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20112022_120741_Exploring Materials Slides.pdf
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- 2. S A M P L E F O O T E R T E X T 2 Contents 1. What areMaterials 2. Classification of Materials 3. TypesofMaterials 4. Properties ofMaterials 5. Choosingthe RightMaterials for Objects
- 3. What are Materials 3 •Materials are thingsthatare usedtomakeobjects. • All theobjects aroundus are madeof somekindof materials • We usematerialsto buildhouses, shops, schools and othertypes of buildings • Onetype of materialcan be usedtomakemanydifferentobjects • e.g. glass bottles, glass bowls. glass tumblers, glass vases, mirrors etc • Differenttypes of materialscan beused tomakethesametype of object • e.g. A spatula can be madeof metal,wood or plastic • A combination of differentmaterialscan be usedtomakea singleobject • e.g. A fanwhich is madeof plastic andmetal • Differentmaterials have differentproperties. Theseproperties helpus decide which materialis suitabletomakeanobject. • We willstudy about theclassification of materials,differenttypes of materials, theirproperties andchoosingtheright materialsto makeobjects
- 4. Natural • MaterialsfromPlants:Wood, Rubber, *Fabrics(Cotton, Linen) • Materialsfrom Animals:*Fabrics (Leather, Wool, Silk) • Materialsfrom Ground: Metal,Rock Man-made • Materialsmade by Man: Plastic,*Fabrics (Nylon, Polyester), **Glass,**Ceramic, *Fabricscanbeboth natural orman-made **Although glass andceramic areman-made materials, the raw materials used to make them arenatural. Glass madefrom sand while ceramicmadefrom clay that arefound naturally Classification ofMaterials 4 • Materialscomes from various sources and canbe naturalor man-made • Naturalmaterials are materialsthat comes from plants, animalsandground • Man-madematerials arematerials obtained from naturalmaterialsand made through chemical processes artificially.
- 5. 5 Natural Materials Materials thatcome from plants, animals and ground Fabric: Cotton (cotton plant) Rock Fabric: Leather (cow) Fabric: Wool (sheep) Wood (trees) Metal Plants Animals Ground Rubber (rubber tree’s latex) Fabric: Silk (silkworm)
- 6. Objects madefromNatural Materials 6 SourcesNatural Materials Uses/Objects Plants Wood chair, table, cupboard, paper Rubber balloon, tyre, glove, eraser Fabrics Cotton shirt, towel, scarf, curtains Animals Fabrics Leather handbag, belt, shoes, wallet Wool sweater, blanket, cardigans Silk dress, nightgown, neckties Ground Metal spoon, kettle, jewellery, electrical appliances Rock (e.g clay and sand) house, road, bridge, wall
- 7. 7 Man-made Materials Materials obtainedfrom natural materials and made through chemical processes artificially bottle Plastic Glass Ceramic Fabrics chair cup windows bowl flower vase swimwear (nylon) Dri-FIT shirt (polyester)
- 8. Objects made fromMan-made Materials 8 8 Man-made Materials Sources Uses/Objects Plastic petroleum bottle, chair, containers, straws, bags Glass sand, lime, soda cup, fish tank, windows, mirrors, spectacle lens Ceramics clay bowl, vase, flower pot, teapot, walls and floor tiles Fabrics Nylon coal, air, water swimwear, stockings, socks toothbrush bristles Polyester petroleum Dri-FIT shirt, pants, jackets windbreakers, tote bags
- 9. 9 Types ofMaterials • Weare goingto study the differenttypes ofmaterials, their sources, properties,disadvantages, uses and examplesindetails • We willbefocusingon7 groupsofmaterials 1. Metals 2. Wood 3. Glass 4. Ceramics 5. Rubber 6. Fabrics(cotton,linen,leather, wool,silk,nylon, polyester) 7. Plastics
