Polymers and Sustainability

The positioning of a product depends mainly on its efficient use of resources, on the environmental impact of its production, on the enviromnental savings by using it in the marketplace, and by the amount of final waste left at the end of its lifetime — in other words, on its ability to be recycled. Plastics make a positive contribution in most of these sectors. 

Polymers use their main feedstock—the crude oil—more efficiently than the direct incineration of it which is true today for more than 82% of fuel consumption. Plastics—which need ca. 6% of the total fuel demand in Germany—can be considered as the first recycling loop of crude oil since aU the energy content of the fuel is preserved and can stiU be used after disposal of plastic products. 

Plastics rely on a feedstock used for energy production, but at the same time they need less of it per ton of product than other materials. The European Association of Plastic Manufacturers (APME) in Brussel has made a big effort over the last decade to develop a life-cycle analysis approach for an environmental positioning of all major plastic materials [1]. Meanwhile, the data for most polymers for resource demand and major emissions have been evaluated and published based on the average data of all European production sites. 

The issue of hazardous substances is very complex—if you only consider, for example, the issue of possible endocrine effects of substances. It is a topic of its own and will not be dealt with in this chapter. 

Use of Plastics — Examples for Saving Total Primary Energy Demand 

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ISO 14043 2000 - Environmental management - Life cycle assessment - life cycle interpretation. Murphy R., Bartle I. Biodegradable polymers and sustainability insight from life cycle assessment, Summary Report. 

YoUes, S., and Sartori, M. F., Degradable polymers for sustained drug release, in Drug Delivery Systems (R. L. Juliano, ed.), Oxford University Press, New York, 1980, pp. 84-111. 

Kohn, J., Niemi, S. M., Albert, E. C., Murphy, J. C., Danger, R., and Fox, J. G., Single step immunization using a controlled release, biodegradable polymer with sustained adjuvant activity, J. Immunol. Meth., 95. 31-38, 1986. 

A number of the water-soluble polymers also have adhesive properties which are being extensively evaluated for drug delivery (9). These polymers will adhere to the mucous coating in the gastrointestinal tract, the nose, and the mouth to delay passage and sustain drug release. Those polymers with the best adhesive properties are those with hydroxyl and carboxyl groups. Table II lists some of the bioadhesive polymers and their adhesive properties. 

Some tablets combine sustained-release and rapid disintegration characteristics. Products such as K-Dur (Key Pharmaceuticals) combine coated potassium chloride crystals in a rapidly releasing tablet. In this particular instance, the crystals are coated with ethylcellulose, a water-insoluble polymer, and are then incorporated into a rapidly disintegrating microcrystalline cellulose (MCC) matrix. The purpose of this tablet is to minimize GI ulceration, commonly encountered by patients treated with potassium chloride. This simple but elegant formulation is an example of a solid dosage form strategy used to achieve clinical goals. 

Figure 8.16 shows the principal components of a coefficient of friction tester. Polymer samples in the form of thick sheets or molded plaques are attached to the base and a sled with standard dimensions, weight, and surface properties is drawn over the surface. The load beam measures the force required to initiate movement and sustain motion at a given rate of crosshead travel. Thin films can be taped to the sled and drawn across a contact surface that has known properties. 

Creep and stress-relaxation tests measure the dimensional stability of a material, and because the tests can be of long duration, such tests are of great practical importance. Creep measurements, especially, are of interest to engineers in any application where the polymer must sustain loads for long periods. Creep and stress relaxation are also of major importance to anyone interested in the theory of or molecular origins of Viscoelasticity. 

Three types of polymeric materials are used inert polymers, active polymers, and azide polymers. No exothermic heat is produced when inert polymers are decomposed thermally. On the other hand, exothermic reactions occur when active polymers and azide polymers are decomposed. Self-sustaining burning is possible when active polymers and azide polymers are ignited. 

Biorelated Polymers Sustainable Polymer Science and Technology. Kluwer, New York. Chiellini, E., Sunamoto, J., Migliaresi, C., Ottenbrite, R.M., and Cohn, D. (Eds.) 2001. Biomedical Polymers and Polymer Therapeutics. Kluwer, New York. 

This reference discusses new uses for UV and EB irradiation, the response of polymers to irradiation, and tests related to dosimetry and radiometry, as well as safety and hygiene. It is also fortified with new problems and worked solutions, in addition to useful figures and tables, and appendices with supplementary information on equipment manufacturers, raw materials suppliers, and principles of green chemistry and sustainability. 

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