Section 2 Flashcards
Define strength
The ability to withstand forces like compression without breaking
Define hardness
The ability to withstand scratching, abrasion or denting
Define toughness
How hard a material is to break or snap
Define elasticity
How well a material can, stretch and bend and then return to its original shape
Define ductility
Ductile materials can be drawn into a wire
Define malleablity
The ability for materials to be bent or shaped
What are examples of working properties of materials?
-Ductility
-Malleability
-Hardness
-Toughness
-Strength
-Elasticity
What are some examples of physical properties in materials?
-Electrical conductivity
-Thermal conductivity
-Fusability
-Density
-Absorbency
Define electrical conductivity
Electrical conductors allow electricity to travel through them
What are some examples of materials with good electrical conductivity?
-Electrical wires
-Metals
-Fabrics can be coated/blended with metal
What are examples of insulators?
Plastics
Define thermal conductivity
Thermal conductors let heat travel through them easily
Define an electrical insulator
A material that doesn’t let electricity travel through it
Define a thermal insulator
A material that doesn’t let heat travel through it
What are examples of thermal conductors?
-Metals
-Pans (metal)
What are some examples of thermal insulators?
-Plastic
-Board
-Wood
Define fusability
Materials with a high fusibility have a low melting point
What is an example of a material with a high fusibility?
Solder
Define density
The density of a material is a measure of its mass per unit volume
Define absorbency
Materials that are absorbent are good at soaking up moisture
What is an example of an absorbent material?
Paper towels
Natural fibres (wool and cotton)
What are properties of absorbent materials?
-Dyed easily
-Vulnerable to stains
-Dry slower
What is an example of a material that is non absorbent?
Synthetic fibres like polyester
What are the properties of non metals compared to metals?
-More brittle
-Not always solid at room temperature
-Poor electrical conductors
-Dull looking
-Less dense
What are the properties of metals compared to non metals?
-Strong
-Malleable
-Good conductors of heat and electricity
-Not fusible
-Have high melting and boiling points
What is an alloy?
A mixture of two or more metals or a mixed metal with one of more elements
What are the different types of paper?
-Cartridge
-Layout
-Tracing
-Grid
-Bleed proof
What are the properties of cartridge paper?
-High quality
-Textured surface
-Good for sketching with different drawing materials like pencils, crayons and inks
What are the properties of layout paper?
-Thin
-Translucent
-Used for general design work and sketching ideas
What are the properties of tracing paper?
-Semi transparent
-Used for copying images
What are the properties of grid paper?
-May have a square of isometric pattern
-Used for orthographic and scale drawings
-Isometric paper is used for isometric drawings
What are the properties of bleed proof paper?
-The ink doesn’t spread out/bleed
-Used when drawing with felt tips and marker pens
What is a paper above 200gsm (weight)?
A board
What are the types of board?
-Solid white
-Ink jet card
-Corrugated card
-Duplex card
-Foam core board
-Foil lined board
What are the properties of solid white board?
-High quality bleached surface
-Ideal for printing
-Used for primary packaging
What are the properties of ink jet card?
-Used for ink jet printing
-The ink doesn’t bleed
-Allows for a sharply defined and high quality image
What are the properties of corrugated card?
-Made up of a fluted inner core sandwiched between two layers
-The liner can be printed on
-The flutes add strength and rigidity
-Used in secondary packaging to protect products
What are the properties of duplex board?
-Has a different colour and texture on each side
-Only one surface can be seen which is smooth as it is used for printing
-Used for food packaging
What are the properties of foam core board?
-Made by sandwiching expanded polystyrene foam between 2 layers of card
-It is stiff and lightweight
-Used for making models and posters
-The outer layer can be scored
What are the properties of foil lined board?
-Lined with aluminium foil
-Used for package food
-Keeps the flavours in and air and moisture out
Where and how do softwoods grow?
-Colder climates
-Fast growing
Why are softwoods cheap and readily accesible?
As they are fast growing
What are examples of softwoods?
-Larch
-Spruce
-Pine
What are the properties of pine?
-Yellow with brown streaks
-Strong and cheap
-Knotty - makes it harder to work with
-Used for fences and cheap furniture
What are the properties of larch?
-Attractive yellow to reddish colour
-Harder, tougher and stronger than most softwoods
-Rot resistant
-Used for decking, cladding and fence posts
What are the properties of spruce?
