How Is the Moisture Barrier of a Laminated Fiber Tray Quantified?
The laminate's WVTR (water vapor transmission rate) determines strength retention in humid and frozen environments. PE and PP lamination keeps moisture-induced strength loss to a minimum.
Moisture Essentials
WVTR is the key metric
Lower is better; always state test temperature and humidity.
Material sets the ceiling
PE and PP outperform PLA and PBAT for moisture.
Edges are the weak spot
Unsealed tray rim remains an ingress path even with full-face lamination.
Validate per supply chain
Test chilled chain, humid shelf, and thawing scenarios separately.
Measured WVTR Data (DNW Films)
Single-run laboratory measurements; values vary slightly between tests due to gauge and process variation — the latest test report always prevails.
| PP/EVOH laminate | 1.86 g/m²·d (38 °C / 90% RH, ASTM F1249) |
|---|---|
| PE/EVOH laminate | 2.22 g/m²·d (38 °C / 90% RH, ASTM F1249) |
| CPET+EVOH laminate | 4.88 g/m²·d (38 °C / 90% RH, ASTM F1249) |
| PE film | 5.62 g/m²·d (38 °C / 90% RH, GB/T 26253) |
| PP film | 7.65 g/m²·d (38 °C / 90% RH, GB/T 26253) |
| CPET film | 10 g/m²·d (23 °C / 100% RH) |
| PETG (GPET) film | 17.43 g/m²·d (38 °C / 90% RH, ASTM F1249) |
| PLA film | 131.5 g/m²·d (38 °C / 90% RH, ASTM F1249) |
| PBAT film | 272 g/m²·d (38 °C / 90% RH, GB/T 26253) |
| Uncoated fiber tray | Hundreds g/m²·d (strongly hygroscopic — greatly reduced after lamination) |
Moisture FAQ
How long can laminated trays sit on a humid shelf?
It depends on WVTR and humidity — run 7–30 day accelerated validation along the real distribution chain.
Is lower WVTR always better?
For dry and frozen goods, yes. For respiring fresh produce, moderate permeability is preferable.
How do I test my tray?
Measure film per ASTM F1249; for whole trays use gravimetric gain under simulated distribution conditions.
Need an Assessment for Your Application?
Share your tray geometry, application and performance requirements — a DNW engineer will help evaluate film structure and process parameters.
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