What Is AAP (Absorbency Under Pressure)?
Direct Answer
AAP (Absorbency Under Pressure) measures how much liquid SAP retains while under a load (simulating a baby sitting), reflecting real-world lock-in performance.
Key Takeaways
- AAP (Absorbency Under Pressure) measures how much liquid SAP retains while under a load (simulating a baby sitting), reflecting real-world lock-in performance.
- How it works: AAP tests soak SAP in saline under a standard pressure (typically 0.3 or 0.7 psi) and measures retention.
- High-AAP SAP prevents liquid squeezing out when a baby sits on a full diaper
- Myth: Free-swell capacity predicts performance. AAP (under pressure) is closer to real use — free-swell alone overestimates
How AAP (Absorbency Under Pressure) Works
AAP tests soak SAP in saline under a standard pressure (typically 0.3 or 0.7 psi) and measures retention. High AAP means the gel holds liquid even when the baby sits, crawls or lies on it. It complements free-swell capacity (CRC) by adding the pressure dimension. High-AAP SAP is preferred for cores that must stay dry under body weight.
Examples and Applications
- High-AAP SAP prevents liquid squeezing out when a baby sits on a full diaper
- Manufacturers balance AAP and absorption rate — very fast SAP can gel-block
AAP (Absorbency Under Pressure) vs. Related Terms
| Term | What it is | Key difference |
|---|---|---|
| CRC (centrifuge retention capacity) | AAP (Absorbency Under Pressure) | CRC is retention after centrifuge; AAP adds a pressure load, closer to sitting on a diaper |
Limitations and Common Misconceptions
- Myth: Free-swell capacity predicts performance. AAP (under pressure) is closer to real use — free-swell alone overestimates
- Myth: Higher AAP always wins. Speed and SFC matter too; extremes trade off
What is AAP in diaper testing?
Absorbency under pressure — how much liquid SAP retains while compressed, simulating a sitting baby.
Why is AAP better than free-swell?
Free-swell ignores pressure; AAP reflects real conditions where liquid is squeezed against the body.
References
- BASF - Superabsorbents (HySorb / SAVIVA), how SAP works — BASF (accessed 2026-08-02)
- Family Cares - The Science of Absorbency: Superabsorbent Polymer in Diapers — 行业媒体 (accessed 2026-08-02)