ISO 19935-2:2026
(Main)Plastics — Temperature modulated DSC — Part 2: Measurement of specific heat capacity cp
- Abstract
This document establishes a method for measurement of specific heat capacity, cp, using temperature modulated differential scanning calorimetry.
- Status
- Published
- Publication Date
- 28-May-2026
- Technical Committee
- ISO/TC 61/SC 5 - Physical-chemical properties
- Drafting Committee
- ISO/TC 61/SC 5/WG 8 - Thermal analysis
- Current Stage
- 6060 - International Standard published
- Start Date
- 29-May-2026
- Due Date
- 19-May-2027
- Completion Date
- 29-May-2026
ISO 19935-2:2026 is an International Standard from ISO for measuring the specific heat capacity, cp, of plastics by temperature modulated differential scanning calorimetry (TM-DSC). It specifies a standardized test method for laboratories, researchers, and quality teams that need cp data for data sheets, databases, research, quality assurance, or routine checks.
What does ISO 19935-2:2026 specify?
ISO 19935-2:2026 specifies a method for measuring specific heat capacity, cp, using temperature modulated DSC. The document is organized into clauses 1 to 10, with informative Annexes A to D that give worked examples for polystyrene and calibration.
| Annex | What it covers |
|---|---|
| Annex A | Example cp values of polystyrene (PS) |
| Annex B | Example calibration constant K(ω) from α-Al2O3 literature values |
| Annex C | Example reversing heat flow rate curve and comparison with cp |
| Annex D | Example cp determination using multifrequency modulation |
The introduction explains that the method is intended for standardized thermoanalytical testing and can support data sheets, databases, research, quality assurance, and routine checks, unless special product or atmosphere standards require something different.
What are the key requirements of ISO 19935-2:2026?
ISO 19935-2:2026 sets out how to generate cp from TM-DSC signals, how to prepare and calibrate the instrument, and what to report. In practice, the reader needs to control the modulation, measure the sample consistently, and document the exact test conditions.
Measurement principle and calculation
Clause 5 states that cp is determined from the modulated heat flow signal, which makes the method useful even when a stable baseline is difficult to maintain. For the step scan method, the document uses an isothermal iso-kinetic (iso-K) base line and calculates cp from the heat flow over one cycle. For the general modulated method, cp is calculated from the amplitudes of sample temperature and periodic heat flow, together with sample mass, angular frequency, and the calibration constant K(ω).
Modes of operation
Clause 5 distinguishes cp measurement with no processes, reversing and non-reversing cp, step scan, and multiple frequencies. This matters because the user must choose the mode that fits the material behavior, for example when studying transitions, curing, or crystallization.
Apparatus and temperature control
Clause 6 refers to the apparatus requirements in ISO 19935-1 and adds temperature-control expectations for TM-DSC. The instrument must be able to apply periodic, stepwise, or pulse-sequence modulation with typical amplitudes of ±0.1 K to 2.0 K and frequencies down to 10 mHz on top of an underlying scanning rate typically below 3 K/min. In practice, this means the instrument settings must match the material and the cp range being measured.
Calibration
Clause 7 covers calibration, including modulation amplitude and phase. Accurate calibration is important because the cp result depends on how well the instrument reproduces the imposed temperature modulation and how precisely the signal phase is known.
Procedure and examples
Clause 8 says the general TM-DSC handling steps follow ISO 11357-1, including setup, loading, measurement, and removal of crucibles. It also notes that the chosen modulation conditions depend on the cp value to be determined. The annexes then show examples of the resulting curves and calculations for PS and sapphire.
Reporting and quality limits
Clause 9 states that precision and bias are not known because interlaboratory data were not available at publication. Clause 10 requires the test report to identify the specimen, DSC type, crucible, purge gas, calibration procedure and materials, specimen conditioning, geometry, mass, thermal history, temperature program, mass change, results, and any additional relevant operating details.
What terms does ISO 19935-2:2026 define?
- Temperature modulation - A controlled periodic, stepwise, or pulsed temperature input applied during DSC measurement.
- Scanning rate - The underlying rate at which temperature is changed during the test.
- Heat flow rate - The heat flow signal measured by the DSC instrument, used here to derive cp.
- Specific heat capacity, cp - The heat needed to raise the temperature of a unit mass of material by one kelvin.
- Reversing heat flow rate - The part of the heat flow that follows the temperature modulation and is used to obtain reversing cp.
- Non-reversing heat flow rate - The part of the heat flow associated with processes that do not follow the modulation, such as some transitions or reactions.
- Calibration constant K(ω) - The frequency-dependent factor used in the cp calculation.
Who uses ISO 19935-2:2026?
ISO 19935-2:2026 is used by plastics laboratories, thermal analysis specialists, research teams, and quality assurance staff. It is relevant when producing cp data for material datasheets, databases, routine incoming checks, finished-product checks, and studies of thermal behavior such as curing or crystallization.
What changed in ISO 19935-2:2026 from the previous edition?
ISO 19935-2:2026 cancels and replaces ISO 19935-2:2020 as a minor revision. The main stated change is a correction to the unit for the modulated temperature in the key to Figure 1.
Which standards are used with ISO 19935-2:2026?
