Materials (EdExcel)

I. Introduction to Materials in Design and Technology

  • Definition: Materials are substances used to make things. 

  • Importance of Material Selection:

    • Functionality: The material must be suitable for the product's intended purpose and performance requirements (e.g., strength, flexibility, durability).

    • Aesthetics: The material's appearance (color, texture, finish) contributes to the product's design and appeal.

    • Manufacturing: The material must be compatible with the chosen manufacturing processes (e.g., cutting, shaping, joining, finishing).

    • Cost: Material costs significantly impact the overall product cost and profitability.

    • Sustainability: Environmental impact and ethical sourcing of materials are increasingly important considerations.

II. Material Categories

Materials are broadly classified into categories based on their origin and properties.

A. Metals
  • Characteristics of Metals:

    1. Strong and Durable: Resistant to wear and tear.

    2. Good Conductors: Excellent conductors of heat and electricity.

    3. Malleable and Ductile: Can be shaped (malleable) and drawn into wires (ductile).

    4. Opaque: Not transparent.

    5. Lustrous: Shiny when polished.

    6. Magnetic (Ferrous Metals): Some metals are magnetic.

  • Types of Metals:

    1. Ferrous Metals: Contain iron and are usually magnetic and prone to rust.

      • Mild Steel:

        • Properties: Tough, ductile, malleable, good tensile strength, prone to rust.

        • Uses: Car bodies, construction girders, machine parts, nails, screws.

      • Medium Carbon Steel:

        • Properties: Stronger and harder than mild steel, less ductile and malleable, can be hardened by heat treatment.

        • Uses: Springs, gears, garden tools.

      • High Carbon Steel (Tool Steel):

        • Properties: Very hard, brittle, loses hardness if overheated when worked.

        • Uses: Cutting tools (drills, saws, chisels), blades.

      • Cast Iron:

        • Properties: Hard, brittle, good in compression, good castability, rusts.

        • Uses: Engine blocks, machine bases, cookware (cast iron pans), manhole covers.

    2. Non-Ferrous Metals: Do not contain iron, are not magnetic, and generally more resistant to corrosion than ferrous metals.

      • Aluminum:

        • Properties: Lightweight, corrosion-resistant, ductile, malleable, good conductor of heat and electricity.

        • Uses: Aircraft parts, drink cans, window frames, cooking foil, bike frames.

      • Copper:

        • Properties: Ductile, malleable, excellent conductor of heat and electricity, corrosion-resistant.

        • Uses: Electrical wiring, plumbing pipes, cookware bases, printed circuit boards.

      • Brass (Alloy of Copper and Zinc):

        • Properties: Corrosion-resistant, harder than copper, casts well, good conductor of heat and electricity.

        • Uses: Musical instruments, decorative items, plumbing fittings, door handles.

      • Tin:

        • Properties: Soft, malleable, ductile, corrosion-resistant, low melting point.

        • Uses: Coating steel cans (tin plating), solder, alloys (e.g., pewter).

      • Zinc:

        • Properties: Corrosion-resistant, relatively weak, low melting point.

        • Uses: Galvanizing steel (protective coating), die casting, batteries.

    3. Alloys: Mixtures of two or more metals (or a metal and another element) to enhance properties.

      • Stainless Steel (Alloy of Steel, Chromium, Nickel):

        • Properties: Corrosion-resistant, strong, hard, hygienic.

        • Uses: Cutlery, kitchen sinks, medical instruments, chemical processing equipment.

      • Duralumin (Alloy of Aluminum, Copper, Magnesium, Manganese):

        • Properties: Lightweight, strong, machines well, work hardens.

        • Uses: Aircraft structures, high-performance automotive parts.

B. Polymers (Plastics)
  • Characteristics of Polymers:

    1. Lightweight: Generally less dense than metals and ceramics.

    2. Insulators: Poor conductors of heat and electricity.

    3. Versatile: Can be molded into complex shapes.

    4. Corrosion-Resistant: Generally resistant to chemicals and weathering.

    5. Variety of Properties: Properties vary widely depending on the type of polymer.

  • Types of Polymers:

    1. Thermoplastics: Can be repeatedly softened by heating and hardened by cooling. Recyclable.

      • Acrylic (PMMA - Polymethylmethacrylate):

        • Properties: Hard, stiff, brittle, good optical clarity, weather-resistant.

        • Uses: Signs, lenses, safety screens, baths, aircraft canopies (Plexiglass/Perspex).

