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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.