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 how are polymers reformed into products? Now, this is an absolutely fascinating topic because you only have to look around your homes, your schools to see so many products made from polymers.

And today we're gonna explore how they become those products.

So hard hats on, let's get cracking.

Our outcome for today is we will be able to explain and compare small-scale and industrial reforming processes.

We have four keywords today: reform, which is reshaping a material into a new form without changing its basic chemical structure.

Mould, which is a hollow shape, which can be used to form materials.

Recycle, which is how we convert waste into reusable materials.

And upcycle, which means turning old or unwanted materials or products into something useful.

We have three learning cycles today, small-scale reforming processes, industrial reforming processes, and lastly, conserving resources.

We're gonna start off today with small-scale reforming processes.

Reforming processes change the shape or structure of a material without changing its chemical composition.

For polymers, reforming usually involves melting and reshaping to create new products in different forms. Small-scale reforming in workshops include injection moulding, using a hot glue to manufacture small parts.

And I've put these pictures in from my workshop because you might have tried injection moulding using a similar process at your school.

The glue from the glue gun is injected into the mould, and inside that mould are three little bolts, and basically that glue goes around the heads of those bolts to encase the heads of the bolts.

Time for a quick check-in.

Which of the following best describes the reforming process in polymers? Is it A, cutting polymer into small pieces, B, burning polymers, C, painting polymers to protect them, or D, melting and reshaping polymers to make new products? Have a think, come back to me when you've got a great idea.

Well done if you've got D, melting and reshaping polymers to make new products describes reforming processes for polymers.

Some you may be lucky enough to have a 3D printer in your schools or maybe even in your homes.

So let's take a little look at the process in a bit more detail.

3D printing is a process of making three dimensional objects by adding material layer by layer based on a digital design.

So first of all, step one, you create a CAD, which stands for computer aided design drawing.

You then download it as an STL file, and then you use slicer software to generate G-code, which is basically the print instructions for the 3D printer.

Fused filament fabrication, otherwise abbreviated to FFF, is a type of 3D printing process where layers of material are melted and deposited to build objects.

Once the file is prepared, it can be sent to print.

So onto step four, the filament is extruded through the heated nozzle.

Step five, the material is laid down a layer at a time onto the build plate.

And that repeats, so those layers are repeated until the object is complete.

So what happens when filament is extruded in 3D printing? A, it cools inside the nozzle, B, it turns into powder, C, it melts and forms layers, or D, it gets cut and glued.

Have a think, come back to me when you've got an answer.

Well done if you got C.

When filament is extruded in 3D printing, it melts and forms layers.

Polymer SLS, which stands for selective laser sintering, is a 3D printing process that uses a laser to fuse powdered polymer into solid layers.

The laser, and you can see that in green there, selectively melts the powder layer by layer to build the object up.

Unused powder supports the part during printing, so it doesn't need any other support.

So as I've said, you can see the laser in green there.

Then if you look at my next label, that little circle with the plus, it says layers of powder are being refilled.

So basically, that section on the left is where all the extra powder is.

So every time the laser sinters part of that powder, another layer is put across the top, so that the laser can then go over again and sinter the parts that it needs to.

And then finally, the object is produced.

It is used, so SLS is used for detailed parts in engineering and prototyping.

SLA, which stands for stereolithography.

What a name.

That's a difficult one to say.

Is a 3D printing process that uses ultraviolet UV light to cure liquid resin into solid layers.

Basically it's exactly the same as SLS, however, rather than using powder, it uses a resin instead.

So the UV laser traces each layer, hardening the resin bit by bit to build the object.

So the way that works, the yellow is the resin there, and then you can see the product, which is the D&T, that's slowly lowered so that it builds it up layer by layer, because you've gotta move it down to add more resin so that the laser can then meet that level of resin to harden it.

And then finally, the object is produced.

Now, SLA is used for high detail smooth parts, such as dental products and prototypes because it gives a really good smooth finish.

