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Polyurethanes
History of Polyurethanes: Polyurethane Chemists
• Dr. Otto Von Bayer (1937)– IG Farben Industries
• Rigid and flexible foams• TDI and polyols
– Attempts to reduce natural rubber use
History of Polyurethanes:Polyurethane Chemists
• Adolf Wurtz (1848)• Karl-Heinz Hentschel (1884)–Phosgenation of amines
Isocyanate Monomer Synthesis
• Dr. Otto Bayer (1937)– First diisocyante synthesis
• Toluene Diisocyanate Synthesis (TDI)– Reaction creates 80/20 mixture of 2,4-TDI and 2,6-TDI
Isocyanate Monomer Synthesis• Diphenylmethane Diisocyanate (MDI) Synthesis
– Attempt to find less toxic monomer for PU reactions– MDI chemistry is more complex
• Allows for more specific applications
Imperial Chemical Industries
• ICI and WWII applications of isocyanates– Barrage balloons
• Used MDI as cross-linking agent – Resistant to hydrogen
– Applications also included rigid foams in planes• War applications soon faded
• Isocyanates and water• Carbon dioxide is side product• Initially a defect it was turned into an application as foam
• ICI takes notes from Bayer AG – Designs a machine outside of the Germans patented machine
Imperial Chemical Industries
• Toxicity of TDI (1950s)– Led to design of MDI/polyester systems• Portable refrigerators, domestic chambers of ships,
chemical plan insulation
• Further improvements with CFC’s– CFC blowing agents created superior insulating
foams• Thin walled refrigerators create interest rigid PU
foams around the world
Polyurethanes
• Polyurethanes are much more than just foam
• PU’s can be– Elastomers– Paints– Adhesives– Fibers
• Spandex
Breakdown of the PU Industry
Figure from Essentials Chemical Industry on University of York website
Economics
• The PU industry was estimated to produce 13.65 million tons of plastic in 2010 and is expected to grow to 17.95 million tons by 2016
• The PU industry is expected to grow from $33 billion in 2010 to $55.5 billion in 2016
• North America, Asia-Pacific, and Europe account for 95% of the PU market
Numbers found from source 6
Polyurethane Structure
Carbamate bonds created by isocyanates reacting with hydroxy groups of a polyol
Polyurethane Reactions
• Tertiary amines catalyze the reactions
• Isocyanate groups react with polyols
Polyurethane Monomers
• Polyurethanes consist of different block co-polymers• MDI- 4 4'-diphenylmethane diisocyanate• TDI- Toluene-2,4-diisocyanate
Polyurethane Monomers
Polyols- hydroxy terminated polyether, polyester, polyolefins, and glycols
Polyurethane: Block Copolymers
• Soft block/hard block microphases-Poly(1,4-butylene adipate) is part of the soft block microphase-Soft blocks have 600-3000 MW and Tg below room temperature
-The hard block consists of TDI or MDI-Higher density of phenyl rings and urethane links cause hardness
-The soft block cross-link interaction with the hard block gives rise to the rubbery nature of these elastomers
Soft/Hard Block H-Bonding Interactions
Figures from source 7
Importance of Polyol choice
Figures from source 7
Polyurethane Reactions
• Multiple types of reactions make up different end products of polyurethanes
• Polyurea reactions are important for spandex production
Which sometimes can be a bad thing!
• Someone needs to introduce this guy to pants and suspenders!
• Suspenders are made of polyesters– Dr. Tisko should tell this
guy how awesome suspenders are
Bibliography1. http://www.pslc.ws/macrog/urethane.htm2. http://www.8linx.com/cnc/polyurethane_foam.htm3. http://www.essentialchemicalindustry.org/polymers/polyurethane.html4. http://sunilbhangale.tripod.com/pu.html 5. http://www.poliuretanos.com.br/Ingles/Chapter1/132comercial.htm6. http://www.plastemart.com/Plastic-Technical-Article.asp?
LiteratureID=1674&Paper=global-polyurethane-market-PU-foams-thermoplastic-elastomers
7. J.M. Buist. Developments In Polyurethane-1; Applied Science Publishers LTD, UK, 1978.