-Reddish brown colour
-Hard and good strength to weight ratio
-Knotty and not very durable
-Used for aircraft, ship masts and crates
Where and how do hardwoods grow?
-Warm climates
-Slow growing
Why are hardwoods expensive?
As they are slow growing
What happens when ink bleeds?
It spreads out
What is the difference between a paper and a board?
Boards are above 200gsm whereas papers are below 200gsm
What are some examples of hardwoods?
-Oak
-Mahogany
-Beech
-Balsa
-Ash
What are the properties of oak?
-Light brown
-Tough, durable and strong
-Attractive grain
-Used for flooring and furniture
-It does corrode steel screws and fittings
What are the properties of mahogany?
-Red brown colour
-Durable and easy to work with
-Expensive
-Used for expensive furntiure
What are the properties of beech?
-Pinkish brown
-Hard enough to resist dents
-Can be bent using steam
-Doesn’t splinter
-Used in children’s toys and chairs
What are the properties of balsa?
-White or tan colour
-Low density for a hardwood
-Very soft
-Easy to cut and shape
-Great for modelling
-High strength to weight ratio
What are the properties of ash?
-Pale cream colour
-Tough and absorbs shock well
-Used for tool handles and sports equipment
-Attractive - used in furniture
What are ferrous metals?
Metals that contain iron
What are examples of ferrous metals?
-Cast iron
-Low carbon steel
-High carbon steel
What are the properties and uses of cast iron?
-very strong if compressed
-Brittle and not malleable
-Used for bench vises and car brake disks
What are the properties and uses of low carbon steel?
-Quite strong and cheap
-Rusts easily
-Can’t be hardened
-Used for car bodies, screws and nuts and bolts
What are the properties and uses of high carbon steel?
-Harder than low carbon steel
-Can be hardened
-Not easy to work with
-Rusts
-Used for Tools, chisels, files and drills
How can you prevent a ferrous metal from rusting?
Adding a protective coating like paint
What are non ferrous metals?
Metals that don’t contain iron
What are examples of non ferrous metals?
-Aluminium
-Brass
-Copper
-Tin
-Zinc
What are the properties and uses of aluminium?
-Lightweight and corrosion resistant
-Expensive and not as strong as steel
-Hard to join
-Used for aeroplanes, cans and ladders
What are the properties and uses of brass?
-Quite strong
-Corrosion resistant
-Malleable
-Ductile
-Used for electrical parts, door handles and taps
What are the properties and uses of copper?
-Relatively soft
-Malleable
-Ductile
-Very good electrical conductor
-Used for pipes and electrical wiring
What are the properties and uses of tin?
-Soft
-Corrosion resistant
-Malleable
-Ductile
-Low melting point
-Used for tin cans, foil and alloying metal in solder
What are the properties of zinc?
-Not very strong
-Corrosion resistant
-Used for coating steel, buckets and watering cans
What are the properties of the alloy high speed steel?
-Keeps hardness when heated to high temperatures
-Used in high speed cutting tools
What are the properties and uses of brass (Copper and zinc)?
-Harder and stronger than both copper and zinc
-Malleable
-Ductile
-Good electrical conductor
-Resistant to corrosion
What are the properties and uses of stainless steel (iron and carbon and chronium and nickel)?
-High strength, toughness, ductility
-More rust resistant than low and high carbon steel
-Used for surgical equipment, sinks and cutlery
What are the 2 types of plastics?
-Thermoforming
-Thermosetting
What is a thermoforming polymer?
-Plastics that have a low heat resistance
-Easily formed into different shapes by heating, melting and remoulding
-Easy to recycle
What are examples of thermoforming polymers?
-Acrylic (PMMA)
-High density polyethylene (HDPE)
-Polyethylene terephtalate (PET)
-High impact polystyrene (HIPS)
-Polyvinyl chloride (PVC)
-Polypropylene (PP)
What are the properties of acrylic (PMMA)?
-Hard
-Stiff
-Shiny
-Resists weather well
-Used for motorcycle helmet visors and signs
-Quite brittle
What are the properties of high density polyethylene (HDPE)?
-Stiff
-Strong
-Lightweight
-Used for washing up bowls and folding chairs
What are the properties of polyethylene terephtalate (PET)?
-Light
-Strong
-Tough
-Used to make see through drink bottles and fibres for clothes
What are the properties of high impact polystyrene (HIPS)?
