ISO 22314:2023

Overview

ISO 22314:2023 provides a standardized method for determining the length of glass fibres in fibre-reinforced products. The method is designed for thermoplastics reinforced with short glass fibres (fibres < 1 mm after moulding; initial fibre length ≤ 7.5 mm). It covers separation of fibres by calcination, dispersion, image-based measurement and reporting of results for moulding materials and moulded parts.

This second edition revises apparatus and procedural requirements and clarifies calcination time and measurement counts compared with the prior edition.

Key Topics

• Scope and limitation: Applicable to thermoplastics reinforced with short glass fibres; not developed for thermosets, long fibres or carbon fibres without further development.
• Principle: Separate fibres from the polymer by calcination, disperse individual fibres, and measure lengths from a magnified image.
• Apparatus highlights:
  • Muffle furnace capable of 625 °C ± 20 °C under a ventilated hood
  • Crystallizing dish (80–110 mm) and degreased glass microscope slides
  • Ultrasonic device for dispersion (basic lab ultrasonic baths are suitable)
  • Microscope/stereoscope with video camera and image acquisition for at least ×50 magnification
  • Reference micrometer for calibration and a drying oven at 130 °C ± 5 °C
• Procedure essentials:
  • Calcination at 625 °C for about 1 h 30 min (extend if needed)
  • Ultrasonic dispersion in demineralized water with surfactant
  • Evaporation on a slide and imaging at 50–100× to display ~100 fibres per image
  • Manual measurement: 100 ± 20 fibres per image from three images (total 300 ± 60 fibres)
  • Semi‑automatic methods allowed but should measure ≥ 360 fibres; note bias toward smaller fibres
• Results and statistics:
  • Mean length, standard deviation, histogram of ranges
  • Weighted mean length and coefficient of distribution width (D)

Applications

• Quality control of glass-fibre reinforced thermoplastics in production and incoming materials inspection.
• Process optimization where fibre length influences mechanical properties and part performance.
• Material characterization and specification verification for moulding compounds and finished parts.

Practical benefits include reproducible measurement practice, a defined sample preparation route, and statistical reporting to support material acceptance decisions.

Related Standards

• ISO 1172 (calcination methods for textile-glass and mineral-filler content) - referenced for calcination practice
• ISO 472 (plastics vocabulary) - terminology

Notes for Test Reports

Report items specified by ISO 22314:2023 include reference to the standard, sample identification, sample quantity, crystallizing dish diameter and water amount, magnification used, measured results with min/max, measurement date, and any procedural deviations.