The “12 Principles of Green Chemistry” enunciates the goals and merits of green chemistry. Green chemistry has its main role in inventing novel synthetic routes in the product development phase leading to no or minimum byproduct formation. Examples for green chemistry innovations include synthetic routes without using volatile organic solvents, extensive use of catalysts, and high atom economy. Atom economy is defined as the ratio of the mass of the desired product to the mass of the total material (desired product plus waste/byproducts) in a chemical reaction. High atom economy is achieved by addition reactions while lower atom economies are typical for substitution and condensation reactions. For example acrylics form via addition reaction therefore they have high atom economy while nylon forms via condensation reaction resulting in lower atom economy in polymerization. Green Engineering is the design and implementation of engineering solutions using input from Green Chemistry development that take environmental issues into account throughout the entire product life cycle.
In the next posts we will dive a little deeper into an example of evaluating some common polymers from and LCA and green design perspective.
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