Injection Molding
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Insufficient elongation at break of random copolymer polypropylene injection molded products
Fenómeno do problema
The elongation at break of the product in tensile testing is lower than standard requirements, and the material behaves brittlely.
Insufficient elongation at break indicates poor material toughness, and brittle fracture easily occurs in actual use.
Análise das causas
(1) Melt temperature is too low; severe molecular chain orientation limits plastic deformation ability
(2) Mold temperature is too low; crystallization is imperfect or uneven
(3) Holding pressure is too high; residual stress limits molecular chain slippage
(4) Material thermal degradation reduces molecular weight and decreases toughness
(5) The product contains bubbles, impurities and other defects that serve as crack sources
Solução
(1) Increase melt temperature to the higher value within the 190-260°C range to promote molecular chain relaxation
(2) Increase mold temperature to the higher value within the 40-80°C range to improve crystallization
(3) Appropriately reduce holding pressure to reduce residual stress
(4) Control barrel temperature to prevent thermal degradation and avoid prolonged high-temperature residence
(5) Ensure raw material is dried and clean, reducing bubbles and impurities
Conclusão principal
Insufficient elongation at break reflects poor material toughness; plastic deformation ability needs to be improved by optimizing temperature parameters and reducing defects.
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