Injection Molding
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Insufficient elongation at break of general-purpose polyethylene injection molded products
Fenómeno do 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 material toughness, and brittle fracture is easy to occur in actual use.
Análise das causas
（1）The melt temperature is too low, and the severe molecular chain orientation limits the plastic deformation ability
（2）The mold temperature is too low, and the crystallization is imperfect 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 a decrease in molecular weight and a decrease in toughness
（5）The product contains defects such as bubbles and impurities as crack sources
Solução
（1）Raise the melt temperature to the higher value within the range of 160-260°C to promote molecular chain relaxation
（2）Raise the mold temperature to the higher value within the range of 30-80°C 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 that the raw material is dry and clean to reduce bubbles and impurities
Conclusão principal
Insufficient elongation at break reflects poor material toughness, and the plastic deformation ability needs to be improved by optimizing temperature parameters and reducing defects.
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