HDPE 

• Common source is milk bottles, which come from households, cafes, restaurants, farms and other industry events.
• Previous recycled products include storage containers, lumber, outdoor/patio furniture, playground equipment, automobile parts, trash cans, compost bins and recycling bins.

Properties

• Common source is milk bottles, which come from households, cafes, restaurants, farms and other industry events.
• Resistant to most solvents
• Can be stiff, but can also have a flexible form, like in the case of bags
• High strength characteristics
• Lightweight
• Impact resistant
• Long-lasting, weather-resistant, like in the case of plastic lumber and outdoor furniture
• Resists mold, mildew, rotting and insects, like in the case of pipes
• Easily mouldable and malleable, perfect for recycling
• MELTING POINT: "For common commercial grades of medium- and high-density polyethylene the melting point is typically in the range 120 to 180 °C (248 to 356 °F)", according to Wikipedia. 
• Doesn't breakdown under sunlight exposure

Sources: Precious Plastics Download Kit and others