      • PVC (Polyvinyl Chloride):

        • Properties: Rigid or flexible (depending on plasticizers), tough, chemical-resistant, waterproof, good insulator.

        • Uses: Pipes, window frames, flooring (rigid PVC), raincoats, inflatable products (flexible PVC).

      • Polyethylene (Polythene - LDPE and HDPE):

        • LDPE (Low-Density Polyethylene): Flexible, tough, good insulator, chemical-resistant.

          • Uses: Plastic bags, cling film, squeeze bottles.

        • HDPE (High-Density Polyethylene): Stiffer, stronger, tougher than LDPE, chemical-resistant.

          • Uses: Milk crates, bottles, pipes, buckets, жесткая plastic toys.

      • Polypropylene (PP):

        • Properties: Tough, flexible, chemical-resistant, fatigue-resistant, can be colored easily.

        • Uses: Containers, packaging, hinges (living hinges), ropes, carpets, car bumpers.

      • ABS (Acrylonitrile Butadiene Styrene):

        • Properties: Tough, hard, rigid, good impact resistance, scratch-resistant.

        • Uses: Mobile phone cases, Lego bricks, car interior parts, vacuum cleaner bodies.

      • Polystyrene (PS):

        • Properties: Rigid, brittle, lightweight, good insulator, can be expanded (EPS - Expanded Polystyrene).

        • Uses: Packaging (EPS foam), model kits, disposable cups, food containers.

      • PET (Polyethylene Terephthalate):

        • Properties: Strong, tough, transparent, good barrier properties (for food and drinks), recyclable.

        • Uses: Drinks bottles, food packaging, synthetic fibers (fleece).

    2. Thermosetting Polymers: Undergo a chemical change when heated, becoming permanently hard and rigid. Cannot be softened or reshaped once set. Not recyclable in the same way as thermoplastics.

      • Epoxy Resin:

        • Properties: Hard, rigid, strong adhesive, chemical-resistant, good insulator.

        • Uses: Adhesives, coatings, encapsulation of electronics, composites (e.g., fiberglass).

      • Urea Formaldehyde (UF):

        • Properties: Hard, rigid, brittle, good insulator, heat-resistant, scratch-resistant.

        • Uses: Electrical fittings (sockets, switches), worktop surfaces, adhesives in MDF and chipboard.

      • Melamine Formaldehyde (MF):

        • Properties: Hard, rigid, brittle, heat-resistant, stain-resistant, food-safe.

        • Uses: Laminates for worktops, tableware (plates, bowls), electrical insulation.

      • Polyester Resin:

        • Properties: Hard, rigid, brittle, good chemical resistance (when cured), can be reinforced with glass fibers (GRP - Glass Reinforced Plastic).

        • Uses: Boat hulls, car body parts, furniture, casting.

    3. Elastomers (Rubbers): Can be stretched and return to their original shape.

      • Natural Rubber (Latex):

        • Properties: Elastic, flexible, tough, waterproof, good insulator, degrades in UV light and chemicals.

        • Uses: Tyres, seals, hoses, erasers, gloves.

      • Synthetic Rubber (e.g., Neoprene, Silicone Rubber):

        • Properties: Vary depending on type, often better resistance to heat, chemicals, and weathering than natural rubber.

        • Uses: Seals, hoses, gaskets, wetsuits, belts, flexible moldings.

C. Woods
  • Characteristics of Wood:

    1. Natural Material: Renewable resource (if sustainably managed).

    2. Aesthetic Appeal: Natural grain and warmth.

    3. Strength and Durability: Varies depending on species.

    4. Workable: Can be easily cut, shaped, and joined.

    5. Biodegradable: Environmentally friendly at end-of-life.

    6. Susceptible to Moisture and Pests: Can rot or be attacked by insects if not treated.

  • Types of Wood:

    1. Hardwoods: Deciduous trees (lose leaves in winter), generally denser, slower-growing, and more expensive than softwoods.

      • Oak:

        • Properties: Strong, hard, tough, durable, attractive grain, can be resistant to rot (especially European Oak).

        • Uses: Furniture (high-quality), flooring, construction (beams), barrels, veneers.

      • Beech:

        • Properties: Hard, tough, strong, close-grained, smooth finish, prone to warping if not dried properly.

        • Uses: Furniture (chairs, tables), toys, tool handles, workbenches.

      • Mahogany:

        • Properties: Durable, medium density, reddish-brown color, polishes well, resistant to rot and insects.

        • Uses: High-quality furniture, veneers, boat building, musical instruments.

