n CH₂=CH₂ → (−CH₂−CH₂−)ₙExample of addition polymerization of l’ethene.
Use when: Overall scheme, without mechanism or synthesis conditions.
Polymers, plastics and elastomers
Linking macromolecular chains, formulation and shaping processes.
What is happening?
A polymer is made up of macromolecules with many linked units. The structure of the chains and their crosslinking influence flexibility, fusion and mechanical behavior.
A thermoplastic can generally be softened again within its processing window. A cross-linked thermoset does not remelt in the same way; a crosslinked elastomer has an elasticity specific to its network.
The formulas, with their conditions.
DPₙ ≈ Mₙ / MmotifDPₙ: average degree of polymerization; molar masses in the same unit.
Use when: Approximation for long chains, neglecting terminal groups.
Where is this principle used?
Plastics factory
Extrude, inject or blow objects.
Rubber factory
Formulate and crosslink elastomeric products.
What to observe in the experiment
Compare the behavior of a heated thermoplastic and that of an already crosslinked network, then choose a compatible shaping process.
References and readings
This sheet explains the principles and their assumptions. Educational simulation can simplify the process; an industrial model requires suitable data and validation.
Have you understood the essentials?
Only one correct answer per question. Answer all three questions, then view the answer key.
Intu Lab · Understanding sheet · Kimba Christian