Materials Science

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Define ‘Materials Science’.

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Section 1 - Types of

Materials

(1) Indicate the correct material class for each material listed:

____ tile ____ Popsicle stick ____ plastic bag ____ paper clip

A. metalB. ceramic C. composite D. polymer

Applied Physical Science Unit 2

Name:

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(2) Describe some physical properties of each of the materials.

Physical properties

Tile

Popsicle stick

Plastic bag

Paper cup

(3) What are the differences between metals and ceramics when subjected to force?

(4) What similarities do polymers and metals have when subjected to a force?

(5) Why would a metal be preferred as a bridge building material as opposed to a ceramic material?

Section 2 - Structure of Materials

Define and give an example of each of the following:

Atom –

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Element –

Compound –

Molecule –

Mixture –

Draw diagrams to show the difference between heterogeneous and homogeneous mixtures:

Heterogeneous mixture Homogeneous mixture

Define and give an example of the following:

Ionic bond –

Covalent bond –

Four classes of materials – complete the following table

Material Metal Ceramic Polymer CompositeStructure

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Examples

Some uses

Section 3 - Properties of Materials

General Comparison of MaterialsProperty Ceramic Metal Polymer

Hardness

Elastic modulus

Thermal expansion

Ductility

Corrosion resistance

Wear resistance

Electrical conductivity Depends on material

Density

Thermal conductivity Depends on material

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Magnetic Depends on material

Choosing MaterialsCircle the right properties for the task

Hockey stick flexible/stiff/strong/weak/brittle/hardBathroom Window pane transparent/opaque/translucentBone flexible/stiff/strong/weak/brittle/hardBrick flexible/stiff/strong/weak/brittle/hardCycle helmet flexible/stiff/strong/weak/brittle/hardElectrical cable flexible/stiff/strong/weak/brittle/hardPlastic carrier bag flexible/stiff/strong/weak/brittle/hard

Other factors that must be considered when choosing a materialWrite in the table why they must be considered, using examples where possible.

Factors Why?Cost

Is it durable?

Environmental

impact

How easily can

it be shaped

Aesthetic

appeal

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Forces and materials

What does mechanical properties mean? ……………………………………………………………………………

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Draw below diagrams to show the forces on a beam, describe what is happening in each

case

Tension Compression

Draw the forces on a beam in a 3 point bend test

Elastic behaviour

Investigation: Your task is to find out if the stretching of a rubber band is affected by

soaking it in bromine water.

Apparatus:

Retort stand and clamp

Rubber bands

Dilute aqueous bromine

1N weights with hanger

Ruler

Boiling tube with bung

Fume cupboard (to leave the boiling tube with the

bromine water and rubber band in over night)

Write a lab report

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Section 4 – Examples of Materials

Metals and Alloys

1. Define ‘alloy’: …………………………………………………………………………………………………………………

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2. The alloy used in aircraft is called Duralumin. It

is made of mostly aluminium and what other

elements

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3. (a)Steel is another commonly used alloy. What is steel an alloy of?

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(b) Name two benefits of steel. ………………………………………..………………………………………………….

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4. Metals are useful because they are ductile. Define ‘ductile’…………………………………………..

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5. Metals are used in electrical wiring because they are ductile and also because of another

property. Circle the correct property

Electrical insulator/electrical conductor/heat conductor

6. A mouthful of materials Amalgam is used to fill dental cavities. Most metal fillings are made of amalgam which is an alloy of metals including mercury. Fill in the table below

Advantages of amalgam Disadvantages of amalgam

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Fill in the table below for the advantages and disadvantages of composite fillings

Advantages of composites Disadvantages of composites

A suitable polymer

Polymer

Strength in Tension (MN/m2)

Stiffness (GPa)

Density (g/cm3)

Highest working temperature (oC)

A 60 4.1 1.39 60B 80 0.7 1.12 120C 15 0.2 0.92 85D 40 3.0 1.05 65

The table above gives data about different properties of 4 different polymers. A chair manufacturer is choosing materials to make stools for a science lab. The stool needs a frame that will not break and a seat that will be comfortable. Suggest a polymer for this task and explain your answer using the data in the table.

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Section 5 – STEM Investigations

Making a viscoelastic materialIntroduction: Polymers are encountered in everyday life and are used for many purposes. Polymers are chains made up of monomer subunits. The structure and chemical composition of the polymer chain determines the physical properties of the material. Some polymers are used for their rigid strength, others for their flexibility, and still others for resistance to corrosion.

In this activity, we will use poly(vinyl alcohol) and sodium tetraborate solutions to make a slimy polymer resembling silly putty. It is a viscoelastic material, that exhibits some properties you would expect in a solid and some properties you would expect in a liquid.

Poly(vinyl alcohol), found in white glue, is a long chain of repeating ethyl alcohol monomers -(CH2-CHOH). Sodium tetraborate (Borax) is an ionic compound that acts as a linker between the long chains of the polymers (see diagram on the right).

Depending on the ratios of polymer and sodium tetraborate solutions the putty can tend to be more bouncy, gooey or stretchy.

Safety:

Sodium tetraborate solution (Borax) is a bleaching agent and can burn eyes

Goggles should be worn at all times Do not taste, eat or lick the silly putty Hands should be washed after working with the putty

Preparation: Pour 10ml water into a disposable cup and mark the level of water on the outside of the cup. Pour another 10 ml in and mark another line. Repeat two more times.

Trial 1:

1) Plaee 10 ml water in a disposable cup.2) Add 3-4 drops of food colouring (optional)3) Add white glue until it reaches the 20ml line.4) Add 10 ml of saturated sodium tetraborate solution.5) Stir immediately6) Remove the putty from the cup, leaving the excess water behind, and knead

the putty on a plate.

