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Injection molding process, plastic composition and application conditions (2)

Update:03 Apr 2020
Summary:

PE-LD low density polyethylene 1. Typical applications: […]

PE-LD low density polyethylene
1. Typical applications: bowls, cabinets, pipe couplings
2. Injection molding process conditions: dry: generally no melting temperature: 180 ~ 280C mold temperature: 20 ~ 40C In order to achieve uniform cooling and more economical heat removal, it is recommended that the diameter of the cooling cavity is at least 8 mm, and Distance to mold surface
3. It should exceed 1.5 times the diameter of the cooling cavity. Injection pressure: up to 1500bar. Holding pressure: up to 750bar. Injection speed: It is recommended to use fast injection speed. Runners and gates: Various types of runners and gates PE can be used. They are particularly suitable for hot runner molds.
4. Chemical and physical properties: The density of commercial PE-LD materials is 0.91 ~ 0.94 g / cm3. PE-LD is permeable to gas and water vapor. PE-LD has a high coefficient of thermal expansion and is not suitable for processing long-term products. If the density of PE-LD is between 0.91 ~ 0.925 g / cm3, then the shrinkage is between 2% ~ 5%; if the density is between 0.926 ~ 0.94 g / cm3, then the shrinkage is between 1.5% ~ 4 %between. The current actual shrinkage depends on the injection molding process parameters. PE-LD can resist many solvents at room temperature, but aromatic and chlorinated hydrocarbon solvents can make it swell. Similar to PE-HD, PE-LD is prone to environmental stress cracking.

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