Overview
ISO 9073-12:2002 - Textiles - Test methods for nonwovens - Part 12: Demand absorbency defines a laboratory method to evaluate the demand absorbency (also called demand wettability) of fabrics and nonwoven materials. The test measures how much liquid a sample absorbs when one face is in contact with a liquid under a defined mechanical pressure. It is intended for comparative assessment of absorbent materials and not to simulate in-use conditions of finished products.
Key topics and technical requirements
- Principle: A test piece is placed on a specified porous plate connected by a siphon to a liquid reservoir. Absorption is recorded as the decrease in reservoir mass versus time.
- Measured outputs:
- Maximum absorbed mass (A) - mass of liquid absorbed when mass change stabilizes.
- Demand absorbency capacity (DAC) - A divided by sample mass (g/g).
- Maximum absorption rate (MAR) - maximum absorption rate calculated over a 1 s period (g/s); special rules for very fast materials.
- Apparatus highlights:
- Porous glass plate: ~60 mm diameter, 4 ± 1 mm thick, porosity rating 2 (4 µm–90 µm), target flow 2.5–3.5 g/s (see calibration Annex A).
- Reservoir and siphon assembly with specified tube diameters and alignment.
- Electronic balance accurate to 0.01 g and a data acquisition system capable of ≥4 readings/s (higher rates for very fast-absorbing materials).
- Hydrophobic foam and cylindrical weight providing an imposed pressure of ~2.50 kPa (total weight ≈ 605 g).
- Procedure essentials: Cut conditioned 55 mm test pieces (five replicates), affix to foam/weight, start data acquisition, record reservoir mass until absorption stabilizes (mass change