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7) Draw up a suitable results table showing the quantities of the materials and observations of the properties of the products. Think about what types of observations you are make and measure.

Trial 2: Modify the procedure slightly by altering the ratios of glue to borax. Record your results.

Challenge: Modify the procedure to make a polymer that bounces high or has the longest stretch. (Think about how to record the results.)

Questions:

1) In your own words, describe a polymer.

2) What adjustments were needed to make the putty bouncier/stretchier?

3) How does the addition of sodium borate change the physical properties of the poly(vinyl alcohol) solution?

4) Draw a schematic of a polymer that would be stretchy or one that would bounce well.

5) What are the physical properties you observed about saturated sodium tetraborate solution?

6) What happens when a cross-linker is added to a polymer material?

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7) Do you think the crosslinking event is a physical or chemical reaction? Explain your reasoning.

Rebuilding New Orleans Composite Materials Lab

Purpose

To design a strong, lightweight material. To construct and analyse a graph of stress vs. strain for the composite material. To compare the different composite materials and determine which is the best

building material based on its strength and density.

Materials (each group)

Marshmallows ButterPuffed rice cereal Small Chocolate Chips (optional)Spoon RulerBalance Microwave-safe containerWeights Microwave

Wooden blockProcedure

Part 1 – Design

Create a composite material with the greatest ratio of strength to density using Puffed Rice cereal, chocolate chips (optional), butter and marshmallows. The Puffed Rice are hollow and will serve to strengthen the marshmallows, which will serve as the matrix.

1. Determine the amount of marshmallows, butter, Rice cereal and chocolate chips (optional) you will add to make each of your three composites. List your “recipe” in Table 1.

Table 1. Composite RecipesMass of each Ingredient (g)

Rice Krispies Marshmallows Butter Chocolate Chips

Composite Material 1

Composite Material 2

Composite Material 3

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2. Measure and record the mass of each of the components that you are adding. Remember your goal is to create a material with the greatest strength that is also lightweight.

3. Measure out the specified amount of butter and marshmallows, based on your recipe Table 1, and put them in a bowl.

4. Place the bowl in the microwave for 30 seconds. Stir immediately.

5. Add Rice cereal (and chocolate chips). Stir until it is well-mixed.

6. Pour the mixture in a cupcake wrapper or baking paper and wait for it to cool.

7. Repeat steps 2-6 and for each composite mixture.

Part 2 – Analyse the Material

Determine the density of the composite material. Record your data in Table 2.

1. Remove the cooled sample after 10 minutes from the wrapper and shape the Rice cereal treat into a cylinder so that it is about the same size as a large marshmallow.

2. Measure each sample's mass using a balance.

3. Measure each sample's dimensions. (Record the height and diameter of the top.)

4. Calculate and record the area of the top of each sample. Area of a circle = πr2

5. Calculate and record each sample's volume (surface area of the top x height).

6. Calculate and record each sample's density (mass/volume).

Table 2. Composite RecipesMass (g) Height

(cm)Diameter

(cm)Area of the top (cm2)

Volume (cm3)

Density (g/cm3)

Composite Material 1

Composite Material 2

Composite Material 3

Part 3 – Strength Test

Determine the composite material's Young's modulus. Record your data in Tables 3a-c.

1. Use a wooden block to uniformly compress your composite. Measure the mass of the wooden block.

2. Place the wooden block on top of the composite material you made, and measure the new (compressed) height of the sample after the block has been on the material for about 15 seconds.

3. Calculate the force applied to the block. The force is equal to the weight applied.

weight=mass (g )×9.8N /kg

4. Calculate and record the distance the sample compressed. (This is the difference between the original height and the compressed height.)

distance=originalheight−compressed height

5. Calculate the strain by dividing the distance the sample compressed by the original height of the sample.

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strain= compressionoriginal height

6. Calculate the stress by dividing the force applied by the surface area of the sample.

stress= applied forcesample surfacearea

7. Add weights to the wooden block and record the distance the material compresses until you have completed five different trials.

8. Repeat for each composite sample.

Table 3a. Strength Test Results for Composite Material 1

Trial Mass Applied (g)

Force applied(N)

Original height of

sample (cm)

Compressed Height of

Sample (cm)

Distance Material

Compressed (cm)

Strain (cm/cm)

Stress (N/cm2)

1

2

3

4

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Table 3b. Strength Test Results for Composite Material 2

Trial Mass Applied (g)

Force applied(N)

Original height of

sample (cm)

Compressed Height of

Sample (cm)

Distance Material

Compressed (cm)

Strain (cm/cm)

Stress (N/cm2)

1

2

3

4

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Table 3c. Strength Test Results for Composite Material 3

Trial Mass Applied (g)

Force applied(N)

Original height of

sample (cm)

Compressed Height of

Sample (cm)

Distance Material

Compressed (cm)

Strain (cm/cm)

Stress (N/cm2)

1

2

3

4

5

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AnalysisUsing Microsoft Excel® or similar software, graph stress vs. strain for each composite material on the same set of axes. Include a line of best fit and an equation of the line for each of the three composite materials’ data.

Discussion Questions

1. Find Young's modulus for each of the materials.

Material 1 Material 2 Material 3

2. Do stiffer materials have a larger or smaller Young's modulus? Explain your answer.__________________________________________________________________________

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3. Which of your samples has the greatest ratio of strength to density? Why?__________________________________________________________________________

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4. Considering the materials' strengths and densities, which material would you prefer to use for building in New Orleans? Explain.__________________________________________________________________________

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Extension Questions

1. How could you improve on your design to make a better material for building? Explain.__________________________________________________________________________

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2. Research a material that has syntactic foam and explain how it is used and why building with hollow spheres is desirable.

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3. Describe a material or object that could be improved by making it with syntactic foam. Explain.

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