Overview
EN ISO 3146:2022 - Plastics: Determination of melting behaviour (melting temperature or melting range) of semi-crystalline polymers by capillary tube and polarizing-microscope methods - is a CEN-adopted international standard that specifies two laboratory methods to evaluate the melting behaviour of semi‑crystalline polymers. The standard replaces the 2000 edition and updates apparatus specifications and calibration references (ISO 3146:2022).
Key topics and requirements
- Scope: Defines two methods for determining melting temperature or melting range of semi‑crystalline polymers.
- Method A - Capillary tube:
- Based on observable changes in particle shape on heating.
- Applicable to all semi‑crystalline polymers and their compounds.
- Also useful for assessing softening of some non‑crystalline solids.
- Method B - Polarizing microscope:
- Based on changes in optical properties (birefringence) of the crystalline phase.
- Applicable to polymers that exhibit birefringent crystalline zones; not suitable for heavily pigmented or additive‑filled compounds that interfere with birefringence.
- Test conditions and repeatability:
- Addresses sample preparation, conditioning (references ISO 291), calibration and measurement procedures.
- Recognizes that measured melting range depends on molecular mass, crystallinity, thermal history, and heating rate; results from different methods can differ by several kelvins.
- Documentation:
- Specifies required details for the test report (method used, sample condition, heating rate, observed melting temperatures/range, equipment).
Practical applications and users
Who uses EN ISO 3146:2022:
- Polymer laboratories and materials testing labs performing routine quality control.
- R&D teams characterizing new semi‑crystalline polymers or formulations.
- Manufacturers validating processing windows (injection moulding, extrusion) and selecting grades by melting behaviour.
- Failure‑analysis and recycling operations assessing thermal behavior of recovered plastics.
Practical uses:
- Determining melting temperature or range for product specification, process optimization and troubleshooting.
- Comparing batches or suppliers for consistent crystallinity and melting behaviour.
- Screening materials for suitability in thermal processing and in service at elevated temperatures.
Related standards
- ISO 11357‑3 - another method applicable to semi‑crystalline polymers (differing technique).
- ISO 291 - standard atmospheres for conditioning and testing (referenced for sample conditioning).
- ISO 472 - plastics vocabulary (terms and definitions used).
Keywords: EN ISO 3146:2022, ISO 3146:2022, plastics, semi‑crystalline polymers, melting behaviour, melting temperature, melting range, capillary tube method, polarizing microscope method, polymer testing, material characterization.