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DT Year One > working with woods, plastics and polymers > Flashcards

working with woods, plastics and polymers Flashcards

1
Q

fabrication

A

joining together of component parts to make a product

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2
Q

what is laminating ?

A

when thin veneers or flexible plywood are glued together to make a permanent curved profile
-former helps apply uniform pressure to the layers whilst the adhesive cures
even costing of glue between layers

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3
Q

wastage

A

removal of material

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4
Q

forming

A

changing the shape of a material

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5
Q

addition

A

material is added in order to create a form

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6
Q

what might be considered when choosing a joint?

A

-angle and strength
-time
-skill required
-aesthetic
-cost

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7
Q

dovetail and comb joints +ve -ve

A

-create repeated aesthetic patterns
-difficult to ensure consistency
-takes a lot of time
-not designed for disassembly
-requires lots of skill
-difficult to transport

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8
Q

methods of joining with components

A

-wood screws
-nuts and bolts
-coach bolts
-knock down fittings

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9
Q

what’s a coach bolt

A

-used in wooden structures
-square section embeds into wood and prevents bolt spinning during assembly
-once installed it’s impossible to remove from the head

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10
Q

what’s a KD fitting

A

-strong but collapsible joint
-glue free so good for disassembly
-easy to install
-reduces manufacture costs

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11
Q

how is a vacuum bag used?

A

-laminate is placed on a one part mould and encapsulated in a heavy duty polythene bag
-pump sucks air out of bag
-resulting atmospheric pressure forces it into position

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12
Q

positives of vacuum bag?

A

-low cost
-low skill

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13
Q

negatives of vacuum bag?

A

-time consuming
-bag could get punctured

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14
Q

how does steam bending work?

A

-steam box heats up and softens the wood fibres so they bend
-wood can be bent in all directions to form complex bends and twists

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15
Q

how does the steam box work?

A

-it’s made up of a vented container and steamer
-steam must be able to circulate and excess steam and water need to be able to leave
-steamed wood must be mover quickly to a robust former

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16
Q

3 hand processes

A

-chisel
-gouges
-planes

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17
Q

4 examples of machine processes

A

-turning between centres
-turning with a chuck and faceplate
-milling
-routing

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18
Q

how does turning on a lathe work?

A

-it holds and spins the work piece while cutting tools are used to create waste

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19
Q

what’s turning between centres used to create and how does it work ?

A

long cylindrical forms
-the prepared stock is secured in lathe at both ends which gives extra stability
-rotation speed is changed depending on diameter of wood

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20
Q

how does a chuck and faceplate work?

A

-material is secured at one end only
-secures larger work more easily
-work piece is either screwed to faceplate or clamped in chuck

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21
Q

what’s a milling tool made from and how does it move?

A

tungsten carbide
-moves up and down work laterally

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22
Q

how can 3D statues be created?

A

-milling machines fitted with robotic arms

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23
Q

why are finishes applied to wood?

A

to improve aesthetics and performance

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24
Q

how do finishes protect the wood

A

improve moisture resistance and guarding against insect and fungal attack

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25
Q

how do you prepare wood for finishes?

A

-timber must be sanded smooth along the grain
-rub down timber with methylated spirit which removes surface dust and freeze
-finishes are applied with a brush, cloth, roller or spray

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26
Q

polyurethane varnish

A

-extremely tough and hard wearing
-highly resistant to heat, water and chemicals
-sold as matt, satin or gloss finish
-used on boats and wooden flooring

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27
Q

pros of polyurethane varnish

A

-gives lustrous finish
-water based are better for environment and safer to use

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28
Q

cons of polyurethane varnish

A

-makes wood look plastic and fake
-solvent based have a long drying time and pose a greater risk to health
-yellows over time
-not resistant to uv

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29
Q

pros of acrylic varnish

A

-fast drying time
-doesn’t yellow with age
-adds durability if put on top of paint
-hard wearing
-non toxic
-odour free
good for interior use

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30
Q

cons of acrylic varnish

A

-less resistant to solvents and heat
-can’t be used exteriorly

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31
Q

pros of water based paints

A

-available in any colour
-can be watered down for a translucent look
-little odour
-low levels of volatile organic compounds(VOC)
-hardwearing, quick drying, easy to use and clean up

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32
Q

what are waterbased paints used for

A

-woodwork and furniture

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33
Q

what are stains?

