Lesson video

Hello, my name is Mrs. Collins and I'll be taking you through the learning today.

This lesson forms part of the unit industrial chemistry and is called comparing materials and their properties.

During this lesson, you will compare the properties of glass, clay ceramics, polymers and composites, and explain how the properties of materials are related to their uses.

Here are the key words for today's lesson, material, composite, matrix, reinforcement and quantitative data.

Pause the video at this stage, read through those explanations and write down anything you feel you need to.

Today's lesson will be divided into two parts, materials and their properties and comparing materials.

So let's start with materials and their properties.

Natural materials are derived from living organisms or naturally occurring minerals.

Minimal processing is required.

So examples include wood, cotton, silk, leather, and natural rubber, and we see some of the objects that have been made with these materials here.

Synthetic materials though are human made, and these are typically derived from petrol chemicals or other chemical processes, and they include things like plastics, composites and synthetic rubber, and we can see their use here.

Understanding the properties and applications of natural and synthetic materials is crucial for construction, manufacturing and textiles.

Glass ceramics and building materials such as concrete and bricks are human made from natural materials.

Their natural raw materials undergo manufacturing processes and or some chemical reactions to reach their final forms. So one example is concrete.

This is made by mixing cement with sand, gravel, and water.

And another example is bricks.

These are typically made from clay or shale.

They're shaped and fired in a kiln at high temperatures.

Here's a question based on that learning.

Which of the following are examples of natural materials? So pause the video here, answer the question, and I'll see you when you're finished.

Welcome back.

So the answer is wood, cotton and silk.

So well done if you got that correct.

Industrially built materials.

So if we build these materials on a very large scale, we try to make materials at a low cost, but as part of that, it might encourage developers to consider the materials, performance, sustainability, and aesthetics, and as a result, they may sometimes discover new materials.

So that whole process of doing something on a large scale, thinking about the performance, the sustainability, the aesthetics, might mean we've got new materials that are being discovered.

So here's a question based on that learning, this time, true or false.

So pause the video here and answer the question and I'll see you when you're finished.

Welcome back.

So let's go through that question then.

So new materials are rarely discovered in the development of production processes for industrial materials is false, and that is because new materials are continuously being discovered as part of the development of production processes.

So well done if you got that correct.

Most of the glass we use is called soda lime glass, and it's produced by heating a mixture of sand, sodium carbonate and limestone, but it's not useful for all things that we want to use glass for.

So there's another type of glass called borosilicate glass, and this is made from sand and boron trioxide, and this melts at higher temperatures and is used for more heat resistant applications such as lab glassware and cookware.

So if you've got any cookware made of glass, it's likely to be made of borosilicate glass, and this is what's used to make things like beakers and conical flasks, et cetera, that you use in the lab.

Glass has got several notable physical properties.

So firstly, one of its physical properties is that it's transparent, and this is why it's so useful to be used as windows and screens.

It's also hard and resistant to scratches, which is useful, but it's also brittle, and this means it can break easily under stress.

Clay ceramics are made by shaping wet clay and heating it in a furnace.

Examples include pottery and bricks, and this production process has been around for thousands and thousands of years, and it's a proven method for producing durable, heat resistant materials used regularly in construction, art, and even for food.

So your plates, et cetera, will be a ceramic too.

Clay ceramics exhibit properties like hardness, making them strong and durable for construction.

For example, bricks.

They're excellent at withstanding high temperatures, making them suitable for bricks and tiles.

Clay ceramics can be brittle, however, which means they can crack or shatter under heavy impact.

And also their porosity can vary.

So porosity is how porous they are.

So it means how easily they let things pass through, like water.

So this can affect water absorption and therefore durability.

If we glaze the pottery, this reduces their porosity.

And the glaze is essentially like a form of glass, providing a smooth, impermeable surface.

So you can see there some pots and they've been glazed and that's quite important because they're gonna be for putting flowers in, so we're going to water those flowers and plants, and that means we don't want all of the water soaking out of the surface of the pot.

Here's a question based on that learning, which of the following statements correctly describe both glass and clay ceramics? So pause the video here, answer the question and then I'll see you when you're finished.

Welcome back.

So the answer is they are hard and brittle.

They are used in construction and they require heating during their production processes.

So well done if you got that correct.

Polymers are made from repeating units called monomers, through a process known as polymerization, which we've discussed before.

So monomers are small molecules that can join together to form polymers and polymers are large molecules made up of repeating monomer units.

So we've got an example here of a monomer, and here we've got a section of a polymer where all of those monomers have been chemically bonded together.

So a polymer is a chain of monomers chemically bonded together.

Examples of polymers include polythene and polypropylene.

There are two major forms of polythene used in various applications.

The first one being low density polythene is produced under high pressure and temperature resulting in a flexible material, and the polymer is used to make plastic bags, foams and films. The second is called high density polythene and it's produced under low pressure with a catalyst and it results in a strong rigid material that's heat resistant.

