Final Study Guide

Final Study Guide - PTFE FINAL STUDY GUIDE What is the...

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PTFE FINAL STUDY GUIDE What is the difference in the addition/condensation description of polymer type and the chain-growth/step-growth description of polymer type? Addition and condensation polymer types are observational descriptions. A polymerization is addition if the entire monomer molecule becomes part of the polymer. It is condensation if part of the monomer is removed, such as water, when the monomer becomes part of the polymer. Step growth and chain growth polymer types are mechanistic descriptions. In chain growth polymerization, monomers become part of the polymer one at a time through (1. Initiation 2. Propagation 3. Termination). In a step growth polymerization, the growing chains may react with chains of all lengths to form even longer chains. Polyester Nylon Kevlar Polyurethane Polyolefin Polyacrylate Linear Branched Dendritic Star
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What are the primary constituents in composites? Composites are made up of a fiber and a matrix material. What percent of petroleum is used to make plastics? What percent of petroleum is used in transportation? About 4% of petroleum worldwide is used to make plastics whereas about 55% of petroleum is used in transportation. Describe the benefits of plastics in food packaging. Plastic packaging in the developed world leads to low wastage (less than 2%) whereas in the undeveloped world about 50% of the food produced becomes rotten. Describe the benefits of plastics in transportation. Plastics play a key role in transportation. The lightness of plastics in the making of cars results in a lighter vehicle, which allows for less fuel and lower emissions. What is the role of recycling in the life cycle of a material? What are the costs? Do the costs outweigh the benefits? Recycling a material conserves and extends life of limited resources and eliminates the need for landfilling. Recycling is not always a net gain. Energy is needed, other materials are consumed, and waste is generated. Is a piece of clothing made of polyester more harmful to the environment than one made of cotton? A piece of clothing made of polyester is not more harmful to the environment than one made of cotton. Cotton garments require frequent washes at high temperatures and generally must be tumble dried and ironed. A polyester blouse, by contrast, takes more energy to make, but requires less energy when it comes to washing and drying. Over a lifetime, a polyester blouse uses less energy than a cotton t-shirt. Describe the primary difference between thermoplastics and thermosets.
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Final Study Guide - PTFE FINAL STUDY GUIDE What is the...

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