🔩 General principles of differential scanning calorimetry (DSC) of polymers and polymer blends — thermoplastics, thermosets and elastomers; definitions (DSC, reference crucible, heat flow rate, change in heat ΔQ, specific heat capacity cp, instrument, specimen and virtual baselines, step, endothermic and exothermic peak, peak area, height and width) and characteristic temperatures Ti, Tei, T1/2, Tp, Tef, Tf with subscripts g, c, m; common basis of the further parts of the ISO 11357 series, PN-EN ISO 11357-1

Materials and NDT PN-EN ISO 11357-1

Overview

WHAT THE STANDARD COVERS. We read the text of the standard in two iTeh samples: SIST EN ISO 11357-1:2023 (English text) — from the title page through the contents, foreword, introduction and Clauses 1–2 to the introduction of Clause 3 on page 1 — and ISO 11357-1:2023 (French version) — Clause 3 from 3.1 to 3.10 with the key to Figure 2 (characteristic temperatures) on page 7 inclusive. Outside the samples remain Clauses 4 (principles: heat-flux and power-compensation DSC), 5 (apparatus and materials), 6 (specimen), 7 (test conditions and conditioning), 8 (temperature, heat and heat flow rate calibration), 9 (procedure: purge gas, baseline, crucibles, specimen mass, scanning and isothermal mode, post-run checks), 10 (test report) and Annexes A–E (among them recommended calibration materials).

ACCORDING TO THE TEXT OF ISO 11357-1:2023 (foreword, introduction, Clauses 1–3, to 3.10 and Figure 2). The standard was prepared by ISO/TC 61/SC 5 “Physical-chemical properties” in collaboration with CEN/TC 249 “Plastics” under the Vienna Agreement; the fourth edition replaced ISO 11357-1:2016; main changes: the examples of materials for temperature and enthalpy calibration were updated, as were the sapphire data for heat flow rate calibration. According to the introduction the methods of the series can be used for quality assurance, routine checks of raw materials and finished products or for obtaining comparable data for data sheets and databases, as long as product standards or standards for conditioning atmospheres do not specify otherwise. Scope (1): the ISO 11357 series covers DSC methods for the thermal analysis of polymers and polymer blends — thermoplastics (polymers, moulding compounds and other moulding materials, with or without fillers, fibres or reinforcements), thermosets (uncured or cured) and elastomers — for observing and measuring physical transitions (glass transition, melting, crystallization, polymorphic transitions), chemical reactions (polymerization, crosslinking, curing), oxidation stability and heat capacity; Part 1 specifies the common aspects: principle, apparatus, sampling, calibration, general procedure and report, while the further parts give the details of the methods. Normative references (2): ISO 472 (plastics vocabulary) and ISO 80000-5 (thermodynamic quantities). Terms (3): DSC — technique in which the difference between the heat flow rates into the specimen crucible and the reference crucible is derived as a function of temperature or time, under the same controlled temperature programme and specified atmosphere, in a symmetrical system; the curve is plotted with temperature or time on the abscissa, with the endothermic direction up and the exothermic down (energy absorbed positive); calibration material — with homogeneous and well-known thermal properties, for calibrating the instrument or evaluating a method; reference crucible — normally empty, for highly filled or reinforced specimens or specimens with a heat capacity comparable to the crucible it may contain a thermally inert material of similar heat capacity (e.g. the filler alone); heat flow rate dQ/dt in W or mW; change in heat ΔQ — heat absorbed (positive) or released (negative) over a time or temperature range, ΔQ = ∫dQ/dt dt or (60/β)∫dQ/dt dT, in J, J/g or J/mol, β — constant heating or cooling rate in K/min; at constant pressure ΔQ = ΔH; specific heat capacity cp = (1/m)(dQ/dT)p = (1/m)(60/β)(dQ/dt)p in J/(g·K), the measured cp must not include heat of reaction or transition; baseline — part of the curve without reactions or transitions (isothermal or dynamic), in the quasi-steady-state range; instrument baseline — with empty crucibles of the same mass and material, needed for heat capacity measurements; specimen baseline — outside transition zones, dependent only on the specimen heat capacity and the instrument baseline; virtual baseline — drawn through the transition zone assuming zero heat of transition, by interpolation or extrapolation (with linear change in heat capacity a straight line, with a large change — sigmoidal); step — abrupt change in curve height over a limited temperature range (e.g. glass transition), its height measured between the extrapolated baselines at the point of the curve equidistant from both; peak — deviation from the specimen baseline to a maximum or minimum and return (chemical reaction or first-order transition); endothermic peak — more heat flows into the specimen crucible than into the reference crucible, exothermic — less; peak area — between the peak and the interpolated virtual baseline; peak height in W or W/g is not necessarily proportional to specimen mass; peak width — between the start and end temperatures or times; characteristic temperatures and times are read from the curve, and the temperature at the reference position is preferred — if the temperature at the specimen position is used, this shall be stated in the report; temperatures in °C, differences in K, times in s or min. Figure 2: Ti — first detectable deviation from the extrapolated initial baseline, Tei — intersection of the virtual baseline (or the extrapolated initial baseline for a step) with the tangent at the inflection point of the start of the peak or step, T1/2 — half step height, Tp — temperature of the greatest distance of the curve from the virtual baseline in the peak, Tef — the corresponding intersection at the end, Tf — last detectable deviation from the extrapolated final baseline; second subscript: g — glass transition, c — crystallization, m — melting.