The polymer is used to make bottles, pipes and plastic containers.

Things like your milk bottle containers will be made of this.

So here's a question based on that learning.

Monomers are made from repeating units called polymers.

Is that true or false? So pause the video here, answer the question and I'll see you when you're finished.

Welcome back.

So the answer to that question is false, and that's because monomers are generally small molecules that are then joined together to form the polymers.

Well done if you got that correct.

The properties of polymers can vary widely.

There are things called thermosoftening polymers, and these melt when they're heated.

They can be reshaped, but they have linear molecular chains.

So here we've got the polymer chains, they're linear and running parallel to each other.

And applications for this type of polymer are things like plastic containers and packaging materials.

We can add cross-links to these chains though and these form thermosetting polymers.

These do not melt when heated.

They're suitable for heat resistant applications and they have strong cross-linked molecular chains preventing remoulding after hardening.

So applications for these include things like electrical plug sockets and heat resistant handles.

So here's a question based on that learning.

Which statements correctly describe thermosoftening and thermosetting polymers? So pause the video here, answer the question, and I'll see you when you're finished.

Welcome back.

So the answer to that question is thermosoftening polymers can be reshaped when heated and thermosoftening polymers have linear molecular chains, and thermosetting polymers have cross-linked chains.

So well done if you got that correct.

Here's the second follow-up question.

Which characteristics apply to both thermosetting polymers and high density polythene? So pause the video here, answer the question, and I'll see you when you're finished.

Welcome back.

So the answers to that question is strong and rigid and suitable for heat resistant applications.

So well done if you got that correct.

Composites are made by combining a matrix, or a binder, with reinforcement materials like fibres or fragments.

This structure allows composites to combine the properties of different materials and that gives it an enhanced performance.

So a good example here of a composite material, the grey layer shows the matrix holding everything together, the blue and yellow layers represent reinforcement materials, providing strength and other desirable properties.

Concrete is one of the most used composite materials.

So there are two common types of concrete used.

There's concrete, which is the cement with the matrix and the aggregate, which is things like bits of gravel and small stones, and that provides the reinforcement.

And the second is reinforced concrete.

So this is where you have the cement, which forms the matrix with aggregate and steel rods to provide the reinforcement.

So we've added steel to it.

Regular concrete is used to make bricks, but using steel rods allows for the production of multi-story car parks, bridges, and high rise buildings that can withstand larger loads than a regular concrete can.

The properties of composites can vary widely depending on the materials that are actually used, and we've got some other examples alongside those concrete examples.

We've got carbon fibre, reinforced plastic and fibreglass as well.

And what's important is it increases the versatility so we can combine together different substances and make use of their physical properties that we want.

And we can be quite creative with this to produce a material that suits a particular purpose.

Carbon fibre composites have a high strength to weight ratio.

So that means they're very strong, but they're also very light and they're often used in aerospace and sports equipment.

So the reinforcement material in this case is the carbon fibres and the matrix is the plastic.

So examples are things like aircraft wings and fuselage components, so that's parts of the aircraft.

And then we've got sports equipment like tennis rackets and bicycles, for example, made of carbon fibre.

So they're very light, very strong, very versatile.

Fibreglass, that other example, is very durable and resistant to corrosion, and this makes it suitable for things like boats and roofing.

So we can see a boat there with a fibreglass hull.

The reinforcement material in this case are glass fibres, and the matrix, again, is the plastic, and the examples are boat hulls like in the image, but also things like roofing panels as well.

So here's a question based on that learning, true or false this time, composites are mixtures of materials made up of a single element.

Is this true or false? And then justify your answer using the statements below.

So pause the video here, answer the question, and I'll see you when you're finished.

Welcome back.

So the answer to that question is false, and that's because composites are mixtures of materials that consist of a matrix and a reinforcement.

So well done if you got that correct.

We're now going to do task A.

Some students are discussing materials and their properties, identify who is correct, and update any incorrect statements.

So pause the video here and answer the question, and I'll see you when you're finished.

Welcome back.

So Andeep and Lucas are both correct, but Sofia was incorrect.

So clay ceramics are strong and durable for construction, however, they are brittle and can crack and shatter under heavy impact, and Laura was also incorrect.

Industrially built materials aimed to be low cost, however, demand can encourage developers to consider performance, sustainability or aesthetics.

So well done if you got that correct.

We're now moving onto part two of the lesson, comparing materials.

So data can be classified into qualitative and quantitative types.

Each is used for depending on the context.

So qualitative data describes the properties.

It's non-numerical, which means it's not a number, and it can include things like texture and colour.

Quantitative data measures properties.

It's numerical.

So that means it consists of numbers.

And examples include things like time and distance.

Quantitative data is essential for precise comparisons and decision making in material selection.

