LDPE is a resin used across plastics processing — mainly for films and packaging. This page covers what it actually does and how it compares to HDPE.
What is it?
LDPE is polyethylene with a highly branched molecular structure — long-chain branching, per ASTM D883’s terminology — unlike the predominantly linear structure of HDPE (ASTM D4976). For film applications specifically, ASTM D4635 specifies a density range of 0.910–0.925 g/cm³ — well below HDPE’s more linear, less-branched grade (see Limitations).
Why should I use it?
- Higher branching means higher flexibility and clarity — the opposite trade-off from HDPE’s stiffness (see Limitations for how that plays out).
- Widely used, but a real recycling gap exists. LDPE film is common in packaging, but actual recycling rates for that category remain low in practice — see the breakdown below.
How it’s used
In Plastics & Polymers, LDPE is used mainly for films — general-use and packaging film, qualified under ASTM D4635. In the US, plastic bag, sack, and wrap waste (predominantly LDPE/LLDPE film) totaled 4.2 million tons generated in 2018, of which only 10% was recycled (EPA) — film recycling in practice lags well behind the material’s actual usage volume.
Limitations — when it isn’t the right choice
- Where stiffness or chemical resistance is the priority instead of flexibility, HDPE is the better fit. Same polyethylene family, but HDPE’s more linear structure and higher density (ASTM D4976/D1248) give it the rigidity LDPE doesn’t have. (A dedicated comparison article — HDPE vs. LDPE — is planned.)
- The low recycling rate isn’t a reason to assume the material can’t be recycled — it reflects real-world collection and processing gaps rather than a property of LDPE itself, and it’s a genuine factor to weigh in sustainability-sensitive packaging decisions.