Lesson video

Hello, I am Mrs. Adcock, and welcome to today's lesson.

Today's lesson is on polymer properties and problems. So, we are going to be looking at some different polymers, having a look at their properties, and seeing how these different polymers, based on their properties, have different uses.

We are then going to look at some of the problems associated with polymers and have a think about if there are ways we can overcome these problems. Today's lesson outcome is, "I can relate the uses of certain polymers to their properties and describe methods of reducing the problems associated with polymers." Some of the keywords we will be using in today's lesson include properties, landfill, combustion, recycling, and raw materials.

You can see those keywords written here in a sentence.

It would be a good idea to pause the video now and read over those sentences.

You might like to even make some notes that you can refer back to later in the lesson.

Today's lesson on polymer properties and problems is split into three parts.

The first part is on properties of polymers, then we are going to look at how we can dispose of polymers, and finally moving on to recycling polymers.

Let's get started looking at properties of polymers.

Different polymers have different properties, and properties are features or characteristics of a substance that can be used to classify it or describe how it behaves.

For example, some polymers are hard and brittle, whereas others are tough and flexible.

The different properties mean that polymers have different uses, and we can see here two different polymers that are used in very different ways.

We've got polyethene, which is used in plastic bags, and polytetrafluoroethene, which is used in pans.

Polyvinyl chloride, which we often shorten to PVC, is a polymer that is tough, and it can be made hard or flexible and is a good electrical insulator.

PVC can be used in many different places, but some of the places it's used include window frames, door frames, gutters, and to insulate electrical wires.

So, we can see some PVC, so a polymer there, used in a window frame, PVC guttering, and also PVC used to insulate electrical wires.

So, PVC is good for all of these uses because of its properties.

Time for a check for understanding.

Which property of PVC makes it useful as a coating of electrical wires? Is it good as a coating for electrical wires because it is, A, hard, B, brittle, or C, an electrical insulator? Well done if you chose option C.

PVC has the property of being an electrical insulator, and this makes it useful as a coating of electrical wires.

Polytetrafluoroethene is often known as PTFE, so we shorten it, or Teflon.

And PTFE is slippery, and it has a high melting point and is chemically unreactive.

And it's because of these properties that it is useful as a non-stick coating on cooking pans.

We can see an image there of a pan containing a PTFE coating.

Polypropene, also called polypropylene, can be used in crates, carpets, ropes, and buckets.

So, they're some of the places where we use polypropene, and you can see an image there of it used in a carpet and in rope, and polypropene is suitable for these uses because it is flexible and strong.

Another polymer, called polyethene, we can get different forms, so we can get low-density polyethene, which we shorten to LDPE, and high-density polyethylene, that we shorten to HDPE.

And these are both made from ethene, so the monomer is ethene, but they are made under different conditions, and because of these different conditions, these two polymers have different properties.

It says there, "These addition polymers have different properties," and they are addition polymers because they were made from monomers that contain that carbon-carbon double bond, and when they were made, there was no other product other than the addition polymer.

We've got LDPE, shown there in a polytunnel, and LDPE is soft, flexible, and can be made into films, whereas HDPE is hard and strong, and we can see it used there in shampoo bottles.

Time for another check for understanding.

Which property of polypropene makes it a useful polymer in carpets.

Is it A, slippery, B, hard, C, flexible? So, try to think which of those options would be a useful property for carpets to have.

Well done if you chose option C.

Polypropene is flexible, and this makes it a useful polymer to use in carpets.

Time for our first practise task of today's lesson.

What you need to do is use the information in the table to decide which addition polymer would be most suitable for a drinking cup.

Once you have made your choice, then you need to explain your reasoning.

So, pause the video now, look through that table, which shows you the three polymers, and it's got some different properties of those polymers, and then you've got to decide which is most suitable for a drinking cup, explaining your reasoning.

Have a go at that question, and then come back when you're ready to go over the answer.

Hopefully you've had a good go at that question.

Let's go through a possible answer.

So, your answer may include, polymer B is most suitable for a drinking cup because it has a high melting point, so can withstand high temperatures for washing, it is strong, so it will not break easily, and it is inert, so will not react with the contents of the cup.

Inert means it's unreactive.

Hopefully your answer was similar to this.

You might like to pause the video and add any extra details that you missed from your answer.

We've looked at some of the properties of polymers and how these different properties mean that polymers have different uses.

We're now going to have a look at the disposal of polymers, so what happens to the polymers once we finish using them.

Billions of tonnes of polymer waste, and here we're talking about plastic waste as opposed to talking about biological polymers, so billions of tonnes of polymer waste has been created globally over the years, and it's thought about 80% has ended up in landfill.