So here's a question based on that learning.

Qualitative data measures properties numerically.

Is that true or false? So pause the video here, answer the question, and I'll see you when you're finished.

Welcome back.

So that answer is false, and that's because quantitative data measures properties numerically, not qualitative.

So well done if you got that correct.

Here's a follow-up question.

Which of the following describe qualitative data? So again, pause the video here and I'll see you when you're ready.

Welcome back.

So answer to that question are colour of material and texture of a surface.

Remember, qualitative data is non-numerical, and there are two examples of non-numerical data.

So well done if you got that correct.

We can compare the physical properties of clay and glass ceramics to reveal their unique characteristics.

So we've got a table here of the different properties of glass and clay ceramics, and we can see the major difference is in tensile strength and fracture toughness.

So glass has a higher tensile strength, but it's more brittle compared to ceramics, and that's indicated by its lower fractional toughness.

So here's a question based on that learning.

Why is glass preferred for laboratory glassware over clay ceramics? So pause the video here, answer the question and I'll see you when you're ready.

Welcome back.

So we need to consider the use that we're putting the glassware to.

So if we're using it in the laboratory, think about what we do with the glassware in the laboratory and therefore, which of these properties is important? And it's that tensile strength and the high melting points.

So well done if you got that correct.

So low density polythene and high density polythene are produced from ethenes.

They're polythene, many ethenes.

So ethene is the monomer, and you have many of these ethenes joined together to form polythene.

Now, compared to high density polythene, low density polythene is more flexible, has a lower tensile strength and is weaker.

So here's a true or false question based on that.

So high density polythene is preferred over low density polythene to make plastic bags.

Is that true or false? So pause the video here, answer the question and I'll see you when you're ready.

Welcome back.

So the answer to that question is false, and that's because low density polythene is more flexible than high density polythene.

Remember, high density polythene is used for things like your plastic milk bottles.

Thermosoftening polymers melt when heated due to their linear chain structure.

This allows them to be reshaped.

So here we've got the properties of the two different types of plastic here, thermosetting and thermosoftening.

We can see the melting point there and we can see the structure.

So remember those cross-linked chains in the thermo setting, and that makes it tougher.

So thermosoftening polymers are able to melt and reshape when they're heated.

So here we're going to be working on a project that involves frequent reheating and remoulding of the material, which polymer is more appropriate for this task, and why is that the case? So I want you to pause the video here, answer the question, and I'll see you when you're ready.

Welcome back.

So the answer is thermosoftening, and that's because thermosoftening polymers can be reheated, melted and reshaped multiple times due to their linear chain structure, so they don't have those cross links, remember.

Metals and composites can be compared based on their physical properties as well.

So we've got the metal aluminium and we've got a composite carbon fibre and we're looking at the density, tensile strength and their corrosion resistance.

So we can see there that although aluminium has got a low density, carbon fibre is actually less dense than aluminium.

Carbon fibre has got a higher tensile strength and it's got higher corrosion resistance as well.

So carbon fibre composites provide high strength with low weight, making them ideal for high performance applications.

Things like high-performance cars, for example, and things like sports equipment.

Here is a question based on that learning.

You're designing a lightweight frame for a high performance racing bicycle.

Which material would be better suited for this purpose? Is it aluminium or carbon fibre composite, and why? So pause the video here, answer the question and I'll see you when you're ready.

Welcome back.

So the answer would be carbon fibre composite.

And that's because carbon fibre composite provides high strength with low density, making it ideal for high performance applications like a racing bicycle frame.

So well done if you got that correct.

We're now going to do task B.

When selecting materials for a bridge, engineers compare materials based on their strength, durability, cost, and environmental impact.

Carefully examine the table below, then evaluate and select the best material for constructing a bridge.

So when we evaluate, we need to give the advantages and disadvantages and draw a conclusion.

So you need to decide which one is best and you need to justify that answer.

So pause the video here, answer the question, and I'll see you when you're ready.

Welcome back.

So here's a potential answer to that question.

The composite has the highest tensile and compressive strengths, outperforming steel and concrete.

Steel exhibits the highest fracture toughness, indicating excellent resistance to cracking.

The composite is better than concrete.

Concrete is the least expensive, making it budget friendly, followed by steel with a moderate cost.

The composite is the most expensive.

There isn't much difference in terms of environmental impact, but concrete is worse than the composite or the steel alone.

The composite is the best choice for constructing a bridge due to its exceptional strength and good durability, despite the higher cost.

So well done if you got something similar.

Here's a summary of today's lesson.

Production processes for industrial materials are under continuous development with new materials discovered.

Composites are mixtures of materials made up of a matrix and a reinforcement.

Qualitative data describes properties, while quantitative data measures properties numerically.

Several factors direct a choice of materials, performance, production processes, cost, aesthetics, and others.

So thank you very much for joining me for today's lesson.