lecture 23 - ME 330 Engineering Materials Lecture 23...

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Lecture 23 Polymers Stephen D. Downing Mechanical Science and Engineering © 2001 - 2010 University of Illinois Board of Trustees, All Rights Reserved ME 330 Engineering Materials
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ME 330 - Lecture 23 © 2010 Stephen Downing, University of Illinois at Urbana-Champaign, All Rights Reserved 1 of 46 This Lecture . .. ± Polymer Structure Review ± Mechanical Properties ± Deformation and Strengthening ± Thermal Properties ± Viscoelasticity ± Polymerization ± Processing Techniques
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ME 330 - Lecture 23 © 2010 Stephen Downing, University of Illinois at Urbana-Champaign, All Rights Reserved 2 of 46 + C H HH H C ± Saturated all bonds are single; molecule not reactive ± If unsaturated, double bond present, and catalyst ( R ) will react: ± Often indicate polymers by: ± Basic repeating structure ± n > 1000! * From Hydrocarbons to Polymers +… Polyethylene C H H C* H H R mer Polymer Ethylene C H H C H H R* + mer C H H C H H n
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ME 330 - Lecture 23 © 2010 Stephen Downing, University of Illinois at Urbana-Champaign, All Rights Reserved 3 of 46 Mer Structures to Memorize PE - polyethylene PP - polypropylene PVC - poly(vinyl chloride) PS - polystyrene TEFLON - polytetrafluoroethylene
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ME 330 - Lecture 23 © 2010 Stephen Downing, University of Illinois at Urbana-Champaign, All Rights Reserved 4 of 46 A Few Definitions ± Homopolymer - all mers are of the same type ± Copolymers - two or more mer units of different structure ± Bifunctional - mer units with two active sites available for covalent bonding ± Trifunctional - mer units with three active sites available for covalent bonding ± Aromatic ring - H H H H CC C C
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ME 330 - Lecture 23 © 2010 Stephen Downing, University of Illinois at Urbana-Champaign, All Rights Reserved 5 of 46 ± Molecular weight indicates the size of a polymer molecule ± Measure polymer size distribution ± Number-average Weight-average = i i n M x M = i i w M w M Molecular Weight Molecular weight (10 3 g/mol) 0.1 0.2 0.3 Number fraction 10 20 30 40 x 1 M 1 Molecular weight (10 3 g/mol) 0.1 0.2 0.3 Weight fraction 10 20 30 40 w 1 M 1 Count the number of chains that are a certain length (molecular weight) Weigh the number of chains that are a certain length (molecular weight)
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ME 330 - Lecture 23 © 2010 Stephen Downing, University of Illinois at Urbana-Champaign, All Rights Reserved 6 of 46 ± Average number of mers per chain ± is the mer molecular weight ± Number average degree of polymerization ± Weight average degree of polymerization Degree of Polymerization m M n w w = m m M n n n =
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ME 330 - Lecture 23 © 2010 Stephen Downing, University of Illinois at Urbana-Champaign, All Rights Reserved 7 of 46 Molecular Structure ± Linear ± Tangled covalently bonded chains ± Secondary interchain bonds ± Branched ± Tangled covalently bonded chains with side branches ± Secondary interchain bonds ± Crosslinked ± Tangled covalently bonded chains ± Covalent and secondary interchain bonds ± Networked ± Highly crosslinked polymer
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ME 330 - Lecture 23 © 2010 Stephen Downing, University of Illinois at Urbana-Champaign, All Rights Reserved 8 of 46 Polymer Classifications I ± Thermosetting polymers : ±
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lecture 23 - ME 330 Engineering Materials Lecture 23...

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