    2. Softwoods: Coniferous trees (evergreen, needles), generally less dense, faster-growing, and cheaper than hardwoods.

      • Pine (e.g., Scots Pine, Yellow Pine):

        • Properties: Relatively soft, lightweight, easy to work, knotty, resinous.

        • Uses: Construction (framing, roofing), furniture (cheaper), paper pulp, packaging.

      • Fir (e.g., Douglas Fir):

        • Properties: Lightweight, straight-grained, good strength-to-weight ratio, less knotty than pine.

        • Uses: Construction (framing, plywood), furniture, musical instruments.

      • Cedar (e.g., Western Red Cedar):

        • Properties: Lightweight, aromatic, naturally resistant to rot and insects, low shrinkage.

        • Uses: Cladding, shingles, outdoor furniture, wardrobes, pencils.

    3. Manufactured Boards: Engineered wood products made by bonding wood strands, particles, or fibers together with adhesives.

      • Plywood:

        • Construction: Layers of wood veneer glued together with grains at right angles for strength.

        • Properties: Strong, stable, good dimensional stability, available in large sheets.

        • Uses: Construction (flooring, walls, roofing), furniture, boat building, packaging.

      • MDF (Medium Density Fiberboard):

        • Construction: Fine wood fibers bonded with resin under heat and pressure.

        • Properties: Smooth surface, easy to machine, dense, uniform, less strong than plywood, absorbs moisture.

        • Uses: Furniture (flat-pack), cabinets, interior moldings, speaker boxes.

      • Chipboard (Particle Board):

        • Construction: Wood chips bonded with resin under heat and pressure.

        • Properties: Cheapest manufactured board, less strong and moisture-resistant than MDF, can be veneered or laminated.

        • Uses: Low-cost furniture, flooring underlayment, shelving (often laminated).

D. Textiles
  • Characteristics of Textiles:

    1. Flexible: Can be bent and draped.

    2. Porous: Allow air and moisture to pass through (breathable).

    3. Variety of Textures and Finishes: Can be woven, knitted, non-woven, dyed, printed, etc.

    4. Absorbent: Can absorb liquids (varies depending on fiber).

    5. Insulating: Can provide thermal insulation.

  • Types of Textiles:

    1. Natural Fibers: Derived from plants or animals.

      • Cotton:

        • Properties: Soft, absorbent, breathable, comfortable, relatively inexpensive, creases easily, shrinks.

        • Uses: Clothing (t-shirts, jeans), bed linen, towels, upholstery.

      • Linen (Flax):

        • Properties: Stronger than cotton, absorbent, breathable, cool to wear, creases easily, more expensive than cotton.

        • Uses: Clothing (suits, shirts), bed linen, tablecloths, tea towels.

      • Wool:

        • Properties: Warm, absorbent, elastic, naturally flame-resistant, can shrink when washed, can be itchy for some people.

        • Uses: Clothing (sweaters, coats), carpets, blankets, upholstery, felt.

      • Silk:

        • Properties: Luxurious, smooth, lustrous, strong, absorbent, drapes well, expensive, delicate.

        • Uses: Clothing (dresses, scarves, ties), bed linen, upholstery, parachutes.

    2. Synthetic Fibers: Man-made fibers produced from chemical processes, often derived from petrochemicals.

      • Polyester:

        • Properties: Strong, durable, crease-resistant, hydrophobic (water-repellent), inexpensive, can be blended with other fibers.

        • Uses: Clothing (shirts, trousers), sportswear, bedding, curtains, upholstery, fleece.

      • Nylon (Polyamide):

        • Properties: Strong, elastic, tough, abrasion-resistant, quick-drying, can melt when heated.

        • Uses: Stockings, sportswear, ropes, tents, carpets, parachutes.

      • Acrylic:

        • Properties: Soft, warm, bulky, good drape, crease-resistant, less absorbent than natural fibers, can pill.

        • Uses: Sweaters, blankets, fake fur, carpets, upholstery.

      • Lycra (Elastane/Spandex):

        • Properties: Highly elastic, can stretch many times its original length and return to shape, lightweight, breathable.

        • Uses: Sportswear, swimwear, underwear, figure-hugging clothing.

    3. Blended Fabrics: Made by combining two or more different types of fibers to get the benefits of each.

      • Polycotton (Polyester and Cotton): Combines the crease resistance and durability of polyester with the comfort and absorbency of cotton.

      • Wool and Acrylic Blends: Combines the warmth of wool with the crease resistance and lower cost of acrylic.