- 10. 10 1. Metals Source • Metalsarenaturalmaterialsthatcomesfrom ground •They exitsin theformofores withother mineralson Earthwhich areseparatedto obtainpure metal • Therearemanydifferenttypesofmetalssuch asiron, nickel,silver andgoldintheEarth’s crust Disadvantages • Corrode (rust) easily • Metalsarelimitedresources • Weneedtoconserve metalby recycling Properties • Have shiny surface • Malleable(can beeasilyhammered) • Ductile(canbe pulled,stretchedandpressed intosheetsandmadeintowires) • Hard,stiffandstrong • Can besoftandflexiblewhenthinandflat • Goodconductors ofheatandelectricity • Opaque(do notallow lighttopassthrough) • Waterproof • Sink inwater
- 11. 11 Uses • Metalshave awidevariety of usessuchas inbuildings, coins, jewellery,kitchenware, electricalappliances and vehiclesbodies • Some metals are soft andrust easily whenthey are pure, for example, pure iron isvery soft and rust easily • Tochangethisproperty of pure metal, a smallamountof other metals or non-metals are added to it. Thenew metalis calledan alloy. • Alloysare strong hard and do not corrode easily • Some examples ofalloys are brass, bronze andsteel • Metals are used to makemagnets
- 12. 12 Examples Aluminum Copper Ironand Steel Gold and Silver • Coins • Jewellery • Ornaments • Trophies • Plaques • Electrical wires • Alloys e.g bronze and brass • Aircraft bodies • Vehicles’ bodies (car, train,buses) • Cookingpots • Kitchenfoil • Drinks and food cans • Electrical appliances • Nails • Kitchenware • Cutlery • Rods • Pipes
- 13. 13 2. Wood Source • Woodis naturalmaterialwhich comes from trunks,stemsand roots of trees • Wood is thehard substancesfound insidethebark in trunksandthick branches of trees • Good wood is obtainedfrom pine,teak, oak androse wood Disadvantages • Can beeasily destroyed by fungiand termites • Catchesfire easily Properties • Light,strongandhard • Durable(long-lasting) • Can becut easily andmadeintodifferent shapes • Float on water • Poor conductor of heatandelectricity • Opaque(does not allowlight topass through) • Not waterproof (absorbs water) • Somewood are soft whilesome are hard
- 14. 14 Uses • Wood areusetomakehouses,buildings,hutsand furniture • Somespecial wood are usetomakemusical instrumentssuch as violins, piano and guitars • Hard wood is used tomakehouses,boats andferries • Soft woods such as wood pulp is usedtomakepaper • We usepaper tomakebooks, envelopes, disposable cups and paper plates • Paperis anothermaterialwhich has its own properties differentfrom wood Examples house table stool guitar
- 15. 15 3. Glass Source • Glassisman-made material • It ismade upof a mixtureof sand(foundnaturally),lime and sodawhichare naturalmaterials andheatedtovery high temperature Disadvantages • Glassis easilybroken • It isnot flexible Properties • Can betransparent (allow alllightto pass through)or translucent(allow somelight topass through) • Brittle(breaks easily) • Poor conductor of heatand electricity • Does notcorrode (does not rust) • Rigidand stiff(not flexible) • Can bemouldedintoshapes • Waterproof (does not absorb water)
- 16. 16 Uses • Glassis usedtomake glassware/kitchenwaresuchas plates,cups andbowls • It isuse tomake laboratoryapparatus,lenses,medicine bottles,vases, ornaments, windowpanes,lightbulbs,mirrors Examples cup light bulb laboratory apparatus mirror
- 17. 17 4. Ceramics Source • Ceramicsare man-made materials • They are made from clay(found naturally)andother non-metallic solidsby heatingathigh temperature tohardenit Disadvantages • Breaks easily • Heavy Properties • Strongandhard • Brittle • Do notcorrode(does notrust) • Poor conductor ofelectricity(do notconductelectricity) • Poor conductor ofheat(some ceramicsare usedfor cooking) • Canbe mouldedintoshapes before beingfiredinovens • Opaque (nolightpassthrough) • Waterproof
- 18. 18 Uses • Ceramics areused tomake ceramic tiles(floor tilesandwalltiles) • They are used tomake vases, pots,mugs, plates,cups, andfoodcontainers, decorativepieces, bricks, flowerpots, claypotandteapot Examples bowl vase teapot floor tiles
