Linear low-density polyethylene sits at a similar density to LDPE but behaves like a different material, because it is made a different way. Ethylene is copolymerised with an alpha-olefin over a catalyst, producing short-chain branching instead of the long branches of high-pressure LDPE. The result is much stronger film at the same thickness — which is why LLDPE took over the film market — and a specification with one extra variable most buyers forget to ask about.
Why does the comonomer matter in LLDPE?
The alpha-olefin used as comonomer sets the length of the side branches, and that governs toughness. Three are common, and they are not interchangeable in value:
- Butene (C4) — the shortest branch and the lowest-cost route. Adequate general-purpose film, weaker on puncture and tear.
- Hexene (C6) — a longer branch, noticeably better tensile, puncture and dart impact. The common mid-market choice.
- Octene (C8) — the longest branch and the strongest performance, particularly at reduced film thickness. Priced accordingly.
- Metallocene (mLLDPE) — a catalyst distinction rather than a comonomer one, giving a much narrower molecular weight distribution, superior sealing and toughness, and a premium price.
An offer that says only "LLDPE film grade, MFI 1.0, density 0.918" is incomplete. C4 and C8 material at those same numbers are different products with a real price gap between them.
How else are LLDPE grades specified?
- Melt flow index at 190°C and 2.16 kg — film grades commonly sit around 0.5 to 2, rotomoulding grades higher, injection grades higher again.
- Density, roughly 0.915 to 0.925 g/cm³, trading stiffness against toughness and clarity.
- Application family — blown and cast film dominate, with rotomoulding, injection moulding and stretch film as distinct grade sets.
- Additive package — slip, antiblock and processing aids, plus UV stabilisation for agricultural and outdoor film.
Stretch and cling film deserve a separate mention: they are usually mLLDPE or C6/C8 blends engineered for cling and puncture resistance, and recovered stretch film is a well-defined recycled stream in its own right.
How does LLDPE compare with LDPE and HDPE?
All three are polyethylene, and the differences come from branching. LDPE has long-chain branching, giving gloss, clarity, melt strength and easy extrusion, but modest strength. LLDPE has short-chain branching, giving far better tensile, tear and puncture at the cost of optics and a stiffer, more demanding melt. HDPE has very little branching, making it the stiffest, hardest and most chemically resistant of the three.
Film producers routinely blend LDPE into LLDPE to recover processability and optics, so recovered film described as one is often a blend. Worth confirming before buying it as a single polymer.
What drives the price of LLDPE?
- The comonomer — C8 and metallocene grades carry a genuine premium over C4 for the same MFI and density.
- The virgin ethylene and resin market, which recycled and off-spec material tracks at a moving discount.
- Condition — prime, near-prime, off-spec, regrind or recycled, each a step down in price and up in the diligence it deserves.
- Colour and cleanliness in recovered film: clear and natural above coloured above mixed and printed.
- Form — regranulate above washed flake above bales, reflecting the processing already done.
- Quantity, location and incoterm, with freight a larger share of delivered cost on baled material than on pellets.
These move independently, so no fixed list stays right for long. LLDPE is best priced against live offers of the same comonomer class, condition and form.
How does Prime Polymers handle LLDPE?
LLDPE listings state the grade, condition, quantity, location, incoterm and the seller's own asking price per tonne, so you can compare offers on the same basis rather than guessing. Prices are shown exactly as sellers enter them — never computed, adjusted or benchmarked by us. Browsing is free and open without an account. If nothing on the board matches your comonomer and MFI, a Wanted post puts the specification in front of sellers. Prime Polymers is operated by ARC Polymers Ltd, a UK polymer trading company.
Frequently asked questions
- What is the difference between C4, C6 and C8 LLDPE?
- They name the alpha-olefin comonomer — butene, hexene and octene. Longer comonomers give longer side branches and better tensile, tear and puncture performance, particularly in thin film. C4 is the lowest-cost general-purpose option; C8 performs best and prices highest, with C6 in between.
- What is metallocene LLDPE?
- mLLDPE is made with a metallocene catalyst, which produces a much narrower molecular weight distribution than conventional Ziegler-Natta grades. The result is better sealing, clarity and toughness, allowing thinner film for the same performance. It carries a premium price.
- Is LLDPE stronger than LDPE?
- In tensile, tear and puncture terms, yes — significantly, which is why it dominates film. LDPE holds the advantage in clarity, gloss, melt strength and ease of processing, which is why the two are so often blended rather than one replacing the other.
- Can LLDPE and LDPE be recycled together?
- They are frequently recovered together because so much film is already a blend, and many applications tolerate the mix. But a blended stream is worth less than a clean single-polymer one, because it narrows what the buyer can make from it. Declare the blend rather than describe it as one polymer.
- How can I see what LLDPE is trading at?
- Compare live offers of the same comonomer class, condition and form. On Prime Polymers each LLDPE listing shows the seller's asking price per tonne next to grade, quantity, location and incoterm. If nothing matches, post a Wanted requirement and let sellers approach you.