E. Paper and Boards
  • Characteristics of Paper and Boards:

    • Made from Cellulose Fibers: Usually derived from wood pulp, but can also be from recycled paper or other plant sources.

    • Versatile: Can be used for drawing, printing, packaging, construction.

    • Biodegradable and Recyclable: Environmentally friendly if responsibly sourced and managed.

    • Relatively Inexpensive: Generally cheaper than other materials.

    • Wide Range of Types and Thicknesses (GSM - Grams per Square Meter): Different types are suited for different purposes.

  • Types of Paper and Boards:

    • Layout Paper:

      • Properties: Thin, translucent, smooth surface, lightweight, inexpensive.

      • Uses: Sketching, quick ideas, tracing, overlays.

    • Tracing Paper:

      • Properties: Very thin, transparent, smooth surface, allows for detailed tracing.

      • Uses: Tracing detailed drawings, technical drawings, overlays.

    • Cartridge Paper:

      • Properties: Medium thickness, slightly textured surface, good for general drawing and sketching, takes color well.

      • Uses: Drawing, sketching, painting, general purpose paper.

    • Card (Cardstock):

      • Properties: Thicker and stiffer than paper, available in various thicknesses and finishes, can be scored and folded.

      • Uses: Greeting cards, packaging, model making, business cards, presentation folders.

    • Corrugated Cardboard:

      • Construction: Fluted (wavy) inner layer sandwiched between two outer layers of card.

      • Properties: Strong for its weight, provides cushioning, good insulator, recyclable.

      • Uses: Packaging (shipping boxes), protective packaging, model making.

    • Bleed-Proof Paper:

      • Properties: Coated paper that prevents marker ink from bleeding through, smooth surface.

      • Uses: Marker pen drawings, illustrations, graphic design.

    • Foam Board (Foamcore):

      • Construction: Polystyrene foam core sandwiched between two layers of paper or card.

      • Properties: Lightweight, rigid, smooth surface, easy to cut, good for mounting.

      • Uses: Model making, architectural models, presentations, mounting posters.

    • Solid White Board/Grey Board:

      • Properties: Thick, rigid, strong board, good for structural models and packaging prototypes.

      • Uses: Model making (structural parts), packaging prototypes, bookbinding.

III. Material Properties

Understanding material properties is essential for selecting the right material for a specific application.

A. Physical Properties
  • Density: Mass per unit volume (how heavy a material is for its size).

    • Example: Aluminum is less dense than steel (lighter).

  • Strength: Ability to withstand forces without breaking or deforming.

    • Tensile Strength: Resistance to pulling forces (tension).

      • Example: Steel has high tensile strength, good for cables.

    • Compressive Strength: Resistance to squashing forces (compression).

      • Example: Concrete has high compressive strength, good for foundations.

    • Shear Strength: Resistance to forces acting across the material, causing layers to slide past each other.

      • Example: Rivets and bolts need good shear strength.

  • Hardness: Resistance to scratching, indentation, or wear.

    • Example: Diamond is very hard, used for cutting tools.

  • Toughness: Ability to absorb energy and withstand sudden impacts without fracturing.

    • Example: Nylon is tough, used for gears and bearings.

  • Elasticity: Ability to return to its original shape after being deformed and the force is removed.

    • Example: Rubber bands are very elastic.

  • Plasticity: Ability to be permanently deformed without fracturing.

    • Example: Clay is very plastic, easily molded.

  • Durability: Ability to withstand wear, weathering, and degradation over time. Example: Stainless steel is durable and corrosion-resistant.

  • Melting Point: Temperature at which a solid material changes to a liquid.

    • Example: Solder has a low melting point for easy joining.

  • Thermal Conductivity: Ability to conduct heat.

    • Example: Copper has high thermal conductivity, used in heat exchangers.

  • Electrical Conductivity: Ability to conduct electricity.

    • Example: Copper and aluminum are good electrical conductors.

  • Magnetism: Property of being attracted to magnets (primarily for ferrous metals).

    • Example: Steel is magnetic, aluminum is not.

  • Corrosion Resistance: Ability to resist chemical attack and degradation (rusting, oxidation).

    • Example: Stainless steel and plastics are corrosion-resistant.

  • Water Resistance/Waterproof: Ability to repel or prevent water penetration.

    • Example: PVC is waterproof.

  • Biodegradability: Ability to decompose naturally by microorganisms.

    • Example: Paper and wood are biodegradable.

