Cambridge iGCSE DT - resistant materials - materials

Shape Memory Alloy

returns to shape when heated / contract with current

used in stents

Shape Memory Polymer

deform in response to an external stimulus

valves or pumps?

Thermochromic inks

change colour with temperature

forehead thermometers

Photochromic inks

change colour in response to changes in light level

light reacting or spectacles

Lenticular sheets

make surface appear deeper

adds aesthetic

Polymorph

pellets can be moulded to tough polymer

prototyping

Smart grease

viscous gel controlling friction

dampen movement on volume knobs

Nylon

resists abrasion, low friction, chemical

toothbrush bristles

LDPE and HDPE

chemical

injection and blow moulding

PET - polyethylene terephthalate

hard, stiff, strong, low absorption, chemical

bank/smart cards

PVC - polyvinyl chloride

chemical, strong, resistant, water and fire

rain, water, sewage pipes

PMMA - acrylic

hard, strong, UV, colours

signs, kitchen products

PS - polystyrene

packaging, hairdryers

PP - polypropylene

chemical, impervious to water, flexible

chemical containers

ABS

durable, weather, rubber-like

boat/dinghy hulls

Melamine Formaldehyde

hard, chemical

electrical plugs, switches and sockets

Urea Formaldehyde

strong, hard, low absorption

toilet seats

Phenol Formaldehyde

hard, thermal stability, chemical

lab worktops, billiard balls

Polyester resin

stable, low cost, mechanical and chemical

glass reinforced for bat hulls

Epoxy resin

high adhesive strength, electrical insulation, chemical

adhesives

Scots pine

knotty, pale, strong, cheap

low-cost furniture

Parana pine

hard, knot-free, strong, expensive, pale

furniture

Spruce

creamy-white, small, hard knots, not hardwearing

indoor furniture

Yellow cedar

pale, light in weight, rigid

furniture, boat building

Redwood

strong, knotty, durable, low cost

general woodwork

Ash

creamy-brown

sports, wooden ladders

Beech

white, hard and strong, warps

toys, tool handles

Elm

light brown, tough, resists splitting, durable

indoor and outdoor furniture

Mahogany

rich reddish, strong, durable

good quality furniture

Oak

light brown, strong, tough, corrodes screws

high quality furniture

5 types of manufactured boards

blockboard, chipboard, hardboard, MDF, plywood

Advantages of manufactured boards

available in much larger sheets than solid timber

consistent properties throughout the board

more stable, less like to split

reduce waste wood

designed for specific purposes

available ready finished

Glass-fibre reinforced polymer (GRP)

glass fibres and polyester resin

car bodies, boat hulls

carbon-fibre reinforced polymers (CFRP)

best strength-to-weight ratio, expensive

woven carbon fibres and polyester resin

aerospace industry, formula 1 cars

Kevlar

way stronger than steel

only composite when combined with resin

bullet-proof vests

Cast iron

manhole covers

Stainless steel

cutlery

High speed steel

drill bits

Mild steel

construction

High carbon steel

chisels, saws

Lead

roofing

Tin

cans, roofs

Zinc

coating on screws, nuts etc

Duraluminium

aeroplanes

Aluminium

window frames

Brass

door handles

Bronze

artistic pieces

Copper

electrical wires, cooking