Lesson video

Hello there, my name is Mrs. Dhami.

Thank you for joining me for your design and technology lesson today.

Now the big question for today is where do polymers come from and in what forms are they supplied to us? So we're gonna explore this together.

Let's get cracking.

Our outcome for today is we will be able to describe where different materials come from and identify their common stock forms, with a real specialism on polymers.

We have four key words today.

Source is where a material originates from.

Raw material is a natural material in its original state.

Process is changing a material to make it suitable for making products.

And lastly, stock form is the standard shape or size a material is supplied in.

We have two learning cycles today.

Firstly, sourcing and processing materials.

And secondly, material stock forms. So let's start off with sourcing and processing materials.

A source is where a material originally comes from.

Polymers have two main source categories.

We have naturally occurring, which means that they come from nature, they're not made or altered by humans.

And then we have synthetic polymers which are manufactured through chemical processes.

Within both of these categories, some are biodegradable and others are not.

Polymers can be identified through the number inside their recycling triangle, which is great because there are many, many polymers.

So for example, number two stands for HDPE.

So if you are using any milk later, have a little look inside that milk lid.

And inside that lid you will find the number 2 within a recycling triangle, that identifies that it is made from HDPE.

And it's great when polymers are sorted so that they can be recycled with polymers from the same category.

The source for the majority of synthetic polymers is crude oil or natural gas.

Crude oil, as you may or may not know, is a fossil fuel, therefore it is non-renewable and is made from the buried remains of plants and animals that lived millions of years ago.

Let's take a little look at this in a bit more detail.

So if we start on the left, there are the dead organisms, plants and animals, and they get covered in a layer of earth.

As time goes on, they get covered in more and more and more layers of earth until they start to become fossils.

The fossils then, with more time and more pressure, turn into coal, oil, and natural gas.

And as I've just said, this takes millions of years, hence why they are non-renewable.

Let's take a look at the processing of crude oil.

So first of oil.

First of all not oil.

First of all, the oil has to be drilled to extract the crude oil from the ground.

Then it goes for a process called fractional distillation.

Now this happens by lots of heat heating up the crude oil and separating it into fractions such as naphtha.

Now naphtha is the raw material.

And that is then broken down through a process called cracking to produce monomers such as propene.

Then polymerization happens.

Polymerization is a process where lots of monomers are joined together to make polymer chains such as polypropylene.

So the propene turns into polypropylene.

Polymers can then be manufactured into products through manufacturing processes such as blow moulding for bottles, injection moulding for toy bricks, and extrusion for pipes.

Time for a quick check-in.

Order the following steps for the processing of crude oil into polymers.

So we have, A, cracking, B, polymerization, C, drilling, and D, fractional distillation.

Have a go at putting them into the correct order.

Come back to me when you've got an answer.

Well done if you've got this order.

We have drilling, fractional distillation, cracking into monomers, and then polymerization, where the monomers are joined into long polymer chains.

Let's take a look at some synthetic polymers made from crude oil.

So we have HDPE, which we touched on a few slides ago.

That is a thermopolymer, meaning that it can be heated up and reshaped.

Example products include milk bottles, bottle lids, recycling or refuse wheelie bins.

And we actually melt these down at my school to make sheets of HDPE that my students work with.

We also have urea-formaldehyde.

What a name.

Urea-formaldehyde is a thermosetting polymer.

That means that you can't reheat it and reshape it, okay? If you heat it up to such a temperature, it will just burn but not reshape.

So urea-formaldehyde is used in plug sockets and light switches.

And then we also have silicone, which again is a thermosetting polymer just like urea-formaldehyde.

That is used in flexible baking trays and bathroom sealant.

So where does crude oil come from? The majority of crude oil comes from Saudi Arabia, USA, Russia, Canada, and Iran.

Now the majority of plastic production hubs tend to be China, USA, Germany, India, and South Korea.

As we identified at the start, not all polymers are synthetic and not all polymers come from crude oil.

So let's take a look at a few polymers from natural sources.

We have PLA, which is a manufactured polymer, often made from corn starch or sugars.

It's biodegradable and has a low melting point.

And if you have a 3D printer at your school, it stands a good chance that your 3D printer probably uses PLA purely for the fact of its low melting point.