-Rigid
-Fairly cheap
-Used for boxes like CD cases and smoke detector casings
What are the properties of polyvinyl chloride (PVC)?
-Quite brittle
-Cheap
-Durable
-Used for blister packs and window frames
What are the properties of polypropylene (PP)?
-Quite tough and flexible
-Can be made in a variety of bright colours
-Used for plastic chairs
-Confortable
What are thermosetting plastics?
-Plastics that resist heat and fire
-They undergo a chemical change when heated and moulded
-Once moulded they’re permanently hard and rigid
-Difficult to recycle
What are examples of thermosetting plastics?
-Epoxy resin
-Urea formaldehyde (UF)
-Melamine formaldehyde (MF)
-Phenol formaldehyde (PF)
-Polyester resin (PR)
What are the properties of epoxy resin (ER)?
-Rigid
-Durable
-Corrosion resistant
-Good electrical insulator
-Used for circuit boards and wind turbine rotor blades
What are the properties of Urea formaldehyde(UF)?
-Hard
-Brittle
-Good electrical insulator
-Used for plug sockets and cupboard handles
What are the properties of melamine formaldehyde(MF)?
-Strong and scratch resistant
-Used to laminate chipboard and for plates and bowls
What are the properties of polyester resin(PR)?
-Hard
-Stiff
-Cheap
-Good electrical insulator
-Waterproof
-Used for kayaks, shower stalls and garden furniture
What are the properties of Phenol formaldehyde?
-Hard and heat resistant
-Easily moulded
-Used in bottle caps and snooker balls
What are natural fibres?
Fabrics that can be harvested from plants and animals
What are the properties of natural fibres?
-Biodegradable
-Recyclable
-Renewable
-Absorbent
-Strong when dry
-Poor resistance to biological damage
What are the positives of cotton?
-Strong and hard wearing
-Comfortable to wear
-Can add colour to
-Easy to wash
What are the uses of cotton?
-Jeans
-T-shirts
–Soft furnishings
-Blouses
What are the benefits of wool?
-Warm
-Absorbent
-Good elasticity
-Low flammability
-Crease resistant
What are the uses of wool?
-Suits
-Jumpers
-Coats
-Dresses
-Carpets
What are the benefits silk?
-Smooth
-Resistant to shrinking
-Absorbent
-Low flammability
-Sun resistant
What are the uses of silk?
-Lingerie
-Underwear
-Dresses
-Shirts
-Ties
What are synthetic fibres?
-Fibres made from polymers
What are the properties of synthetic fibres?
-Non renewable
-Resistant to biological change
-Can be changed by heating
-Not very absorbent
-Hard to dye
What are examples of natural fibres?
-Wool
-Cotton
-Silk
What are examples of synthetic fibres?
-Elastane
-Polyester
-Polyamide
What are the benefits of elastane?
-Extremely elastic
-Strong
-Hard wearing
-Lightweight
What are synthetic fibres made from?
-Coal and oil
What are natural fibres made from?
Plants and animals
What are the uses of elastane?
-Sportswear
-Underwear
What are the positives of polyester?
-Strong even when wet
-Low flammability
-Good elasticity
-cheap
-Resists creasing
What are the uses of polyester?
-Sportswear
-Bed sheets
-Curtains
-Cushions
What are the positives of polyamide?
-Strong and hard wearing
-Warm
-Crease resistant
-Fairly cheap
What are the uses of polyamide?
-Sportswear
-Socks
-Tights
-Carpets
How are fabrics made?
Fibres that are spun into yarns
What are the 2 types of yarn?
-Staple fibres (short lengths)
-Filaments (longer lenghts)
What are the properties of filament yarn?
-Smooth
What are the properties of staple fibre yarn?
-Hairier
What are the 3 ways of turning fibres into frabrics?
-Woven
-Knitted
-Non woven
How are woven fabrics made?
Interlacing two sets of yarns
How are knitted fabrics made?
-By interlocking one or more yarns using loops
-The loops trap air so they insulate
-The stretch more than woven fabrics
How are non woven fabrics made?
-Held together by bonding or felting
-They don’t fray and can be cut in any direction
-Little waste
What is the weft?
Woven fabric that goes from right to left
What is the warp?
The woven fabric that goes up and down
What are the advantages and uses of a lain weave woven fabric?