Now, you're probably not lucky enough to have an SLA machine in your school.

You might do, but I very much doubt it.

However, you might have come across this process in your school anyway in a much simpler version.

So in a small-scale workshop, a simple ultraviolet UV light commonly used for setting nail vanish can be used to cure liquid resin into solid layers.

So you can get a UV lamp just like the one that people use with setting their nail varnish, and then you can grab a silicon mould.

So a silicon mould enables the forming of intricate shapes.

Therefore, if you put the resin inside of that, and you might like to add say a little bit of pigment, or you might like to add some little bits of details such as little beads, little bits of timber or gold leaf, you can then put that underneath the UV lamp, set it, and you can use those to make some beautiful, beautiful jewellery.

And these are some examples from my jewellery club.

Now, we find a little bit like SLA, you do kind of need to do it in layers.

So sometimes we pour the resin in, we then pop it under the UV lamp, take it back out and do the next layer of resin.

Other times what we do is we pour it into the silicon mould, we put it under the UV lamp, we set it, and then we flip it over just to properly set the other side with the UV light too.

It's very, very similar to SLA, and hopefully some of you have had the opportunity to have a go with UV resin.

Which manufacturing process represents SLS, selective laser sintering? Is it A, B, or C? Have a think.

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

Well done if you got C.

Those tiny little dots on image C show the powder that is used in selective laser sintering to build up the product.

Onto task A.

Part one, I'd like you to explain what a reforming process is, and give two examples related to polymers.

Part two, I'd like you to describe how 3D printing can be used in polymer reforming.

Part three, I'd like you to compare two small-scale polymer reforming processes in terms of their benefits.

Good luck.

Give it a really good go and come back to me when you've got some great answers.

Part one, I asked you to explain what a reforming process is, and give two examples related to polymers.

You could have said a reforming process changes the shape or structure of polymers without altering its chemical structure.

Reforming with polymers always requires heat.

Examples can include injection moulding and 3D printing.

Part two, I asked you to describe how 3D printing can be used in polymer reforming.

You could have said 3D printing with polymer filaments involves melting and layering polymer to create precise complex polymer objects.

It reduces waste and is suitable for small-scale production.

Part three, I asked you to compare two small-scale polymer reforming processes in terms of their benefits.

You could have chosen SLS, so SLS fuses powdered polymer with a laser and is ideal for strong complex parts, without the need for support structures, 'cause if you remember that powder acts as the support.

SLA uses UV light to cure resin, producing highly detailed parts with smooth finishes, making it great for precision prototypes or products, such as smooth dentist products such as crowns.

Onto learning cycle two, industrial reforming processes.

Industrial reforming is used to create polymer products on a large scale using automated methods.

These methods ensure speed, mass production is faster than manual processes that we might do inside a school workshop.

Accuracy, machines produce consistent precise parts.

And focusing on that word consistency again, it means that identical parts can be made repeatedly.

So you could make 1000 products and they could all look exactly the same.

Which of the following is a key benefit of using automation for industrial polymer reforming? Is it A, it requires no adhesives or heat, B, it ensures speed and consistent quality, C, it creates unique one-off products, or D, it uses hand tools for precise cuts? Have a think.

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

Well done if got B.

Using automation for industrial polymer reforming ensures speed and consistent quality throughout all of the products made.

The first polymer manufacturing process we're going to look at is injection moulding, and the start of injection moulding is the key to some of our processes, so make sure you listen really carefully.

Injection moulding enables large volumes of identical polymer products, such as bottle caps.

So let's say you've got a drinks bottle, that little cap at the top, that is injection moulded.

So are toys and so are casings, just like lots of mobile phone casings.

So let's take a little look at the process in some more detail.

So first of all, step one, polymer granules are fed into the hopper.

Now if you look very, very carefully, you'll see lots of little dots.

They are the granules.