STATUS (as of 03.10.2026). The PKN search (term “PN-EN ISO 11357-1”, 03.10.2026) shows PN-EN ISO 11357-1:2023-09 (English version, “Introduces: EN ISO 11357-1:2023 [IDT], ISO 11357-1:2023 [IDT]”) without a withdrawal note and three earlier withdrawn editions: PN-EN ISO 11357-1:2016-11 (replaced by 2023-09), PN-EN ISO 11357-1:2009 (replaced by 2016-11) and PN-EN ISO 11357-1:2002 (Polish version, replaced by 2009). In the iTeh catalogue (read on 03.10.2026) ISO 11357-1:2023 and EN ISO 11357-1:2023 have the status “Published” (stage 60.60, 17.02.2023 and 08.03.2023 respectively). The determination of the temperature and enthalpy of melting and crystallization according to Part 3 is described in a separate entry.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, load up to 17.09.2026, read on 03.10.2026). The number 11357-1 appears in 8 records at 5 laboratories: AB 163 (3), AB 1376 (2), AB 1490, AB 1882, AB 1907. In the current PCA documents (read on 03.10.2026, issues from 03.04.2025 to 02.07.2026) the number appears in 8 rows of the same laboratories (AB 163 — 3, AB 1376 — 2, the others 1 each); in none of the five documents are page numbers repeated. Always together with a specific part: with PN-EN ISO 11357-2:2020-09 (glass transition; AB 163, AB 1376), PN-EN ISO 11357-3 (melting and crystallization; in the 2018-06 edition at AB 1376, 2025-12 at AB 163, AB 1882 and AB 1907, at AB 1882 also “ISO 11357-3:2025”), PN-EN ISO 11357-6:2025-12 and PN-EN 728:1999 (oxidation induction time; AB 163), at AB 1490 with “PN-EN-ISO 11357-2”, “PN-EN-ISO 11357-3” and ASTM D3418. The form “PN-EN ISO 11357-1:2023-09” at four laboratories, “PN-EN ISO 11357-1” without year at AB 1490. None of these items is suspended. The “Laboratories” tab (term “PN-EN ISO 11357-1”) shows 4 laboratories: AB 163, AB 1490, AB 1882 and AB 1907; AB 1376 is under “PN-EN ISO 11357-2”, because that designation stands first there — checked with tab queries on the production server labcoda.pl on 03.10.2026.