- 19. 19 5.Rubber Source • Rubber isnaturalmaterialfrom plant • Rubber comes fromlatex(a milkyliquid (sap)) obtainedfromrubber trees • Thelatexis processed toobtain different types of rubber Disadvantages • Rubber is soft andeasily damagedby heat • It produces poisonous gases whenburnt Properties • Elasticandflexible • Tough • Durable(long-lasting)andableto withstandwear and tear • Waterproof • Opaque(no lightcan pass through) • Poor conductor of heatandelectricity
- 20. 20 Uses • Rubber isusedtomake tyres of motor-vehicles • It isused tomake boots, solesofshoes, water hoses, erasers,elasticbands, mattresses,gloves, balloonsandtoys Examples tyre water hose gloves eraser
- 21. 21 6.Fabrics Source • Fabricscanbe naturalorman-made • Fabricscancome fromanimals, plants,mineralsandsynthetics fibers Disadvantages • Fabricscatchfire easily • They canbe easilytorn Properties • Softandlight • Flexibleandrelativelystrong • Durable • Poor conductorsof heatand electricity • They canbe cutandsewneasily • Not waterproofsoitableto absorb dyes • Canbe either smoothor rough Uses • Differentfabricsare usedto make differentclothes • Towels,curtains,bedsheets andblanketsare made offabrics
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- 23. NaturalFabricsfrom Plants cotton linen •Comefromcotton plant • Made fromthefruit thatprotects the seeds of cotton plant • Use tomakethreads which are woven intocottoncloth • Soft,flexibleandabsorbent • Cheap,cool andcomfortable towear • Can bewashedanddried easily • Creases easily unlesstreatedwith chemicals • E.g: CottonT-shirts • Comes from the stem of flaxplant • Rougher texture thancotton • Naturallinencreases easilyunless treatedwithchemicals • E.g Fine linenuse tomake delicate tableclothswhilethicklinenuse to make suitsanddresses
- 24. 24 24 wool silk leather • Comesfrom skin of animals such as cow, pigs, snakes, crocodiles etc • Strong and durable • Soft and flexible • Poor conductor of heat • Waterproof • Has the animal natural patterns on it to makethe design • Can beeasily damageby fungus • Needs to take careto maintain texture • E.g wallets, belts, bags, shoes, jackets, sofa • Comes from fur of sheep • Wool fibre sheared from the sheep’s body is spun into woollen threads • Threads areknitted or woven into clothes • Poor conductor of heat • Warmand suitable for winter wear • Soft, flexible, elastic and crease-resistant • Will shrink if not washed carefully • Expensive • E.gcardigans, gloves, blankets, sweaters, coats • Comes from silkworms of moth • Silkworms spins long thread of silk around its own body to form a cocoon • When the cocoons areharvested, they areplacein water, silk treads loosen andthe farmer unwinds them • Soft, smooth, flexible, strong and has attractive shine • Cooling to wear • Can beexpensive • E.gscarf, neckties, nightgowns, Chinese cheongsams, dress NaturalFabricsfrom Animals
- 25. 25 Man-made Fabrics nylon polyester •Made fromchemicals obtainedfrom coal, air andwater • Flexibleandelastic • Soft andlight • Strongandsmooth texture • Do notshrink • Crease-resistant(do not needto iron) • Waterproof, not absorbent • E.gstockings, socks, swimsuits,clothes • Made fromchemicals obtainedfrom petroleum • Stronganddurable (do not teareasily) • Do notshrink • Winkle-resistant(do not needtoiron) • Waterproof, not absorbent • Dries quickly • E.gOuterwearsuch as parkas, windbreakers, suits,pants, sports wear
- 26. 26 7. Plastic Source • Plasticisman-madematerial(synthetic andartificial) • Made frompetroleum(crude oil) and chemicals thatcomes from fossil fuels from underground Disadvantages • Easily damagedby heat • Releaseharmfulgases intoatmosphere whenburnt • Non-biodegradable (cannot be decomposed) andwill causeland pollution Properties • Strongandlight • Durable • Water proof • Poor conductors of heatandelectricity • Do notcorrode(do notrust) • Can beeasily coloured andmadeinto shapes • Can betransparent,translucentor opaque • Can beflexibleor stiff,rigid • Can besoft or hard