A

-a finish you apply to wood that apply colour whilst keeping the natural grain

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34
Q

pros of stains

A

-aesthetic
-available in bright colours and natural tones

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35
Q

con of stains

A

no protection against decay

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36
Q

pros of wax finishes

A

-easy to apply and gives natural finish that prevents moisture getting in
-food safe and non toxic

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37
Q

con of wax finish

A

-will need to be reapplied regularly
-several coats needed

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38
Q

what’s oil finish used for?

A

to replace natural oils lost overtime to revive natural beauty

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39
Q

cons of oils

A

oils deep into wood which gives little scratch protection

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40
Q

pros of oils

A

non toxic
food safe
used on kids toys as it’s safe

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41
Q

pros of danish oil

A

-water resistant
-durable
-satin finish
-can be used as primer before paint
-food safe once aired

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42
Q

what preservative does pressure treated timber use

A

antimicrobial copper based preservatives

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43
Q

what’s pressure treatment used for

A

high level protection where timbers are exposed to constant weathering and fungal attack
-used for construction, landscaping, fencing and play grounds

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44
Q

name 8 stock forms of wood

A

-rough sawn
-planed square edge
-planed all around
-sheets
-board
-moulding
-dowel
-plank

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45
Q

rough sawn timber

A

-cheapest
-rough surfaces from industrial saws
-used in construction

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46
Q

planed timber

A

-prepared using a planer and thicknesser
-90* edge

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47
Q

PSE and PSR

A

-planing makes timber smaller and smoother
-3mm from each surface
-PSE has one square edge
-PAR square on all sides
-PSE and PAR you pay more for less material

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48
Q

what are mouldings and what are they used for

A
  • machined profiles made for functional and aesthetic purposes
  • used for decorative features in interiors
    -skirting boards
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49
Q

what are softwoods and examples

A

-fast growth, low cost, long straight shape from coniferous trees
-pine
-spruce
-cedar
-larch
-douglas fir

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50
Q

what’s pine

A

-softwood
-most commonly used in furniture and wood flooring
-lightweight
-straight grain
-has knots

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51
Q

what’s cedar

A

-has a high oil content so resistance to decay, moisture, weathering and insect attack
-lightweight, easy to work with, knot free
-used for bit building
-softwood

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52
Q

what’s larch

A

-hard timber with an attractive reddish brown colour- fades to grey in sunlight
-high resin content- clogs up cutting blades
-used for veneers

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53
Q

what are hardwoods and examples

A

-slow growing and need more land which means it’s expensive
-deciduous
-favoured for aesthetics
-strong and durable
-oak
-mahogany
-teak
-birch
-beech
-ash

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54
Q

oak

A

-tough
-durable
-hardwearing
-resistant to rot
-contains tannic acid which erodes steel
-hardwood

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55
Q

ash

A

-springy hardwood
-large open pores which gives elastic quality
-shock resistant
-used for tool handles
-hardwood

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56
Q

mahogany

A

-aesthetic
-working properties make is expensive
-excellent stability, workability and grain
-long timber as tree is tall
-hardwood

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57
Q

teak

A

-naturally high in oils so ideal for outdoor products
-decay resistant
-high resistance to acid and alkalis
-hardwood

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58
Q

birch

A

-hardwood
-fine grain=uniform, even texture so used for veneers
-less resilient to rot and insect attacks

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59
Q

plywood

A

-manufactured board
-strong, can’t split across grain
-uses lower grade hardwood and softwood veneers
-hard, smooth, uniform surface
-some knots

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60
Q

flexible plywood

A

-manufactured board
-aero ply and flexi ply can be curved into shape

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61
Q

what’s aeroply made from

A

-several birch veneers

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62
Q

what’s flexi ply made of

A

-thin central veneer, 2 softer outers

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63
Q

chipboard

A

-larger chips
-less predictable

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64
Q

MDF

A

-fine wood dust particles bonded with resin under pressure
-perfectly smooth finish and uniform density
-ideal for CNC milling

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65
Q

polymer laminated

A

-melamine formaldehyde laminates are used to give a protective and attractive surface finish to low cost timbers
-make materials hard and durable

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66
Q

wood veneers

A

-veneers r stuck to surface and edges of manufactured boards to add to aesthetics
-add aesthetics without cost of using hardwoods

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67
Q

what can woods be tested for

A

-tensile strength
-toughness
-hardness
-corrosion
-malleability

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68
Q

how do you test tensile strength

A

-tested by applying weight to test piece and monitoring how much the material bends and deflects
-ruler or vernier callipers can measure the deflection

