1. Compare three types of polymers, molecule structure, crystalline structure, stress-strain curves?...

1. Compare three types of polymers, molecule structure, crystalline structure, stress-strain curves?

materials thermoplastics thermosets elastomers

Molecule structure

Crystalline structure

Stress-strain curveExplain strength and ductility on the curves

2. Compare the crystal structure, stress-strain curve between metals and polymers

MountingMounting is required when (1) sample is small or oddly shaped to be handled.(2) The sample edge area needs to be examined.

Thermal mounting:

The sample is embedded in thermosetting plastics at elevated temperatures and pressure.

3. Class discussion

Polymers-forming

Cold mounting:The sample is embedded in epoxy type of materials.

Class discussion Polymers-forming

4. What type(s) of bonding would be expected for each of the following materials?

• Ni-Cu alloy:

• Fe:

• NaCl:

• Si wafer:

• Polyetyer [-(CH2)mCH2-O-]:

• MgO:

5. What properties would be expected for each of the following materials?

Materials Conductivity density Corrosion Melt point

Ni-Cu alloy

MgO

Polyetyer

Si wafer

6. Indicate whether statements are true or false① Polyester and epoxy are examples of the

rmosets

② It has been estimated that over three-quarters of all matrices of PMCs are thermosets.

7. Mark the correct completions① Thermosetting polymers

a) are also known as thermoplastic polymers,b) are also known as rubbers,c) Readily cross-link during curing,d) Cannot be cured,e) Cannot be reheated and reshaped.

② Thermoplasticsa) Are cross-linked polymer,b) Are linear polymers,c) May have branched chains,d) Readily flow at elevated temperatures,e) Cannot be reheated and reshaped.

③ Compared with a ceramic, a polymer normally has a(a) Greater strength,(b) Lower stiffness,(c) Lower density,(d) Better high temperature performance,(e) Lower hardness.