Module 6

Question 1

What property distinguishes metals from non-metals in engineering materials?

Answer 1

Ductility

Question 2

What is the defining feature of alkanes in organic chemistry?

Answer 2

All C bonds to 4 distinct atoms

Question 3

What does the presence of at least one double bond in a compound indicate about its saturation?

Answer 3

It’s unsaturated.

Question 4

What process creates thermoplastics like PolyVinyl Chloride (PVC)?

Answer 4

Chain Growth (Addition Polymerization)

Question 5

What is the key difference between thermoset and thermoplastic polymers?

Answer 5

Thermoset is irreversible, thermoplastic is reversible.

Question 6

What is the glass transition temperature (Tg) in thermoplastics?

Answer 6

Transition point where thermoplastics become brittle or ductile.

Question 7

What are mixtures of different monomers within polymer chains called?

Answer 7

Copolymers

Question 8

What material is strong enough for body armour and has a tensile strength of approximately 35 MPa?

Answer 8

UHMWPE

Question 9

What is the key difference between thermosets and thermoplastics in terms of reusability?

Answer 9

Thermosets can’t be reshaped after curing; thermoplastics can.

Question 10

What is the most effective strengthening mechanism in polymers?

Answer 10

Crosslinking

Question 11

What effect do pendant groups have on chain molecules?

Answer 11

Increases stiffness

Question 12

What makes polymer fabrics like nylon and polyester strong in all directions?

Answer 12

Strong, thin polymer fibres woven together

Question 13

What makes polar polymers hydroscopic?

Answer 13

Electronegative elements (Cl, F, O)

Question 14

What property allows polymer fabrics like nylon and polyester to be strong in all directions?

Answer 14

Weak intermolecular forces

Question 15

What is the process called that adds sulphur and heat to create crosslinks in an elastomer?

Answer 15

Vulcanization

Question 16

What is the primary component of glass?

Answer 16

Silica (SiO2)

Question 17

What is vulcanization in the context of elastomers?

Answer 17

Adding sulphur and heat to create crosslinks

Question 18

Why is pure silica difficult to cast and shape?

Answer 18

Extremely viscous when melted

Question 19

What are vitreous ceramics primarily made up of?

Answer 19

Alumina and silica

Question 20

What are the main classes of engineering ceramics?

Answer 20

Oxides, Carbides, Nitrides, Intermetallics

Question 21

What is the highest naturally occurring hardness material?

Answer 21

Diamond

Question 22

What is the purpose of the sintering process?

Answer 22

To bond ceramic particles together and create high-quality ceramics.

Question 23

What are nitrides used for?

Answer 23

Gas turbines, rocket engines, specialized electronics devices (blue LEDs)

Question 24

Give an example of a product that undergoes vulcanization.

Answer 24

Car tires

Question 25

What is the purpose of presintering?

Answer 25

To remove the wax binder and soften the glass binder.

Question 26

What are the four steps of the sintering process?

Answer 26

Blending, forming, presintering, and sintering.

Question 27

What is the purpose of the matrix in a composite material?

Answer 27

To hold and support the composite's shape, provide toughness, protect the reinforcement, and transfer load

Question 28

How does the creep resistance of glass compare to other ceramics?

Answer 28

Glass has much less creep resistance than other ceramics.

Question 29

When can machining be done in the ceramic manufacturing process?

Answer 29

Before sintering, while the material is still soft.

Question 30

What is the purpose of the reinforcement in a composite material?

Answer 30

To provide strength, load carrying ability, hardness, and stiffness

Question 31

What is the weak point of a composite?

Answer 31

The bond between the matrix and reinforcement

Question 32

What are the different types of composites?

Answer 32

Fibre Reinforced Composites, Laminar Composites, or Particulate Composites

Question 33

What happens during sintering?

Answer 33

The ceramic particles bond together, resulting in a stronger and tougher material.

Question 34

What are the characteristics of fibre reinforced composites?

Answer 34

Flexible, stronger along the direction of the fiber, weaker across the direction of the fiber

Question 35

What is the interface in a composite material?

Answer 35

The bond between the reinforcement and matrix, The first point to fail in a composite

Question 36

How can the contact area between the matrix and reinforcement be increased?

Answer 36

By choosing a smaller reinforcement

Question 37

What is the reinforcement shape in particulate reinforced composites?

Answer 37

Particles

Question 38

What is the purpose of a coupling agent?

Answer 38

To get the matrix to 'wet' to the reinforcement surface

Question 39

Where are bidirectional composites commonly used?

Answer 39

Surfaces (Ex. plywood floor, canoe hull, pressurized pipe)

Question 40

What is an advantage of composites?

Answer 40

High strength to weight ratio and High Stiffness to weight ratio, Corrosion resistance

Question 41

What is an example of a coupling agent for glass epoxy?

Answer 41

Silane

Question 42

What is the main difference between particulate reinforced composites and fiber or laminar reinforced composites?

Answer 42

Less strengthening

Question 43

What can cause delamination in materials with low toughness?

Answer 43

Repeated cyclic stresses, impact, and other factors

Question 44

What type of matrix sticks well to the reinforcement?

Answer 44

Epoxy

Question 45

Are particulate reinforced composites isotropic or anisotropic?

Answer 45

Isotropic

Question 46

How can the problem of delamination be eliminated?

Answer 46

Coating

Question 47

What is a limitation of composites?

Answer 47

High material and manufacturing cost

Question 48

What happens when the interface between the matrix and reinforcement fails?

Answer 48

A region of disbondment is created

Question 49

What is a limitation of composites?

Answer 49

Slow production rates, high production and manufacturing costs.

Question 50

What are some examples of particulate reinforced composites?

Answer 50

Concrete, Grinding/Cutting Wheels, Cermets, Metal Matrix Composites

Question 51

What limits the temperature range for polymer-based composites?

Answer 51

Creep in the polymer matrix

Question 52

What is the size range of particles in dispersion strengthened composites?

Answer 52

0.01-0.2 micrometers

Question 53

What can degrade the polymer matrix in composites?

Answer 53

Hydrolysis (absorbed moisture and solvents)

Question 54

What are the challenges with joining and repairing fiber and laminar composites?

Answer 54

Requires specialized methods and is expensive

Question 55

What is the property of fiber and laminar composites that varies in different directions?

Answer 55

Highly anisotropic