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Unformatted text preview: ME 418: Lecture 1 - Rubber Follow the 5 P's o The philosophy behind this course o Should be the philosophy for designing polymers 1. Polymer - Thorough understanding of the Polymer / Plastic 2. Process - Processed into product, cast, stretched, molded 3. Product - Will have performance and fiber orientation 4. Performance - Mechanic behavior / permeability (soda bottle) o Induce biaxial molecular orientation (makes bottles less permeable to increase shelf life) o Determined by material, production, 5. Post-consumer life - More than just recycling, sustainability o Dump, recycling, biodegradable o Some polymers have lead content from polymerization processes i. Bad for health of users / consumers - needs to be watched out for What are polymers? They can be found throughout history Several thousand years old - natural rubber container made from tree sap in Amazon o Made by dip-coating, cover stick in uncooked clay ball and dip in vat of tree sap Clutch from truck o Polyamide - reinforced with glass fibers Natural Rubber o Comes from rubber trees o Monomer - Isoprene (also comes from dandelions - white liquid) o CH 2 =CH-CH=CH | CH3 o Isoprene comes with water and minerals - with UV rays, trigger a reaction -> Polymerization o Polymerize into Polyisoprene-[ CH2-CH=CH-CH]- n | CH2 o Done with very little effort and energy - minerals are a catalyst Minerals open up the double bond "holding hands" with the monomer o One of first applications in Europe - Eraser (name comes from rubbing action) Native name: weeping trees o Isoprene melting point: -16C - became sticky in summer & brittle in winter in 1800s o Charles Goodyear added Sulfur Each repeating block has the ability to "hold hands" o Each double bond can open up and form a bridge with Sulfur o Cross-linked process which anchored the molecules down o Called Vulcanization o Also required addition of heat o (More options available today, such as peroxides) Vulcanization allowed new product development o Pneumatic Tire development -> Automobile, condoms, rain coats (cloth covered with rubber) o Source in 19th Century 98% came from Amazon Basin, 2% from Belgian Congo at 19th century Indians were only ones who could gather rubber - became slave labor to cartels British smuggled out rubber seeds, grew in England, and took to their colonies to start Plantations Today no rubber comes from Amazon Basin o Natural rubber is better than synthetic rubber Longer chains (higher molecular weights) Less wear and higher friction Synthetic Rubber...
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This note was uploaded on 03/30/2008 for the course ME 418 taught by Professor Osswald during the Fall '08 term at Wisconsin.
- Fall '08