B. Aesthetic Properties
  • Texture: Surface feel and appearance (rough, smooth, glossy, matte).

  • Color: Visual hue of the material.

  • Finish: Surface treatment or coating applied to the material (polished, painted, varnished).

  • Formability: How easily a material can be shaped into different forms.

  • Transparency/Opacity: How much light passes through the material (transparent, translucent, opaque).

C. Working Properties
  • Machinability: How easily a material can be cut, shaped, or machined using tools.

    • Example: MDF machines well.

  • Formability: How easily a material can be shaped into different forms (bending, molding, casting).

    • Example: Thermoplastics are easily formable when heated.

  • Joinability: How easily a material can be joined to itself or other materials (welding, soldering, gluing, screwing).

    • Example: Wood is easily joined with adhesives and screws.

  • Workability: Overall ease with which a material can be processed and manufactured.

  • Finishability: How easily a material can be finished (painted, polished, varnished, etc.).

    • Example: Wood and metals can be finished in many ways.

IV. Material Selection Criteria 

Choosing the right material is a critical design decision. Consider these factors:

  • Functionality/Performance Requirements:

    • Strength and Load Bearing: Will it support weight or stress?

    • Durability and Lifespan: How long must it last?

    • Environmental Conditions: Will it be exposed to weather, chemicals, heat, etc.?

    • Movement and Flexibility: Does it need to bend, flex, or move?

    • Insulation (Thermal/Electrical): Does it need to insulate or conduct?

    • Water Resistance/Waterproof: Must it repel or block water?

    • Safety: Is it safe for its intended use (non-toxic, flame-retardant)?

  • Aesthetic Considerations:

    • Appearance: Color, texture, finish, form, style.

    • Visual Appeal: Does it match the desired aesthetic and target market?

    • Tactile Qualities: How does it feel to the touch?

  • Cost:

    • Material Cost: Price per unit of material.

    • Manufacturing Cost: Cost of processing and shaping the material.

    • Overall Product Cost: Material cost as a percentage of the total product cost.

    • Budget Constraints: Does it fit within the project budget?

  • Availability:

    • Supply Chain: Is the material readily available and reliably sourced?

    • Lead Times: How long does it take to obtain the material?

    • Local vs. Global Sourcing: Impact on cost and environmental footprint.

  • Manufacturing Processes:

    • Forming and Shaping: Is the material suitable for the intended manufacturing techniques (molding, machining, etc.)?

    • Joining Methods: Can it be easily joined using available methods?

    • Finishing Processes: Can it be finished to the desired standard?

    • Production Volume: Is the material suitable for the intended production scale (mass production, batch production, etc.)?

  • Environmental Impact and Sustainability:

    • Life Cycle Assessment (LCA): Evaluate environmental impact from raw material extraction to disposal.

    • Renewable vs. Non-Renewable Resources: Is it from a renewable source?

    • Recyclability: Can it be recycled at the end of its life?

    • Biodegradability: Will it decompose naturally?

    • Energy Consumption in Production: How energy-intensive is its production?

    • Carbon Footprint: Greenhouse gas emissions associated with the material.

    • Toxicity: Are there any harmful chemicals involved in its production or disposal?

  • Ethical Considerations:

    • Fair Trade: Is it sourced ethically, ensuring fair wages and working conditions?

    • Child Labor: Is child labor involved in its extraction or production?

    • Conflict Minerals: Is it sourced from conflict zones?

    • Social Impact: Does its production have negative social impacts on communities?

V. Sustainability of Materials 

Sustainability is increasingly important in material selection.

  • Life Cycle Assessment (LCA): A method to evaluate the environmental impacts of a product or material throughout its entire life cycle ("cradle-to-grave"):

    • Raw Material Extraction: Mining, logging, etc. - energy use, pollution, habitat destruction.

    • Material Processing and Manufacturing: Energy use, waste generation, emissions.

    • Product Use: Energy consumption during product use, emissions.

    • End-of-Life: Disposal (landfill, incineration) or recycling, reuse, composting.

  • Renewable vs. Non-Renewable Resources:

    • Renewable Resources: Replenish naturally over a relatively short time (e.g., wood from sustainably managed forests, natural fibers).

    • Non-Renewable Resources: Finite resources that take millions of years to form (e.g., metals, fossil fuels for plastics). Using non-renewable resources depletes them and can have greater environmental impacts.

  • Recycling and Upcycling:

    • Recycling: Processing waste materials to create new products of similar quality. Reduces landfill waste and conserves resources.