We also have shellac, which is the naturally occurring polymer secreted by the lac bug, which is usually found in Thailand.

It does not easily degrade even though it is from a natural source.

And it's often used in nail varnishes and timber varnishes.

Little did you know, on your nails, might be something from a bug.

And then we have amber.

Amber is a naturally occurring polymer formed from sticky tree resin that hardens and becomes fossilised over millions of years.

It polishes well and is lightweight.

And you're probably likely to have seen amber used in some pieces of jewellery.

Let's take a look at the sustainability and environmental impacts of polymers.

So the refining process for crude oil results in carbon emissions and air and water pollution.

There is also the potential for oil spills and fires that can be very hazardous to local habitats and wildlife.

Transporting crude oil or polymers from far locations obviously contributes to carbon emissions.

And in single use polymers contribute to landfill and ocean pollution if they are not recycled properly.

The littering of polymers can have real harm on animals and their habitats.

And I'm sure you've seen pictures of animals and creatures who have become entangled in some of these plastic products.

And you can see that if you look very carefully on the right hand-side of this picture.

Polymers can also break down into small parts and create microplastic pollution.

And some polymers can be really difficult to separate for recycling.

So for example, some juice bottles are made out of laminates where they have a polymer on the outside and then they have more of a foil on the inside.

These are really difficult to separate the materials.

Also, polymers obviously must be sorted.

We've already said there are lots and lots of categories and we need to separate them before they can be recycled.

Time for a check-in.

Polymers using crude oil as their source include.

A, PLA.

B, HDPE.

C, silicone.

Or D, shellac.

Have a think.

Come back to me when you've got an idea.

Well then if you got B and C.

HDPE and silicone all are polymers that use crude oil as their source.

Whereas PLA, that was corn starch and sugars and shellac was the lac bug from Thailand.

On to task A, part one, I'd like you to explain the difference between a raw material and a processed material using polymers as an example.

Part two, I'd like you to, using two examples, explain how sourcing polymers can impact the environment.

And lastly, part three, I'd like you to identify a sustainable polymer not made from crude oil and state how it could be used.

Come back to me when you've got some great answers.

Part one, I ask you to explain the difference between a raw material and a processed material using polymers as an example.

So answers could include.

A raw material is a natural material in its unprocessed or original state.

Crude oil, the source, is refined using heat into different fractions, one of which is naphtha.

Naphtha is the raw material to produce monomers such as propene.

These monomers are then processed through polymerization to form polymers such as polypropylene or HDPE.

Part two, I asked you using two examples, explain how sourcing polymers can impact the environment.

Answers could include.

The refining process results in carbon emissions and air and water pollution.

There is also the potential for oil spills and fires.

PLA can be sourced from corn starch.

Using a renewable source, for example, plants, helps the environment by reducing fossil fuel use.

Part three, I asked you to identify a sustainable polymer not made from crude oil and state how it could be used.

PLA is often processed from cornstarch or sugars.

These are the raw materials.

It is biodegradable, has a low melting point, and is often used in 3D printers including the one in my classroom.

On to learning cycle two, materials stock forms. A stock form is a standard shape and size in which a material is supplied.

Standardising means that the shape and size of the material are made to specific dimensions.

Stock forms allow designers and manufacturers to know which form and material is available in.

This information is required when designing a product and planning its manufacture.

Okay, now I would like you to think about your own school.

What polymer stock forms do you have in your school that you can think of as examples? So remember, it's a standard size or shape.

Have a little think.

Perhaps talk to the person next to you.

Come back to me when you've got an idea.

Okay, hopefully you've thought of some really good examples.

Let's take a little look at some of mine from my school.

So we have rod, which is a solid cylindrical shape.

For example, it's used with dowels and handles.

We then have tubes, which is hollow cylindrical shape.

For example, piping and straws.

We use it in our desk tidies for the pens and pencils to get in.

Then we have sheet.

So for example, for vacuum forming, packaging and signage, we buy it in a set sheet.

And we do that with the vacuum former.

We buy the standard size sheet that fits our vacuum former perfectly.

We also have foam.

So foam is often used for prototyping or for insulation or packaging inserts.