- ISO 472 - Provides plastics vocabulary used for terms in this document.
- ISO 11357-1 - Gives the general DSC principles and the procedural steps used for specimen handling and measurement.
- ISO 19935-1 - Provides the general principles for TM-DSC, including symbols, modulation terms, and related operating modes.
- ISO 80000-5 - Supplies quantities and units for thermodynamics.
What does the ISO 19935-2:2026 document contain?
ISO 19935-2:2026 contains the scope, references, terms, symbols, principles, apparatus requirements, calibration, procedure, precision statement, and test-report items. It also includes examples of cp results for polystyrene, a calibration example using α-Al2O3, a reversing heat-flow example, and a multifrequency modulation example. These figures and annexes are there to support calculation, instrument setup, and interpretation of TM-DSC results in practice.
Relations
- Effective Date
- 07-Dec-2025
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Frequently Asked Questions
ISO 19935-2:2026 is a standard published by the International Organization for Standardization (ISO). Its full title is "Plastics — Temperature modulated DSC — Part 2: Measurement of specific heat capacity cp". This standard covers: This document establishes a method for measurement of specific heat capacity, cp, using temperature modulated differential scanning calorimetry.
This document establishes a method for measurement of specific heat capacity, cp, using temperature modulated differential scanning calorimetry.
ISO 19935-2:2026 is classified under the following ICS (International Classification for Standards) categories: 83.080.01 - Plastics in general. The ICS classification helps identify the subject area and facilitates finding related standards.
ISO 19935-2:2026 has the following relationships with other standards: It is inter standard links to ISO 19935-2:2020. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ISO 19935-2:2026 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
International
Standard
ISO 19935-2
Second edition
Plastics — Temperature modulated
2026-05
DSC —
Part 2:
Measurement of specific heat
capacity c
p
Plastiques — DSC à température modulée —
Partie 2: Mesurage précis de la chaleur spécifique c
p
Reference number
© ISO 2026
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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms. 1
4.1 Temperature modulation, T(t) .1
4.2 Scanning rate .1
4.3 Heat flow rate, Φ(t) . .1
5 Principles of determination of specific heat capacity with temperature modulated DSC . 2
5.1 General .2
5.2 Specific heat capacity with no processes .2
5.3 Reversing and non-reversing specific heat capacity .2
5.4 Step scan method .2
5.5 Multiple frequencies .2
6 Apparatus and materials . 2
6.1 General .2
6.2 Temperature control of the modulated differential scanning calorimeter .2
7 Calibration . 3
7.1 General .3
7.2 Calibration of modulation amplitude .3
7.3 Calibration of phase .3
8 Procedure . 3
8.1 General .3
8.2 Calculation of the specific heat capacity .3
8.3 Examples of the results .4
8.3.1 Modulated heat flow rate and scanning rate of modulation .4
8.3.2 Determination of specific heat capacity .4
9 Precision and bias . 5
10 Test report . 5
Annex A (informative) Example of the c values of polystyrene (PS) . 7
p
Annex B (informative) Example of the calibration constant K(ω) determined with the literature
[4]
values of α-Al O . 8
2 3
Annex C (informative) Example of a reversing heat flow rate curve based on a modulated heat
flow rate curve and a comparison with the specific heat capacity . 9
Annex D (informative) Example of determination of specific heat capacity based on a
multifrequency modulated heat flow rate curve .10
Bibliography .13
iii
Foreword
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with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
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This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 5, Physical-
chemical properties.
This second edition cancels and replaces the first edition (ISO 19935-2:2020), of which it constitutes a minor
revision.
The main changes are as follows:
— unit for the modulated temperature in the key to Figure 1 has been corrected.
A list of all parts in the ISO 19935 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
This document describes the realization of standardized thermoanalytical test methods which can be
used for the determination of specific heat capacity data needed for data sheets or databases as well as for
research purposes. It can also be applied to quality assurance or to routine checks of raw materials and
finished products, if desired. The procedures mentioned in this document apply as long as special product
standards or standards describing special atmospheres for conditioning of samples do not require alternate
regulations.
For scientific investigations or resolution of special analytical problems, all technical capabilities of the
instruments beyond the regulations of this document may be used.
v
International Standard ISO 19935-2:2026(en)
Plastics — Temperature modulated DSC —
Part 2:
Measurement of specific heat capacity c
p
1 Scope
This document establishes a method for measurement of specific heat capacity, c , using temperature
p
modulated differential scanning calorimetry.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 472, Plastics — Vocabulary
ISO 11357-1, Plastics — Differential scanning calorimetry (DSC) — Part 1: General principles
ISO 19935-1, Plastics — Temperature modulated DSC — Part 1: General principles
ISO 80000-5, Quantities and units — Part 5: Thermodynamics
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 472 , ISO 11357-1, ISO 19935-1 and
ISO 80000-5 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Symbols and abbreviated terms
4.1 Temperature modulation, T(t)
Temperature modulation shall be in accordance with ISO 19935-1.
4.2 Scanning rate
Scanning rate shall be in accordance with ISO 19935-1.
4.3 Heat flow rate, Φ(t)
Heat flow rate shall be in accordance with ISO 19935-1.
5 Principles of determination of specific heat cap
...