They are going into that hopper to start off the process.

Let's take a closer look.

On the left is the motor.

Now, the motor is going to drive what we call the Archimedes screw, which is the way that that polymer is going to meet the mould, and you can see the mould on the right.

The mould is a two part mould, so that it'll be able to open up later.

So let's take a little look at step two.

I've put the granules that have been fed into the hopper are heated.

Those orange arrows there are showing the heat.

So the granules are heated and they are pushed by the Archimedes screw, which is rotated by the motor, towards the mould.

Step three, once that polymer meets the mould, it's injected into the mould.

And you can see step three, that blue polymer is filling that mould.

Step four, the mould opens and the product is released.

Toy bricks are made by injection moulding.

Now, if you remember toy bricks, you might have played with them younger.

You might like me still play with them now.

Toy bricks are those little things that you can build to make houses, you can make boats, you can make pretty much anything with toy bricks.

I love them.

Anyway, they're made from injection moulding, and hopefully you are sat there asking yourself the question, why would one toy brick be made at a time with injection moulding? Well, great question to ask yourself because although my diagram shows that one product is made within the mould, this is just a diagram.

If you're making toy bricks, lots of them will be within one mould, so that lots of toy bricks can be injected all at once.

Our next process is blow moulding.

Now, blow moulding enables large volumes of identical, thin-walled, hollow polymer products such as bottles to be manufactured.

So we've already looked at injection moulding for the little bottle lid.

Now we're looking at a bottle itself.

Now I've already popped the start of the diagram on here.

Hopefully you are noticing it is very similar to the start of injection moulding.

Let's take a little look at the blow moulding process then.

Exactly the same as injection moulding, first of all, the polymer granules are fed into the hopper.

And again, you can see the little dots as the granules there.

Step two, the granules are heated and pushed by the Archimedes screw, which is being powered by the motor, towards the mould.

Again, exactly the same as injection moulding, but hopefully you've noticed that the mould is somewhat slightly different.

It's still a two part mould because it will release at the end to release the product, but it looks slightly different.

So let's zoom into that for step three.

The polymer is injected into the mould, but this time it's injected as a parison.

Look really carefully.

Can you see that massive U shape there? That is what we call a parison, and that's a different word that we didn't come across with injection moulding.

Now the reason it's injected as an parison is because step four, the air is then blown into the middle of that parison, which forces the polymer to the sides of the mould.

Therefore, step five, the mould opens, because it's a two part mould, and the product is released.

The main difference with injection moulding and with blow moulding is that the products tend to be hollow with blow moulding in comparison to injection moulding.

Moving on to extrusion now, and again, I've put the start of the process already on your screen, and hopefully you've noticed again, it's exactly the same as the start of injection moulding and the start of blow moulding.

So let's take a look at how extrusion is different.

Extrusion enables large volumes of polymer products with identical cross sections to be manufactured, such as pipes and door frames.

Now for those of you who are thinking, "Oh, that word cross section, what does that mean?" Take a pipe.

Think about if you had to slice that pipe at any point along that pipe.

The cross section, which is the part that you'd open up and be able to see would be the same wherever you cut it.

Therefore, it's the same cross section throughout the whole of the product, and that is the purpose of extrusion.

Let's take a look at it through the steps.

Step one, you're great at this now, step one, the polymer granules are fed into the hopper, just like injection moulding and blow moulding.

Step two, exactly the same apart from the last word, the granules are heated and they're pushed by that Archimedes screw, which is powered by the motor, but this time not towards a mould, this time towards a die.

So what does the term die mean for extrusion? Let's take a little look.

The die is the shape of the cross section that is going to be produced, therefore, the shape of the die can be changed depending on which product is being produced.

So the polymer is injected through that die as a long, long piece, which has exactly the same cross section throughout.

The lengths will be identical with their cross sections as they are produced, and they are normally at this point also cooled as they come through.

Rotational moulding is our last industrial reforming process today.

