Lec 11 - ENGR ENGR 4250 Advanced Materials Engineering...

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ENGR 4250 ENGR 4250 – Advanced Materials Engineering Lecture 11 Applications & Processing of Polymers
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Porosity in Ceramics
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Influence of Porosity
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Polymers hat is a polymer? What is a polymer? Poly mer many repeat unit H H H H H H H H H H H HH H H H repeat unit repeat unit repeat unit dapted from Fig 14 2 allister 7e C C C C C C H H H H H H Cl Cl Cl C C C C C C H H H H H C C C C C C CH 3 CH 3 CH 3 H Adapted from Fig. 14.2, Callister 7e.
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POLYMER MICROSTRUCTURE Poly mer = many mers H H H H H H mer H H H H H H mer H H H H H H mer C C C C C C H H H H H H Polyethylene (PE) Cl Cl Cl C C C C C C H H H Polyvinyl chloride (PVC) Polypropylene (PP) CH 3 C C C C C C H H H CH 3 CH 3 Covalent chain configurations and strength: Adapted from Fig. 14.2, Callister 6e. secondary bonding irection of increasing strength Branched Cross-Linked Network Linear 2 Direction of increasing strength Adapted from Fig. 14.7,
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Ancient Polymer History • Originally natural polymers were used ood ubber – Wood – Rubber – Cotton – Wool – Leather – Silk
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Hydrocarbons
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Phenyl Group
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Polymers Adapted from Fig. 14.1, Callister 7e. Note: polyethylene is just a long HC araffin is short polyethylene - paraffin is short polyethylene
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Bulk or Commodity Polymers
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MOLECULAR WEIGHT Molecular weight , M i : Mass of a mole of chains. polymer of wt total Lower M higher M molecules of # total = n M w i i n M w M M x M Σ = Σ = i i M w is more sensitive to higher molecular weights Adapted from Fig. 14.4, Callister 7e.
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Molecular Weight Very long chains Not all chains are same length Average molecular weight i i n M x M = i i w M w M =
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Degree of Polymerization, n n = number of repeat units per chain CCCCCCCC H HHHHHHHH CCCC HHHH H () n i = 6 HHHHHHHHHHHH w n M M = = = i i w i i n m n w n m n x n m = unit repeat of weight molecular average where
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Properties and Molecular Weight • M 100 g/mol gas or liquid • M 1000 g/mol Wax like • M 10000 g/mol Solid • M STRENGTH
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Polymers – Molecular Shape y p Conformation – Molecular orientation can be changed by tation around the bonds rotation around the bonds note: no bond breaking needed Atomic bond configurations
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End to End Distance, r Adapted from Fig. 14.6, Callister 7e.
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Molecular Structures • Covalent hain onfigurations and strength: Covalent chain configurations and strength: secondary bonding Direction of increasing strength Branched Cross-Linked Network Linear Adapted from Fig. 14.7, Callister 7e.
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Relative Usage of Plastics
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Thermosets Vulcanization of rubber
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Thermosets Epoxies Polyurethanes Unsaturated Polyesters Phenolics
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This note was uploaded on 10/18/2010 for the course ENGR 3360 taught by Professor Ahmadbarari during the Fall '10 term at UOIT.

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Lec 11 - ENGR ENGR 4250 Advanced Materials Engineering...

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