Thermoplastics vs. thermosets, polymer chain structure and molecular weight effects on properties, the glass transition temperature, viscoelastic behavior, and common engineering polymer applications.
Polymers behave nothing like the metals covered in Module 4, because their properties come from chain length, chain architecture, and crosslinking rather than dislocation motion and grain structure. This module builds the chain-level reasoning behind why a thermoset can never be remelted while a thermoplastic can, why two parts labeled with the same polymer name can behave completely differently in service, and why the glass transition temperature — not the melting point — is often the number that actually governs whether a polymer part is safe to use.
By the end of this module you should be able to explain why a polymer part can loosen or crack months after assembly with no change in applied load — a viscoelastic creep and stress-relaxation effect this module frames from first principles, and one Module 7's composite matrix content returns to directly when it covers long-term composite performance under sustained load.