Now, unfortunately, it doesn't have the same start as all the other three, but this one is a great one.

Rotational moulding enables large volumes of identical, thick-walled, hollow polymer products to be manufactured, such as canoes, recycling bins, and playground equipment.

Take note of that word hollow.

Just have a little think.

Can you think of another process that produces a hollow product? Pause the video.

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

Hopefully you thought of blow moulding.

So blow moulding and rotational moulding are the main two that produce hollow products, but the difference with rotational moulding is that they tend to be thick-walled.

Let's take a look at how it works.

First of all, the polymer powder.

Notice I'm not saying granules this time, it's powder, so it's much finer.

So the polymer powder is placed into a mould.

Step two, the powder is heated and melted whilst the mould is being rotated.

And you can see I've put two green arrows for the rotation because it's been rotated in one way, but it's also been rotated in another direction too to make sure that that polymer is absolutely forced to the outsides of those moulds, and to make sure that it's forced evenly too.

Step three, the polymer is cooled, but the rotation doesn't stop.

The rotation in two different directions still continues so that it keeps that consistent wall thickness.

Lastly, the two part mould opens and the product is released.

Now, after some of these reforming processes, some little finishing touches are needed, some little finishing processes.

So if the manufacturing process requires injecting into a mould, so that's injection moulding and that's blow moulding, the product will need what we call degating.

Let's say that again, degating.

Now, degating is to remove the excess polymer left where it has entered the mould.

Take a little look, which bit do you think I am referring to? Perhaps speak to the person next to you, perhaps tell me.

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

Well done if you noticed just there where I've put the circle, that is the part that needs to be degated, because that is where it has been injected into, and it's still attached to the product, so degating will require that being taken off.

Now, if a two part mould is used, and we know lots of them are two part moulds, we've got injection moulding, we've got blow moulding, and we've got rotational moulding.

Well done if got that right.

Deflashing may be needed to trim the excess polymer that seeps out at the mould join.

And if you look very carefully at those two circles I've just brought up, they show the deflashing.

So if you think there's gonna be an absolutely tiny, tiny, tiny part where those two part mould joins where a tiny bit of polymer might seep out, and that's what we mean by deflashing.

Quick check-in.

Which industrial reforming process produces hollow products? Is it A, blow moulding, B, injection moulding, C, extrusion, D, rotational moulding? Have a think.

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

Well done if you got A and D.

Both blow moulding and rotational moulding produce hollow products.

Onto task B.

Part one, I'd like you to order and label the injection moulding steps.

Part two, I'd like you to compare extrusion and injection moulding.

And lastly, I'd like you to use diagrams to explain the process of rotational moulding.

Good luck with your answers.

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

Part one, I asked you to order and label the injection moulding steps.

So step C is first, where the polymer granules are fed into the hopper, the granules are heated and pushed by the Archimedes screw towards the mould.

The next steps are A and D where the polymer is injected into the mould.

And the last step is B, where the mould is open and the product is released.

Well done if you got that right.

Part two, I asked you to compare extrusion and injecting moulding.

Answers could include: extrusion and injection moulding are both processes used to reform molten polymers.

In extrusion, the polymer is pushed through a die, which forms a continuous shape with a constant cross-section, such as tubing or window frames.

In contrast, injection moulding involves injecting polymers into a mould, which is hollow as the shape of the final product, such as bottle caps or toys, so that polymer can take that shape.

Part three, use diagrams to explain the process of rotational moulding.

So step one, the polymer powder.

Remember it's powder, not granules for rotational moulding.

The polymer powder is placed into the mould.

Step two, the powder is heated and melted whilst the mould is being rotated in two different directions, remember.

The polymer is forced to the outside because of the heating and rotating.

Step three, the polymer is cooled while still being rotated to ensure even and consistent wall thickness.

And lastly, the mould is released and the product is produced.

Onto our final learning cycle, which is conserving resources.

