Material properties.

Name:

Teacher:

Unit 3

Set:

AQA Design & Technology

Knowledge organiser: Different types of paper and board

Bleed proof paper is smooth and has a special coating to reduce absorbency. When drawing with a marker pen or writing with ink, the paper keeps the ink on the surface which creates a crisper line or mark. Bleed proof paper is it resists bleeding and feathering and it’s lightweight at around 70-80gsm.

Cartridge paper is a thick, quality paper with a slight texture. It’s used particularly for pencil and ink drawings and paintings. It is available in a range of weights, a heavier paper at 200gsm is more suitable for watercolour and acrylic painting.

Plotting paper also known as grid paper has printed squares or isometric grids. These are printed with feint lines that enable the user to draw graphs and diagrams, plot mathematical functions or add scientific data. The lines can be printed in different weights and is used to improve the accuracy when drawing a plan such as a new kitchen design because each grid is a measurement. i.e. one square is equal to 1cm.

Design and layout paper in the early stages of planning for a painting or design, artists may use layout paper and tracing paper for working sketches and ideas. Layout paper is lightweight and smooth with greater opacity than tracing paper. It accepts pencil and most other media well. Tracing paper is smooth and sold in pads and rolls. Ranging from 40gsm up to 280gsm for specialist uses. It is made in the same way as ordinary paper, but is passed through a bath of acid which partially dissolves the paper. This increases the translucen-cy, and it also increases the stability of the paper. This method is also used to produce grease proof paper for the kitchen.

Cardboard A heavy duty paper available in a range of thicknesses and strengths. Board is measured in microns – 1000 microns equal 1mm. Board can be made from recycled paper and it can be laminated to other materials to increase strength or provide an alternative surface, all of these characteristics make board a very versatile product.

Corrugated board is made up of one or two outer flat layers and a corrugated layer and is commonly used for delivery containers and packaging because it’s lightweight, but strong, with a smooth surface that can be printed on. The three main benefits of corrugated card is that carries a wide range of weight, protects against moisture and provides a sustainable packaging solution.

Foil lined board this is made from a stiff card lined with aluminium foil on one side. It is often used for Cartons containing liquid making it food safe. The card also has a waxy coating to make it resistant to oils and liquids. It can also be found as the lid for foil food containers, where the bottom side is foil to touch the food and the other side is cardboard for the person the write on.

Duplex board is made up of two layers, the exterior will have a wax coating to pro-vide a moisture barrier and give it a glossy sheen. Its smooth white surface makes it suitable for offset printing. Its weight, 200 – 500gsm, also makes it ideal for folding and die cutting. This type of board is good for packaging of pharmaceuticals, garments, ciga-rette packets and paper plates and cups due to its moisture barrier. It is also used in ca-tering to hold products such as cakes.

Foam board consists of a sheet of polystyrene foam sandwiched between outer layers of paper. It is rigid and lightweight, which makes it suitable for backing material for graphic signage. It cuts cleanly with a sharp blade making it very suitable for architectural models or prototypes. Foam board or foam core is made of a type of plastic called polystyrene which is difficult to recycle which means it is bad for the environ-ment.

Solid white board is a high quality board with a bright white finish which weights range from 200gsm – 500gsm. It’s strong, smooth surface makes it suitable for book covers and product packaging. It accepts printing and surface finishes, to produce the bright white board bleach is used during the production process.

Ink jet card is designed for use with an inkjet printer, the inks sit on the surface of the paper with a special coating this increases the stability of the print. A good smooth surface, ensures even ink coverage and absorbency. It’s available in weights ranging from 120-350gsm and can have either a matt or gloss coating enabling a variety of images to be printed.

Comprehension Questions: paper and boards

Task 1

You have been given a brief of designing the layout and interior design for a new café. Following are the out-line stages of the client requirements. For each stage, suggest an appropriate paper for your team to produce their designs and presentation.

1. Produce an overhead plan view of the room, with dimensions and scale marked.

Paper choice: _________________________________________________________

Reason: _____________________________________________________________

2. Create a series of preliminary sketches, with ideas for the interior design and colour suggestions.

Paper choice: ________________________________________________________

Reason: _____________________________________________________________

3. Present an artist’s impression of the exterior view of the building produced in water colour. This piece of work may be framed and hung in the café.

