Overview
EN ISO 3344:1997 specifies a standard laboratory method for the determination of moisture content in reinforcement products used for composites. It applies to continuous-filament yarn, staple-fibre yarn, rovings, chopped strands, mats, woven fabrics and other textile glass, carbon or aramid fibre reinforcements. The method supports consistent quality control and reliable composite performance by providing a repeatable procedure for moisture measurement.
Key Topics
- Scope and definition: Moisture content is expressed as the mass of water in the product, given as a percentage of the mass of the moist product.
- Principle: A test specimen is weighed at ambient temperature, dried (typically at 105 °C), then re-weighed to determine mass loss due to moisture.
- Apparatus: Required equipment includes a forced‑circulation oven (air‑change rate 20–50 h⁻¹) capable of 105 °C ± 3 °C, a desiccator, specimen holders, stainless steel tweezers, a balance accurate to 0.1 mg, and cutting tools or punches for specimen preparation.
- Specimen selection: Guidance is provided for sampling different forms of reinforcement: yarns and rovings (typically 5–30 g), chopped strands and milled fibres (≥ 5 g), woven fabrics (100 cm² specimens or larger to reach ≥ 5 g), and mats (specified square specimen per product requirements).
- Conditioning: For products expected to have < 0.2 % moisture, condition in the standard atmosphere defined in ISO 291 until equilibrium (commonly ≥ 6 h). For products > 0.2 % moisture, test rapidly after sampling and store samples in hermetically sealed containers to prevent moisture loss.
- Procedure and calculation: Weigh specimen (with or without holder) before and after drying. Calculate moisture content H as a percentage: H = (m1 - m2) / (m1 - m0) × 100, where m0 is holder mass, m1 is initial mass, and m2 is dry mass.
- Precision: Interlaboratory precision was not available at the time of publication; a precision statement was to be added in a later revision.
Applications
This standard is used by manufacturers, testing laboratories and quality assurance teams who need to:
- Verify moisture levels in reinforcement materials prior to composite processing.
- Control production conditions for resin impregnation and curing.
- Validate incoming material quality for glass, carbon and aramid reinforcements.
Adopting EN ISO 3344:1997 helps reduce defects related to moisture (e.g., poor adhesion, voids) and supports reproducible composite manufacturing results.
Related Standards
- ISO 291 - Plastics: standard atmospheres for conditioning and testing (referenced for conditioning and temperature).
- ISO 1886 - Sampling of reinforcement fibres (elementary unit definition referenced).
For test reporting, include reference to EN ISO 3344:1997, product identification, specimen dimensions and mass, number of specimens, individual results, any non‑standard operations and the test date.
Keywords: EN ISO 3344:1997, moisture content, reinforcement products, glass fibre, carbon fibre, aramid, yarn, rovings, composites, quality control.