- 27. 27 Uses • Basedontheir textureandproperty, plasticsare used tomake a wide range of products • The mostimportantpropertyofplasticisits lightweightandstrength • Comparedto other materialsofthe same size, plasticsnotonlyweigh lessbut canalsowithstandheavyload • They have been usedto replacemany materialslikeglass,wood, metaland rubber • They are use tomake foodcontainers,grocery bags, table,chairs, compartmentinaircraftsandcars, footwearandclothing • They are alsouse tomake casingofmany electricalappliancessuchas fans, televisionas they does not allowelectricitytopassthrough, sowe won’tget electricshock fromtouchingthem
- 28. Examples Polythene Polyvinyl chloride(PVC)Polystyrene • Grocery bags • Clingfilm for food wrap • Pails • Milk bottles • Cups • Water pipes • Raincoats • Insulationmaterials for electrical wires • Floor coverings • Sofa upholstery (stuffing to add padding to furniture) • Packingmaterials • Food containers • Disposables utensils • Boxes to keep thingscold 28
- 29. 29 Bakelite • Plugcovers • Bottlecaps •Handles of cookware and electrical appliances • Cameras Plastic foam (Styrofoam is type of polystyrene) Nylon • Mattresses • Cushions • Paddings • Artificialsponges • Clothes(nylon) • Socks and stockings • Strings • Ropes Examples
- 30. 30 Properties ofMaterials • Apropertyofamaterialis adescriptionof thecharacteristics whichithas.Theyareadjectiveswhichtellusaboutthe material. • Materialshavedifferent propertiesand characteristics dependingonwhattheyareusedfor. • Somematerialsarehard,others aresoft.Somearestrong, othersareweak. • Knowingthephysicalpropertiesofamaterialisvery importantinhelpinguschoosetherightmaterialtomakean object
- 31. 31 List of propertiesof materials 1. Waterproof 2. Transparency 3. Flexibility 4. Strength 5. Ability to float or sink (buoyancy) 6. Thermal conductivity 7. Electricalconductivity
- 32. 32 1. Waterproof • Materialsareclassifiedbasedonweather they are waterproofor absorbent • A waterproofmaterialdoes notabsorbwater atall (alsoknownas water-resistant) • An absorbentmaterialabsorbsandtakes upwater • Examplesofwaterproofmaterialsare plastic,glass,metal, ceramics • Examplesofabsorbentmaterialsare fabricssuchascottonandwoolas wellas wood • Waterproofmaterialsare usedwhenever water needs to be kept inor out • Raincoatsandtents are made ofwaterproofmaterialstokeep rainout • Boatsneed to be completelywatertighttokeep water out • Aquariumsare made of waterproofmaterialsto keep water in • Cardboardandpaper are absorbentbut canbe made waterproofby rubbingwax over itor sprayinga clear spraysuchas acrylicsprayontoit
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- 34. 34 2. Transparency • Transparencyis the ability of the material to allow how much light to pass through it • Materials are classified basedon their degree oftransparency to light: • Transparent: Allows all/most light to pass through • E.gGlass usein car windscreenand plastic inspectacle lens • Translucent: Allows some light to pass through • E.gFrosted glass use inbathroom window,fabrics useinlampshade, plastic in plastic bag, tracing paper • Opaque: Allows no light to pass through • E.gMetal andceramicuse incooking pots, wood useinfurniture, rubber use intyre andleather use inhandbag
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- 36. 36 3. Flexibility • Flexibilityisthe abilityof a material to bend without breaking • Materials canbe classifiedinto flexible or rigid(stiff) • Flexible materials are easy tobend • Rigid materials are difficult tobend • Examples of flexible materials are rubber, fabrics, some plastics,paper • Examples of rigidmaterials are wood, ceramics,glassand metal
