Testing Conditions:
1.For fast foaming, samples are taken from the center of the foam. For molded foam, samples are taken from the central part or tested as a whole.
2.Newly produced foam should be matured in a natural state for 72 hours before sampling. Samples should be placed in a controlled environment with a temperature of 23±2℃ and relative humidity of 50±5% (as per GB/T2918).
Density:
Formula: Density = Mass (kg) / Volume (m³)
Hardness:
- Indentation Load Deflection (ILD) and Compression Load Deflection (CLD) are two methods to measure hardness. The main difference is the loading area. ILD tests a compressed area of 323 cm², whereas CLD compresses the entire sample. This document focuses on the ILD test method.
- ILD Test Method:
- Sample Size: 38 × 38 × 50 mm
- Test Head Diameter: 200 mm (with a 10 mm radius round corner on the bottom edge)
- Support Plate Holes: 6 mm diameter, 20 mm apart
- Test Head Loading Speed: 100±20 mm/min
- Procedure:Apply a 5N pressure as the zero point; Compress the sample to 70% of its thickness from the zero point, then unload at the same speed; Repeat loading and unloading three times as pre-loading; Immediately after pre-loading, compress the sample at the same speed to 25±1% and 65±1% of its thickness, holding for 30±1 seconds at each level and recording the relative indentation value.
- Compression Ratio: 65% ILD / 25% ILD, which indicates foam comfort.
Tensile Strength and Elongation at Break:
- Tensile Strength: Maximum tensile stress applied until fracture.
Formula: Tensile Strength = Load at Fracture / Original Cross-sectional Area
- Elongation at Break: Percentage elongation of the sample at fracture.
Formula: Elongation at Break = (Fracture Distance – Original Distance) / Original Distance * 100%
Tear Strength:
Measures the material’s resistance to tearing.
- Sample Size: 150 × 25 × 25 mm (as per GB/T 10808), with thickness direction as the foam rise direction.
- Procedure:
- Make a 40 mm long incision along the thickness direction at the center of one end.
- Measure thickness along the sample thickness direction.
- Clamp the sample in the test machine fixture.
- Apply load at 50-20 mm/min using a blade, keeping the blade at the center.
- Record the maximum value when the sample tears at 50 mm.
- Formula: Tear Strength = Maximum Force Value (N) / Average Thickness of Sample (cm)
Resilience:
Measures rebound performance by dropping a steel ball onto the foam sample.
- Test Requirements:
- Sample Size: 100 × 100 × 50 mm
- Steel Ball: Diameter 164 mm, Weight 16.3 g
- Drop Height: 460 mm
- Formula: Resilience Rate = Steel Ball Rebound Height / Steel Ball Drop Height * 100%
- Note: Samples should be horizontal, steel ball should be static before dropping, each sample is tested three times with 20-second intervals, and the maximum value is recorded.
Compression Permanent Deformation:
Observes deformation impact on thickness after maintaining constant deformation.
Formula: Compression Permanent Deformation = (Initial Thickness – Final Thickness) / Initial Thickness * 100%
VOC (Volatile Organic Compounds)
This document provides an overview of testing methods for polyurethane foam properties, including density, hardness (ILD), tensile strength, tear strength, resilience, compression deformation, fire resistance, and VOC emissions.
