ISO 62:2008

Overview

ISO 62:2008 - Plastics - Determination of water absorption describes standardized test methods to measure how much water solid plastics absorb through their thickness. The standard covers procedures for immersion in water (ambient and boiling), exposure to controlled humidity, and measurement of water‑soluble matter lost. Results are reported as mass change (percentage) and, for homogeneous materials, can be used to calculate the through‑thickness moisture diffusion coefficient assuming Fickian diffusion.

Key topics and technical requirements

• Test principle: Water uptake determined by change in mass of defined test specimens after exposure; results expressed as percentage of initial mass.
• Test methods:
  • Method 1 - immersion in distilled water at 23 °C (equilibrium moisture content).
  • Method 2 - immersion in boiling distilled water.
  • Method 3 - determination of water‑soluble matter lost.
  • Method 4 - exposure to controlled humidity (50 % RH) at specified temperatures.
• Diffusion analysis: For single‑phase homogeneous plastics (and reinforced polymer‑matrix composites below Tg), the standard permits calculation of diffusion coefficient using Fick’s laws. Multi‑phase absorption behaviour (e.g., some hardened epoxies) is not covered.
• Specimens and preparation: Square plates (typically 1.0 mm thick), tubular sections, rod sections or cut specimens from finished products; at least three specimens per material. Surface cleaning, dimensional control and machining per ISO guidance are required.
• Apparatus & accuracy: Precision balance (±0.1 mg), ovens (50 ±2 °C or agreed temp), controlled humidity chambers and distilled water baths.
• Limitations: Not applicable to cellular plastics, granulates or powders (capillary effects). Results are comparative unless equilibrium moisture content is used for cross‑material comparisons.

Applications and users

• Quality control and batch comparison of thermoplastics and thermosets.
• Material selection for applications where moisture exposure affects dimensional stability, mechanical properties or electrical performance (automotive, aerospace, consumer goods, electronics).
• Research and development for diffusion modelling and lifetime prediction of polymer components.
• Typical users: materials engineers, polymer scientists, testing laboratories, product designers, and compliance teams requiring standardized water absorption testing.

Related standards

• ISO 175:1999 - Effects of immersion in liquid chemicals
• ISO 294‑3 - Injection moulding of test specimens (small plates)
• ISO 2818 - Preparation of test specimens by machining

ISO 62:2008 is essential when you need reproducible, comparable data on water uptake, moisture diffusion, and the effect of humidity on plastics performance.