Non-metallic and structural materials

Question 1

What are the 3 motivations to choosing materials?

Answer 1

– Introduction of a new product
– Need to improve a current product (Product Development)
– A problem situation

Question 2

What are 4 criteria for choosing materials?

Answer 2

– Function
– Manufacture/Production
– Appearance
– Cost

Question 3

What are 3 factors of costs?

Answer 3

– Materials Processing Costs
– Manufacturing Costs
– Maintenance Costs

Question 4

What are 3 economic considerations?

Answer 4

• A product must make economic sense
• To minimize product cost materials engineers
must consider three factors
• Other significant factors include labor & fringe benefits, insurance, and profit

Question 5

What are 2 things that make a product make economic sense?

Answer 5

• • the price must be attractive to customers

- - it must return a sustainable profit to the company

Question 6

What are 3 factors to consider to minimise product cost materials?

Answer 6

• • component design
• • material selection
• • manufacturing techniques

Question 7

What are 3 components of green design?

Answer 7

Reduce, reuse, recycle

Question 8

What does reduce mean? example.

Answer 8

design the product to use less material, less energy

example: PET bottles with thinner walls

Question 9

What does reuse mean? example.

Answer 9

fabricate the product of a material that can
be reused
example: refillable bottles and shipping containers

Question 10

What does recycle mean? example.

Answer 10

reprocess the material into a new product example: convert PET bottles to carpet fibers

Question 11

What are 2 advantages to recycling?

Answer 11

• reduced pollution emissions

- reduced landfill deposits

Question 12

What are two issues with recycling?

Answer 12

• Product must be disassembled or
  shredded to recover materials
• Collection and transportation costs are significant factors in recycling economics

Question 13

Why is better to reprocess metals that refining raw ore? (2)

Answer 13

– is more energy efficient

– produces less waste (pollution)

Question 14

What is one difficulty to reprocess metals?

Answer 14

• Difficult to recycle metals that are susceptible to Corrosion

Question 15

How can toxic metals be handled? (3)

Answer 15

• Toxic metals (e.g., Cd and Hg):
– must be handled as hazardous waste
– are difficult to reprocess
– should not be added to landfills

Question 16

What are 3 things to consider when it comes to recycling glass?

Answer 16

– raw materials inexpensive
– relatively dense - expensive to transport
– must be sorted by
• color – clear, amber, green, brown
• type – plate vs. container
• composition – soda-lime, leaded, borosilicate

Question 17

How are thermoplastic polymers recycled? (3)

Answer 17

– grind into pellets, melt, and extrude or mold into
new product
– must be sorted by polymer type – polyethylene,
polystrene, PET, etc.
– properties degrade in each reuse

Question 18

How are thermosetting polymers recycled though they are difficult?

Answer 18

– can be ground up and use as filler

– depolymerize to make monomer

Question 19

What are some biodegradable polymers?

Answer 19

Current generation based on biorenewable materials such as poly(lactic acid) (PLA)

Question 20

Why are biodegradable polymers hard to recycle? (3)

Answer 20

• Difficult to recycle because they contain an intimate mixture of materials – difficult to separate
• Some composites are recyclable
• Components must separated by shredding or dissolution

Question 21

What are composite materials?

Answer 21

Composite Materials effectively form the fourth classification of materials, and are essentially born of the first three classifications, namely metals and alloys, polymers and ceramics and glasses.

Question 22

What are 3 guidelines for composite materials?

Answer 22

● A composite material is a mixture of two or more distinct constituents or phases, whereby:

• Both constituents are present in reasonable proportions eg >5%.
• Constituent phases must have noticeably different properties.

● In man-made composites, the composite material is produced by intimate mixing and consolidation of the constituents (not by the development of one constituent from another within the process eg phase nucleation in metals and alloys).

● A viable composite material will have properties superior to those of the individual constituents (properties described by the law of mixtures).

Question 23

What are basic properties of composites? (2)

Answer 23

● Increase stiffness of low modulus material

● Increase toughness of brittle material

Question 24

What is the law of mixtures?

Answer 24

To describe and develop the properties of composite materials the law of mixtures is used.
In terms of modulus, when two linear elastic solids of a different moduli are combined, composite moduli (in longitudinal direction)