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69
Q

how do you test hardness

A

hit a centre punch into material and measure dent size

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70
Q

how do you test for toughness

A

-hold test piece in vice and hit with equal pressure
-most brittle materials will snap
-toughest will absorb impact like beech and birch

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71
Q

how to test for corrosion

A

-test pieces of same size and shape can be left outside for same amount of time to asses damage

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72
Q

what’s industrial testing

A

-highly accurate tests that require specialist equipment

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73
Q

what does a tensile testing machine do

A

-clamps test piece at each end and pulls the material apart until it breaks

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74
Q

what does the worm drive test do

A

-pulls clamps apart at a constant rate and the load and distance travelled is plottet

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75
Q

what’s the janka hardness test

A

-measures the ability of wood to resist scratches or dents
-measures average force needed to plunge a 0.44” or 11.28mm steel ball halfway into a piece of wood

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76
Q

what are charpy and izod tests

A

tests toughness as materials are set to size with 2mm deep notch in the centre
-pendulum is dropped to strike the test piece
-the distance pendulum travels after contact with test piece shows how tough the material is

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77
Q

how do izod and charpy tests differ

A

-charpy= material is horizontal, notch faces away from hammer
-izod= material is verticals, notch faces hammer

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78
Q

what are non destructive tests

A

-tests for tensile strength, toughness and hardness without breaking the material

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79
Q

what’s the ultrasound test

A

-sound waves are pulsed into material and intensity or reflected sound waves are recorded which deferents internal deflects
-highly accurate and can be used in any material, it’s quick and portable

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80
Q

whats the x-ray beams test

A

-x-rays are passed through the material and project an image onto a film on a screen and can measure density and weight

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81
Q

how can wood be enhanced?

A

-combining wood with resin to create a composite material
-adding a preservative or finish to increase resistance
-adding a laminate to improve surface properties

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82
Q

what do preservatives do?

A

-guard against insect and fungal attack, moisture, fire damage and rot aswell as enhancing aesthetics
- they often contain copper which has antimicrobial properties which reduces chances of fungal attack

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83
Q

what’s glulam

A

-combines natural wood planks with glued to create large laminated curved beams for structural architecture
-sustainable
-finger joints connect small planks to larger lengths
-joints are staggered to avoid weakness

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84
Q

traits one off production

A

-time consuming
-requires a high level of skill
-expensive to produce

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85
Q

traits of batch production

A

-10-100000 products
-use of jugs, templates and patterns
-more highly mechanised
—eg moulded furniture and toys

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86
Q

what are patterns

A

-positive forms used in resin casting to produce negative moulds
-enables us to produce identical copies
-can be made from many materials
-sprayed with release agent before casted

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87
Q

what are moulds

A

-may be made from a range of materials depending on how many times it will be used

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88
Q

what’s mass production

A

-uses production line to produce high numbers of identical products quickly
-highly automated
-requires less skill labour
-eg plastic bags and cups
-materials purchased in bulk

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89
Q

continuous production

A

-no down time in manufacture
-uses production line

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90
Q

what’s calendering

A

-production process which uses a serious of rollers to produce a thin polymer sheet
-polymer pellets are heated and softened
-softened polymer feedstock is extruded through a series of heated rollers
-flattens and stretches the polymer
-final rollers cool the sheet and it’s rolled and cut to length

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91
Q

what’s extrusion

A

-production method used to create a continuous flow of plastic that’s pushed through a die to create a specific profile
-used for cables and pipes

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92
Q

what forms do polymers come in to start with

A

powder or granule and are processed to produce usable stock forms for manufacture

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93
Q

where’s vacuum forming used

A

school workshop and industrial businesses

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94
Q

what’s vacuum forming used to make

A

plastic yogurt pots and bath tubs

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95
Q

what polymers are used in plastic forming

A

school- HIPS
industry- ABS, Acrylic, polyester

96
Q

process of vacuum forming

A

-produce mould
-a sheet of thermoplastic is heated and pressed onto mould by atmospheric pressure as vacuum reduces the pressure below the softened thermoplastic
-the plastic takes on the shape of the mould then cools and sets in position before mould is removed

97
Q

when mould making, what must the mould have

A

-round corners and edges with small radius so doesn’t puncture plastic
-have a positive draft angle >3* for easy removal
-have vent holes where there’s dips in the profile to stop air being trapped
-have a smooth finish so doesn’t effect outcome
-avoid undercuts so mould can be removed

98
Q

what’s line bending

A

uses strip heaters which creates a permanent fold in a piece of thermoplastic
-ideal for display stands and menu holders
-batch produced

