Some Engineering Plastics:
Here are the some engineering Plastics with their properties and application
| Name of polymer | Monomer/ preparation | Properties | Applications |
| PVC/polyvi nyl chloride | Vinyl chloride / emulsion of monomer in presence of hydrogen peroxide under | -Colorless, odorless, inflammble; syndiotactic, -chemically inert; resistant to oxygen; -high softnening point(148 C); -greater rigidity and stiffness but brittle; -can be made flexible with plasticisers(tricresyl phophate) -Beyond 2000C – discoloration occurs - stabilizers are added (alk. Earth oxides) | Rigid PVC- Sheets, tank lining, safety helmets, fridge components, tyres, cycle, motor cycle mud guard. Plasticised PVC in cable insulation, continuous sheets of different thickness, conveyor belts, thermal insulating foam |
| Polytetraflu oroethylene( PTFE) | Tetrafluoroethy lene / Polymerization of water emulsion of tetrafluoroethyl ene under P in benzoyl peroxide | -High softening point(350 C) due to strong attractive force between chains; -Slippery & waxy to touch; -Extreme toughness; -Chemical resistant to acids, alkalis & salts; -Low coefficient of friction; - Good electrical & mechanical properties | - In insulating materials (in wire & cable, in motors, generators, coils, transformers: - In chemical carrying pipes, tank linings, gaskets; - For coating & impregnating glass fibres, asbestos fibre -In non-lubricating bearings, stop-cocks for burettes, kitchen utensils etc; |
| Polycarbona tes(PC) Lexan, Merlon | Diphenyl carbonate & bis-phenol - A | -High impact & tensile strength over wide T range; -Possess good dimensional stability, stiffness & transparency | -In moulded domestic ware; -Plugs, sockets, switches; -As electrical insulator in electrical industries; - In sterilisable transparent containers ; |
| Polyurethan e (perlon-U) | 1,6-hexane diisocyanate & 1,4--butanediol | - Less stable than polyamides at elevated T; - Resistant to abrasion & solvents except moisture(diisocynate decomposes in moisture to produce amine & CO2 ); | - As coatings, films, foams, adhesives; - As fibres(spandex) in swim suits; - As leather substitute(corfoam) Polyurethane elastomers – enhance life of tyre treads due to excellent hardness, resistant to abrasion, good elasticity, resistance to oils/ greases. Thermocole: a foamed plastic of polyurethane is an ideal packaging material |
| Nylon 6:6: polyamide (polyhexam ethylene adiptimide) | Adipic acid and hexamethylene diamine | ● Thermo plastic ● Softening 250C ● High temp stability and high intermittent temp use ● good abrasion resistance ● high mechanical strength and superior resistance to wear and organic chemicals. ● Insoluble in common org solvent slike sprit, benzene, actone ● Soluble in phenol and formic acid They absorb little moisture ● Fire Retardant Excellent resistance to flame and fire ( Very low rate of flame propagation) Non- burning/self extinguishing. | ● The first engineering resin- used in applications ranging from electronic, marine, and automotive, to fibers used to make carpet. socks, ladies hoses, under garments, dresses, carpets etc ● Synthetic replacement of silk. It replaces silk in military applications such as parachutes and flak vests, and used in many types of vehicle tires. Reinforced nylon: The addition of glass fibre to nylons leads to very significant increases in strength, stiffness, heat distortion temperatures, abrasion resistance and dimensional stability |
| PET: Polyethylene terephthalate | Dimethyl terephthalate and diethylene glycol in presense of Mn acetate as catalyst at temp 140-250C | ● Recyclable ● Thermoplastics ● Have excellent transparency, strength and gas barrier property, ● Very low gas permeability and water vapor transmittance ● Excellent chemical resistance and anti- hydrolysis characteristics ● Less resistant to alkalis ● Zero flavor adsorption ● Blockage of ultraviolet-rays provides good protection for contents | ● With excellent barrier (CO2 permeation) and mechanical properties PET is becoming the polymer of choice for food and beverage packaging applications for soft drink and some milk bottles, oven safe plastic wrap ● Used as engineering resins often in combination with glass fiber. ● The most important raw materials used in man-made fibers ● Trade names of PET products are Dacron, Diolen, Terylene, |
This comment has been removed by the author.
ReplyDeleteThis comment has been removed by the author.
ReplyDelete