WHAT THE LABORATORIES TEST (items in PCA). Plastics and plastic products (AB 163, AB 1376, AB 1882), composites and plastics (AB 1490), plastics, thermoplastic polymers and plastics, recycled thermoplastic materials (AB 1907). Characteristics: glass transition temperature (AB 163, AB 1376, AB 1490), temperature and enthalpy of melting and crystallization (all five), oxidation induction time (AB 163); differential scanning calorimetry (DSC) method. Temperature ranges: (0–300) °C (AB 1376), (35–450) °C (AB 1882), (30,0–400,0) °C (AB 1907), from −40 °C to +500 °C (AB 1490).

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. With the axis direction: endothermic up, exothermic down — the reverse convention changes the sign of ΔQ (3.1, Note 2). With temperature: the temperature at the reference position is preferred; use of the specimen temperature must be recorded in the report (3.10). With the peak baseline: a straight line only without significant change in heat capacity, otherwise sigmoidal; interpolated and extrapolated lines may differ (3.7.3). With cp: the result must not include heat of reaction or transition, and an instrument baseline with empty crucibles is needed (3.6, 3.7.1). With peak height: not proportional to specimen mass (3.9.4). With the reference crucible: normally empty; filling only with thermally inert material (3.3). With the reference: Part 1 alone is not sufficient — the determination is carried out according to the relevant further part of the series.

WHAT WE DO NOT GIVE. We did not read the design of the instruments, the requirements for the specimen and its mass, purge gas, heating rate, calibration procedures and calibration materials, measuring modes, post-run checks or the report form (Clauses 4–10, Annexes A–E).

Method principle

In DSC the specimen crucible and the reference crucible undergo the same controlled temperature programme in a specified atmosphere, and the instrument in a symmetrical system derives the difference in heat flow rates as a function of temperature or time. On the curve first-order transitions and reactions give peaks (endothermic up, exothermic down) and the glass transition gives a step; the heat of transition is obtained from the peak area above the virtual baseline, and the characteristic temperatures Ti, Tei, T1/2, Tp, Tef, Tf from the intersections of tangents and baselines.

Applications

• Thermoplastics, thermosets and elastomers, with or without fillers or reinforcements (1)
• Glass transition, melting, crystallization, curing reactions, oxidation stability, specific heat capacity — together with the further parts of ISO 11357 (1)
• Plastics, composites and recycled plastics — DSC items in the accreditation scopes of 5 laboratories in PCA

Key parameters

Standard

Standard number

PN-EN ISO 11357-1:2023-09

Title (PL)

Tworzywa sztuczne — Różnicowa kalorymetria skaningowa (DSC) — Część 1: Zasady ogólne

Title (EN)

Plastics — Differential scanning calorimetry (DSC) — Part 1: General principles

Step-by-step procedure

1. Choice of part of the series

   Determination according to the relevant part of ISO 11357 (e.g. 2 — glass transition, 3 — melting and crystallization); Part 1 gives common principles. PN-EN ISO 11357-1:2023-09 without a withdrawal note (03.10.2026).

2. Calibration

   Temperature, heat and heat flow rate according to Clause 8 (not read) on calibration materials (3.2).

3. Baseline and specimen

   Instrument baseline with empty crucibles; specimen in the crucible, reference normally empty (3.3, 3.7.1).

4. Measurement

   Controlled temperature programme in a specified atmosphere; recording of the heat flow rate difference (3.1).

5. Evaluation of the curve

   Virtual baseline, peak area (ΔQ), temperatures Ti, Tei, Tp, Tef, Tf or T1/2 of a step; in the report the position of temperature measurement (3.7.3, 3.9, 3.10).

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Hot crucibles and measuring cell — risk of burns
• Decomposition of specimens at high temperature — exhaust of gases from the instrument

Frequently asked questions