99
Q

process of line bending

A

-mark out using chinagraph pencil or non permanent parker
-strip heater is heated to temperature
-marked line on workpiece is placed along the heating strip
-time needed on heater depends on thickness and type of material
-line is tested for flexibility and when ready bent to required angle
-can use a mould
-leave to cool

100
Q

what’s laminating or lay up forming

A

-thermosetting polymer resins can be combined with fibres to produce a variety of rigid 3d products like speed boats

101
Q

lay up process

A

-mould can be made from timber, board or metal
-a release agent is applied to the mould
-polyester resin gel coat is applied and cured
-matting is laid into the mould and resin is mixed with catalyst and brushed onto the matting
-in industry chopped strands mixed with resin may be sprayed onto the mould
-then rolled to remove air bubbles once set

102
Q

what’s thermoforming and the process

A

process of forming a heated, softened polymer sheet
-uses both female and male mould
-male mould is lowered into the heated sheet pressing into the female mould
-the vacuum assists in pulling the polymer into the mould
-forms fruit tubs

103
Q

what’s injection moulding

A

-commonly used in industry to create complex shapes
-moulds constructed from steel in two parts
-ABS , acrylic and PVC are suitable for injection moulding

104
Q

process of injection moulding

A

-starts with thermoplastic granules being fed into hopper
-hopper feeds on archimedes screw that drags the granules past a heater where they r plasticised
-when the soft, pliable plastic reaches the end of the screw, a hydraulic piston forces it into the mould

105
Q

what’s ejection and finishing

A

-water is used to cool and set the plastic quickly
-the mould is separated and ejector pins release the moulding -process is repeated
-any excess polymer flashing is trimmed and recycled
-mass production

106
Q

what’s blow moulding

A

uses a two part mould and compressed air to make hollow shapes

107
Q

what polymers does blow moulding use

A

-HDPE
-PET
-PP
-LDPE

108
Q

process of blow moulding

A

-polymer granules are heated and extruded to create a plastic tube(parison)
-the parison is fed into the mould and pinched at the bottom as the mould closes tightly
-it is filled with heated compressed air until the parison inflates to fill the mould
-the plastic cools and takes the shape of the mould
-any excess is automatically trimmed

109
Q

what is rotational moulding

A

used to create hollow plastic forms
-polymers like HDPE and PP used
-gives seamless finish
-used for heavy duty items like water tanks and kayaks

110
Q

process of rotational moulding

A

-polymer granules or powder is weighed depending on desired wall thickness and put into mould
-mould is placed on a rig in a huge oven and heated
-as it’s heated it is rotated slowly in 2 axes allowing the polymer to coat the inside of the mould evenly
-once the desired thickness is reached the mould is cooled

111
Q

what’s compression moulding

A

used to form thermosetting polymers using a hydraulic press
-polymers like urea formaldehyde and melamine formaldehyde are used to create simple profiles
-cake moulds and rubber shoe soles

112
Q

process of compression moulding

A

-male and female mould create void
-moulds heated, charge is placed between
-pressure exerted on mould, heats charge into void to create part
-left to cool before part is removed using injector pin

113
Q

what are performance characteristics

A

-describes how a material behaves in different contexts and what it looks like

114
Q

performance characteristics of wood include:

A

-grain pattern or direction
-warpage, shrinkage and splitting
-machining qualities
-resistance to decay and moisture
-toxicity

115
Q

describe wood structure

A

-wood fibres are made from hollow straw like cells which are held in lignin
-tracheid carry water and nutrients to and from the roots and leaves
-these straw like cells make wood strong along it’s grain

116
Q

what is an anisotropic material

A

-when the grain gives natural wood different physical properties in different directions

117
Q

what woods are more predictable with surface finish

A

-manufactured boards are more uniform and predictable then natural woods

118
Q

what are the types of surface defects

A

-knots (can fall out when wood shrinks)
-machining can create marks with saw mill
-woods can be damaged by insect attack, disease and rot
- these affect the stability of wood

119
Q

how can wood be prevented from distortion

A

-can be seasoned

120
Q

what is hygroscopic

A

when wood acts like it’s a sponge
-it absorbs moisture and swells up in damp conditions

121
Q

what happens if moisture evaporates too quickly in wood

A

wood can distort
-may twist, warp, bow, cup or split

122
Q

why is seasoning done

A

to prevent warpage, shrinking and splitting

123
Q

what are the two types of seasoning

A

-air dried (AD)
-kiln dried (KD)

124
Q

what is air dried seasoning

A

when timber planks are stored under cover and left to dry naturally
-this way wood is already adjusted to the environment

125
Q

what is kiln dried seasoning

A

-uses steam to artificially dry the timber and speed up the drying process

126
Q

what are the working properties of seasoned timber?