      • Examples: Recycling aluminum cans, paper, some plastics.

    • Upcycling: Transforming waste materials or unwanted products into new products of higher quality or value.

      • Example: Making furniture from pallets.

  • Biodegradability and Composting:

    • Biodegradable Materials: Can be broken down by microorganisms into natural components.

      • Examples: Paper, wood, natural fibers.

    • Compostable Materials: Biodegradable materials that can be broken down in a compost heap, enriching soil.

      • Example: Some bioplastics, paper-based packaging.

  • Sustainable Sourcing:

    • FSC (Forest Stewardship Council) Certified Wood: Wood from forests managed sustainably to protect biodiversity and ecosystems.

    • Organic Cotton: Cotton grown without synthetic pesticides and fertilizers, reducing environmental impact.

    • Fair Trade Materials: Sourced ethically, ensuring fair wages and working conditions for producers.

  • Ethical Sourcing:

    • Conflict-Free Minerals: Ensuring materials are not sourced from areas where their extraction funds conflict or human rights abuses.

    • Responsible Mining and Extraction Practices: Minimizing environmental damage and ensuring worker safety.

VI. Material Processes and Techniques 

Understanding how materials are processed is important for design and manufacturing.

  • Metals:

    • Cutting: Sawing, shearing, laser cutting, plasma cutting.

    • Shaping: Bending, rolling, forging, pressing, casting, machining (turning, milling, drilling).

    • Joining: Welding, soldering, brazing, riveting, bolting, adhesives.

    • Finishing: Polishing, painting, powder coating, plating, anodizing.

  • Polymers (Plastics):

    • Cutting: Sawing, laser cutting, die cutting, guillotining.

    • Shaping: Injection molding, blow molding, rotational molding, vacuum forming, extrusion, thermoforming.

    • Joining: Adhesives, welding (plastic welding), mechanical fixings.

    • Finishing: Painting, printing, polishing.

  • Woods:

    • Cutting: Sawing (hand saws, power saws), chiseling, turning (wood lathe).

    • Shaping: Carving, bending (steam bending), laminating.

    • Joining: Adhesives, screws, nails, dowels, joints (mortise and tenon, dovetail).

    • Finishing: Sanding, varnishing, painting, staining, polishing, waxing.

  • Textiles:

    • Cutting: Scissors, rotary cutters, die cutting.

    • Shaping: Sewing, knitting, weaving, felting, embroidery.

    • Joining: Sewing, adhesives, heat sealing.

    • Finishing: Dyeing, printing, embroidery, embellishment.

  • Paper and Boards:

    • Cutting: Scissors, craft knives, guillotines, die cutting.

    • Shaping: Folding, scoring, bending, creasing.

    • Joining: Adhesives, staples, tape.

    • Finishing: Printing, laminating, varnishing.

VII. Emerging and Smart Materials 

  • Smart Materials: Materials whose properties can change in response to external stimuli (temperature, light, pressure, electricity, etc.).

    • Shape Memory Alloys (SMAs): Metals that can return to a predefined shape when heated.

      • Uses: Medical stents, eyeglass frames, actuators.

    • Thermochromic Materials: Change color with temperature.

      • Uses: Color-changing mugs, novelty items, temperature indicators.

    • Photochromic Materials: Change color with light intensity.

      • Uses: Light-sensitive sunglasses.

    • Piezoelectric Materials: Generate electricity when pressure is applied, or change shape when electricity is applied.

      • Uses: Sensors, actuators, spark lighters.

    • Electrochromic Materials: Change color when voltage is applied.

      • Uses: Smart windows, dimmable mirrors.

  • Composites: Materials made from two or more constituent materials with significantly different physical or chemical properties, which when combined, produce a material with characteristics different from the individual components.

    • Fiberglass (GRP - Glass Reinforced Plastic): Glass fibers embedded in a polyester resin matrix. Properties: Strong, lightweight, corrosion-resistant.

      • Uses: Boat hulls, car body parts, shower trays.

    • Carbon Fiber Composites (CFRP - Carbon Fiber Reinforced Plastic): Carbon fibers embedded in a resin matrix (often epoxy). Properties: Very strong, very lightweight, stiff, expensive.

      • Uses: Aircraft parts, high-performance sports equipment, racing car components.

    • Kevlar: Aramid fibers. Properties: Very high tensile strength, impact resistant, lightweight, heat resistant.

      • Uses: Bulletproof vests, body armor, ropes, tires.


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