Paper choice: ________________________________________________________

Reason: _____________________________________________________________

4. Present a premium quality draft of the menu.

Paper choice: _________________________________________________________

Reason: ____________________________________________________________

Task 2

Congratulations, your designs have been accepted. The client would now like to move to the next stage of planning.

Make an architectural model of the building. Suggest a suitable material to make this model from and justify your reason for selection.

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The client is working abroad so your model must be shipped to their offices. You should arrange for a high quality presentation box to encase the model. The boxed presentation should then be shipped in a very durable box with the address details clearly printed on the outside.

(a) What material will you select for:

(i) Presentation box

Paper choice: _________________________________________________________

Reason: ____________________________________________________________

(ii) The shipping container

Paper choice: _________________________________________________________

Reason: ____________________________________________________________

(b) Give a suitable weight for your suggested materials.

____________________________________________________________

3. Your presentation should be accompanied by a series of photographs showing the premises and the inte-riors. These should be displayed on a large board.

(a) Suggest a suitable material for:

(i) Printing the photographs

Paper choice: _________________________________________________________

Reason: ____________________________________________________________

(ii) The mounting board

Paper choice: _________________________________________________________

Reason: ____________________________________________________________

(b) Justify your material choice for parts (a)(i) and (a)(ii) above.

_________________________________________________________________________

Task 3

Fantastic news. The client loved your presentation and architectural model proposals. The café has been built and the interior fitted out. The management team would now like help with designing the packaging for their take-away menu.

Customers will be able to take-away:

A: Hot drinks with a heatproof sleeve

B: Cold food such as cake or sandwiches

C: Hot food in a foil container with a protective lid

For each item suggest an appropriate food safe material for production of the take-away containers.

(a)___________________________________________________________________

(b)__________________________________________________________________

(c) __________________________________________________________________

Exam Questions:

1. Which of the following is a unit of paper measurement? [1]

⬨ Milligram

⬨ Grams per square metre

⬨ Micron

⬨ Nanometre

2. Wood fibre is used to make paper pulp.

(a) Name two alternative fibres that can be used? [2]

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(b) Give two reasons why wood fibres are most commonly used. [2]

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3. Name one common paper with high absorbency. [1]

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4. Describe the properties of one board that make it suitable for displaying artwork. [2]

_______________________________________________________________________________________________________________________________________________________________________________________________________________________________________

5. Study the packaging below. Considering the physical and working properties of the materials used, explain one reason why each type of paper and board has been utilised. [6]

Knowledge organiser: Different types of woods and timber

Wood has played a key role in the history of civilization. Man has used wood over the centuries for many purposes, both practical and decorative.

Natural wood is categorised as either hardwood or softwood. Most hardwood and softwood trees have characteristics that help us recognise them. Both types can be grown and harvested responsibly in managed forests. This makes wood a sustainable and biodegradable resource. Natural wood is a useful and versatile material, it is aesthetically pleasing, a good insulator, durable and tough. Wood generally has a good strength to weight ratio.

Softwood comes from coniferous trees. Most coniferous trees have needles, are evergreen, and they keep their needles all year round. Softwood trees grow faster than hardwood trees making it relatively cheap and readily available. The grain is wider making it more absorbent, however this can cause the wood to bow or change shape if it absorbs too much moisture.

Hardwood is sourced from deciduous trees. Deciduous trees drop their leaves in the autumn and new leaves grow in spring. Hardwood is slower growing and is therefore more expensive. Sought after for its variety of colours and grains, it has good aesthetical and physical properties. It has a closer grain, making it more dense and hardwearing. Oak is the most common Hardwood tree to grow in the UK.

Felling. A tree is ‘felled’ when it is cut down, traditional methods of felling used saws and axes, whereas chainsaws are used in modern felling. Agricultural logging uses machinery with large chainsaw attachments. These can fell, de-branch and log a tree in one swift action. This is a quicker, safer and more accurate pro-cess than doing this by hand.

https://www.youtube.com/watch?v=UGnDzE9mfUc

Working properties. Each timber has a different property which help decide what product it is most suitable for. Below are the different properties that make up different timbers.

