Why are PVC foam sandwich panels prone to core crushing during vacuum bag molding?

Vacuum bag pressure is typically one atmosphere (about 0.1 MPa). If the PVC foam’s compressive strength is below this value, it will crush permanently. Low-density (40 kg/m³) soft PVC foam has a compressive strength of only 0.08 MPa and will permanently deform under vacuum. Solutions: 1) Use PVC foam with density >80 kg/m³ (compressive strength ≥0.3 MPa); 2) Mechanically perforate or groove the core to allow resin flow and pressure equalization inside; 3) Use semi-rigid or flexible bag films to limit pressure transmission; 4) Use a low-pressure (<0.05 MPa) process combined with heat curing. Alternatively, PET foam or high-strength PU foam can be used, but compatibility with the resin must be re-evaluated.


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