1 IV. Properties and uses of step polymers A. Polyamides 1. Properties a. Good tensile strength and elasticity i. Nylon 4,6 and 6,6 have best strength due to arrangement of hydrogen bonds. ii. Nylons absorb moisture and the water acts as a placticizer. b. Nylons have higher Tg than polyesters due to hydrogen bonding. c. Aramids (Kevlar) have very high tensile strength. d. Nylons have a low coefficient of friction. e. Nylons are resistant to oil. 2. Uses a. Fibers i. clothing ii. bulletproof vests iii. tire cord iv. carpeting v. rope b. Bulk i. gears and bearings ii. wheels iii. foams a) diacid + diisocyanate foams with CO2 2 B. Polyesters 1. Properties a. Maintains high tensile strength at higher temperatures. (Lower Tg than polyamides. b. High impact strength c. High resistance to fatigue d. Good solvent resistance e. Good moisture resistance 2. Uses a. Polyethylene terephthalate (Dacron, Mylar) i. Clothing fabric (permanent press) 1 ii. support fabric (magnetic tape) iii. beverage containers (blow molding of bottles) iv. blister packs for pharmaceuticals b. Resin for fiberglass c. Filters for separations d. Tarps, canoes, paints C. Polycarbonates 1. Properties a. High impact strength b. Very high moisture resistance c. Not solvent resistant d. Good high temperature mechanical stability (dishwasher safe) e. High refractive index 2. Uses a. Optical lenses b. Drinking glasses c. Bulletproof glass - ply in-between glass layers 3 D. Polyurethanes 1. Properties a. High elasticity b. Solvent resistance c. Abrasion resistance d. High impact strength e. Low coefficient of friction 2. Uses a. Foams i. automotive seats ii. low quality mattresses iii. architectural insulation a. made with n-pentane or 1,1,1,2-tetrafluoroethane (R-134a) as blowing agents iv. acoustic barriers b. Bowling pins c. Swimsuits (spandex, co-polymer with polyurea) d. Sneaker soles e. Floor coatings 4 E. Polyureas 1. Properties a. High Tg, Tm b. Highly solvent resistance c. Generally expensive to produce d. High strength, resistance to puncture 2. Uses a. Automotive parts i. Created with reaction injection molding (RIM) ii. Amine terminated pre-polymer is sprayed together with aromatic isocyanate together into mold. b. Chemical waste containers c. Truck bed liners d. Fuel storage and transport F. Polysulfides 1. Properties a. Solvent/grease resistance b. Heat resistance c. Linear polymer is elastomeric d. Crosslinked polymer has high tensile strength e. Very pungent f. Good thermal stability 5 2. Uses a. Structural plastic (engineering plastic) i. Polyphenylsulfide (PPS) Cl Cl + Na2S R S R' b. Heat resistant coatings (paints) c. Conductive polymers (with Na or I2 doping) d. Sealants, gaskets e. Rocket fuel binder G. Polyethers 1. Properties a. Water solubility b. Crosslinked polymer have good strength. c. Non-toxic 2. Uses a. Surfactants i. Polyethylene glycol (PEG) a) approximately 3 to 20 units b) nonionic surfactant c) detergents, emulsifiers, defoamers b. Thickeners i. Foods, cosmetics ii. H-bonding along the chain creates low-strength “crosslinking” to make gel. c. Coatings and Adhesives (Epoxies) 6 d. Polyphenylene oxide (PPO) CH 3 CH 3 CuCl - pyridine OH R O R' O2 CH 3 CH 3 i. High Tg ii. Engineering polymer iii. Blends with polystyrene to reduce crystallinity and higher flame resistance iv. Moisture resistant v. Often blended with polystyrene to improve workability e. Polyetheretherketone (PEEK) CH 3 R O O C O CH 3 i. High electrical resistance (good insulator) ii. Excellent oxidative stability iii. Solvent and acid resistance iv. Nuclear waste containers v. Engineering polymer C R' 7 H. Polysulfones 1. Properties a. High resistance to oxidation and hydrolysis (autoclavable) b. Thermal stability c. Solvent resistance d. Low flammability 2. Uses a. Surgical equipment b. Filters c. High temperature applications i. hair dryers ii. cookware I. Polyimides 1. Properties a. High thermal stability b. Brittle (must be “plasticized” with co-polymer, e.g. polyether) 2. Uses a. Adhesives b. Heat resistant coatings . J. Phenol-formaldehyde 1. Properties a. High tensile strength b. Moisture resistant c. Somewhat brittle d. Subject to UV degradation 2. Uses a. Bakelite (first commercial polymer) b. Plywood laminate c. Consumer goods (stiff) (cheap) d. Cookware e. Coatings and adhesives 8 K. Melamine-formaldehyde 1. Properties a. High tensile strength b. Moisture/solvent resistance c. Brittle d. Heat resistant 2. Uses a. Countertops (Formica) b. Plastic Dinnerware c. Coatings and adhesives d. Paint detackifiers L. Urea-formaldehyde 1. Properties a. High tensile strength b. Moisture resistance c. Brittle 2. Uses a. Plywood laminate b. Coatings and adhesives c. Rigid foams (insulation)