ldpe process conditions and physical and chemical properties

LDPE (Low Density Polyethylene)

Injection molding process conditions:

Drying treatment: generally not required Melting temperature: 180~280℃ Mold temperature: 20~40℃

In order to achieve uniform cooling and faster cooling, it is recommended that the diameter of the cooling circuit be greater than 8mm, and the distance from the cooling circuit to the mold surface should not exceed the diameter of the cooling circuit 1.5 times

Injection pressure: up to 150MPa Holding pressure: up to 75MPa

Injection speed: It is recommended to use fast injection speed

Runners and Gates: Various types of runners and gates are available. LDPE is especially suitable for hot runner.

Chemical and Physical Properties:

Commercial LDPE materials have a density of 0.91~

0.94g/cm3. Gas and water vapor are permeable to LDPE. LDPE has a high thermal expansion coefficient and is not suitable for processing products that are used for a long time.

When the density of LDPE is between 0.91~0.925g/cm³, its shrinkage rate is between 2%~5%;

When it is between 0.926~0.94g/cm³, its shrinkage rate is between 1.5%~4%. The actual shrinkage also depends on the injection molding process parameters.

LDPE is resistant to many solvents at room temperature, but aromatic and chlorinated hydrocarbon solvents can cause it to swell. Similar to HDPE, LDPE is prone to environmental stress cracking.