Strength – the amount of load or compression it can withstand

Toughness – absorption of energy through shock before splitting

Elasticity - will it return to shape after being compressed?

Hardness – how resistant is the surface? Will it survive scratches, knocks and abrasion?

Hardwoods are used in wide range of applications and each type of hardwood has different properties.

Ash is very tough, but also flexible and shock resistant Beech is tough and very durable with a fine finish Oak is tough, hard and durable with a variable grain

Although balsa wood is a soft and lightweight material, it is a hardwood tree. Balsa trees are very fast growing which gives the wood a coarse, open grain. The living tree has large cells that fill with water – this gives the wood its spongy texture. Strong in relation to its weight and density, Balsa is used for lightweight, rigid structures such as prototypes, model bridges and model aircraft.

Mahogany is sought after hardwood for its durability, colour and aesthetics. Its deep rich reddish brown hue gives beauty and warmth to furniture, musical instruments, boats and interi-or panelling. Unfortunately man’s desire for mahogany has increased the destructive and illegal logging trade. If illegal logging continues to take place in the Amazon rainforest we will lose 20% of the world’s oxygen, so it must be protected. It is essential to source wood from sustainably managed forests to prevent us of running out.

Softwood is cost effective and readily sourced, making it an ideal choice for the construction industry.

Pine is lightweight and easy to work with

Larch is durable, tough and has good water resistance

Spruce has a high stiffness to weight ratio

Cedar contains natural oils which offer natural water resistance

Softwood planks are usually narrower than hardwood planks because the trunk of the tree is not as large.

Tone wood. Some woods possess tonal properties that make them ideal for use in stringed instruments

Spruce is commonly used in violins, piano and guitar families of instruments

Its high stiffness to weight ratio makes it ideal for the soundboard, which transmits the vibrations from the strings.

Mahogany is used for necks and sides of acoustic guitars and sometimes for the body of electric gui-tars.

Manufactured board: These can be made from sawmill scraps, recycled wood, low grade timbers and even sawdust. Wood pieces are bound together with adhesives to make man-made / manufactured board. Boards are rigid, stable and supplied in large sheets, however they are susceptible to moisture, which means they do not last as long as natural wood. The benefit of getting manufactured board in sheets means that the manufactured board can be ordered to a larger width than natural wood.

Veneers and laminates can enhance the look of manufactured board. Veneers may be made from real wood, a man made finish or plastic. Using a veneer or laminate on manufactured board also reduces the amount of moisture that is absorbed. This makes the material suitable to be used in a kitchen or bathroom.

Natural timbers can have natural defects. The most common natural defect is a knot. Softwoods such as pine, larch and cedar can also seep resin at the knot. The knot makes timber more difficult to work with as it is difficult to cut through. It can also affect the aesthetics of the wood because the knot can fall out this also means the wood timber is un-stable.

Comprehension Questions: Natural and manufactured timbers

Task 1

Reinforce your knowledge of tree types. Complete the table below, indicating whether the tree is deciduous or evergreen and the type of wood.

Task 2

Look at the selection of wooden items and state whether it would be made from hardwood or softwood.

Explain the reason for your choice.

Telegraph pole

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Fence Panel

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Hockey Stick

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Task 3

(a) In the construction of a timber-framed house, select and justify three timber based materials used for the build.

(i)

(ii)

(iii)

Telegraph pole Fence panel Hockey stick

Tree Ash Beech Larch Mahogany Oak Pine Spruce

Deciduous

Evergreen

Softwood

Hardwood

(b) Below is an interior view of a house.

Suggest a suitable timber based material for making each of the following:

(i) Kitchen cabinet carcase / frames

(ii) Front door

(iii) Wardrobe doors

(iv) Dining table – Premium quality

(c) For each of your answers to (b) above, describe the properties that make these an appropriate choice.