-Hard wearing
-Strong and holds its shape well
-Smooth finish
-Cheapest weave to produce
-Used to make cotton based fabrics
What are the advantages and uses of weaving fabrics using looms?
-Used for shirts, upholstery and trousers
-Industrial looms can produce yarn on a large scale
-Yarn can be mass produced and high speed
What are the 2 ways to knit yarns?
-Weft
-Warp
What are the properties and uses of weft knitted fabrics?
-The yarn runs across the fabric making interlocking loops with the row of yearn beneath
-These fabrics stretch and can lose their shape easily
-Can unravel forming a ladder
-The’re used to make jumpers, socks and T-shirts
What are the properties and uses of warp knitted fabrics?
-The yarn runs up the fabric in loops which interlock vertically
-They’re stretchy but keep their shape
-Hard to unravel
-Made by machine
-Used in swimwear, tights and fleeces
What are the 2 ways to make non woven fibres?
-Bonded
-Felted
What is a bonded fabric?
-A web of synthetic fibres that are glued, needle punched, stitched or melted together
-Used in medical masks and artificial leathers
What is a felted fabric?
-Felt is made by combining pressure, moisture and heat to interlock a mat of wool fibres
-Felt is used to make carpets, jewellery and snooker table coverings
What are the 2 ways of combining fabrics?
-Blend
-Mix
How do you blend fibres?
-When two of more different fibres are combined to produce yarn
-This is them woven or knitted to make a blended fabric
How to you mix fibres?
-When a fabric is made up of two or more different types of yarn
-The two different types of yarn can be knitted or woven together to make a mixed fabric
What are examples of manufactured boards?
-Medium density fibreboard (MDF)
-Plywood
-Chipboard
What are the properties of MDF?
-Made from tiny fibres of softwood timber held together by glue
-No natural grain
-Cheap
-Dense
-Porous and can be damaged by moisture
-Used for shelves and flat pack funriture
What are the properties of plywood?
-Plywood is made up of several layers of softwood of hardwood
-They are glued with their grain at right angles to one another
-Very strong
-Used for building and funiture
What are the properties of chipboard?
-Chipboard is made by compression wood chips, shavings and sawdust together
-It usually has a veneered surface
-It is cheap
-Not very strong
-Absorbent
-Can be damaged by moisture
-Used for cheap self assembly furniture
What three blocks can systems be broken down into?
-Input
-Process
-Output
What is a system?
A collection of parts that work together to do a particular function
What is a signal?
Something like movement or light that passes from one block to the next
What is a printed circuit board (PCB)?
Boards with thin copper tracks connecting components in a circuit instead of wires
What are the advantages of a PCB?
It reduces size and the manufacturing cost of electronic systems
Why is copper used for the wire of tracks in a circuit?
As it is a good electrical conductor, malleable and ductile
What is voltage?
-From a power cell or the mains pushes the electric current around a circuit
What do resistors do?
Can be used to reduce the current in a circuit
In a circuit what are examples of input, process and output blocks?
Input = switch or button
Process = Timer
Output = Buzzer, lamp
What are the 3 types of switches?
-Toggle
-Push
-Slide
What is the function of variable resistors?
-Change the resistance of the circuit based on an external factor
-This alters the current
What are the 3 types of variable resistor?
-Thermistors
-Pressure sensors
-Light dependent resistors
What external factor do thermistors detect and what are the uses?
-Detect temperature
-In hot conditions -resistance falls
-Used in central heating
What external factors do light dependent resistors detect and what are the uses?
-Light sensors
-Brighter light resistance falls
-Used in automatic night lights
What external factors do pressure sensors detect and what are the uses?
-Detect pressure in a system
-In cars they’re used to detect if there is a leak in a fuel system
-A leak causes pressure to fall which triggers a warning light
What is an integrated circuit (IC)?
-They’re tiny self contained circuits which have billions of components built in
-They help simplify electronic systems by reducing the number of separate components that are needed in a circuit
What are the advantages of using systems with ICs (Integrated circuits)?
-They’re cheaper
-They’re smaller
-They use much less power
What is a microcontroller?
A mini computer on a chip
What are the advantages of microcontrollers?
-Microcontrollers can do the jobs of multiple ICs so they simplify the system even further
-They can be reprogrammed for different uses
What are the disadvantages of microcrontrollers?
-They’re more expensive than other ICs
What are the ways in which you can program microcontrollers?
