Everything you need to know about SYLLABUS-LISTED plastics in concise form

1. Geometrical and Mechanical Engineering
Drawing: Unit 2 Module 2
Plastics
A plasticmaterial of a wide range of synthetic/semi-syntheticorganicsolidsthatare mouldable.They
are typicallyorganicpolymersof highmolecularmassbutusuallycontainother substances.Mostare
syntheticandcommonlyderivedfrompetrochemicals.
Properties
Low cost,ease of manufacture,versatility,imperviousnesstowater,usuallylow meltingpoint,electrical
insulator(exceptstretch-orientedpolyacetylene).Some maydecomposetotoxicsubstanceswhen
heated.
Thermoplastics
A thermoplastic, also called a thermo-softening plastic is a plastic which becomes pliable or
mouldable above a specific temperature and returns to a solid state upon cooling.
Most thermoplastics have a high molecular weight. More aesthetically pleasing, expensive
forming process, less resistance to mechanical creep, not suitable for use in EXTREMELY
temperatures, little to no cross-linking in microstructure, eco-friendly forming process.
Polyvinyl Chloride (PVC)
PVCcomesintwo forms,rigid(forconstructioninpipe andindoorsand windows) andare made more
flexible byadditionof plasticizers(phthalates).[Addease ofwork, usedfor cables,lowersglass
transition temperature,increasedflexibility anddurability]
Properties
Highhardness,highmoduli of elasticity(rigid-type),verylow moduliof elasticity(flexible),poorheat
stability,small expansioncoefficient,goodflameretarding,electrical insulator
Uses
PVCpipes,electriccable insulation,uPVCinplace of wood,signs,clothing,furniture
Polytetrafluoroethylene (PTFE)
PTFE isa fluorocarbonsolidwhichcannotbe wetbywater
Properties
Highstrength,toughnessandself-lubricatingdownto5K.Good flexibilityabove194K,highlycorrosion
resistant,thirdlowestcoefficientof friction,subjecttocreep,electrical insulator

2. Uses
Wiringinaerospace andcomputing,printedcircuitboards,TEFLON,plainbearings,gears
Polyethylene
The most commonplastic,mixture of organiccompounds.
Properties
Relativelylowmeltingpoint,corrosionresistant(fromacidsandbases),burnsslowlywithablue flame
High-Density Polyethylene(HDPE)
Density>= 0.941g/cm3
, Low degree of branchinglow tensile strength,usedinmilkjugs,detergent
bottles, garbage containersandwaterpipes.
Medium-Density Polyethylene(MDPE)
Density0.926-0.940g/cm3
Goodshock anddrop resistance,lessnotchsensitive thanHDPE,stress
cracking resistance alsobetter.Usedingaspipesandfittings,sacks,shrinkfilmand carrierbags.
Low-Density Polyethylene(LDPE)
Density0.910-0.940g/cm3
, lowertensile strength,increasedductility,usedforrigidcontainersand
plasticfilmapplications.
Polystyrene (PS)
Syntheticaromaticpolymer,canbe rigidorfoamed.
Properties
Clear,hard,brittle,lowmeltingpoint,poorbarriertooxygenandwater,glassyatRTP, can be cast into
mouldsforfine detail,slowtobiodegrade
Uses
Protective packaging,containers,lids,bottled,trays,napalm-B
Polypropylene
Properties
Tough,flexible,usedasanengineeringplasticwhencopolymerizedwithethylene,goodresistance to
fatigue,chaindegradationdue tosunlight,corrosionresistant,resilienttoimpactandfreezing,canbe
joinedbyheatfusion,heatresistant,lightweight,durable
Uses
Plastichinges,asa dielectric,kettles,foodcontainers,carpets,rugs,ropes,PVCalternative,electrical
cables,plasticmouldings(bottle tops,bottles,andfittings),clothing,andEPPtoyaircraft.

3. Polyamide - Nylon
Macromolecule withrepeatingunits,artificial andnatural.
Properties
Veryelastic,strong,highcrystallinity,hightensile strengthwhendrawnusingheatedrollsathigh
speeds,clear,colourlessormilky,easilydyed,goodelectrical insulator.
Polymethylmethacrylate (Perspex)
Shatterresistantwhichisalsocalledacrylicglass
Properties
Moderate strength,easyhandlingandprocessing,low cost,brittle whenloaded,prone toscratching,
varietiesblockvisible lightwhile allowingtransmissiononIRlight
Uses
Transparentglasssubstitute (submersibles,aircraft,riotcontrol,aquariums),daylightradiation,
implants,acrylicpaint
Thermo-Setting Plastics
A thermosettingresin(a.k.a.athermoset) isapetrochemical thatirreversiblycuresbyheat,chemical
reactionor suitable irradiation.More complex formingprocedure,more resistance tocreep/chemical
erosion,heavilycross-linked.
Epoxy
An epoxyisthe endcuredproductof an epoxy-resin,typicallytworesinsthatneedtobe mixedtogether
before use.
Bakelite
Properties
Heat resistant,electrical insulator,brittle,complexityof production,hard,dense,tendtowellinareasof
perpetual dampness
Uses
Wire insulation,brake pads,whistles,cameras,gun-grips,table-topgames,heat-shields
Melamine
Properties

4. Fire retardant,
Uses
Kitchenutensilsandplates,high-pressurelaminates,countertops,cabinetsandfurniture making