HDPE Specific Gravity (Density)
HDPE (High-Density Polyethylene) is produced via low-pressure coordination polymerization, featuring highly linear molecular chains with minimal branching and high crystallinity. It offers excellent rigidity, strength, chemical resistance, and stress crack resistance, with the highest density among general-purpose polyethylenes. It is a core structural material for pipes, injection-molded products, hollow containers, fibers, and films. HDPE density is primarily affected by polymerization process, molecular weight distribution, and branching control. Virgin material density has a clear range, with a significant increase after filling or reinforcement. Accurate density is critical for structural part strength and container pressure-bearing design.
Virgin HDPE: 0.941–0.965 g/cm³, typical value 0.950 g/cm³. It offers high rigidity, chemical resistance, and stress crack resistance with higher density, suitable for water supply pipes, gas pipes, plastic drums, turnover boxes, and industrial components.
Pipe-Grade HDPE: 0.945–0.955 g/cm³. Regular molecular chains ensure stable density, primarily improving long-term hydrostatic strength and weather resistance for municipal water supply and gas pipeline systems.
Hollow-Grade HDPE: 0.941–0.948 g/cm³. Optimized molecular weight distribution results in lower density, enhancing impact resistance and environmental stress crack resistance for food packaging drums and chemical storage tanks.
Glass Fiber Reinforced HDPE: 1.05–1.25 g/cm³. Density increases with glass fiber content, significantly improving rigidity, heat resistance, and dimensional stability for high-load structural parts and automotive components.
Filled Modified HDPE: 0.950–0.980 g/cm³. Inorganic fillers increase density, reducing costs and improving rigidity for low-end injection-molded products and sheets.