A

-stronger
-more stable
-less prone to decay or rot
-less likely to corrode
-absorbs preservatives better

127
Q

what can acid content in woods like oak do?

A

-corrode ferrous metal fixings

128
Q

how does insect attack rot wood

A

-beetles and other insects like termites are attracted to starches and sugars in wood
-insects lay larvae in tiny crevices
-once hatched they will bore through the wood inside out
-this ruins the structural integrity of the wood

129
Q

how does fungal attack make woods rot

A

-fungal spores attach to the wood and feed off the nutrients stored in the cells and the wood causing it to rot

130
Q

what woods endure wet conditions

A

-oily woods like teak and redwood

131
Q

what part of trees can pose health risks and how

A

-tree sap and sawdust
-can irritate skin, cause realities problems, nausea and affect vision

132
Q

Why are polymers considered self finishing and self colouring?

A

Because pigments are added before, and during production

133
Q

what does adding colour pigment do to polymers?

A

enhances:
aesthetic’s, economics and function

134
Q

what is a stock forms of pigment?

A

Granules, sheets or films

135
Q

What are pigments?

A

fine powders added in production

136
Q

what are pigments added to prior to manufacture of polymers?

A

Hoppers
Rotation moulding
Straight into mould

137
Q

what can be done to polymers to enhance aesthetics?

A

They can be polished, brushed or textured

138
Q

how can polymers be coloured?

A

By using pigments, paints or pigmented gelcoats

139
Q

What are thermochromic pigments?

A

They added to polymers to create a colourful reaction to thermal changes. They change colour according to temperature rising or falling.

140
Q

what are the applications of thermochromic pigment?

A

Plastic cutlery
Bowls and cups for babies
Plastic films in thermometers

141
Q

what are non-reversible pigments used for?

A

Used to warn against a temperature sensitive products, such as medical vaccines or food items that can go off in the room temperature

142
Q

what are phosphorescent pigments?

A

They are charged by the exposure to natural light, the phosphors in the pigment release, the energy they have stored, whilst exposed which produces a visible glow in the dark product

143
Q

Applications of phosphorescent pigments?

A

watches
Toys
Recreational items, such as stars for decor
fire escape signs

144
Q

what is hydrographic printing?

A

Colour images are printed onto water soluble film which floats in a tank, the product is submerged and the image wraps around it giving a colourful finish

145
Q

What is electroplating?

A

When plastics are covered in a conductively or etched before plating with a metal

146
Q

when is electroplating used?

A

Mainly in the automotive industry for car trims, but also in electronics and fittings

147
Q

positives of electroplating?

A

very high and feel and look to a product at a lower cost as well as being light weight

148
Q

what is rubberising spray?

A

It’s slightly textured coating with a matte finish, which can be sprayed onto various materials to provide grip such as game controllers

149
Q

what is polishing -polymers

A

Plastic can become rough, scratched when processed and become weathered or faded if left outside so polishing issues to restore high quality finish

150
Q

give an example of a polish use to polish polymers

A

brasso is used to get a lustrous shine to plastic and it’s used in school workshops

151
Q

How can polymers be joined?

A

Can be chemically welded by solvent cement once brushed on the surfaces permanently fuse

152
Q

what is the two forms chemical welds come in?

A
  1. liquid solvent cement (water like consistency, which uses capillary action to travel along a joint. It can’t fill gaps.)
  2. Tensol 12 ( thicker variety and can fill small gaps )
153
Q

negative of chemical welds

A

-methane based and contain VOCs which are given off when they evaporate

154
Q

what is UV hardening adhesive

A

liquid adhesive is applied to surfaces that require bonding and UV light cures it which creates a very strong permanent bond

155
Q

applications of UV hardening adhesive

A

UV hardening resins have been used in dentistry and developed for use in 3D printers as a separate adhesive

156
Q

what are the 2 main categories for applying finishes

A

-protection
-aesthetics

157
Q

how can polymer finishes be applied

A

-brushed on
-sprayed on
-applied

158
Q

why are spray on products bad

A

-not environmentally friendly and contain high levels of VOCs

159
Q

what is gel coating

A

part of the lay up process used to create a rigid glass reinforced plastic shell which creates a coloured finish
-Pigment is added to polyester resin and applied to the inside of a mould and allowed to cure hard before Lay up continues .
-it requires no further finish, but can be buffed and polished to a very high shine.

