Materials and Properties - Timber Metals Polymers Textiles and Papers
Materials and Properties — Timber, Metals, Polymers, Textiles and Papers
Knowing material categories, their properties, and appropriate applications is fundamental to AQA GCSE D&T. You must be able to select and justify materials for given design contexts.
Material Properties — Key Vocabulary
| Property | Meaning |
|---|---|
| Hardness | Resistance to scratching, cutting or indentation |
| Toughness | Ability to absorb impact without fracturing |
| Tensile strength | Resistance to being pulled apart (stretched) |
| Compressive strength | Resistance to being crushed or squashed |
| Elasticity | Ability to deform under force and return to original shape |
| Plasticity | Ability to be permanently deformed without fracturing |
| Malleability | Ability to be hammered or pressed into shape without cracking |
| Ductility | Ability to be drawn into wire or stretched without breaking |
| Conductivity (thermal/electrical) | Ability to transfer heat or electricity |
| Absorbency | Ability to take in moisture |
| Fusibility | Ability to be melted and joined (welded) |
| Corrosion resistance | Ability to resist degradation from chemical reactions (e.g. rusting) |
Timber
Timber is classified into three groups:
Hardwoods — from broad-leaved, deciduous trees (slow-growing):
| Timber | Properties | Uses |
|---|---|---|
| Oak | Hard, tough, attractive grain, durable | Furniture, flooring, boat building |
| Mahogany | Hard, durable, easy to work, reddish colour | High-quality furniture, veneers |
| Beech | Hard, tough, fine grain, good for steam bending | Chairs, toys, tool handles |
| Balsa | Extremely lightweight, soft, low density | Model making, insulation |
| Ash | Tough, flexible, shock resistant | Sports equipment (cricket bats), tool handles |
Softwoods — from coniferous, evergreen trees (fast-growing):
| Timber | Properties | Uses |
|---|---|---|
| Pine (Scots pine) | Relatively strong, easy to work, knotty, affordable | Construction, furniture frames |
| Spruce | Lightweight, moderate strength, pale colour | Construction timber, paper pulp |
| Cedar | Naturally rot-resistant, aromatic, lightweight | Outdoor cladding, fences, sheds |
Manufactured boards — engineered from timber products:
| Board | Construction | Properties | Uses |
|---|---|---|---|
| MDF | Fine wood fibres + resin, hot pressed | Smooth surface, easy to machine, no grain, swells if wet | Furniture carcasses, shelving, painting/veneering |
| Plywood | Thin veneers glued at 90° alternating | Strong in all directions, resists warping, available in large sheets | Furniture, construction, boat hulls |
| Chipboard | Wood chips + resin, compressed | Cheap, smooth when laminated, weak when wet | Flat-pack furniture, kitchen worktops (when laminated) |
Metals
Ferrous metals — contain iron, magnetic, prone to rust (except stainless steel):
| Metal | Properties | Uses |
|---|---|---|
| Mild steel | Tough, ductile, malleable, cheap, rusts easily | Car bodies, nuts and bolts, structural steel |
| High carbon steel | Very hard, brittle, difficult to weld | Cutting tools, chisels, drill bits |
| Stainless steel | Hard, corrosion resistant (chromium content) | Cutlery, surgical instruments, sinks |
| Cast iron | Hard, brittle, good compressive strength, self-lubricating | Engine blocks, manhole covers, vices |
Non-ferrous metals — no iron, non-magnetic, generally corrosion resistant:
| Metal | Properties | Uses |
|---|---|---|
| Aluminium | Lightweight, ductile, good conductor, corrosion resistant | Drinks cans, aircraft, foil, bike frames |
| Copper | Excellent conductor, malleable, ductile, antimicrobial | Electrical wiring, plumbing, PCB tracks |
| Brass (Cu + Zn) | Hard, corrosion resistant, golden colour, casts well | Taps, door handles, musical instruments |
| Zinc | Low melting point, corrosion resistant | Galvanising steel, die casting |
Alloys — mixtures of two or more metals (or metal + non-metal):
- Brass = copper + zinc
- Bronze = copper + tin
- Stainless steel = iron + carbon + chromium (+ nickel)
- Duralumin = aluminium + copper + manganese (aircraft)
Polymers
Thermoplastics — can be reheated and reshaped repeatedly:
| Polymer | Properties | Uses |
|---|---|---|
| Acrylic (PMMA) | Transparent, hard, scratches easily, good insulator | Display cases, signs, light fittings |
| ABS | Tough, impact resistant, good surface finish | LEGO, phone cases, car dashboards |
| PET | Strong, lightweight, recyclable, food-safe | Drinks bottles, food packaging |
| HDPE | Strong, stiff, chemical resistant | Pipes, bottles, crates |
| PVC | Tough, chemical resistant, good insulator | Window frames, guttering, cable insulation |
| Polypropylene (PP) | Tough, flexible, fatigue resistant | Living hinges, medical equipment, rope |
Thermosetting plastics — set permanently when heated; cannot be remelted:
| Polymer | Properties | Uses |
|---|---|---|
| Epoxy resin | Very strong adhesive, chemical resistant | PCB coating, composite matrix, adhesives |
| Melamine formaldehyde | Heat resistant, hard, scratch resistant | Kitchen worktop laminates, plates |
| Urea formaldehyde | Hard, brittle, heat resistant, good insulator | Electrical fittings, plug sockets, MDF binder |
| Polyester resin | Hard, brittle alone, good in composites | GRP (fibreglass), casting |
Textiles and Papers
Natural fibres: cotton (absorbent, soft, breathable), wool (warm, elastic, felts), silk (strong, lustrous, expensive), linen (strong, cool, creases easily).
Synthetic fibres: polyester (strong, crease-resistant, quick-drying), nylon (tough, elastic, abrasion resistant), elastane/Lycra (very stretchy, shape retention).
Papers and boards: cartridge paper (drawing), corrugated card (packaging protection), solid white board (food packaging, book covers), duplex board (cereal boxes — grey back).
Exam Tips
- Learn at least two properties and two uses for every material listed above
- When justifying material choice, always link specific properties to the product's requirements
- Know the difference between hardness (surface) and toughness (impact) — they are NOT the same
- Thermoplastic vs thermosetting is a very common question — know the difference and give examples of each
- When comparing materials, use a table in your answer to organise your points clearly
Key Definitions
- Ferrous: A metal that contains iron and is magnetic
- Non-ferrous: A metal that does not contain iron and is non-magnetic
- Alloy: A mixture of two or more metals, or a metal and a non-metal, designed to improve properties
- Thermoplastic: A polymer that can be repeatedly softened by heating and reshaped
- Thermosetting plastic: A polymer that undergoes an irreversible chemical change when heated and cannot be reshaped