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Environmentally Conscious Design & Manufacturing

Environmentally Conscious Design & Manufacturing. Class 17: Plastics. Prof. S. M. Pandit. Agenda. Use of Plastics Fundamentals of plastics Design guidelines Recycling and degradation of plastics. Use of Selected Commodities. Material in a Typical U.S. Automobile. Unit:kg.

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Environmentally Conscious Design & Manufacturing

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  1. Environmentally Conscious Design & Manufacturing Class17: Plastics Prof. S. M. Pandit

  2. Agenda • Use of Plastics • Fundamentals of plastics • Design guidelines • Recycling and degradation of plastics

  3. Use of Selected Commodities

  4. Material in a Typical U.S. Automobile Unit:kg

  5. Flow of Plastics in an Automobile Unit:kg

  6. Fundamentals of Plastics • Composition: polymer molecules and various additives • General characteristics: lower density, strength, elastic • modulus and thermal and electrical conductivity, and • higher coefficient of thermal expansion • Two major classes of polymers: • Thermoplastics • Thermosets

  7. Fundamentals of Plastics (cont.) • Major molecular structure which determines the • properties of the polymer • linear • branched • cross-linked • network. • Additives • fillers • plasticizers • colorants

  8. Thermoplastics • Definition: Type of polymer which softens and melts when heated but resolidified upon cooling • Typical examples: • Acrylics • Nylons • Polyethylene • Polypropylene • Polystyrene • Recyclability • Easy to recycle

  9. Thermoplastics: Applications Source:Kalpakjian, S., “Manufacturing processes for engineering materials”

  10. Thermosets • Definition: Type of polymer which does not soften • appreciably when heated. • Typical examples: • Epoxy • Polyester • Polyimides • Recyclability • Difficult or impossible to recycle • Burned to recover a portion of their chemical bond energy

  11. Thermosets: Applications Alkyds: Good electrical insulating properties, impact resistance, dimensional stability applications: electrical and electronic components Epoxies: excellent mechanical and electrical properties, dimensional stability, strong adhesive properties, good resistance to heat and chemicals applications:tools and dies, adhesives, pressure vessels, tanks Polyesters: good mechanical, chemical, and electrical properties applications: boat, luggage, chairs, automobile bodies Polyimides: good mechanical, chemical, and electrical properties applications: pump components, electrical connectors for high-temperature use

  12. Processing of Plastics Source: Kalpakjian, S., “Manufacturing processes for engineering materials”

  13. Toxic Chemical Released byIndustries

  14. Design Guideline • The American Plastics Council provided design guideline • for designers: • Using fewer materials to make the new product • is better • Using plastics can be compatible for recycling • Using material that can be recycled

  15. Recycling of Plastics: Facts • In the plastics industry, only a small portion is recycled • (that is, PET bottles, styrofoam cups, plates and trays). • 58 billion pounds of plastic resin sold in the United States and less than 1 % was recycled. • One of the most pressing environmental issues is the • mounting problem of solid waste disposal. Plastic materials of all kinds present about 7 percent of the municipal waste stream

  16. Recycling Technology • The following recycling technologies for plastics are needed: • Complete plastic identification • Ways to remove paints, metallic coatings, well adhered • labels, or foam insulation from recyclable plastic • Separation of rubber and other elastomers from plastics with similar densities • Separation of metal foils from recyclable plastic • Identification and removal of potentially hazardous materials (small batteries, mercury relays, beryllium copper and lead-based solder) Source: Zhang et al.: J.of Manufacturing systems 16(5), 1997

  17. Materials Compatibility • The mingling of different polymers in the recycled • stream makes recycling of plastics difficult. • There is a need for separating plastic components into • appropriate categories based on composition. • Design consideration: • Use as few different types of materials as possible • Ensure all materials can be easily separated from the • primary plastics • More than one type of plastics used should be compatible • with one another

  18. Materials Compatibility Chart

  19. Materials Identification • When many types of plastics are used in a product and • plastic formulations are incompatible, identification • system will make recycling easy. • Three major plastics identification systems: • ISO 1043-1 • ASTM D1972-91 • SPI Voluntary National Container Material Code System

  20. Plastics Identification System (ISO 1043-1)

  21. Categories of Plastics(The Society of Plastics Industry)

  22. Use of Plastics in Packaging

  23. Plastics Degradation • It takes at least 50 year for plastics to break down in the environment. • Degradation accelerates the breakdown of plastics. • Degradation can be implemented by chemical, biological activity, or exposure to sunlight.

  24. Degradable Plastics • Biodegradable plastics • Degradation results from the action of naturally occurring microorganisms such as bacteria, fungi, and algae. • E.g. synthetic biodegradable materials • Photodegradable plastics

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