-By writing a series of commands using programming language
-Creating a flowchart
What is the use of a timer in an electronic system?
-To add a time delay to a process
-They generate a pulse after a particular length of time has passed
What is the use of a counter in an electronic system?
-Counters count pulses of voltage produced by an input device
What are two uses of timers in electronic circuits?
-Controlling flashing lights like car indicators
-The timer in microwaves that time the length of time food cooks for
What are uses of counters in an electronic circuit?
-A microcontroller counts the number of revolutions that show how fast the engine is turning in a car
What are logic gates?
They make decisions based on a collection of inputs
What are the 3 types of logic gate?
-AND
-OR
-NOT
How does an AND logic gate work?
-They have 2 inputs and both need to be on for the output to be on
-For example tumble dryers won’t work unless the start button has been pressed and the door is closed
How do OR logic gates work?
-They have 2 inputs if one input or the other one is on then the output is on
-For example automatic doors
-The door detects if someone is on the inside of outside
How do NOT logic gates work?
-They have 1 input
-If that input is on then the output is not on
-For example pressing an emergency stop switch will stop the output
What are the 3 examples of output devices and what signal do they produce?
-LED - Turns electrcitty into light
-Buzzer - Makes a noise
-Speaker - Turns electrical signals into sound
What are the 4 types of motion?
-Linear - Moving in a straight line
-Reciprocating - Moving backwards and forwards in a straight line - a piston
Oscillating - Backwards and forwards in an arc - a s wing
Rotary - Moving in a circle - a wheel
What is first order lever?
-Where the pivot is between the effort and the land
-If the load is closer to the pivot than the effort the lever gives a mechanical advantage which means the effort is smaller
-As you move the pivot closer to load it becomes easier to life
What is second order lever?
-Where the pivot is at one end of the leaver and the effort is at the other end
-An example of this is a wheelbarrow
-The closer together the pivot and the load are the easier it is to life
What is third order lever?
-Where the effort is in between the load and the pivot
-An example of this is a fishing rod and tongs
-Moving the effort and pivot further apart makes it easier to move or lift the load
What is a linkage?
When levers are connected
How does a push/pull linkage work?
-It used two fixed pivots
-The input and output motions of the linkage are in the same direction.
-The motion of the link arm is in the opposite direction
How does a bell crank linkage work?
-A bell crank changes the direction of a force by 90 degrees
What is a gear?
-Toothed wheels that interlock and transfer motion
What is a gear train?
When two or more gears are linked together and they can be used to change the direction of motion
How do you work out gear ratio?
Number of teeth on the driven gear/ the number of teeth on the driver gear
How do you work out output speed of gears?
Speed of driver gear/ gear ratio
How do you work out velocity ratio of pulleys?
Diameter of the driven pulley wheel/ the diameter of the driver pulley wheel
How do you work out output speed of a pulley?
Speed of driver pulley wheel/ velocity ratio
What are the parts contained in a cam mechanism?
-Cam
-Follower
What does a circular CAM produce?
A uniform reciprocating motion
How does a snail CAM work?
For half a turn the follower will not move then it will gently rise and then suddenly drop
It only works in one direction
How does a pear CAM work?
For half a turn the follower will not move then it will gently rise and fall
How does a four lobed CAM work?
-Has four lobes
-For each turn the CAM follower will rise and suddenly fall four times
-This only works in one direction
What is a pulley system made up of?
-Wheel
-Cable
-Rope or belt
What is the output speed, torque and direction like when the driver pulley and driven pulley are the same size?
Direction: Same
Torque: Same
Output speed: Same
What is the output speed, torque and direction like when the driver pulley is bigger than the driven pulley?
Direction: Same
Output speed: Faster
Torque: Less
What is the output speed, torque and direction like when the driver pulley is smaller than the driven pulley?
Direction: Same
Output speed: Slower
Torque: Increased
What is the output speed, torque and direction like when the driver pulley and driven pulley are the same size when the belt is crossed?
Direction: Opposite
Output speed: Same
Torque: Same
What are examples where belt drives are used?
-Pillar drills
-Washing machines
Define the term modern materials
Materials that have been developed with a specific application in mind by either inventing new materials or improved manufacturing processes
What are examples of modern materials?
-Graphene
-Metal foams
-Titanium
-LCDs (Liquid crystal displays)
-Coated metals
-Nanomaterials
What are the properties of graphene?
