LDPE, LLDPE and MDPE are polyethylenes with similar densities but different structures, and that changes how the film behaves on your line.
Side-by-side comparison
| LDPE | LLDPE | MDPE | |
|---|---|---|---|
| Typical density (g/cm³) | 0.910 to 0.925 | 0.915 to 0.940 | 0.926 to 0.940 |
| Structure | long branches | linear, short branches | intermediate |
| Strength | clarity, processability | impact, tear, puncture | intermediate stiffness |
| Typical use | blown film, packaging | stretch film, heavy-duty sacks, industrial | heavier-gauge film, pipe |
General ranges. The value for each grade is on the manufacturer's technical data sheet.
LDPE
Made under high pressure, it has long branches. It produces transparent, glossy film that is easy to process. Example from Esfera's portfolio: Lupolen 2426H.
LLDPE
A linear chain with short branches from the comonomer (butene C4, hexene C6 or octene C8). It produces film with higher impact, tear and puncture resistance. The larger the comonomer, the higher the resistance: the octene in Dowlex 2045G delivers a dart impact of 220 g. Butene examples: Taisox 3224 and LLDPE 7042.
MDPE
Medium-density polyethylene, between LDPE/LLDPE and HDPE. Its stiffness sits halfway, and it is used in heavier-gauge films, gas pipes and some rotomolded parts.
Why blend LDPE and LLDPE
Many factories use both together: LDPE improves processability and clarity; LLDPE adds strength. The ratio depends on the film you produce.