ISO 3146:2022 PDF

Plastics — Determination of melting behaviour (melting temperature or melting range) of semi-crystalline polymers by capillary tube and polarizing-microscope methods

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Title (English):

ISO 3146:2022

Plastics — Determination of melting behaviour (melting temperature or melting range) of semi-crystalline polymers by capillary tube and polarizing-microscope methods

Document status:: Active
Format:: Electronic (PDF)
Number of pages:: 9
Publication date:: March 11, 2022
Edition:: ISO IS 3146 edition 4 version 1
ICS:: 83.080.01

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Description (English):

This document specifies two methods for evaluating the melting behaviour of semi-crystalline polymers. a) Method A: Capillary tube This method is based on the changes in shape of the polymer. It is applicable to all semi-crystalline polymers and their compounds. NOTE 1 Method A can also be useful for the evaluation of the softening of non-crystalline solids. b) Method B: Polarizing microscope This method is based on changes in the optical properties of the polymer. It is applicable to polymers containing a birefringent crystalline phase. It might not be suitable for plastics compounds containing pigments and/or other additives which can interfere with the birefringence of the polymeric crystalline zone. NOTE 2 Another method applicable to semi-crystalline polymers is described in ISO 11357‑3.

Technical details

Technical committee: ISO/TC 61/SC 5 - Physical-chemical properties
SKU: ISO 3146:2022

Abstract

Overview

ISO 3146:2022 specifies two standardized laboratory methods to evaluate the melting behaviour (melting temperature or melting range) of semi‑crystalline polymers. The standard describes:

Method A - Capillary tube: visual observation of shape change during controlled heating. Applicable to all semi‑crystalline polymers and useful for assessing softening of some non‑crystalline solids.
Method B - Polarizing microscope: observation of optical (birefringence) changes under crossed polarizers. Applicable to polymers with a birefringent crystalline phase; pigments or additives can interfere.

The document defines sample preparation, conditioning, apparatus requirements, calibration procedures and test reporting to ensure repeatable, comparable melting‑point/range results.

Key topics and technical requirements

Definition of melting range: temperature interval over which particles lose crystalline characteristics or shape.
Apparatus (Method A): metal heating block with chamber and viewing window, capillary tube (closed end, preferred max external diameter 1.8 mm), calibrated thermometer (0.1 °C divisions) and controlled heating system.
Heating protocol: initial heating up to ~20 K below expected melt point (rate ≤ 10 K/min), then slower heating at (2 ± 0.5) K/min for determination (as specified).
Sample types: powders (preferably ≤100 µm), films (10–20 µm thickness), moulded or pelleted materials; comparison tests require similar particle size/thickness.
Conditioning: default conditioning at (23 ± 2) °C and (50 ± 5) % RH for 3 hours (per ISO 291) unless otherwise agreed.
Calibration: periodic thermometer calibration using certified melting standards (table provides examples such as gallium, indium, naphthalene, benzoic acid, tin, etc.).
Limitations: Method B may be unsuitable for pigmented or highly filled plastics that mask birefringence; melting temperatures can vary between methods due to material and test variables.

Applications

Quality control and acceptance testing of semi‑crystalline plastics (PE, PP, PET, PA grades where applicable).
R&D and polymer formulation development to compare crystallinity effects, molecular weight distributions or additives on melting behaviour.
Failure analysis and materials verification when thermal transformation characteristics are needed for processing or performance.
Regulatory and specification compliance where an agreed melting‑range test method is required.

Who uses this standard

Polymer testing laboratories and contract test houses
Quality assurance teams in plastics manufacturing
Materials scientists and R&D engineers
Standards bodies, procurement teams and regulators specifying thermal properties

Related standards

ISO 11357‑3 (another method for semi‑crystalline polymers)
ISO 291 (conditioning for testing)
ISO 472 (plastics vocabulary)

Keywords: ISO 3146:2022, melting behaviour, melting temperature, melting range, semi‑crystalline polymers, capillary tube method, polarizing microscope, plastics testing, polymer characterization.

Related standards

Standards mentioned in the description

Abstract

Overview

ISO 3146:2022 specifies two standardized laboratory methods to evaluate the melting behaviour (melting temperature or melting range) of semi‑crystalline polymers. The standard describes:

Method A - Capillary tube: visual observation of shape change during controlled heating. Applicable to all semi‑crystalline polymers and useful for assessing softening of some non‑crystalline solids.
Method B - Polarizing microscope: observation of optical (birefringence) changes under crossed polarizers. Applicable to polymers with a birefringent crystalline phase; pigments or additives can interfere.

The document defines sample preparation, conditioning, apparatus requirements, calibration procedures and test reporting to ensure repeatable, comparable melting‑point/range results.

Key topics and technical requirements

Definition of melting range: temperature interval over which particles lose crystalline characteristics or shape.
Apparatus (Method A): metal heating block with chamber and viewing window, capillary tube (closed end, preferred max external diameter 1.8 mm), calibrated thermometer (0.1 °C divisions) and controlled heating system.
Heating protocol: initial heating up to ~20 K below expected melt point (rate ≤ 10 K/min), then slower heating at (2 ± 0.5) K/min for determination (as specified).
Sample types: powders (preferably ≤100 µm), films (10–20 µm thickness), moulded or pelleted materials; comparison tests require similar particle size/thickness.
Conditioning: default conditioning at (23 ± 2) °C and (50 ± 5) % RH for 3 hours (per ISO 291) unless otherwise agreed.
Calibration: periodic thermometer calibration using certified melting standards (table provides examples such as gallium, indium, naphthalene, benzoic acid, tin, etc.).
Limitations: Method B may be unsuitable for pigmented or highly filled plastics that mask birefringence; melting temperatures can vary between methods due to material and test variables.

Applications

Quality control and acceptance testing of semi‑crystalline plastics (PE, PP, PET, PA grades where applicable).
R&D and polymer formulation development to compare crystallinity effects, molecular weight distributions or additives on melting behaviour.
Failure analysis and materials verification when thermal transformation characteristics are needed for processing or performance.
Regulatory and specification compliance where an agreed melting‑range test method is required.

Who uses this standard

Polymer testing laboratories and contract test houses
Quality assurance teams in plastics manufacturing
Materials scientists and R&D engineers
Standards bodies, procurement teams and regulators specifying thermal properties

Related standards

ISO 11357‑3 (another method for semi‑crystalline polymers)
ISO 291 (conditioning for testing)
ISO 472 (plastics vocabulary)

Keywords: ISO 3146:2022, melting behaviour, melting temperature, melting range, semi‑crystalline polymers, capillary tube method, polarizing microscope, plastics testing, polymer characterization.

ISO 3146:2022 PDF

Technical details

Abstract

Overview

Key topics and technical requirements

Applications

Who uses this standard

Related standards

Related standards

Abstract

Overview

Key topics and technical requirements

Applications

Who uses this standard

Related standards

Related standards

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