MDPE Specific Gravity (Density)
MDPE (Medium-Density Polyethylene) has a density between LDPE and HDPE, with moderate branching and crystallinity. It balances flexibility and rigidity, offering excellent stress crack resistance, low-temperature resistance, and processability. It is a premium material for gas pipes, drinking water pipes, packaging films, and injection-molded structural parts. MDPE density is primarily affected by polymerization process, ethylene partial pressure, and branching control. Virgin material density is stable, with a slight increase after reinforcement or filling. Accurate density is critical for pipe pressure-bearing capacity and film performance regulation.
Virgin MDPE: 0.926–0.940 g/cm3, typical value 0.930 g/cm3. It balances rigidity and flexibility with excellent stress crack resistance and moderate density, suitable for gas transmission pipes, drinking water pipes, medium packaging films, and injection-molded containers.
Pipe-Grade MDPE: 0.930–0.935 g/cm3. Optimized molecular chain regularity ensures stable density, primarily improving pressure-bearing capacity and long-term hydrostatic strength for municipal gas and water supply systems.
Film-Grade MDPE: 0.926–0.932 g/cm3. Fine-tuned branching structure results in lower density, optimizing film toughness and puncture resistance for heavy-duty packaging and industrial liner films.
Filled Modified MDPE: 0.935–0.960 g/cm3. Inorganic fillers increase density, reducing costs and improving rigidity for low-end pipes and injection-molded structural parts.