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- 38. 38 4.Strength • Strength isthe ability of material to withstand heavy loads without breaking • Materials can be classified into strong or weak • Materials that are strong are difficult to break • Materials that are weak are easy to break • Examples of strong materials are metal, wood, plastics, leather • Examples of weak materials are glass, ceramics • The strength of materials is relative. For example a metal spoon is stronger than plastic spoon while a plastic bag is stronger than paper bag • Most pure metal are weak. However, they can be make stronger combining with other metals or non-metals. For example, steelis made from iron and carbon and ismuch stronger than pure iron
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- 40. 40 5. Ability tosinkorfloat (buoyancy) • Buoyancyisthe abilityofthe materialto sinkor floatinwater • Materialsthatsinkgo downtothe bottom ofwater • Materialsthatfloatstay on the surfaceof the water • Examplesof materialsthatsink aremetals,ceramics,glass,leather • Examplesof materialsthatfloatarewoodandplastics • Weatheramaterialsinksorfloatsin waterdependson its density • For example,apebbleandametalballsinkin waterbecausethey havehigherdensitythan water.On the otherhand,acorkfloats on waterbecauseitislessdensethan water
- 41. 41 Sink Float Materials thatgo down to the bottom of water Materials that stay on the surface of water piggy bank marble glass cup metal spoon leather purse cork tree branches Ping Pong ball plastic spoon rubber duck paper clip pencil
- 42. 42 6. Thermal conductivity •Thermalconductivity is thematerialability toallow heattoflowthroughit easily • Materials are classified as good conductors of heator insulatorof heat • Good conductors of heatare materialsthatconduct heatvery quickly, allow heattopass througheasily • Insulators of heatare materials conduct heatpoorly, do not allow heattopass through easily (also knownas poor conductor of heat) • Examples of good conductors of heatare metals usein cookingappliances/utensilsand electric iron • Examples of insulatorof heatare wood andplastics usein handleof cooking utensilsand cooler box
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- 44. 44 7. Electrical conductivity •Electrical conductivity refers to thematerialabilityto allowelectricity topass through • Materials can beclassified as good conductors or insulatorof electricity • Good conductor of electricity conducts electricity which is allow electricity topass through • Insulatorof electricity does notconducts electricity which is does notallow electricity to pass through • Examples of good conductor of electricity are metals usein electricalwires andfilamentin lightbulb • Examples of insulatorof electricity are ceramic, glass, wood, rubber andplasticusein casingof plug,wires andswitch
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- 46. 46 When choosing amaterialto make an object, the properties of materialmust match the uses andfunctions of the objects Choosingthe Right Materials forObjects No. Material Uses Functions Reasonsfor choosingmaterial 1. Metal Electrical wires Conduct electricity Good conductor of electricity, strong, ductile 2. Plastic Raincoats Keeprain out Waterproof, light, strong, durable 3. Glass Laboratory apparatus To dochemical experiments Transparent, light, conducts heat to a certain extent 4. Leather Jackets Keepwarm Durable, strong, light, poor conductor of heat 5. Rubber Car tyres To support and direct vehicle Hard, strong, flexible, waterproof, durable 6. Ceramics Mugs and cups To contain water Strong, hard,poor conductors of heat 7. Wood Furnitures To hold objects Strong, durable, easily madeinto different shapes 8. Fabrics Clothes To beworn Light, canbedyed, smooth, soft
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