-Thin layer of graphite
-Light and strong
-Good conductor of heat and electricity
-Used in tennis rackets, aerospace, vehicles and flexible electronics
What are the properties of metal foams?
-A metal that contains gas filled spaces
-Lightweight
-Stiff, tough and strong under compression
-Used in bone implants and lightweight car parts
What are the properties of titanium?
-Extremely corrosion resistant
-High strength to weight ratio
-Used in the aerospace industry
-Developments in CAD/CAM have helped it reduce machining costs and make it more usable
-It can also be used for bikes, ships, armour and dental and bone implants
What are the properties of LCDs (liquid crystal displays)?
-Used in flat screen displays
-Thin
-Lightweight
-Energy efficient
-Made of a mixture of chemicals and when a current is applied the crystal’s shape changes the image of the screen
What are the properties of coated metals?
-Iron and steel can be galvanised with zinc to prevent rusting
-Anodised aluminum has a coating of aluminium oxide to make the surface harder and corrosion resistant
What are the properties of carbon nanotubes?
-Carbon nanotubes - are tiny carbon cylinders with a high strength to weight ratio
-Good conductors
-Used in electronics and can be added to materials to strengthen it without adding much weight
What are the properties of self cleaning fabric nanotubes?
-They have a nanoparticle coating that remove odors and stains when exposed to light
What are the properties of Antibacterial fabrics?
-Use nanoparticles of silver to kill bacteria
-Have lots of medical uses like face masks and dressings
-Used in anti bacterial toys and odour free socks
Define the term smart material
Materials that change their properties in response to stimuli like temperature and light
What are examples of smart materials?
-Shape memory alloys
-Photochromic inks
-Thermochromic pigments
What are the properties of shape memory alloys?
-They’re alloys that remember their original shape
-They can be shaped when cool but return to their original shape when heated
-An example is nitinol used in glasses
What are the properties of photchromic pigments?
-They change colour reversibly in response to light
-They can be put on glasses lenses which turn into sunglasses when it’s sunny
What are the properties of thermochromic pigments?
-Inks used in colour changing products which react with temperature
-When the temperature changes the product changes colour
-The object returns to its original colour when the temperature returns to its original temperature
-Examples are baby feeding spoons
What is a composite material?
Composites are made from 2 or more different materials bonded together
What are examples of composite materials?
-GRP - Glass reinforced plastic
-CRP - Carbonfibre reinforced plastic
What are the properties of GRP?
-Glass fibres that are coated in a thermosetting plastic resin
-Stronger and tougher than plastic
-Heat resistant and can be easily moulded
-Used in kayaks and boats
What are the properties of CRP?
-Carbon fibres that are coated in a thermosetting plastic resin
-Lighter than GRP
-Tougher than GRP
-Stronger than GRP
-More expensive than GRP
-Used in protective helmets, sports equipment and bulletproof vests
What is a technical textile?
-Enhanced fabrics designed to be functional
What are examples of technical textiles?
-Kevlar
-Nomex
-Micro encapsulation
-Conductive fabrics
What are the properties of kevlar?
-Synthetic fibre that can be woven into a really strong fabric
-Resistant to abrasion
-Used in bulletproof vests and clothing for motorcyclists
What are the properties of Nomex?
-Fire resistant
-Used in racing drivers’ overalls
-It has fire resistant built into the fibres so it can’t be washed away or worn away
What are the properties of micro encapsulation?
-Tiny droplets of a chemical are coated in shells called microcapsules
-They are used as insect repellent, odour neutraliser or a perfume (antibacterial socks)
What are the properties of conductive fabrics?
-Use fibres that can conduct electricity
-Used to integrate electronics into clothing
-Used in electronic gloves
What are the negatives of wool?
-Can shrink when washed
-Fairly expensive
-Can feel itchy
-Dries slowly
What are the negatives of silk?
-Creases easily
-Might not wash well
-Expensive
-Weak when wet
What are the negatives of elastane?
-Not absorbent
-High flammability
-Not biodegradable
What are the negatives of cotton?
-Creases easily
-High flammability
-Poor elasticity
-Can shrink when washed
-Dries slowly
What are the negatives of polyester?
-Not absorbent
-Not biodegradable
-Damaged by strong acids
What are the negatives of polyamide?
-Not very absorbent
-Damaged by sunlight
-Melts as it burns