Landfill is a waste disposal site.

So, when you put your rubbish out and it gets collected, it will likely be taken to a landfill site.

We've got an image there of a landfill site.

Plastic polymers that are taken here to these landfill sites are not biodegradable, and this means they are not decomposed by microorganisms. As addition polymers are non-biodegradable, so that means they do not biodegrade, the polymers disposed of in landfill will remain, and they remain there for hundreds of years.

We've got some examples here of objects that you might have used.

So, plastic straws, when they go to landfill, they can take up to 200 years to break down.

Plastic water bottles take about 450 years to break down, and toothbrushes can take more than 400 years to break down.

Let's check that we've understood.

What does biodegradable mean? Does it mean, A, it's decomposed by microorganisms, B, it's broken down by light, or C, it's not broken down? Well done if you chose option A.

Biodegradable means it is decomposed by microorganisms. Our plastic polymer waste is not biodegradable.

Rather than sending our polymers to landfill sites, polymers can be disposed of by incinerating them, which involves combustion at very high temperatures.

So, when we combust an item, then it reacts with oxygen, and it will release energy.

Here we've got an image of an incineration plant, where we can take our waste plastic for it to be incinerated.

Combustion of polymers prevents them ending up in landfills, so that's a positive of incinerating our polymers.

The process also releases energy, and this can be used to generate electricity.

There are problems with the combustion of polymers, though, and these include carbon dioxide, which is a greenhouse gas, is produced when we combust polymers, and we can see a model there of carbon dioxide.

So, carbon dioxide has the molecular formula CO2.

Another problem with the combustion of polymers is that toxic gases can be produced.

We've got the hazard symbol there for toxic.

HCl is an example of a toxic gas produced if we combust a polymer that contains chlorine atoms. So, we've seen there are positives of incinerating our plastic polymer waste, but there are also negatives associated with this incineration, too.

Time for a quick question.

Which of the following is a product of combustion of polymers? So, when we combust polymers, do we make, A, hydrogen, B, oxygen, C, carbon dioxide? Well done if you chose C.

Carbon dioxide is a product of combustion of polymers.

Many addition polymer products can either be reused or recycled, so rather than send them to landfill and rather than incinerate them, why don't we try and reuse some of these polymer products in other ways? We could also, if we can't reuse them, recycle them, and we can see here some recycled plastic, and you might have seen a plastic recycling bin near you.

Recycling polymers prevents them ending up in landfill or being incinerated.

How can we dispose of polymers? So, think about all the ways that we've covered so far.

Can we dispose of polymers by, A, sending them to landfill, B, incineration, C, recycling, D, composting? We can dispose of polymers by sending them to landfill, incineration, and recycling.

Time for our second practise task.

Question one, what are the advantages and disadvantages of disposing of polymers by placing them in landfill? And when you've had a go at that question, question two is looking at the advantages and disadvantages of disposing of polymers by incinerating them.

Try to think of as many advantages and disadvantages as you can for both of those methods of disposing of polymers.

Pause the video now, have a go at answering these two questions, and then come back when you're ready to go over the answers.

First of all, we are looking at the advantages and disadvantages of disposing of polymers by placing them in landfill.

Your answer may include, the advantages of landfill are that it is really easy, so it's so easy to just throw waste polymers into the bin.

Some of the disadvantages of landfill include, it uses valuable land, and that land could be used for other purposes; using the land for landfill may destroy habitats; addition polymers, we've seen, are not biodegradable; and landfill sites release greenhouse gases.

Those are not all points that we've covered in today's lesson, so well done if you were able to bring in some of your extra knowledge and include some of those in your answer.

Question two was looking at the advantages and disadvantages of disposing of polymers by incinerating them, and your answer may include, advantages of incinerating polymers include: reduces the waste sent to landfill, and it releases energy that can be used to generate electricity.

The disadvantages of incinerating polymers are that it produces carbon dioxide, and carbon dioxide is a greenhouse gas that contributes to global warming, and also, they may produce toxic gases, such as HCl, which may be produced if the polymer contained chlorine atoms. Well done if your answer included some of those points.

You may have been able to think of some additional advantages and disadvantages.

It's time for us to move on to the final part of our lesson on recycling polymers.

So, we're going to just focus on recycling in a bit more detail and think about some of the advantages and disadvantages of recycling polymers.

Crude oil can be processed to produce alkenes.

Addition polymers are made from alkenes, and we've got an example of an alkene there.

So, alkenes are a homologous series of compounds that contain the carbon-carbon double bond, so you can see an example of an alkene there.

