LDPE vs LLDPE Film Recycling: Differences, Scrap Grades and Uses

LDPE and LLDPE are the two polyethylenes used most in flexible packaging, and their scrap often arrives mixed. Both recycle into granules for film blowing, moulding and extrusion, but they are not identical. Understanding the difference helps buyers choose the right recycled grade and avoid problems on the film line.

How LDPE and LLDPE differ

Both are low-density polyethylenes, typically in a density range of about 0.91 to 0.94 g/cm3, so both float in water and look similar. The difference lies in molecular structure:

• LDPE has long, irregular branches. This gives good clarity, easy processing and melt strength, which helps bubble stability in film blowing.
• LLDPE has short, regular branches on a linear backbone. This gives higher tensile strength, puncture resistance and elongation, which is why it is used in stretch film and heavy-duty bags.

Feature	LDPE	LLDPE
Branching	Long-chain, irregular	Short-chain, linear backbone
Clarity	Generally better	Generally lower
Toughness and puncture resistance	Moderate	Higher
Processing	Easier, good melt strength	Needs more motor power, lower melt strength
Typical film uses	Shrink film, carry bags, liners	Stretch film, heavy-duty sacks

Many commercial films are blends of the two, or multilayer structures combining them, which is one reason film scrap is rarely pure.

Common types of film scrap

Film scrap reaches recyclers in a few broad categories:

• Post-industrial film: trims, start-up waste and rejects from film plants and converters. Usually clean and of known composition. See LDPE film scrap and LLDPE film scrap.
• Stretch film: collected from warehouses and logistics operations. Largely LLDPE and often fairly clean, but may carry labels and tape.
• Shrink film and bags: mostly LDPE-rich.
• Post-consumer packaging film: mixed, printed and sometimes laminated with other materials; needs washing and careful sorting.
• Agricultural film: mulch and greenhouse film, often heavily soiled with sand and moisture.

Printing adds ink and colour, and multilayer laminates with PET, nylon or aluminium layers are much harder to recycle into a clean PE grade. Keeping laminates out of mono-PE film streams is one of the most useful things a supplier can do.

Mixing LDPE and LLDPE in recycled granules

LDPE and LLDPE are compatible and blend well, so mixed film recycling is common. The issue for buyers is consistency rather than compatibility. A granule that is mostly LDPE one month and mostly LLDPE the next will behave differently on the film line: bubble stability, draw-down, tear strength and sealing may all shift.

When buying, ask the supplier:

• what the feedstock is and whether it stays the same month to month;
• the MFI, tested at 190 °C/2.16 kg as per ASTM D1238 or ISO 1133;
• whether the film was washed and how it was dried;
• whether filler such as calcium carbonate is present, which shows up as higher ash content;
• what melt filtration was used, since gels and unmelted particles cause holes in thin film.

It also helps to agree a reference sample. Run a small quantity on your own line, record bubble stability, gauge variation and any gels, and keep part of the sample. When later lots arrive, compare them with this reference before full use. A supplier who can hold the same feedstock mix month after month is usually worth more than one offering a slightly lower rate with an unpredictable blend. If you are unsure whether LDPE, LLDPE or HDPE suits your product, our PP vs HDPE guide shows how to think about polymer choice by application.

Where recycled LDPE and LLDPE are used

Recycled low-density PE granules go into garbage bags, carry bags, industrial liners, agricultural film, irrigation pipes, injection-moulded household items and blends with virgin resin. Thinner, high-performance films demand cleaner, better-filtered material; thicker films and moulded articles tolerate more variation.

Natural recycled film granules are usually sought for lighter colours, while mixed-colour material is often used for black or dark products. If you are running a film line, start with a small proportion of recycled granules and increase it after trials. For grade details, see recycled LDPE granules and the LLDPE page.

Buying recycled film granules through PlasticSetu

When you post a requirement, mention the end product, film thickness if relevant, preferred MFI range, colour and whether you need LDPE-rich or LLDPE-rich material. The sourcing desk takes it to matching suppliers, arranges samples for line trials and tracks dispatch. Get quotes to begin.