Injection Molding
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Insufficient Elongation at Break of High-Density Polyethylene Injection Molded Products
Fenómeno del problema
The elongation at break of the product in the tensile test is lower than the standard requirement, and the material behaves brittle.
Insufficient elongation at break indicates poor toughness of the material, and brittle fracture is likely to occur in actual use.
Análisis de la causa
（1）The melt temperature is too low, and severe molecular chain orientation limits the plastic deformation ability
（2）The mold temperature is too low, and the crystallization is incomplete or uneven
（3）The holding pressure is too high, and the residual stress limits the slippage of molecular chains
（4）Thermal degradation of the material leads to reduced molecular weight and decreased toughness
（5）The product contains defects such as bubbles and impurities that act as crack sources
Solución
（1）Increase the melt temperature to a higher value within the 180-260°C range to promote molecular chain relaxation
（2）Increase the mold temperature to a higher value within the 30-80°C range to improve crystallization
（3）Appropriately reduce the holding pressure to reduce residual stress
（4）Control the barrel temperature to prevent thermal degradation, and avoid long-time high-temperature residence
（5）Ensure the raw material is dry and clean to reduce bubbles and impurities
Conclusión clave
Insufficient elongation at break reflects poor toughness of the material, and the plastic deformation ability needs to be improved by optimizing temperature parameters and reducing defects.
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