Characteristic And Use Of HDPE Plastics

HDPE High density polyethylene chemical and physical properties:

HDPE's high crystallinity results in its high density, tensile strength, high distortion temperature, viscosity, and chemical stability.

HDPE is more resistant to penetration than LDPE. HDPE has low impact resistance. The properties of HDPE are mainly controlled by density and molecular weight distribution. HDPE suitable for injection molding has a very narrow molecular weight distribution. For a density of 0.91~0.925g/cm3, we call it the first type of HDPE; for a density of 0.926~0.94g/cm3, it is called the second type HDPE; for a density of 0.94~0.965g/cm3, it is called the second type HDPE Type III HDPE.

1. Plastic properties:

The material has good flow characteristics, with MFR ranging from 0.1 to 28. The higher the molecular weight, the worse the flow characteristics of LDPE, but it has better anti-shock strength.

LDPE is a semi-crystalline material with a high shrinkage rate after molding, between 1.5% and 4%.

HDPE is prone to environmental stress cracking. Cracking can be mitigated by using materials with very low flow characteristics to reduce internal stresses. HDPE is easily dissolved in hydrocarbon solvents when the temperature is higher than 60C, but its resistance to dissolution is better than LDPE.

2.Injection mold process conditions:

Drying: Drying is not necessary if stored properly.

Melting temperature: 220~260C. For materials with larger molecules, the recommended melting temperature range is between 200 and 250C.

Mold temperature: 50~95C. Plastic parts with a wall thickness below 6mm should use a higher mold temperature, and plastic parts with a wall thickness above 6mm (yi3 shang4) should use a lower mold temperature. The cooling temperature of plastic parts should be uniform to reduce the difference in shrinkage. For optimal processing cycle time, the diameter of the cooling cavity should be no less than 8mm, and the distance from the mold surface should be within 1.3d (here "d" is the diameter of the cooling cavity).

3. Plastic properties:

Injection pressure: 700~1050bar.

Injection speed: High-speed injection is recommended.

Runner and gate: The diameter of the runner is between 4 and 7.5mm, and the length of the runner should be as short as possible. Various types of gates can be used, and the gate length should not exceed 0.75mm. Especially suitable for using hot runner molds.

4.Typical uses:

Refrigerator containers, storage containers, household kitchenware, sealing caps, etc., anti-counterfeiting bottle caps, cosmetic bottle caps, non-woven handbags, masks, surgical gowns and other non-woven materials, body plastic parts, car doors, instrument panels, dustproof Boxes, turn signals, brake lights, automobile instruments, car lights and mirrors, sun visors, interior parts, filters, reflective materials, reflective road studs, bumpers, cables, plastic filters for motorcycles, heat dissipation machine, brake fluid tank, oil cup, water tank, fuel tank, air duct, exhaust purifier, tray filter plate; plastic electronics: prepaid water meter and electricity meter, communication equipment, cordless phone, mobile phone accessories, mobile phone case, battery case, charger , valve-regulated sealed maintenance-free lead-acid battery, 3-inch floppy disk, U disk, SD card, CF card, USB connector, Bluetooth; toys and stationery: folders, photo albums, folding boxes, pen covers, ink cartridges, toner cartridges; medical daily Uses: watches, kitchen utensils, oral liquid bottle caps, IV bottle caps, mobile phone accessories, gold soft brushes, daily necessities, hygiene products, children's products, air mattresses, hangers, knife handles, gardening supplies, cabinets and sanitary ware, showerheads, Welding, welding, riveting, filling and sealing of plastic hoses, automatic filling and welding of plastic lighters, automatic soft brushes, shower heads, coffee pots, washing machines, air dehumidifiers, electric irons, electric kettles, vacuum cleaners and civil engineering grilles Feeding liquid filter, ultrasonic welding, etc.