Which polymer is commonly used to make milk bottles and containables?

Which polymer is commonly used to make milk bottles and containables?

• A. Polythene
• B. PVC
• C. Polypropene
• D. Polystyrene

Answer: (A)

Milk bottles need a plastic that is safe for food contact, strong enough to handle, and a good barrier to moisture so the milk stays fresh. Polythene, especially high-density polyethylene, fits these demands. It can be made into rigid bottles by blow molding, has good toughness, and is a poor conductor for water and many gases, which helps keep milk from spoiling. It’s also cheap and widely recycled, which is why it’s the common choice for milk bottles and other containables. Other polymers don’t fit as well for this use. PVC can contain plasticizers and chlorine, which aren’t ideal for dairy packaging. Polystyrene is rigid but brittle and not great for repeated-use containers. Polypropylene is used for some food containers and caps, but for milk bottles the barrier properties and cost of polythene make it the preferred option.

Milk bottles need a plastic that is safe for food contact, strong enough to handle, and a good barrier to moisture so the milk stays fresh. Polythene, especially high-density polyethylene, fits these demands. It can be made into rigid bottles by blow molding, has good toughness, and is a poor conductor for water and many gases, which helps keep milk from spoiling. It’s also cheap and widely recycled, which is why it’s the common choice for milk bottles and other containables.

Other polymers don’t fit as well for this use. PVC can contain plasticizers and chlorine, which aren’t ideal for dairy packaging. Polystyrene is rigid but brittle and not great for repeated-use containers. Polypropylene is used for some food containers and caps, but for milk bottles the barrier properties and cost of polythene make it the preferred option.