Comparison: Low-Density (LDPE) vs High-Density (HDPE) Polyethylene
Polyethylene properties vary significantly based on the degree of polymer chain branching.
| Property/Feature | Low-Density Polyethylene (LDPE) | High-Density Polyethylene (HDPE) |
|---|---|---|
| Molecular Structure | High degree of short and long-chain branching, which prevents close packing. | Linear structure with minimal branching, allowing chains to pack closely. |
| Density Range | Low density (approx. 0.910–0.940 g/cm³) | High density (approx. 0.941–0.965 g/cm³) |
| Crystallinity | Low crystallinity (approx. 40-50%) due to irregular packing. | High crystallinity (up to 90%) due to dense molecular alignment. |
| Mechanical Strength | Soft, flexible, and high ductility; lower tensile strength. | Hard, rigid, and high tensile strength; more durable. |
| Manufacturing Conditions | Produced under high pressure (1000–3000 atm) using free-radical polymerization. | Produced under low pressure using coordination catalysts (Ziegler-Natta). |
| Melting Point | Lower melting point (approx. 105°C – 115°C). | Higher melting point (approx. 120°C – 135°C). |
| Common Examples | Plastic bags, squeeze bottles, cling wraps, wire insulation. | Milk jugs, detergent bottles, water pipes, fuel tanks. |