(i)

(ii)

(iii)

(iv)

Exam questions: Natural and manufactured timbers

1. Which one of the following is a type of wood from a coniferous tree? [1]

⬨ Beech

⬨ Ash

⬨ Oak

⬨ Larch

2. Give one common characteristic of hardwood trees. [1]

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3. Give one advantage of using ash to make a set of cricket stumps. [1]

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4. (a) Suggest an appropriate type of wood for making a model aircraft. [1]

__________________________________________________________________________________________________________________________________________________________________________________________________________________ (b) Give two reasons for your choice. [2]

__________________________________________________________________________________________________________________________________________________________________________________________________________________

5. An architect has designed a house that is entirely clad in larch.

State and justify one physical or working property of larch that make it suitable for exterior cladding. [2]

__________________________________________________________________________________________________________________________________________________________________________________________________________________

6. A kitchen worktop has been made from melamine laminate covered chipboard. Evaluate the use of chipboard for a kitchen worktop. [4]

_________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Marks out of 12 ___

Knowledge organiser: Different types of textiles

Textiles can be manufactured to exhibit a variety of properties depending on the blend of fibres

Categories include:

Natural fibres

Synthetic fibres

Blended and mixed fibres

Woven and non-woven fabrics

Knitted textiles

Natural fibres are renewable and sustainable fibres that are used to make different textiles. They are made from plants or animals so will never run out, provided they are replaced, for example more cotton plants are grown after they are harvested.

The fruit of a cotton plant is a capsule called a ‘boll’. The mature seed splits open to re-veal the fibres. Once harvested, the fibres are spun into yarn. Cotton is soft, strong and easily washable.

Silk is a natural, raw fibre sourced from the cocoon of the larvae of a silkworm. The shimmering ap-pearance comes from the fibres’ triangular like structure. Silk is a luxury material, its fine finish is soft and gentle to the touch. Silk drapes beautifully and retains its shape well. There is an artificial silk called Rayon as it has similar properties to pure silk. It is more expensive than your average piece of cloth because s ilk is carefully crafted from an insect, mostly a silkworm which produces a protein, made up of ‘fibroin’. The pur-est form of silk is produced from the cocoons of the larvae of mulberry silkworm. While silkworms remain the primary source of production, for mass scale production, silk of moth caterpillars is largely used as a secondary source.

Wool fibre is commonly sourced from sheep fleece. Depending on the source of the wool, it can feel coarse or soft. It can be easily spun, woven or knitted. Wool is naturally crease resistant and absorbs dyes very successfully. Wool absorbs vapours and keeps a layer of dry air next to the skin, which helps re-tain body heat, keeping you warm. Synthetic fabrics are made from different types of polymer, (plastic) derived from petrochemicals. Dyes are added at the manufacturing stage, so a wide range of colours can be easily produced.

Polyester and Polyamide (Nylon) are, hardwearing, with good strength, non-absorbent and wash well. They are easily blended with other fibres.

Blending is the combining of different fibres together intimately to achieve a desired product charac-teristic. Blends can influence colouring, strength, softness, absorbency, ease of washing, resistance to wrin-kling, ease of spinning or cost.

Advantages of blending

When two different types of fibres are blended, the properties of these two different fibres are synergised. For instance, in the blend of cotton and polyester, cotton provides the absorbency and pol-yester provides the strength.

Blending is done to produce a fabric, which is economical by combining the aesthetic comfort proper-ties of the natural fibres with the easy care and strength properties of synthetic fibres.

Blending also helps to provide the fabric’s light weight with all desirable characteristics. Improving spinning, weaving and finishing efficiency and the uniformity of product.

Elastane, Spandex or Lycra® is a synthetic fibre and used where elasticity is required. It can be spun with other textiles to give form fitting properties which are ideal for under garments and swimwear. It must also be breathable to reduce sweat.

Polycotton is a fabric made from a blend of polyester and cotton. It is lightweight, soft and moisture absorbing. A durable fabric, it’s suitable for bed sheets, pillow cases and a range of clothing. It is wrinkle free which means polycotton shirts do need to be ironed, which makes it easier to maintain than a cotton shirt.

