Polyethylene (polythene) classification: which statement best describes its mode of formation?

Introduction / Context:Polyethylene (PE) is the world’s most produced plastic, encompassing LDPE, LLDPE, and HDPE grades. Its manufacture pathway defines key molecular features such as branching and crystallinity.

Given Data / Assumptions:

• Monomer: ethylene (CH2=CH2).
• Mechanism: chain-growth addition polymerisation.
• Catalysts: free-radical (LDPE) or coordination (Ziegler–Natta/metallocene for HDPE/LLDPE).

Concept / Approach:Addition polymerisation adds monomer units without elimination of small molecules, growing chains via active centres (radicals, ions, or coordination sites). PE is not a condensation product and is a thermoplastic, not a thermoset.

Step-by-Step Solution:Recognise ethylene → polyethylene via addition.Eliminate condensation and thermoset options.Select “Addition polymerisation product.”

Verification / Alternative check:Process routes (high-pressure radical LDPE, slurry/gas-phase ZN for HDPE) all rely on addition chemistry.

Why Other Options Are Wrong:Condensation involves by-product elimination; thermosets crosslink irreversibly—neither describes PE.

Common Pitfalls:Confusing polymerisation mechanism with thermal behaviour; PE is thermoplastic and addition-formed.

Final Answer:Addition polymerisation product