Lecture26%20with%20slides

Lecture26 with s - Polymers What is a polymer Lecture 26 Poly mer many repeat unit repeat unit repeat unit H H H H H H C C C C C C H H H H H H H H

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1 1 Lecture 26 Polymers 2 Polymers What is a polymer? Poly mer many repeat unit Adapted from Fig. 14.2, Cal ister 7e. C C C C C C H H H H H H H H H H H H Polyethylene (PE) Cl Cl Cl C C C C C C H H H H H H H H H Polyvinyl chloride (PVC) H H H H HH Polypropylene (PP) C C C C C C CH 3 H H CH 3 CH 3 H repeat unit repeat unit repeat unit 3 Ancient Polymer History • Originally natural polymers were used – Wood – Rubber – Cotton – Wool – Leather – Silk 4 Polymer Composition Most polymers are hydrocarbons – i.e. made up of H and C • Saturated hydrocarbons – Each carbon bonded to four other atoms C n H 2n+2 CC H H H H H H 5 6 Unsaturated Hydrocarbons • Double & triple bonds relatively reactive – can form new bonds – Double bond – ethylene or ethene - C n H 2n • 4-bonds, but only 3 atoms bound to C’s – Triple bond – acetylene or ethyne - C n H 2n-2 H H H H CCH H
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2 7 Isomerism • Isomerism – two compounds with same chemical formula can have quite different structures Ex: C 8 H 18 • n-octane • 2-methyl-4-ethyl pentane (isooctane) CCCCCCCC H H H H H H H H H H H H H H H H H H H 3 CC H 2 CH2 CH2 CH2 CH2 CH2 CH3 = H 3 H CH 3 CH 2 CH CH 2 CH 3 CH 3 H 3 H 2 CH 3 () 6 8 Chemistry of Polymers • Free radical polymerization • Initiator : example - benzoyl peroxide C H H OOC H H C H H O 2 HH H H monomer (ethylene) R + free radical RCC H H H H initiation H H H H H H + H H H H propagation dimer R = 2 9 Chemistry of Polymers Adapted from Fig. 14.1, Cal ister 7e. Note: polyethylene is just a long HC - paraffin is short polyethylene 10 Bulk or Commodity Polymers 11 12
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3 13 MOLECULAR WEIGHT molecules of # total polymer of wt total = n M i i w i i n M w M M x M Σ = Σ = M w is more sensitive to higher molecular weights
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This note was uploaded on 09/15/2010 for the course MATSCIE 250 taught by Professor Yalisove during the Fall '08 term at University of Michigan.

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Lecture26 with s - Polymers What is a polymer Lecture 26 Poly mer many repeat unit repeat unit repeat unit H H H H H H C C C C C C H H H H H H H H

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