Woven textiles. The commonly used types are plain weave and twill weave. A loom weaves two threads – the warp and the weft - at right angles to each other. The self-finished edge is known as the selvedge, which stops the fabric from fraying. Watch video

Plain weave is straightforward to produce and stronger than more

decorative weaves. No matter what thickness yarn is used, plain weave forms a stable fabric construction. This is commonly used with fabrics such as calico, muslin, gingham, taffeta and voile. It ’s typically used with home furnishings and tablecloths

Non – woven fibre is a sheet or web of fibres that are bonded thermally, chemically or mechanically. They are made directly from fibres, no weaving or knitting is required. Non-woven fabrics have specific properties such as absorbency, sterility, stretch, softness, flame retardancy, cushioning, filtering and more. Felt is one of the most common examples of non-woven fibre. These materials are not as strong as woven fabrics therefore they do not last as long. Nonwoven fabrics are mostly used for interlining or to make hats or other handicrafts.

Felt is a dense, non-woven fabric which is produced using matted fibres that are pressed together with heat, moisture and pressure. Felt is usually made of wool, but when mixed with synthetics it becomes more resilient. Using heat and moisture, it can be shaped and formed. Felt doesn’t have a warp or weft which means that the edges will not fray if cut with scissors, which makes it a suitable fabric for craft.

A series of interlocking loops produces a knitted fabric.

Weft knitting – the interlocking loops are formed horizontally, which enable it to stretch, but may lose shape. Weft knits are suitable for close fitting garments as the stretch allows the wearer to move comfortably. Weft knitting is used to make jumpers, socks and T-shirts,

Warp knitting – the loops interlock vertically, so the knit keeps it shape and is less likely to unravel or ladder. Warp knitting is used to make tights, swimwear and bed sheets. Watch Video

Properties of different textiles

Weft Warp

Comprehension Questions: textiles

Task 1

Match the correct raw materials to the fabrics and the products. Each material may apply to more than one product use.

Task 2

Different fabrics have different properties. What properties would each of these fabrics need for the products to function properly? Use the descriptions below to help you.

Descriptions Strong, Cheap, Elastic, Insulating, Soft, Hangs Well, Cool and Warm, Expensive, Easy to care for, Flame Re-sistant, Hard-wearing, Lustrous Finish

Task 3 Complete the table below, adding a tick to describe the material properties.

Task 4

The following jackets are all made from different materials and fabric construction. Fill out the details on fabric and construction and then describe the properties you would expect from each product.

Remember… most textile products come with a care label which will tell you the fabric, as well as care in-structions. This can give you an insight into the properties of the fabrics too i.e. if a product can be tumble dried it is more durable and easy to care for than something which is dry clean/ hand wash only or has to be washed at lower temperatures.

Exam Questions: Textiles

1. Which of the following is an example of a textile from an animal-based source? [1]

⬨ Lycra

⬨ Cotton

⬨ Polyester

⬨ Silk

2. What would be a suitable fabric construction for a pair of tights?

Explain how the fabric construction can improve the performance of a product. [4]

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3. Blended or mixed fabrics are used to combine the most desirable properties of two or more fibres.

Polycotton, made from cotton and polyester, is used by many mass-market clothing manufacturers.

What are the advantages and disadvantages of using polycotton in mass-produced apparel [6]

__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

4. Match the key definitions [4]

Marks out of 15 ________

The age of plastic

For more than 50 years, the global production and consumption of plastic has continued to rise

Approximately 300 million tons of plastic is produced each year

Plastic is relatively inexpensive to produce and very versatile

Name a range of products you have used today that have been made from plastic and try to identify their properties

What are polymers?

Polymers are mostly synthetic materials. They are usually derived from finite resources such as coal, natural gas or crude oil. There are more renewable and sustainable materials such as vegetable starches are being used to make bio-plastics. These types of plastic have lesson of an impact on the environment because they are not made from crude oil which will one day run out.

There are two types of plastic

Thermoplastic pros and cons

Thermoplastics can be repeatedly heated and moulded. Thermoplastics are not suitable for use in areas of heat or UV sensitivity. A good surface finish can be achieved for supe-rior aesthetics. They can be recycled. Each time the plastic is reheated it will try to re-turn to its original shape this is known as plastic memory. This means that thermos plastic has less of an impact on the environment as it can be reheated and reused meaning less crude oil is extracted from the ground.

