Page 55 - Carrahers_Polymer_Chemistry,_Eighth_Edition

18 Carraher’s Polymer Chemistry

the “goal and scope” phase the functional unit is described with effort focused on defining the boundar-

ies of the system or product to be studied. It includes describing the methods used for assessing possible
environmental impacts and which impact categories are to be included in the study. In the “inventory”
phase data is collected, including the description and verification of the data along with various model-

ing programs to be used. In general, items considered include inputs such as quantities of materials, land
usage, and energy and outputs such as air emission, solid waste, and water emissions. Software pack-
ages have been developed, and are being developed, to assist in such evaluations. The “impact” phase is
intended to describe contributions to more global situations such as global warming and acidifi cation.

The final phase, “interpretation,” brings together the other three phases, and conclusions are made.
There are varying types of LCA studies that act to limit or defi ne the type of LCA study being
made. The cradle-to-grave assessment is a full LCA study from manufacture (cradle) to the disposal
(grave) of a product. A cradle-to-gate study looks at the life cycle from manufacture (cradle) to fac-
tory gate (before it is sent to the consumer). These assessments are often used as a basis for environ-
mental product declarations. A cradle-to-cradle assessment involves products where the product is
recycled so the study terminates when a new product is made from the recycled original product. A
life cycle energy analysis looks at all energy inputs to a product and not solely direct energy inputs
during manufacture, including energy necessary to produce components and materials needed for
the manufacturing process.

1.5 SUMMARY

After reading this chapter, you should understand the following concepts:
1. Polymers or macromolecules are giant molecules with large structures and high molecu-
lar weights. In spite of their varieties they are governed by the same laws that apply to small
molecules.
2. If we disregard metals and some inorganic compounds, practically everything else in this world is
polymeric. Polymers form the basis for life itself and for our communications, transportation, build-
ings, food, and so on. Polymers include protein and nucleic acids in our bodies, the fi bers (natural
and synthetic) we use for clothing, the protein and starch we eat, the elastomers in our automotive

tires, the paint, plastic wall and floor coverings, foam insulation, dishes, furniture, pipes, and so on.
3. There are some systems in place that allow us to readily identify the nature of many polymeric
materials including clothing and containers.
4. Early developments in polymers were largely empirical because of a lack of knowledge of poly-
mer science. Advancements in polymers were rapid in the 1930s and 1940s because of the theo-
ries developed by Staudinger, Carothers, Mark, and many other scientists.
5. This is truly the age of the macromolecule. Essentially every important problem and advance
includes polymers, including synthetic (such as carbon nanotubes) and biological (such as the
human genome and proteins). There are more chemists working with synthetic polymers than in
all of the other areas of chemistry combined.
6. The environmental impact of materials with respect to health and the impact on the environment
(today and in the future) is a critical factor as we move forward. Polymers are an essential part
of this impact and the solutions to essentially all of the important environmental issues. We must
be aware of these environmental issues contributing as individuals and as groups to promote and
practice responsible “green science.”

GLOSSARY
ABS: A polymer produced by the copolymerization of acrylonitrile, butadiene, and styrene.
Bakelite: A polymer produced by the condensation of phenol and formaldehyde.
Cellulose: A naturally occurring carbohydrate polymer.
Ecological footprint: A measure of our demand on the Earth’s ecosystems.

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