What is commonly known as high-density polyethylene

Detailed introduction of high-density polyethylene (HDPE) Article ① Name and abbreviation: From scientific name to common name, the corresponding scientific name of high-density polyethylene is "High Density Polyethylene", abbreviated as HDPE in English. Its most common nickname is "low-pressure polyethylene", named after the use of lower pressure (usually 0.5-5MPa) polymerization in the production process; In addition, it is also known as "hard polyethylene" to distinguish it from low-density polyethylene (LDPE) with a softer texture. ② Core performance characteristics: Key data for density and mechanical properties - Density range: 0.941-0.965g/cm ³ (much higher than LDPE's 0.9100.925g/cm ³), therefore the texture is hard and the hardness can reach Shore D hardness of 60-70. -Mechanical strength: tensile strength of 20-30MPa, bending modulus of 800-1200MPa, excellent rigidity and impact resistance (impact strength of simply supported beams at room temperature ≥ 20kJ/m ²). -Chemical resistance: It can tolerate most acid-base salt solutions with pH values of 1-14 (such as sulfuric acid with a concentration of ≤ 50% and sodium hydroxide with a concentration of ≤ 40%), but is not resistant to strong oxidants (such as concentrated nitric acid and potassium permanganate). -Temperature resistance: The continuous use temperature range is -40 ℃ to 60 ℃, and it can withstand high temperatures of up to 80 ℃ in the short term. ③ Practical Application Case: From Municipal Engineering to Field Field Case 1: Municipal Water Supply and Drainage Pipeline (Typical Application of High Pressure Polyethylene Pipe) - Engineering Scenario: An outdoor water supply network renovation project in a residential area, using DN200mm HDPE water supply pipes (SDR11 series, i.e. standard size ratio 11, nominal pressure 1.6MPa). -Operation details: The pipeline connection adopts hot melt docking. The specific steps are:

1. Clean the port and align it;
; two Heat the end face of the pipe with a heating plate at 210 ℃± 10 ℃ (heating time 15-20 seconds, adjusted according to the pipe diameter); three Quickly remove the heating plate and connect it, maintain pressure and cool for more than 30 seconds. Case 2: Agricultural Irrigation and Water saving Equipment - Scene: Drip irrigation tape is laid in a wheat production area in North China, using HDPE material drip irrigation tape (wall thickness 0.2-0.3mm, inner diameter 16mm). -Environmental adaptability: The low-temperature impact resistance of HDPE (-20 ℃ simply supported beam impact strength ≥ 4kJ/m ²) can adapt to the severe cold in northern winter and maintain structural stability under summer exposure (surface temperature 60 ℃), with a service life of up to 5-8 years. ④ Quality control standard: Static hydraulic strength testing ensures safety. Taking HDPE water supply pipes as an example, the key acceptance standard is "Thermal stability test under static hydraulic state" (according to GB/T 13663.2-2018): - Test conditions: Place the pipe sample in distilled water at 95 ℃± 2 ℃, apply a ring stress of 8.0MPa (corresponding to PE100 SDR11 series), and continue for 1000 hours. -Qualification judgment: During the test, there was no rupture or leakage of the pipe material, and there was no significant pressure drop (pressure drop ≤ 5%) after holding for 1000 hours. ⑤ Environmental and industrial adaptability: why has it become the preferred choice in multiple fields? -Weather resistance adaptation: In high-temperature and high humidity southern coastal areas (such as Guangdong), HDPE drainage pipes can replace traditional concrete pipes to reduce the risk of corrosion and leakage due to their UV aging resistance (outdoor service life ≥ 50 years when carbon black content is 2% -3%). -Chemical industry adaptation: In the transportation of acidic and alkaline waste liquids in a chemical plant in Jiangsu, HDPE pipes (with inner wall smoothness Ra ≤ 0.01 μ m) can reduce resistance and withstand hydrochloric acid and sodium hydroxide solutions with a concentration of ≤ 30%. Maintenance costs are reduced by 40% compared to stainless steel pipes.
-Agricultural water-saving adaptation: HDPE infiltration irrigation pipes (with hole diameters of 0.8-1.2mm and spacing of 30cm) promoted in arid areas of northwest China (such as Gansu) can be flexibly laid according to the terrain, increasing water resource utilization by more than 60% compared to flood irrigation.
Summary: High density polyethylene (commonly known as "low-pressure polyethylene") has become a basic material in municipal, agricultural, chemical and other fields due to its high strength, chemical corrosion resistance, and easy processing characteristics. Its quality control and environmental adaptability have led to an annual production of over 50 million tons worldwide, continuing to dominate the plastic application market.
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