For this learning cycle, we're going to focus in on synthetic polymers.

So let's remind ourselves, synthetic polymers are non-renewable resources originating from fossil fuels.

We can conserve our use of polymers by recycling, so processing used polymers into new materials without using more fossil fuels.

And secondly, by upcycling.

Upcycling is creatively reusing polymers without major processing, and we're gonna look at some lovely examples.

Both recycling and upcycling prevent waste from going to landfill or being incinerated, which is a posh word for being burnt.

Both are great ways to help conserve our resources.

Quick check in, which of the following is a benefit of recycling polymers? Is it A, it increases landfill waste, B, adds strength to a material, C, reduces the use of fossil fuels, or D, saves energy? Have a think.

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

Well done if you got C and D.

A benefit of recycling polymers is that it reduces the use of fossil fuels, and at the same time saves energy.

Waste such as polymers can have a detrimental effect on the environment, 'cause often polymers are thrown away and not recycled, or even worse, they end up being discarded.

So if the polymers are thrown in the bin, they enter the landfill sites, which take up huge amount of spaces, and landfill sites, as we know, produce lots of methane gases.

If they are discarded and don't make it into the bins, sometimes they end up in oceans, which causes them to break down into micro polymers, which I'm sure you've learnt about in science, which can end up being eaten by little animals and can end up in our water systems too.

They also, if they don't make it into the oceans, they might make it into wildlife and habitats, which can cause danger to wildlife.

If they don't make it into the bin and if they're not discarded, then quite often they end up being recycled, which is great.

Recycling polymers can enable new products to be designed and manufactured.

But what happens to them when they're recycled? Let's take a little look.

First of all, the polymers have to be recycled by the user, so that decision has to be made by the user to physically do something about not putting it in the bin and putting it into the recycling.

The polymers are then taken to the recycling plant, where they are sorted into categories.

So for example, HDPE will be putting one pile, PVC in another, PET in another too.

Just take note at the absolutely amazing illustration done by our Oak illustrators.

It's a piece of art, isn't it? Step three, once they have been sorted, the polymers are then shredded.

Step four, the shredded polymers are washed to ensure that they're not contaminated, especially if they've been in contact with some food products.

Then once they've been washed, the polymer manufacturing processes are then repeated, such as blow moulding that we talked about earlier to create products such as bottles.

And then lastly, new polymer products are manufactured and sold, meaning no more fossil fuels have been used as the raw material.

One of the questions that you might have asked yourself when we looked at those steps of recycling is why do we need to sort them? It's a great question.

It's important to sort polymers into categories, such as HDPE, PVC, PET, as each one has different properties and different melting temperatures.

So it will depend on what temperature will need to be reached for a certain polymer manufacturing process.

And the way that we can sort polymers is by how they are labelled.

So take any polymer product that you can find, be it a water bottle in front of you, be it the little screw cap on top of the water bottle and have a little look, see if you can find a little triangle imprinted into the plastic.

If you can, you're very likely to see a little number with that triangle, and that number tells us which polymer that product has been made from.

So if you've got a bottle cap from a bottle, it's very likely to have the number two, and that stands for HDPE, high density polyethylene.

So if all the HDPE can be put together, it can then be melted into another piece of material or another product.

Take a little look at this picture down here in the bottom left.

These are my two kids, these are them two very happily playing in a local park, and that local park has got a piece of playground equipment.

Not too sure what you call, it's not a roundabout, it's one of those like spinning top things.

And that has got the outside of it, and you can see I've put inside that circle so you can zoom your eyes into there, that is made from recycled polymers, which I think is likely to be HDPE.

It was very, very beautiful and a lovely way to use recycled polymers.

Now, you may or you may not have used recycled polymers within your school.

So my school, we collect all the number two HDPE bottle lids, and the majority of them are HDPE but some aren't, so you do have to be careful.

