Overview
ISO 845:2006 is an international standard developed by the International Organization for Standardization (ISO) that defines a precise method for determining the apparent density of cellular plastics and rubbers. This standard is essential for accurately measuring the density characteristics of these materials, including both the overall density and the core density (density of the inner "core" once any skins formed during molding or extrusion are removed). The ability to distinguish these densities is critical for quality control, product development, and material comparison in industries using cellular plastics and rubbers.
Key Topics
-
Scope and Application
ISO 845:2006 specifies methods for measuring apparent overall density and apparent core density of cellular plastics and rubbers. If the material has skins formed during molding or extrusion, the standard allows determination of both densities. If no skins are present, only core density applies.
-
Test Specimen Requirements
Specimens must be fabricated to preserve the cellular structure, with a minimum volume of 100 cm³ preferred. At least five specimens should be tested to ensure accuracy and repeatability.
-
Conditioning Procedures
Specimens are conditioned for at least 72 hours post-production to stabilize their properties. Conditioning atmospheres conform to ISO 291, ensuring consistent temperature and humidity for reliable density measurement.
-
Measurement Method
Dimensions of specimens are measured in millimeters with reference to ISO 1923 for accuracy, ensuring volume calculation precision. Specimens are weighed with a balance accurate to 0.1%. Apparent density is calculated based on specimen mass and volume.
-
Data Expression and Accuracy
Calculations yield apparent density values expressed in kg/m³, with correction factors available for low-density, closed-cell materials (accounting for air buoyancy effects). Results include mean density and standard deviation to assess consistency. Interlaboratory tests have shown acceptable reproducibility within 1.7% intralaboratory and 2.6% interlaboratory variation.
-
Reporting Requirements
Test reports must include references to ISO 845:2006, detailed material identification, environmental conditioning data, presence of skins, specimen dimensions, and measured densities with statistical analysis. Any deviations from the procedure must be documented.
Applications
ISO 845:2006 is widely applied across industries utilizing cellular plastics and rubbers where material density is a critical parameter:
- Quality Control: Ensures consistent production density for foamed plastics and rubbers, critical for mechanical properties, insulation, and performance.
- Product Development: Provides baseline density data to optimize formulations and processing conditions in cellular material manufacturing.
- Material Characterization: Facilitates comparison between different cellular materials or batches by standardizing density measurement protocols.
- Research and Testing Laboratories: Enables precise evaluation of new cellular rubber and plastic materials under controlled and repeatable conditions.
- Regulatory Compliance: Supports adherence to international quality and safety standards requiring verified density data.
Related Standards
For comprehensive material testing and conditioning related to cellular plastics and rubbers, consider these complementary standards:
- ISO 291 – Plastics: Standard atmospheres for conditioning and testing, ensuring consistent environmental parameters.
- ISO 1923 – Cellular plastics and rubbers: Determination of linear dimensions, guiding precise measurement of specimen dimensions.
- Additional standards on air buoyancy corrections, material property testing, and mechanical behavior assessments may also support precise characterization of cellular materials.
ISO 845:2006 provides a robust, reliable, and standardized approach for determining the apparent density of cellular plastics and rubbers, essential for quality assurance, material development, and scientific research. This standard is a key reference for industries and laboratories dedicated to advanced polymer foam technologies, ensuring accuracy and reproducibility in density measurement.
