Overview
ISO 11357-3:2025 - Plastics - Differential scanning calorimetry (DSC) - Part 3: Determination of temperature and enthalpy of melting and crystallization specifies a method for measuring melting and crystallization temperatures and enthalpies of crystalline or partially crystalline plastics using conventional DSC. This fourth-edition standard (May 2025) is part of the ISO 11357 series and applies only to conventional DSC as referenced in ISO 11357-1; it explicitly excludes fast DSC methods (ISO 23976).
Key topics and requirements
The standard defines the essential elements required for reliable DSC thermal analysis of plastics:
- Principle: use of conventional differential scanning calorimetry to record thermal transitions associated with melting and crystallization.
- Apparatus and materials: general requirements for DSC instruments and crucibles as referenced to ISO 11357-1.
- Specimen preparation: guidance on sample size, conditioning and handling of crystalline or partially crystalline specimens.
- Test conditions and conditioning: recommended temperature programs, heating/cooling rates and atmosphere considerations (see standard for specifics).
- Calibration: procedures for instrument calibration to ensure accurate temperature and enthalpy results.
- Operating procedure: stepwise workflow covering instrument start-up, sample loading, placing crucibles and running temperature scans.
- Expression of results: methods for determining transition temperatures and calculating enthalpies of fusion/crystallization from DSC traces (see clauses 10.2 and 10.3).
- Fidelity and reporting: criteria for measurement repeatability/uncertainty and the required content of a test report.
Practical applications
ISO 11357-3:2025 is used to generate quantitative, comparable thermal data for plastics:
- Determining melting points and crystallization temperatures for polymer specification and grade control
- Measuring heats of fusion/crystallization to estimate degree of crystallinity
- Supporting processing parameter development (molding, extrusion, annealing)
- Comparing recyclates, blends and formulations for thermal performance
- Failure analysis and material verification in quality assurance
Who should use it
- Polymer R&D and analytical laboratories
- Quality control and production teams in plastics manufacturing
- Certification and testing bodies providing materials compliance services
- Material suppliers, compounders and recyclers seeking validated thermal data
Related standards
- ISO 11357-1 (general principles and equipment for DSC)
- ISO 23976 (fast DSC - excluded by this part)
- Other parts of the ISO 11357 series covering related thermal analysis methods
Keywords: ISO 11357-3:2025, differential scanning calorimetry, DSC, melting enthalpy, crystallization enthalpy, plastics testing, conventional DSC, thermal analysis standard.
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