SIST EN 15702:2009

Overview

SIST EN 15702:2009 is a European Standard developed by the European Committee for Standardization (CEN) that specifies a standardized method for determining the cell count of flexible and rigid cellular polyurethane materials. Cell count refers to the number of cells per 25 mm length in the polyurethane foam, providing a crucial measure of the cellular structure and quality of these materials.

This standard is essential for industries working with cellular plastics, helping to ensure consistency, quality control, and comparability of cellular polyurethane products across Europe and beyond.

Key Topics

• Scope: Defines a clear method for counting cells in both flexible and rigid polyurethane foams.
• Terms and Definitions: Includes definitions related to cell count measurement.
• Apparatus Requirements: Specifies the need for a magnifying device with a scale calibrated in millimeters, typically a 25 mm cloth-counting glass combined with 10x magnification. Small variations in equipment are permissible for fine-celled foams.
• Test Specimens Preparation:
  • Samples must be free from surface skin and large enough to accommodate the counting device.
  • Recommended specimen size: 50 mm x 50 mm x 3 mm.
  • Samples should be cut carefully to avoid damaging the cellular structure.
  • Specimens must account for the orientation of cells if the cellular structure is directional.
• Cell Counting Procedure:
  • Place the specimen flat and count cells under the counting glass.
  • When cell size varies significantly, count in multiple directions (e.g., maximum and minimum cell dimensions).
  • Techniques to enhance visibility for very fine cells include lightly shading or coating the surface with marker ink or white correction fluid.
• Precision and Reproducibility:
  • Validated through an interlaboratory test program (ITP) involving multiple laboratories.
  • Provides repeatability and reproducibility data for different polyurethane grades and cell counts.
• Test Reporting:
  • Reports must detail the counting direction(s), average cell count per 25 mm, magnifying power, counting glass size, surface shading use, and any deviations from the specified method.

Applications

• Quality Control: Ensuring the cellular polyurethane products meet required cellular structure specifications.
• Material Characterization: Provides quantifiable data about foam cell size and density critical for mechanical and thermal performance.
• Research and Development: Used to compare foam formulations or production conditions impacting the cellular structure.
• Compliance Testing: Assists producers and purchasers in compliance with contractual or regulatory standards.
• Product Development: Helps optimize foam characteristics for insulation, cushioning, packaging, automotive, and construction materials.

Related Standards

• ISO/TR 9272: Provides guidance for precision and reproducibility evaluation relevant to this standard’s validation.
• Other CEN/TC 249 Plastics Standards: Complementary testing methods covering mechanical, thermal, and chemical properties of cellular plastics.
• National standards derived from SIST EN 15702:2009, applicable across CEN member countries, ensuring harmonization in testing methods.
• Industry-specific standards addressing polyurethane foam performance properties related to cell structure.

SIST EN 15702:2009 remains a pivotal standard for professionals involved with polyurethane foams, delivering a harmonized approach to cell counting that enhances product quality assurance and technical communication within the plastics industry. The application of this standard supports better product performance evaluation, process control, and regulatory compliance for cellular plastics manufacturing.