High density polyethylene (HDPE)

From the perspective of processing performance, the melt flow rate (MFR) of HDPE is generally between 0.1 and 100 g/10 min. HDPE with lower MFR is suitable for manufacturing large containers, pipelines, etc., while those with higher MFR are commonly used for injection molding small products such as bottle caps and toys.
HDPE has excellent chemical corrosion resistance. At room temperature, it can withstand the corrosion of various acids, alkalis, and salt solutions. For example, in a 50% sulfuric acid solution and a 40% sodium hydroxide solution, long-term immersion will not cause significant chemical reactions. HDPE exhibits excellent resistance to environmental stress cracking. By adding appropriate stabilizers and adopting special processing techniques, its environmental stress cracking time can reach thousands of hours, which makes it highly advantageous in areas such as pipelines and containers for long-term outdoor use. The density of HDPE is usually between 0.941-0.965g/cm ³, and its higher density gives it better barrier properties, which can effectively prevent the penetration of gases and liquids. Therefore, it is commonly used in food packaging, chemical storage containers, etc. From the perspective of thermal performance, the melting point of HDPE is generally around 120-130 ℃, and the heat deformation temperature is between 80-120 ℃. This means that it can maintain good shape stability within a certain temperature range and can be used in some applications that require heat resistance.
During the molding process, HDPE can be processed using various techniques such as extrusion, injection molding, blow molding, etc. During extrusion molding, the length to diameter ratio of the screw is generally between 20-30, and the compression ratio is 2.5-4, which ensures sufficient plasticization and uniform extrusion of the material. The tensile strength of HDPE is relatively high, generally between 20-40MPa, and the elongation at break can reach hundreds or even thousands of percent, indicating that it has good toughness and tensile resistance, and is widely used in the manufacturing of films, ropes, and other fields. Its weather resistance is also worth mentioning. After adding an appropriate amount of UV absorbers and antioxidants, HDPE products can maintain good appearance and physical properties with relatively small performance degradation after being exposed to outdoor conditions for several years. In terms of electrical performance, HDPE has excellent insulation properties, with a volume resistivity of up to 10 ¹⁴ -10 ¹⁶Ω· cm and a dielectric constant between 2.2-2.3, making it an ideal material for wire and cable insulation layers.
HDPE has extremely low water absorption, generally less than 0.01%, which ensures that it can maintain stable physical properties in humid environments and will not cause size changes or performance degradation due to water absorption. It is suitable for underwater engineering, marine facilities and other fields.