We collect those, we melt them down using a heat press into new sheets of HDPE, and then one of my year groups create lighting solutions from those sheets.

You can see one of my student examples there on the right, they've made a beautiful light shade using HDP bottle tops melted into that new recycled polymer sheets.

What a great idea.

Upcycling is one of our keywords today.

Upcycling is when you turn something old or unwanted, be that the materials or the product, into something useful.

Let's take a look at a really exciting example.

So in Taiwan, there are many, many oyster farms. You might have seen an oyster before.

If you haven't, here's a little picture of one to show you what it is.

The main waste from the oyster farms are polystyrene blocks, which are often found on beaches and ports around Taiwan, and there's absolutely loads of it.

So what do they do with it? Have a think.

Pause the video.

Come back to me when you've got an idea, and we'll move on to the next slide.

Hopefully you came up with some great ideas for what they could have done.

Let's take a little look at what they actually did.

So Bart van Bueren is a water architect, and together with Mizuiro, a local art gallery, a Dutch artist and Willem Van Doorn, they came together to consider how to use and upcycle the polystyrene waste, and their ideas led to the development of the floating gardens, which you can see in this picture here.

Let's take a look at how the floating gardens were made.

So the polymer waste was packed in a synthetic cloth and a strong structure was created using discarded fishing nets gathered in various harbours.

So not only was the polystyrene upcycled, but so was the discarded fishing nets.

Two for the price of one, hey? The structure was planted to create beautiful floating gardens that could bring beauty to the local community, improving air quality, whilst upcycling the discarded polystyrene and the fishing nets.

What a fabulous idea.

Now, for those of you who may not know, Taiwan is a hugely populated area and densely built up, therefore there's not loads and loads of space to build all sorts of unusual gardens.

So making use of the water with the floating gardens is such a brilliant way to improve the air quality and bring beauty.

And I bet as soon as those plants started developing and growing, they looked absolutely wonderful.

What a fabulous idea.

True or false, upcycling and recycling polymers are the same? What do you think? Have think, come back to me when you've got an idea.

Well done if you got false.

And why is that? Recycling melts down waste polymers into raw materials to make new products, whereas upcycling creatively reuses the materials to make new products but without having to melt them down completely.

Onto task C.

Part one, I'd like you to describe two environmental benefits of recycling synthetic polymers.

Part two, I'd like you to explain the difference between recycling and upcycling polymers, using an example of each.

And lastly, part three, I'd like you to draw a diagram that explains the process of recycling polymers to create new products.

Good luck.

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

Part one, I asked you to describe two environmental benefits of recycling polymers.

You could have said: Recycling synthetic polymers reduces the amount of fossil fuels required to process polymers and cuts down the amount of waste sent to landfill.

It also means fewer polymers end up in the environment, as this can be dangerous to wildlife.

Part two, I asked you to explain the difference between recycling and upcycling polymers using an example of each.

You could have: Recycling involves melting down polymers to produce new materials, such as bottle tops into sheets of HDPE.

Upcycling reuses polymers in their current form, such as the floating gardens in Taiwan made from discarded polymers from oyster production.

Part three, I asked you to draw a diagram that explains the process of recycling polymers to create products.

So firstly, the polymers are sorted into categories, for example, HDPE, PVC, or PET.

Remember, this is important because they all have different melting temperatures.

The polymers are then shredded.

The shredded polymers are then washed.

And finally, the polymer goes through polymer manufacturing processes to create new products made out of recycled materials.

This brings us to the end of our lesson today.

Let's summarise what we have found out.

Reforming involves reshaping a material into a new form without changing its basic chemical structure.

Small-scale production methods can be used to reform materials.

Reforming materials on a larger scale require different techniques.

And lastly, recycling and upcycling save resources, reduce waste, and give new life to old materials, which has to be a good thing.

Well done with all of your hard work today, and hopefully I'll see you in another lesson soon.

Take good care.

Bye, bye, bye.