Thermosets pros and cons

Thermosets are hard and durable with good structural rigidity. They are able to withstand higher temperatures. They are waterproof when solid, so ideal for use in adhesives (glues). Thermosets are a good electrical insulator. However they cannot be remoulded which means they have a one-time use so have more of an effect on the environment than thermos plastics.

Resin identification codes

Thermoplastics must be recycled separately to enable reuse, where possible. In order to easily separate items, thermoplastics are marked with a common code.

Knowledge organiser: Polymer and plastics

Types of Thermoplastic:

Polyethylene is the most common thermoplastic with over 80 million tonnes produced globally each year. There are several types of polyethylene including;

Polyethylene terephthalate (PETE) High density polyethylene (HDPE) Low density polyethylene (LDPE)

Properties of Polyethylene;

can be rigid with good strength to weight ratio It has good ductility and impact strength Its stability makes it a suitable plastic for blow-moulding

Uses of Polyethylene;

Polyvinyl chloride (PVC) is widely used for packaging, pipes, outerwear, electrical tapes and children ’s toys,

PVC can be rigid and commonly used for making pipes

It is tough and easily extruded

With the addition of plasticisers, it becomes flexible

Why is PVC suitable for sporting because it is flexible and good strength to weight ratio. It is also waterproof.

Polypropylene is a very versatile polymer, polypropylene is used for solid plastics, films and fibres;

It has low density, making it lightweight It is ductile, enabling it to stretch for use in fibres and films It’s chemically resistant and easily cleaned which makes

it very suitable for food containers PP is also suitable for ready meals because it can reach high temperatures without

melting.

High Impact Polystyrene (HIPS) is shatterproof and a good insulator,

It’s flexible and lightweight so ideal for vacuum forming

Impact resistant, it is suitable for food containers particularly yoghurt pots and fast food containers

HIPS is easily mouldable and has a good gloss finish

Other items that are made from hips include toys, packaging, signs, display and point of sale.

Acrylic Polymethyl-Methacrylate

This versatile and hard wearing plastic, comes in a variety of thicknesses and colours

It’s a tough plastic, but becomes brittle if very thin

It can also be spun into threads and woven.

Acrylic is used in knitted apparels such as fleece, socks, sportswear, and sweaters. It is also used to create fake fur, craft yarns, upholstery fabric, carpet, luggage, awnings, and vehicle covers.

Types of thermosetting plastics

Epoxy resins are a class of reactive polymers

Supplied as two liquids; a resin with a hardener which acts as a catalyst to set the resin

Epoxy resins are used as adhesives, for example Araldite® With a good strength to weight

ratio, epoxy adheres well to fibreglass and carbon fibre, reinforcing it.

Epoxy Resin is poisonous, therefore it must be disposed of with hazardous waste to

prevent it from affecting water and sea life. When using ex-poxy resin gloves must be warn

to prevent skin irritation and the room must be ventilated to prevent the user from breathing in toxins.

Polyester resin is a viscous, pale polyester solution and the addition of a catalyst, hardens the resin

The hardened resin is tough with high abrasion resistance which makes a high-performance coating for areas of high wear, for example flooring

Clear polyester resin is suitable for object embedding, clear sculpture casting and jewellery making

Resin replicas e.g. anatomical models can also cast be cast and painted

Composite adhesive Polyester resin is commonly used with composite materials such as fibreglass

Lightweight and weatherproof, it’s used to adhere layers of fibreglass in the making of boat hulls, vehicle parts and panels for caravans.

An early compound, thermoset products made using formaldehyde include:

Melamine formaldehyde

Phenol formaldehyde

Urea formaldehyde

Phenol formaldehyde (created in 1909) was known as Bakelite. It’s very rigid and hard, it was often used for electrical components and household items such as clocks, radios and telephones.

Melamine is a hard thermoset. A heavy material, it has good resistance to heat, chemicals and moisture;

It has good resistance to scratches, but it is prone to chipping

Available in a range of colours and thicknesses, it is often used for picnic wear and as a laminate for kitchen surfaces

Melamine cannot withstand the heat of a microwave so food would need to be transferred to the mela-

mine plate after heating. If it were to go into the microwave it would start to bubble and burn.

