Polymer film properties: given that cellulose acetate films have very high permeability (~5000 g per 100 m^2), which listed polymer typically exhibits the highest film elongation (around 100%)?

Introduction / Context:
Film engineering balances permeability, strength, and extensibility. Elongation at break indicates ductility and toughness, influencing package integrity and drawdown during processing (e.g., blown film).

Given Data / Assumptions:

• Target elongation magnitude: on the order of 100% or higher.
• Commodity films compared: polyethylene (PE), cellulose acetate/cellophane, and PTFE.
• Standard processing conditions and typical commercial grades are assumed.

Concept / Approach:
Polyethylene (particularly LDPE and LLDPE film grades) exhibits high elongation and toughness, routinely exceeding 100% elongation. Cellophane and cellulose acetate films are relatively stiff and brittle compared with PE and generally show lower elongation. PTFE films are creep-resistant and chemically inert but are not known for high elongation at break in typical thin-film applications.

Step-by-Step Solution:
Match high elongation requirement with film-grade PE behavior.Eliminate cellulose-based films and PTFE due to lower ductility.Select polythene as the correct answer.

Verification / Alternative check:
Datasheets for LDPE/LLDPE films report elongation at break between ~100% and 600% depending on formulation and orientation.

Why Other Options Are Wrong:
Cellophane/cellulose acetate: lower elongation; more brittle.PTFE: exceptional chemical resistance but not maximised for elongation at break.

Common Pitfalls:
Equating permeability traits with extensibility; these properties are largely independent.

Final Answer:
Polythene