We also have granules.

These are small pellets often used in moulding processes such as injection moulding.

We also have filament.

Strands of polymer that are used, for example, for 3D printing.

And then we have powder which are very, very fine particles.

They're used in coating or forming.

So for example, powder coating or rotational moulding.

Perhaps you might have powder coating facilities at your school.

And then we have film, so for example, for packaging or decoration.

And this is an example of some low tack that we use with the vinyl cutter.

Perhaps again, you might have that in your school too.

Time for a quick check-in.

What does standardised mean? A, made in different shapes and sizes every time.

B, made the same way every time so it fits and works well.

C, made only by hand.

D, made to be thrown away after one use.

Have a little think.

Come back to me when you've got an idea.

Well done if you've got B.

Standardise means that it is made the same way every time so you know what you're getting, it fits and it works well.

There are many benefits to materials being available in a range of stock forms. So for example, handling.

It makes it easier to store and transport.

We've all got limited spaces in our schools, and therefore, if we know what size it's coming in at, we'll know whether we'll be able to store it in the space that we've got.

Cost.

Quite often bulk production of standard sizes lowers the cost of the material.

Waste.

It means we only buy what is needed.

And some simple calculations can help us to work out what we need.

And we'll try that in a few slides time.

And then, efficiency.

Consistent sizes are easier to work with and you know what you've got.

So for example, if you buy a polymer tube in a certain size and you've got to force in a drill bit to drill a hole, you might be able to drill the exact same size hole so that that tube can fit nice and snug and perfectly into that hole.

Most stock forms of polymer come in the following standard sizes.

So sheets, they come with specific lengths and widths.

So for example, 600 by 900, 1,222 by 2,440 millimetres.

You buy the right size for what you need.

just like as I said with the vacuum former buying it so it fits our vacuum former exactly.

Thicknesses, you can buy different thicknesses, for example, between one and 25 millimetres.

So for example, we make a nightlight and we want the very, very, very thin sheets at one millimetre so that the light can shine through it.

Increase that thickness, and the light won't shine through.

We then have rods, tubes and filaments, that they come with different inner or outer diameters.

So for example, diameter three millimetre up to diameter of 100 millimetre.

Granules and powder tends to be measured in weight.

So for example, 500 grammes to 25 kilogrammes.

What is one main benefit of using materials in standard stock form? A, it ensures all products made from the material will have identical properties.

B, it eliminates the need for quality control.

C, it makes material selection and processing more efficient and cost-effective.

Or D, it allows for completely custom sizing.

Have a think, pause the video, come back to me when you've got an idea.

Well done, if you've got C.

One of the main benefits of using materials in standard stock forms is it makes material selection and processing more efficient and cost-effective.

Sometimes you will need to work out how many pieces of a product can be cut from a length of polymer.

You'll sometimes need to calculate the total cost based on length or volume used.

And you'll sometimes need to estimate waste leftover after cutting.

And this is where your mathematical skills are really, really important for design and technology.

Let's take an example together.

A drainage system requires some pieces that are 600 millimetres long.

One standard piece of PVC piping is 2,400 metres long.

How many full pieces can you cut? Have a little go.

Come back to me when you've had a go.

Hopefully you thought what you need to do is divide 2,400 by 600, and that gives you four pieces.

So four pieces can be cut from that standard piece of PVC.

So if each 600 millimetre piece costs 2 pound 50, what is the cost of four pieces? Have a little think, pause the video, come back to me when you've got an idea.

Well done if you got that you needed to times 2 pound 50 by 4, which makes 10 pound.

Those numbers in the last example went beautifully into each other with no waste.

However, when calculating the amount of polymer required, there may be occasions when you need to round down.

This is because any leftover polymer called an offcut is too short and can't be used to make another full length.

So don't be tempted to round up.

Sometimes you need to round down.

Let's do an example.

My class on making desk tidies, and each student requires a pencil pot 110 millimetres long.

The technician orders a polymer tube 900 millimetres long.

How many full pencil pots can you cut from one length of polymer tubing? Pause the video, have a go, come back to me when you've got an idea.

Okay, so hopefully step one, you divided 900 by 110 to give you 8.

18.

