Polypropylene comes in three main types. Choosing the right one matters more than the brand: it decides stiffness, clarity and how the part behaves in the cold.
Homopolymer (PP-H)
Only propylene. The stiffest and most heat-resistant type, with good clarity in thin film. Used for raffia and woven bags, BOPP and cast film, fibre and nonwovens, thin-wall packaging and general injection parts. Its weakness is low impact strength in the cold.
Random copolymer (PP-R)
A small amount of ethylene is built randomly into the chain. It is clearer and slightly more flexible. Used for clear containers and housewares, transparent film and PP-R hot and cold water pipe (pipe grades are specific).
Impact (block) copolymer (PP-B)
Contains a rubbery ethylene-propylene phase. Much tougher, especially below 0 °C, but less clear. Used for crates, buckets, paint pails, automotive parts, appliance parts and luggage.
Melt flow rate
PP melt flow is measured at 230 °C and 2.16 kg. Typical ranges: raffia and film about 2 to 4 g/10 min; injection about 10 to 35; thin-wall packaging and fibre higher. Lower flow gives tougher parts; higher flow fills thin walls faster.
What to send for a quote
- Type (homopolymer, random or impact copolymer) or your current grade
- The product and process: raffia, film, fibre, injection, thermoforming or pipe
- Melt flow range, and any nucleating, clarifying or antistatic additives
- Food-contact needs for your market
- Quantity, packing, destination port and Incoterm