160
Q

what are acrylic spray paints used to do on plastics?

A

Used to protect in colour, moulded, plastic parts and products
They are used on body coloured bumpers, where ABS parts are mass produced and sprayed after production to match the vehicle. They also used for computer mice, bike helmets, toys and models

161
Q

what does painting do to plastic

A

Adds additional UV protection and improves weather resistance. It’s also fast drying

162
Q

what is the preparation process for painting polymers?

A

1- surface needs to be thoroughly washed and dried
2-then abraded to provide a key
3-must be cleaned again and any residual dust removed
4-apply several coats of acrylic paint

163
Q

why do you polymers need to be prepared for paint?

A

Is required as most followers, so finishing and smooth, and therefore not ideal for paint

164
Q

what does over mouldings due to plastics?

A

They can enhance the look and feel of a polymer products
-Thermoplastic, elastomers, or TPE is often used to create additional grip or texture
-They can work ergonomically, which indicates where to grasp a product

165
Q

What are the applications of over mouldings?

A

-Tool handles
-Sports equipment
-Toothbrushes
-Torches
-Power cables

166
Q

why are use TPEs not other Thermo plastics used for over moulding

A

TPEs are elastomers, so have a spongier, more forgiving feel which increases, comfort and grip

167
Q

what are the two ways of creating over mouldings?

A

1- you can use to separate moulds, one for the substrate and one for the cavity for over moulding
2-or use a single dual cavity mould with two separate injection heads, which can be used in continuous production it’s called twin shot injection moulding

168
Q

what are mechanical properties?

A

The characteristics and material displays when subject to an external force

169
Q

what is toughness in a polymer?

A

It determines that ability to absorb energy and deform plastically without cracking

170
Q

what is elasticity in a polymer?

A

Materials resistance to distortion and ability to return to its original shape

171
Q

what is flexibility and folding of a polymer?

A

The ability to be bent and folded without breaking
stiffness equals rigidity

172
Q

what is mouldability of a polymer?

A

The polymers ability to be shaped into a form or mould, which will dictate to the type of product it’s used for

173
Q

what does the ability to be cut and scored depend on?

A

The hardness of a material

174
Q

what is an example of a polymer, that’s hard and easily scored

A

Acrylic

175
Q

What’s the name of a material that is softer and less easily scored?

A

HDPE and HIPS

176
Q

what are physical properties?

A

a measurable, characteristic and material displays

177
Q

what is thermal insulation of a polymer?

A

The ability to reduce heat transfer, especially between objects and people

178
Q

what are melting points of polymers

A

The temperature at which material changes state from solid to liquid

179
Q

what is UV resistance of polymers?

A

UV bleaches the colour of polymers like ABS, which is used in garden furniture. It makes polymers more brittle as it degrades it.

180
Q

What polymer can be used as an alternative to ABS to give a greater UV resistance

A

ASA as it retains its colour due to a higher UV resistance

181
Q

what polymer is very resistant to chemicals

A

HDPE, which is used for bleach bottles etc

182
Q

what is resistance to liquids polymers?

A

All polymers are resistant to liquid, although some more HDPE and PET are used for plastic water bottles. However, DP is reusable and recyclable, but PET leeches chemicals into the water, so can’t be reused.

183
Q

what polymers are commonly used in food packaging

A

Polymer films and moulded polymer sheets which hygienically protect the goods

184
Q

What is transparency?

A

It dictates how permeable material is to light radiation tells us how see-through it is

185
Q

what does transition mean?

A

Some light may pass through but will be diffused and objects on the other side will not be clear

186
Q

what does opaque mean?

A

Impermeable to light

187
Q

what is a self finishing polymer

A

It means no additional surface finishing is required

188
Q

what are the three additives for processing?

A
  1. plasticers enhance flow characteristics and enable the polymers to be moulded at higher temperatures
  2. thermal antioxidants help prevent oxidation due to heat exposure during manufacture.
  3. Lubricants improve, polymer flow by decreasing viscosity.
189
Q

what do additives for processing improve?

A

They used to make polymers easier and more efficient to work with

190
Q

What are additives for performance used for?

A

Prolonging lifespan and increasing performance

191
Q

what are two additives for performance?