Therefore that means you've got to round down to only eight full pencil pots.

Therefore, the remaining 20 millimetres is an offcut, which is not long enough for another pot.

Well done if you got that right.

Rounding down still applies when calculating sheet material.

So here's a table that my year 10s happy making in their class.

The table top is being laser cut from a 900 millimetre by 600 millimetre sheet of acrylic.

Now the table top dimensions are 280 millimetres by 280 millimetres.

So my question to you is how many table tops could be cut from one sheet? Pause the video, have a go yourself, and when you are ready, click on to the next slide.

Hopefully you've had a chance to have a go at this.

So let's see if your answers match mine.

Step one, tops along the length, which is 900 millimetres.

So 900 divided by 280 equals 3.

21.

That's three full tops with 60 millimetres left over.

Step two, tops along the width, which is 600 millimetres.

So 600 divided by 280 equals 2.

14.

That's two full tops with 40 millimetres left over.

Therefore, the total amount of tops is three tops along the length, two tops along the width, which makes six full tops.

Well done if you got that right.

Time for a check-in.

You're cutting 800 millimetre pieces from a 3,000 millimetre length.

How many full pieces can you cut? Is it A, 3, B, 3.

75, C, 4, or D, 2? Have a little think.

Come back to me when you've got an answer.

Well done if you got A, which was 3.

And why is that? You got to divide, then check if there's enough for another four piece.

So 3,000 divided by 800 is 3.

75.

You've nearly got enough for an extra one, but you haven't, so you're gonna have to round down to only three full pieces.

Well done if you got that right.

On to task B.

Part one, I'd like you to describe what a stock form is.

Give one example of a stock form and explain how it might be used in a product.

Part two, I'd like you to explain two reasons why polymer materials are manufactured and sold in standard sizes.

Pause the video.

Come back to me when you've got some great answers.

Part one, I asked you to describe what a stock form is.

Give one example of a stock form and explain how it might be used in a product.

Answers could include.

A stock form is a standard shape and size in which a material is commonly supplied.

An example is pellets, which are often used for polymer manufacturing processes such as injection moulding or extrusion.

Using stock forms makes it easier and faster to manufacture products as the material is ready to go and does not require any extra processes.

Part two, explain two reasons why polymer materials are manufactured and sold in standard sizes.

Answers could include.

Standard sizes allow manufacturers and designers to plan products more efficiently because the dimensions are predictable, you know what's coming.

This reduces time spent measuring or adjusting materials to non-standard lengths.

Using standard sizes helps reduce material waste because products and components can be designed to fit these dimensions, leading to more efficient use of materials and lower production costs.

Remember the vacuum former example, it comes in the standard size, ready to be used for the vacuum former, which means there is no waste at all.

Part three, a polymer sheet measures 900 millimetres by 600 millimetres.

Heart shaped decorations, with the below dimensions, are required for a project.

How many hearts can be cut from one sheet? And the heart measures 275 millimetres in length and 150 millimetres in width.

Have a good think.

Show your working out.

Come back to me when you've got some great answers.

Let's take a little look.

Step one, hearts along the length, which is 900 millimetres.

900 divided by 150 is 6.

So six full hearts with nothing left over.

Step two, hearts along the width, which is 600 millimetres.

600 divided by 275.

Notice the difference there because we're talking now about the length of the heart, which goes along the width of the acrylic.

So 600 divided by 275 equals 2.

18.

Therefore two full hearts with 50 millimetres left over.

Therefore, step three, total amount of hearts, six hearts along the length, two hearts along the width, which makes us 12 full hearts.

Well done if you got that correct.

This brings us to the end of our lesson today.

Let's summarise what we have found out.

Raw materials need to be sourced and processed into a usable form.

Crude oil is the source of many synthetic polymers.

From crude oil, the raw material naphtha is separated and then cracked to produce small monomers such as propene.

Through a process called polymerization, these monomers are joined together to form polymers such as polypropylene.

Materials are available in a range of stock forms, which influences material selection and production methods.

Rounding down is necessary for calculations because small offcuts can't be used as full pieces.

Well done with all of your hard work today and I look forward to seeing you in another lesson soon.

Take good care.

Bye bye bye.