Urea formaldehyde is a good electrical insulator, with good heat resistance it is used for manufacturing electrical fittings.

The textiles industry treats some fabrics with UF resins to promote easy care properties such as anti-wrinkling.

The paper industry uses UF to improve tear strength.

The timber industry uses UF resin to bind particles in the making of manufactured boards such as MDF.

Forming and moulding of plastic

Plastics can be formed using a variety of processes;

Blow moulding – forming hollow plastic items

Extrusion – creating objects with a cross section profile

Injection moulding – injecting softened plastic into a mould

Vacuum forming - sheet of softened plastic forced onto a mould

Which process has been used for the following items?

______________ ________________ ________________ ______________

Make any notes from the video

Comprehension Questions: textiles

1. Draw two molecular diagrams showing the structure of the two different types of polymer.

(B) Explain what happens to each structure when reheated and cooled.

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Task 2. Match up each polymer type to one appropriate use. Some polymers may be suitable for more than one product. Some products may be made from the same polymer.

Task 3

Which two items below are not made from acrylic?

(b) Explain why acrylic is not so well suited for these two products?

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Task 4

Pictured below is a mop bucket.

Provide three reasons as to why HDPE is a suitable plastic. You might want to think about properties of -HDPE first to help you with this task.

1. _________________________________________________________________________________________________________________________________________________________________ 2. __________________________________________________________________________________________________________________________________________________________________ 3. _________________________________________________________________________________________________________________________________________________________________

(b) Suggest a suitable alternative plastic other than HDPE that could be used. ________________________________________________________________________________ Task 5

The food container above is made through a process called vacuum forming from a thermoplastic polymer known as PETE, also known as polyethylene terephthalate.

Give three reasons as to why the designer chose this material to hold the macaroons.

1. _________________________________________________________________________

2. _________________________________________________________________________

3. _________________________________________________________________________

Name another sheet plastic commonly used in schools that could be used to vacuum form this container. __________________________________________________________________________________________________________________________________________________________________

Exam questions Polymers

1. State the two categories of polymer? [2]

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2. What type of plastic is most commonly used for disposable cups, food containers, cheap toys, and school based vacuum forming? [1]

⬨ Expanded polystyrene

⬨ High Density Polyethylene

⬨ HIPS (High Impact Polystyrene)

⬨ Acrylic

3. Complete the following table by matching each plastic (polymer) with its correct category. The first two have been completed for you. [6]

4. Urea formaldehyde is commonly used in the manufacture of electrical plugs and fittings. Give two properties of urea formaldehyde that make it suitable for these applications. [2]

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5. Bleach bottles are commonly manufactured from HDPE.

Give two properties of HDPE that make it suitable for this use. [1]

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6. Give two reasons as to why PVC is the most widely used polymer in medical applications such as blood bags,

tubes, surgical and examination gloves? [2]

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Marks out of 14 ________

Metal and Alloys

Metals have been essential in the development of civilisation. The word ‘metal’ comes from the ancient Greek word ‘metallon’ which means to mine, excavate or extract from the ground.

Prehistoric man used metals to make tools and weapons.

Stainless steel is the most common metal used in kitchens due to the fact it doesn’t rust when it comes into contact with water.

Ore

The Earth’s crust contains many types of rock. Metallic minerals are found natural-ly in rock or ore. Ore is obtained by mining and the metals within it are extracted. The method used for ex-traction depends on the metal’s reactivity with air, water or acids. The more reactive the metal, the more expensive it is to extract.

Finding metals

Some naturally occurring metals are found as lumps in the rock and don’t require a chemical extraction. Met-als are a non-renewable resource which means that one day they will run out. We can reduce they amount of natural resources we use by recycling metals.

Some metals exist as oxides; (a binary compound of oxygen with another element or group.)

Metals such as copper, iron and zinc are oxides. These are heated with carbon to extract the metal. Electrolysis is used to extract metals such as aluminium.