It's got two carbon atoms as its longest chain, so that is known as ethene, and these alkenes came from the processing of crude oil.

One of the problems associated with addition polymers is that the amount of raw material, crude oil, is finite.

By raw material, we mean the starting material that's used to make a product.

So, the starting material of addition polymers is crude oil, and from crude oil, we can get alkenes, and these alkenes are the monomers that we use to make these polymers.

Time for a check for understanding.

What is the raw material used to make addition polymers? Is it A, alcohol, B, crude oil, or C, carboxylic acid? The correct answer is B, crude oil.

So, crude oil is the raw material, it's that starting material, that is used to make our addition polymers.

Well done if you got that question correct.

You must've been listening well.

Crude oil is a non-renewable resource, and this means we are using crude oil at a faster rate than it can be produced.

We can see an image there showing crude oil.

Recycling polymers conserves the crude oil by making new products from recycled polymers.

So, rather than constantly having to process more crude oil to get those alkenes to make the polymers, we can recycle the polymers, and this will conserve the crude oil.

Recycling also reduces polymers in landfill and from being incinerated.

So, there's another couple of positives of recycling, and a further advantage of recycling polymers is that they can be used to make new products.

So, they conserve crude oil, they prevent waste on landfill, they prevent the amount of polymers being incinerated, and also, we can make new products.

Here we can see watering cans, some clothes, and outdoor furniture are examples of products which can be made from recycled plastic.

What happens when we recycle polymers? The recycled polymers are, first of all, cleaned, then they're sorted into the different polymer types.

Then they are ground into pellets, and we can see an image there showing the polymer pellets.

Then they are melted, and then they can be reformed into new products.

So, are there any disadvantages of recycling polymers? There are disadvantages of recycling polymers.

We're gonna have a look at these now.

Hopefully you were able to think of some of these answers.

Some of the disadvantages of recycling polymers include: polymers can be difficult to sort into the different polymer types; codes and symbols are placed on polymer items to make sorting easier.

So, you may have seen some of these symbols on items before, and these are polymer identification symbols.

If we look closely at those symbols, we can see that they each have a number in the middle, and then they have the name of the polymer underneath.

And these symbols are a little bit misleading because they look similar to the recycling symbol, but not all polymers can be recycled.

Polymers that can be recycled often have the code 1 or 2.

Although recycling polymers is more economically viable than producing new polymers from crude oil, there are costs involved in recycling.

These include labour costs to help sort the polymers, and also the energy costs to process the recycled polymers into a new product, and we can see an image there of a worker sorting the recycled plastic.

Let's see if you can answer this question.

Why do some items contain symbols and codes, like this one that you can see on the right-hand side? Is it A, to show how many times it has been recycled previously? Is it B, to help sort the polymers? Or is it C, to show how many monomers were used to produce the polymer? The correct answer is B.

So, we have symbols and codes on our polymer items, and this is to help sort the polymers when they have been recycled.

For the final practise task of today's lesson, you need to evaluate the advantages and disadvantages of recycling polymers.

So, make sure you mention the advantages, make sure you mention disadvantages, and then, because the question says to evaluate, you also need to add a conclusion.

Pause the video now, have a go at answering this question, and then come back when you're ready to go over the answer.

First of all, we are gonna have a look at some of the advantages of recycling polymers.

Your answer may include: it prevents waste being sent to landfill; it prevents the release of carbon dioxide and possible toxic gases when incinerating polymers; it conserves the crude oil; and it produces a new product.

Disadvantages of recycling polymers include: there are labour costs associated with the difficult task of sorting polymers; there are high energy costs for processing the recycled polymer into a new product; and also, not all polymers can be recycled.

So, well done if you were able to think of many of those advantages and disadvantages of recycling polymers.

As a conclusion, we have, "Overall, I think we should recycle as although not all polymers can be recycled, the ones that can be recycled help conserve crude oil and reduce the production of greenhouse gases from landfill sites and through the combustion of polymers.

Hopefully you've written your own conclusion at the end and you've incorporated some of the advantages or disadvantages to help you decide whether we should recycle polymers.

We have reached the end of today's lesson on polymer properties and problems. Well done for all your hard work throughout the lesson.

Let's just summarise some of the key points that we covered in today's lesson.

We, first of all, looked at the uses of polymers and how these are related to their properties.

We looked at how there are many problems associated with polymers, for example, the availability of raw materials, the use of landfill sites, and also the combustion of polymers.

There are many advantages and disadvantages to recycling polymers, and these include both economical and environmental issues.

Thank you for joining me in today's lesson.

I hope that you're able to join me for another lesson soon.