A
  1. Antioxidants which reduced aggregation and deterioration from exposure to air and water and help prevent, cracking and discolouration.
  2. UV light stabilisers help improve UV resistance
192
Q

what do additives to improve function do?

A

Used to enhance performance characteristics

193
Q

what are three examples of adjectives to improve function

A
  1. Fire retardants
  2. Plasticisers which make it stretchy.
  3. Antistatic additives, which reduce the buildup of static charge.
194
Q

What’s an example of an additive for biodegradability

A

Bio batch materials, which can be added, meaning they can be broken down quickly by natural bacteria

195
Q

what is recyclability and what does it reduce?

A

The process of recovering waste polymers and reprocessing them into useful materials and products. This reduces the reliance on the production of new materials from finite resources.

196
Q

what are the properties and uses of low density polyethylene/LDPE?

A

Properties: very tough, good, chemical resistance, waterproof, translucent, low level of rigidity
Uses: food, wrap, food trays, packaging, bin, liners and detergent bottles
– It’s thermoplastic

197
Q

what’s the safe working temperature of LDPE and HDPE?

A

65°C

198
Q

properties and uses of high density, polyethylene/HDPE

A

Properties: available in translation, form, weatherproof, tough, good, chemical resistance
Uses: chemical drums, long, live, carrier bags, jerrycans and kitchenware
– It’s a thermoplastic

199
Q

what are the properties and uses of polypropylene/PP?

A

Properties: available in translucent, good, chemical resistance, tough and good fatigue resistance, safe, working temperature of 100°
Uses: rope folders, food, containers, and medical equipment
– It’s a thermoplastic

200
Q

What are the properties and uses of high impact polystyrene/HIPS?

A

properties: hard rigid, available in translucent and tough
Uses: yoghurt, pots, single, use cups toilet seats
– It’s a thermoplastic

201
Q

what are the properties and uses of acrylonitrile butadiene styrene/ABS?

A

Properties: tough, hard, available in opaque
Uses: telephone handset, rigid luggage, computer housings
– It’s a thermoplastic

202
Q

What are the properties and uses of polymethylmethacrylate/PMMA?

A

Properties: tough, hard, good chemical resistance available in translucent
Uses: car, light, casings, lighting units, and covers and bath
– It’s a thermoplastic

203
Q

Properties and uses of nylon

A

properties: tough, corrosion, resistance, good temperature resistance, low coefficient of friction
Uses: Bearings, gears, curtain rails
– It’s a thermoplastic

204
Q

properties and uses of rigid, polyvinyl chloride/uPVC?

A

Properties: rigid, opaque, tough hard, good weathering resistance and good chemicals resistance
Uses: window, frames and external doors and guttering
– It’s a thermoplastic

205
Q

what are the properties and uses of flexible polyvinyl chloride/PVC

A

properties: available in translucent, tough flexible, good weathering resistance, good chemical resistance
Uses: hose pipes, cable, insulation and inflatable products
– It’s a Thermo plastic

206
Q

what are the properties and uses of urea formaldehyde?

A

Properties: hard, heat, resistance, good electrical, insulator, and brittle
Uses: electrical fittings and adhesives
It’s a thermoset polymer

207
Q

what are the properties and uses of melamine formaldehyde?

A

Properties: hard, opaque, tough, heat resistant, food, safe and chemical resistant
Uses: decorative laminate, picnic wear and buttons
It’s a thermoset polymer

208
Q

what are the properties and uses of polyester resin?

A

Properties: rigid, heat resistant, chemical resistant, brittle
uses: castings chair, seats, and boat hulls
It’s a thermoset polymer

209
Q

what are the properties and uses of epoxy resin?

A

Properties: rigid, clear, hard, tough, chemical resistant
Uses: adhesives, surface coatings and encapsulation of electrical components
It’s a thermoset polymer

210
Q

what is a properties and uses of natural rubber ?

A

properties: high, tensile strength, low, elongation, good hardness, tough electric, insulator, and good cold resistance
Uses: automotive industry such as tyres, tubes, hoses
– It’s an elastomer

211
Q

what are the properties and uses of butadiene rubber/BR?

A

Properties: tough resistant against friction, good thermal resistance, electrical insulator
Uses: vehicle, tyres shoe, soles toys
– It’s an elastomer

212
Q

what are the properties and uses of neoprene?

A

Properties: good oil, chemical, abrasion and thermal resistance, tough, electrical insulator
Uses: wetsuits, laptop cases, and industrial wire insulation
– It’s an elastomer

213
Q

what are the properties and uses of silicone?

