Plastics - MEGR 2180 PLASTICS MEGR 2180 Engineering...

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MEGR 2180 PLASTICS
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MEGR 2180 Engineering Materials etals lastics eramics omposites Metals Plastics Ceramics Composites Nonferrous Ferrous Oxides Nitrides Carbides Reinforced plastic Metal-matrix eramic atrix Steels Stainless steels Tool and die steels Aluminum Copper Titanium Tungsten Glasses Graphite Diamond Ceramic-matrix Laminates Thermoplastics Thermosets Cast Irons g Elastomers Acrylics ABS Nylons Polyethylene PVC Epoxies Phenolics Polymides Rubbers Silicones Polyurethanes
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MEGR 2180
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MEGR 2180 lastics Chrysler sees plastic car in poorer countries Plastics lastics are everywhere Plastics are everywhere • Advantages ow density with varying Low density with varying degrees of strength – Visual appeal (colors, transparencies) – Ease of manufacturing – Low cost – Insulating properties
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MEGR 2180 lastics (Polymers) Plastics (Polymers) er/Monomer (from Greek “meros”= Mer/Monomer (from Greek meros “part”) olymer Polymer • Polymerization is the process which ers are bonded to form polymers (this mers are bonded to form polymers (this is a chemical reaction) egree of Polymerization average Degree of Polymerization is average number of mers in a chain.
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MEGR 2180 olymerization Polymerization •P o l ymer properties depend on yp p p – Chemical composition (mers) – Length of molecules – Structure of Molecules • Polymerization is the process which mers are onded to form polymers (this is a chemical bonded to form polymers (this is a chemical reaction) •T w o t ypes of Polymerization – Additive – Condensation
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MEGR 2180 dditive Polymerization Additive Polymerization • Also known as chain growth or chain reaction olymerization polymerization • Double bonded carbon monomers open and become available for new covalent bonds Very fast (seconds or minutes) • Generates a spaghetti like amorphous structure o reaction by products No reaction by products H H H H H H H H Heat, Pressure olyethylene C H C H C H C H C H C H C H C H n Catalyst mer polyethylene Click for movie
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MEGR 2180 Condensation Polymerization • Two or more different mers are joined into a larger polymer pplication of heat pressure and a catalyst • Application of heat pressure and a catalyst • Has reaction by products ot as fast as Additive polymerization Not as fast as Additive polymerization • Generates a chain like molecule (thermoplastics) or a network structure (thermosets)
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MEGR 2180 dditives Additives • Fillers – Affect the mechanical properties, provide bulk and strength •P i g m e n t s – Add color and decrease transparency • Plasticizers – Weaken the secondary bonds between chains or larger molecules g • Hardeners – Promote cross linking between linear polymers ubricants Lubricants – Often used to reduce friction between polymer and the dies in extruding or molding lame retardants Flame retardants
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MEGR 2180 Fillers Plasticizers Stabilizers Colorants Flame Retardants Crystalline Lubricants Thermoplastics Acrylics BS Amorphous Mer or mers Polymer ABS
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This note was uploaded on 10/01/2009 for the course MEGR 2144 taught by Professor Sharpe during the Fall '08 term at UNC Charlotte.

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Plastics - MEGR 2180 PLASTICS MEGR 2180 Engineering...

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