Polypropylene (PP) is among the most versatile commodity polymers, moulded and extruded into packaging, automotive parts, fibre, film and housewares. Buying it well means knowing two things first: whether it is homopolymer or copolymer, and its melt flow. This guide is for UK buyers of PP across prime, regrind and recycled grades.
Homopolymer or copolymer?
This is the first divide in PP:
- Homopolymer (PP-H) — stiffer and stronger, for rigid packaging, fibre, film and general moulding. The higher-volume type.
- Copolymer — random copolymer for clarity and impact in packaging, or block/impact copolymer for toughness at low temperature, used in automotive and crates.
A price for homopolymer tells you little about copolymer, and vice versa. Establish which is on offer before comparing.
What else defines a PP grade?
After the homopolymer/copolymer split, melt flow index (MFI) sets the process fit — high-MFI PP for thin-wall injection moulding, lower MFI for extrusion and sheet. Additive packages (nucleation, impact modifiers, UV stabilisers) and any filler such as talc or glass further define it. A complete PP offer states type, MFI and any filler or additive.
Prime, regrind and recycled PP
Prime PP is virgin resin to a datasheet. Regrind is ground production material with one heat history. Recycled PP is reprocessed from the waste stream, post-industrial or post-consumer, with the usual rule that the further from prime, the more verification it deserves. Our guide to polymer grades sets out each condition precisely.
How is PP priced?
PP tracks the virgin polypropylene market, with recycled and off-spec at a discount that shifts with supply and demand. Copolymer, filled and specialty grades price differently from natural homopolymer. Price against live offers rather than a remembered figure — the Prime Polymers board shows the seller's current asking price per tonne alongside grade, quantity and location.
What to check before buying PP
- Homopolymer or copolymer, and for copolymer, random or impact.
- MFI and intended process.
- Any filler (talc, glass) or additive package.
- Condition grade and supporting datasheet or COA.
- Colour, quantity, MOQ, location and incoterm.
Prime Polymers lists PP from UK and international sellers with full specs. A free account shows every listing in full; membership unlocks direct messaging. Operated by ARC Polymers Ltd, a UK polymer trading company.
Frequently asked questions
- What is the difference between PP homopolymer and copolymer?
- Homopolymer PP is stiffer and stronger, used for rigid packaging, fibre and general moulding. Copolymer PP is either random (for clarity and impact) or block/impact (for toughness at low temperature, used in automotive and crates). They are different materials at different prices.
- What does MFI mean for polypropylene?
- MFI (melt flow index) measures flow of the molten resin. High-MFI PP suits thin-wall injection moulding; lower-MFI grades suit extrusion and sheet. Match MFI to your process when buying.
- Can I buy recycled polypropylene in the UK?
- Yes. Recycled PP — post-industrial or post-consumer — trades actively alongside prime and regrind. Establish the source, condition and any contamination, and take a sample for volume orders.
- How is PP priced?
- PP tracks the virgin polypropylene market, with recycled and off-spec at a discount that varies with type (homopolymer/copolymer), filler, colour, quantity and incoterm. Price against live listings on the day.