EN ISO 9944:1995

Overview

EN ISO 9944:1995 is an international standard that specifies a method for determining the electrical conductivity of phenolic resin extracts. Phenolic resins are commonly used thermosetting plastics, particularly as impregnating materials in various industrial applications. This standard is crucial for quality control and performance assessment of these resins by measuring the conductivity of their extracts.

The method involves mixing a resin solution with an acetone/water mixture, causing precipitation. The electrical conductance of the suspension above the resin is then measured, and the conductivity is calculated. Measurements are performed at 23°C ± 2°C to ensure consistency and accuracy.

Key Topics

• Phenolic Resins: Thermosetting plastics widely used in impregnating materials.
• Electrical Conductivity Measurement: Determines the conductivity in microsiemens per centimetre (µS/cm) of resin extracts.
• Test Procedure:
  • Prepare a resin solution or resin powder dissolved in acetone.
  • Add an acetone/deionized water mixture in controlled drops to form a milky suspension without coagulation.
  • Stir and allow the precipitate to settle.
  • Measure conductance of the supernatant using a calibrated conductivity cell.
• Apparatus:
  • Conductivity cell with known cell constant.
  • Conductance meter capable of precise measurements (minimum 1 pS).
  • Magnetic stirrer, precise balance, and standard laboratory glassware.
• Temperature Control: Measurements made at 23°C ± 2°C ensure reliability.
• Alternative Extraction Method: Resin extraction with deionized water at 95°C for 20 hours for specific cases.
• Precision:
  • Repeatability and reproducibility within ±10%.
• Test Report Requirements:
  • Reference to standard EN ISO 9944.
  • Resin type, identification, manufacture and test dates.
  • Conductivity values and blank test results.
  • Any deviations from procedure.

Applications

EN ISO 9944:1995 is essential in industries where phenolic resins are used for impregnation, insulation, and molding processes. Reliable conductivity data helps:

• Quality Control: Confirm purity and consistency of resin batches.
• Material Performance: Predict behavior of resin in electrical and insulating applications.
• Process Optimization: Adjust formulation and processing parameters for desired electrical properties.
• Research and Development: Develop new resin formulations with tailored electrical characteristics.
• Regulatory Compliance: Meet industrial standards and safety requirements for electrical materials.

Practical uses include electrical insulation in transformers, printed circuit boards, motor windings, and other electrotechnical components where phenolic resins act as binders or impregnants.

Related Standards

When working with phenolic resins and their electrical properties, it is beneficial to reference related standards:

• ISO 9001 – Quality management systems, ensuring compliance in material manufacturing.
• EN ISO 178 – Plastic materials - Determination of flexural properties, complementing electrical testing.
• IEC 60243 – Electrical insulating materials - Methods for determining electrical strength.
• ISO 306 – Plastics - Determination of Vicat softening temperature, relevant for thermal and mechanical assessment of phenolic resins.
• EN ISO 527 – Determination of tensile properties of plastics, supporting comprehensive resin evaluation.

Summary

EN ISO 9944:1995 provides a standardized, reliable procedure to assess electrical conductivity of phenolic resin extracts, a critical parameter in resin-based electrical insulation and impregnation applications. Its precise methodology and clear reporting requirements facilitate quality assurance, material development, and regulatory adherence in sectors utilizing phenolic thermosetting plastics. The standard integrates practical lab procedures with key performance insights, making it indispensable for manufacturers, researchers, and technical professionals working with electrical-grade phenolic resins.