Material Analysis
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COC Brittle Fracture
Problem Phenomenon
COC products break brittle when dropped or under assembly force, notched impact strength only 2~3kJ/m² far below PC, thin-walled snap-fit structures have high fracture rate.
Cause Analysis
Unmodified cyclic olefin polymer molecular chains are rigid, inherent impact toughness is low; notch sensitivity is strong, sharp corners and weld lines further weaken impact resistance; brittleness aggravates in low-temperature environment.
Solution
①Structural design eliminates notches and sharp corners, enlarges fillets; ②choose impact-modified grades or blended modified materials; ③optimize gate position to weaken weld line influence; ④verify structural reliability by drop test.
Key Takeaway
COC brittleness is an inherent material characteristic, design and material selection are the main countermeasures; impact-modified grades can improve to above 100J/m; mechanical conditions must be re-evaluated when replacing PC.
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