A

Properties: good flexibility at low temperatures, poor abrasion resistance and resistance to temperature extremes, good weather resistance, Electrical insulator and acts as a good lubricant
Uses: flexible, ice, cube trays, bakeware, mouldmaking

214
Q

What is a synthetic polymer?

A

It’s produced from finite resources, such as cold, gas and oil

215
Q

What is natural polymers?

A

Comes from natural products, like rubber and amber from trees and silk

216
Q

what is cracking?

A

The process of converting large hydrocarbon molecules found in separated fuel types into smaller more useful versions

217
Q

what is polymerisation?

A

After hydrocarbons are obtained from cracking, they are chemically processed the molecules of single compounds known as monomers join together. These atoms are joined and end to form long chains called polymers, which are building blocks of all plastics.

218
Q

what are thermoplastics?

A

Long chain molecules tangled together with no fixed structural pattern. They are soft and flexible with some shape memory and can be re-shaped many times.

219
Q

what are thermosets?

A

More brittle than thermoplastics so better suited to stiffen mouldings they are hard and waterproof, and cannot be re-shaped. They retain their shape at high temperatures.

220
Q

what are eight stock forms of polymers

A

– Sheet
– Film
– Granules
– Rodent and other extruded forms
– Tubes
– Bars
– Foam
– Powder

221
Q

what is sheet stock form of polymer and three examples?

A

It’s a large flat section of polymer in varying thickness
– Solid cast/extruded sheet
– Fluted sheet
– Laminated sheet

222
Q

what is film stock form of polymer and what it used for?

A

Very thin sheet polymer used for packaging film membranes and carrier bags

223
Q

what is granule stock form of polymer and what is it used for?

A

It’s a small particle of plastic that melts quickly. PVC and rubber granules are used for sport and playground services and many thermoplastics are produced from granules.

224
Q

what is a rod stock form and what is it used for?

A

From extrusion, by which polymer granules like nylon, and PP are melted, and formed into a continuous profile
– They used in bearings, gears and seals of cars

225
Q

what are other exuded stock forms of polymers and their uses?

A

– Range of more complex extruded forms can be produced by using metal profile dies
– Thermosetting polymers can be extruded such as PVC,PP and HDPE to form tubing, window frames, Adhesive tape, wire insulation.

226
Q

what is the stock form of foam and its uses?

A

It’s a solid form made by including air or other gases, it’s produced using a combination of polymer, additive/catalyst, heat and gas/air. When the material is mixed, it, expands and tiny gas particles are trapped, which burst creating a spongy or porous foam
– Exercise/sleeping mat
-Packaging and insulation
– Soft furnishing
– Modelmaking

227
Q

what’s the stock form of powder and what is it used for?

A

-It’s a very fine granule of polymer
-It coats, metal surfaces to protect against corrosion
-charged/heated metal parts, adept in powdered polymer to create coatings on railings, bike/car parts, and household appliances

228
Q

what is foam board and it’s advantages and disadvantages

A

The lamination of two white card face layers sandwiched around a foam core
– Is lightweight and easy to cut and score so good for modelmaking and presentation boards
-It’s solvent-based, so the material melts when joining so makes joining difficult

229
Q

what is fluted polypropylene?

A

– Lightweight extruded sheet with integrated channels/flutes
– Used for display and signage and easily creased and bent so good for foldable boxes and folios

230
Q

what is translucent polypropylene and its uses?

A

– Very tough and has good tear and water resistance
-very flexible and can be scored and folded to create envelope styles

231
Q

what is LDPE and its uses?

A

It’s tough flexible and has good chemical resistance
-it’s available in very thin form making it good for food wrap and bags, carrier bins and bubble wrap

232
Q

what is plastazote foam

A

An engineered foam which is tough flexible and very lightweight with a good impact resistance, making it ideal for protective packaging and sportswear like yoga mats. It also has good insulating properties so useful for piping covers.

233
Q

what is cellulose acetate?

A

A tough, transparent and naturally derived thermoplastic film, that’s by degradable used for biodegradable packaging material

234
Q

What is polyacid sheet and film and its uses

A

A biodegradable polymer made from renewable resources like cornstarch and sugarbeet it’s compostable and recyclable
-It’s used as a sustainable alternative to petrochemical based packaging like PET

235
Q

what is a negative of polylactide sheet and film

A

A huge amount of corn is needed, causing long-term problems like deforestation and displacement of people as land is claimed to farm the corn to meet demand

DT Year One (5 decks)

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