Plastics : High Density Plastic (HD) and Low density Plastic (LD)

Basic Properties of High density plastic:

• Strong and rigid material
• Temperature resistant (-60°C to +120°C)
• Chemical resistant
• Recycling code #2 (with symbol ♲2 or HDPE) identifies High-Density Polyethylene plastic.

Common #2 HDPE products (High-Density Polyethylene):

• Milk jugs
• Shampoo bottles
• Detergent containers
• Motor oil bottles
• Food storage containers
• Shopping bags (rigid type)

Properties:

• Durable and stiff
• Good chemical resistance
• Easily recyclable
• Safe for food contact
• Opaque unless specially processed

Advantages of using HDPE: 

HDPE is the most widely recycled plastics and the most commonly collected in most recycling programs:

• Easy to process
• Maintains good properties when recycled
• High demand for recycled material
• Can be recycled multiple times

Common Uses:

• Milk bottles
• Shampoo containers
• Chemical drums
• Food packaging
• Industrial pipes

Advantages:

• Better barrier than LD plastic
• Good for long-term storage
• Easy to recycle
• Cost effective
• Weather resistant

Low Density Plastic (LD):

• Soft and flexible plastic
• Good for making thin films
• Temperature range: -50°C to +80°C
• Recycling code #4
• Common in everyday items
• Less expensive than HD plastic
• Easy to bend and shape

Common Uses:

• Shopping bags
• Food wrap films
• Squeeze bottles
• Plastic films
• Packaging materials

Key Benefits:

• Very flexible
• Good clarity
• Low cost
• Easy processing
• Moisture resistant
• Soft and flexible plastic
• Like plastic shopping bags
• Good for thin films
• Less heat resistant

High Density (HD):

• Stiff and strong plastic
• Like milk bottles
• Good for containers
• More heat resistant
• Recycling code #2

Main Differences:

• LD bends easily, HD holds shape
• LD better for films, HD better for bottles
• HD more chemical resistant than LD
• HD higher temperature resistance
• LD cheaper for thin applications