2-2General Thermoplastics
2-2 General Thermoplastics
Types of plasticsThere are 2 main types of plastics -Thermosets - Made from long chain moleculeswhich bond together stronglywhenthe plastics aremade.This means that they cannot be re-melted.Thermosets are rigid and non-flexible even at hightemperatures.Thermoplastics - Also made from long chainmolecules which are entangled but not bondedtogether.Thismeansthat they canbemelted andre-formed.("Thermo"=heat,"plastic"=abletobeformed)3
Properties & applicationsMaterialPropertiesApplicationsLDPE-LoWdensitySqueezybottles,Polythenetough,flexible,goodtoys,carrier bags,(Polyethylene)TV cablechemicalresistanceMilkcrates,HDPE-Highdensitybottles,pipes,stiffer, harder, can beThermoplasticssterilised,waxyfeelbuckets,bowlsContainerswithPolypropyleneExcellentgeneralpurpose material.Lightintegral hinges,(PP)hard,impactresistant,rope,packagingresistsbending(hinges)kettles,chaireasilyjoined&weldedshells,cratesAcrylicStiff,hard,clear,impactIlluminated signs,resistant,verydurablewindows,rearcar(PMMA)polisheswell,verygoodlights, lightingopticalproperties.units,displays5
Properties & applicationsMaterialPropertiesApplications(a) Conventional-light,-CD cases,Polystyrenehard, stiff, brittle,disposable cups,(PS)clearmodel kits(b) Toughened -better-Refrigeratorlinings, toysimpactresistance,Thermoplasticsstronger,pigmented(c)Expanded (foam)-Packaging,buoyant, light,sound and heatheat/soundinsulatorinsulation,ABSCasesforelectronicHighimpactstrength&(acrylonitriletoughness,verygoodgoods, toys,butadienestyrene)surfacefinish,durablephones,carcomponents6
Properties & applicationsMaterialPropertiesApplications-Hard, tough, gooduPVC-Pipes,gutteringweatherresistance,widebottles,window(polyvinylrange ofcolours,Uvframeschloride)stabilising neededHosepipes,sealPlasticisedPVC-Soft,flexible,goodThermoplasticselectricalinsulatorwallcoveringsPETDrinksbottlesClear,tough,flexiblegood chemical(polyethyleneresistanceterephthalate)NylonBearings,gearHard,tough, wearresistant,low friction,wheels,clothing,(polyamide)brushfilaments,self-lubricating,machines well, goodpowertool caseschemicalresistance7