Packaging films: liners of bags are usually made from which polymer for flexibility, sealability, and cost?

Introduction / Context:
Bag liners require low cost, good heat sealing, chemical resistance, and flexibility. Polyethylene grades (LDPE/LLDPE) dominate due to balanced properties and easy processing.

Concept / Approach:
PE offers excellent sealability and toughness; PVC and polyesters are used for specific applications, while PP is common in woven sacks but liners are typically PE for better seal performance at lower temperatures.

Final Answer:
Polythene (polyethylene)