What is PP (Polypropylene)?

PP (Polypropylene) is a thermoplastic polymer produced by the polymerization of propylene monomers. It is one of the five major general-purpose plastics (along with PE, PVC, PS, and ABS).

Key Characteristics:

• Lightweight: Density of 0.89–0.91 g/cm³, making it the lightest among commodity plastics

• Heat resistant: Melting point of 160–170°C; can withstand boiling water and high-temperature sterilization

• Chemical resistance: Resistant to acids, alkalis, and most organic solvents, but vulnerable to concentrated sulfuric and nitric acids

• Mechanical properties: Good rigidity and excellent flexural endurance (often called the "hinge plastic" because it can be bent repeatedly without breaking)

• Electrical insulation: Excellent

• Disadvantages: Becomes brittle at low temperatures, poor aging resistance (requires antioxidants), and difficult to print on

Typical Applications:

• Food containers (microwave-safe lunch boxes, yogurt cups, disposable takeout containers)

• Medical devices (syringes, IV bottles)

• Automotive parts (bumpers, interior trim)

• Home appliances (washing machine drums, fan blades)

• Woven bags and non-woven fabrics (masks, shopping bags)

Recycling Symbol: Code 5 (a triangle with the number 5 inside, with PP printed below).

Safety: Food-grade PP is recognized as a safe plastic. It can withstand temperatures up to approximately 120°C and is microwave-safe (though note that some PP lids may be made of different materials). When burned, it produces a yellow flame with a blue base, smells like paraffin (candle wax), and drips like candle wax.