IUB CHEM-C 118 - 10-29 chapter 12 (21 pages)

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10-29 chapter 12



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10-29 chapter 12

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Pages:
21
School:
Indiana University, Bloomington
Course:
Chem-C 118 - Principles of Chemistry and Biochemistry Ii
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John W Moore Conrad L Stanitski Peter C Jurs www cengage com chemistry moore Chapter 12 Fuels Organic Chemicals and Polymers Stephen C Foster Mississippi State University 12 Organic Polymers 12 6 Synthetic Organic Polymers Wednesday Wednesday October October 29 29 2014 2014 Read Read Sections Sections 12 6 12 6 for for Wednesday Wednesday 45 45 47 47 49 49 51 51 52 52 55 55 57 57 59 59 63 63 65 65 96 96 Organic Chemicals Originally obtained from plants animals fossil fuels A vital force was thought necessary to make them However W hler 1828 synthesized urea from a mineral NH4 NCO aq ammonium cyanate O C heat H2N NH2 urea 12 6 Synthetic Organic Polymers A polymer is a large molecule formed by linking a series of monomers smaller units Polymers are also called macromolecules Classification thermoplastics soften and flow then harden on cooling thermosetting plastics initially soften but then form a rigid structure that will not remelt Synthetic Organic Polymers Addition Polymers Monomer units add directly to each other Ethylene forms polyethylene Initiation A peroxide R O O R breaks into two RO and attacks a monomer Addition Polymers Propagation Polymer growth Overall n CH2 CH2 H H H H C C n Addition Polymers Termination Two radicals combine Clicker Which of the following is the initiation step in the synthesis of polyethylene 1 CH2CH2 RO R O CH2CH2 2 2 R O CH2 CH2 R O CH2 CH2 CH2 CH2 O R 3 R O CH2 CH2 CH2CH2 R O CH2 CH2 CH2 CH2 4 R O CH2 CH2 CH2 CH2 RO R O CH2 CH2 CH2 CH2 O R Addition Polymers Polyethylene is the world s most widely used polymer High density polyethylene HDPE Linear chains High density high molar mass Hard and semi rigid Addition Polymers Low density polyethylene LDPE Branched chains Cannot pack as closely Soft and pliable Cross linked polyethylene CLPE Short CH2 groups connect adjacent chains Very tough Addition Polymers Substituted ethylene can be used H H CH2 C styrene H C C polystyrene H n Styrofoam is made by expansion molding Polystyrene beads containing 4 7 pentane are heated in a mold The pentane vaporizes expands the beads making the foam into the shape of the mold Addition Polymers Another example CF2 CF2 tetrafluoroethylene polytetrafluoroethylene PTFE Teflon F F C C F F n Addition Polymers Other important substituted ethylenes H H R Monomer H CH3 R Polymer Uses ethylene polyethylene Polythene Squeeze bottles films toys electrical insulation propylene polypropylene Bottles films Vectra Herculon poly vinyl chloride PVC polyacrylonitrile Orlon Acrilan poly vinyl acetate indoor outdoor carpets Floor tile raincoats pipe Cl vinyl chloride CN acrylonitrile O C C H OCCH3 vinyl acetate O PVA COCH3 methyl methacrylate poly methyl methacrylate PMMA Plexiglass Rugs fabrics Latex paint adhesives textile coatings Transparent objects latex paint contact lenses Copolymers Copolymers are made from mixed monomers Styrene butadiene rubber SBR is used to make tires Recycling Plastics Natural Synthetic Rubbers Latex oozes from rubber trees water rubber particle emulsion It becomes gum rubber if the water is removed a sticky elastic and water repellant mass Charles Goodyear 1839 discovered vulcanization Gum rubber sulfur heat vulcanized rubber Natural Synthetic Rubbers Rubber is poly cis isoprene Poly trans isoprene is hard and brittle and comes from another tree H CH3 C C H H C C H H Rubber is an elastomer no permanent change when stretched Condensation Polymers A condensation reaction releases a small molecule Polyesters form when molecules with two acid groups and two alcohol groups react HOOC COOH HO CH2 CH2 OH terephthalic acid HOOC ethylene glycol COO CH2 CH2 OH H2O Condensation Polymers HOOC COO CH2 CH2 OH This product still has two reactive groups and can polymerize O C O C O CH2 CH2 n O poly ethylene terephthalate or PET a polyester Amines Amides Polyamides Dicarboxylic acids and diamines generate polyamides Nylon 66 adipic acid HO C CH2 4 C OH O O hexamethylenediamine H2N CH2 6 NH2 HO C CH2 4 C NH CH2 6 NH2 O O H2O Amines Amides Polyamides


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