Iron can be extracted from iron ore by using a blast furnace and the process of smelting

Smelting extracts common industrial metals such as iron The extreme heat draws off the metals in a liquid state called ‘hot metal’ The impurities are removed and the iron mixed or ‘alloyed’ with a small amount of carbon to

create steel The amount of added carbon affects the strength of the steel

Ferrous metals contain iron and may rust;

Iron and steel can corrode – this is known as rust Rust is a compound called iron oxide and is formed when iron and oxygen react in the presence of mois-

ture or water Most ferrous metals are magnetic

There are two ways to prevent ferrous metals from corroding, you can either paint the metal or galva-

nise the metal. (this means to add a zinc layer ) which prevents corrosive substances from pen-

etrating further into the metal. In addition the zinc acts as a sacrificial anode which means that the

damaging oxidation process of rust will be transferred to the zinc layer.

Properties of metals

Ductile

Will stretch without being damaged

Can be drawn or stretched out into long wires

Copper is highly ductile and can be drawn into long, thin wires

Malleable metals

Can be hammered into a shape without breaking

Can be rolled or pressed into sheets

Will deform under compression

Hardness – a material’s ability to withstand abrasion

A very hard metal is likely to crack or shatter upon impact or force. Cast iron would be described as hard

and brittle

Toughness – metal requires strength and ductility

This is how well a metal can absorb energy and resist fracturing without deforming

Tensile strength is the amount of tensile stress (stretching) a material can withstand be-

fore breaking or failing

Testing for tensile strength is crucial in industry

If a metal has high tensile strength it can be used for a suspension bridge and large in-

dustrial buildings.

Destructive testing is so important because it allows the user to know what temperature

the item with operate under and it also shows the weight an object can withstand before

it breaks preventing injury to the user.

Ferrous metals have varying properties making them suitable for different uses

Low carbon steel is tough, ductile and easily welded

High carbon steel is very hard wearing, but less ductile

or malleable

Cast iron is hard and easily cast into shapes, but brittle.

Non-ferrous metals don’t contain iron

They are often more expensive than ferrous metals owing to their desirable properties which include:

Lightweight

Good conductivity

Ductile and malleable

Resistant to corrosion

Examples of non-ferrous metals include Aluminium, copper, tin and zinc are all non-ferrous metals.

Electrical Conductivity is how easily an electrical current can

flow through a metal. As copper is such an efficient conductor,

it’s most common use is in electrical cabling.

Thermal conductivity measures the ability of a metal to con-

duct heat

Copper is also an excellent conductor of heat and is commonly

used in air conditioning, water tanks, saucepan bases and water

heaters

Tin is commonly associated with a ‘tin can’. In fact, the can is steel, with a thin coating of

tin,

‘tin plating’, which helps preserve the contents. Tin is soft, ductile and malleable. Alloys of tin

include pewter, copper, bronze and soft solder. Working with recycled cans is a technique

called Kapoaka. Used in Madagascar by small scale workshops, crafters make decorative ob-

jects and toys for sale. It has created sustainable employment and helps the poorest in Afri-

ca attain a living from the profits

Alloys

Metals are rarely used in their pure form. Alloys are made by combining two or more elements. This helps

improve the working properties and appearance. Brass and steel are common alloys. Stainless steel is made

by combining iron, with a small amount of carbon and chromium. This protects the alloy from oxygen – which

prevents oxidisation.

Non ferrous metals such as copper and bronze, don’t rust, but may oxidise. Oxidising can be caused by cor-

rosion or weather exposure over a period of time. A thin layer of tarnish that appears on the

surface of the metal is known as a patina. A natural patina occurring on copper is called Verdigris. The green

hue can be manufactured by adding acetic acid to copper and is often used in architecture for aesthetic

purposes

Stainless Steel is an alloy metal available in different forms

Steel has a high resistance to corrosion, staining and friction which makes it suitable for a wide range of

uses

These elements give steel its characteristic properties of hardness

and toughness

High speed steel is formed by alloying elements of carbon, tungsten,

vanadium, cobalt, chromium or molybdenum.

Stainless steel is often used for items that hold water such as a

tap, this is to prevent corrosion that could occur if normal steel was

used.

Products are often made from a range of different metals and they all have different properties, below is

an example of how different metals can be used to make a bike.