Material Analysis
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EVOH product dimensional change during long-term storage
Problem Phenomenon
EVOH product dimensions change ±2-3% after 3 months of storage, exceeding the ±0.5% requirement
Cause Analysis
EVOH physical aging relaxation causing continuous dimensional change; secondary crystallization slowly changing density and dimensions; slow migration of low molecular substances changing local density
Solution
1) Annealing treatment at 80°C/4h before product shipment to stabilize dimensions; 2) Select high molecular weight grades to reduce low molecular substances; 3) Slight crosslinking to reduce molecular chain mobility and suppress aging; 4) Control storage environment temperature at 23±2°C to reduce temperature change effects
Key Takeaway
Dimensional change is caused by physical aging; annealing treatment and slight crosslinking are measures to stabilize dimensions
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