🔩 Determination of the temperature and enthalpy of melting and crystallization of crystalline and partially crystalline plastics by differential scanning calorimetry (DSC) — first heating, cooling and second heating, peak temperatures and heat of transition from the peak area, PN-EN ISO 11357-3

Materials and NDT PN-EN ISO 11357-3

Overview

WHAT THE STANDARD COVERS. Scope from the PKN catalogue card of PN-EN ISO 11357-3:2025-12 (English version), in full (our translation): “This document specifies a method for the determination of the temperatures and enthalpies of melting and crystallization of crystalline or partially crystalline plastics using conventional DSC as specified in ISO 11357-1. This document is not applicable to fast scanning DSC as specified in ISO 23976”. The scope of the 2018-06 edition (PKN card) ended with “plastics” — without the sentences on conventional and fast scanning DSC. We do not have the text of the 2025 edition. We read the text of the previous edition — the sample of ISO 11357-3:2018 (the same was introduced by PN-EN ISO 11357-3:2018-06) from the cover to Clause 12 (test report); only the bibliography is missing.

ACCORDING TO THE TEXT OF ISO 11357-3:2018. The standard was prepared by ISO/TC 61 “Plastics”, subcommittee SC 5 “Physical-chemical properties”; the third edition replaced the second (ISO 11357-3:2011) after a technical revision. Main changes compared with 2011 (foreword): updated normative references; the sample mass refers to the polymer matrix; the procedure has been extended to materials with wider crystallization ranges; the calculation of heats of transition has been clarified to include computer-aided methods. References (2): ISO 472 (vocabulary) and ISO 11357-1 (general principles). Terms (3): melting — transition from a fully or partially crystalline solid state to an amorphous liquid of variable viscosity, an endothermic peak on the DSC curve; crystallization — the reverse transition, an exothermic peak (for liquid crystals “amorphous liquid” is replaced by “ordered liquid”); enthalpy of fusion and enthalpy of crystallization in kJ/kg or J/g. Principle, apparatus and materials, test specimen, test conditions and conditioning, calibration, setting up the apparatus and insertion of crucibles (4–9.3) — according to ISO 11357-1. Specimen mass (9.2): unless otherwise specified in the material standard, preferably 5 mg to 10 mg; with high heats of transition lower masses may be used, with low heats higher masses; for polymer compounds the mass refers to the matrix polymer. Temperature scan (9.4): other heating and cooling rates are allowed by agreement between the interested parties — a high rate gives a larger effect of the transition, a low rate better resolution of overlapping transitions; 5 min nitrogen pre-purge before heating; first heating (recorded) to a temperature that erases the thermal history, typically 30 K above the extrapolated end melting temperature Tef,m, preferably 10 K/min or 20 K/min (higher rates allowed); the measurement is taken from the second heating, and data from the first only for a reactive material or when the properties of a specially pre-conditioned specimen are evaluated, with this deviation recorded in the test report; hold for 5 min (longer if the polymer does not degrade); cooling (recorded) preferably at 10 K/min or 20 K/min to about 50 K below the extrapolated end crystallization temperature Tef,c — with a note on supercooling — and, if glass transitions are evaluated too, to 50 K below the glass transition temperature; another hold of 5 min (note: the point is to create a defined thermal history, needed for a correct result); second heating (recorded) preferably at the same rate as the cooling, to about 30 K above Tef,m; after cooling down, a check whether the crucible has deformed and whether the specimen has overflowed; reweighing of the crucible with the specimen unless the material is known not to lose mass — in case of significant loss, repetition with more strongly dried specimens is considered. Temperatures (10.1): the plot is scaled so that the peak covers at least 25 % of full scale; the baseline is drawn from the initial temperature Ti,m to the end temperature Tf,m at which the peak deviates from the relatively straight baseline; with multiple peaks the baseline covers all of them, and the evaluation is divided between the peaks where possible (the peak separation technique is stated in the test report); for melting, the peak temperature Tp,m of each peak is reported (onset of melting on request), for crystallization the extrapolated onset temperature Tei,c and the peak temperature Tp,c; extrapolated onset and end temperatures — when the peak width is of interest. Enthalpy (10.2): area under the peak to the baseline; ΔHf or ΔHc = ΔHCal · (A · mCal)/(ACal · m), where ΔHCal is the enthalpy of transition of the calibration material, A and ACal the peak areas of the specimen and the calibration material, m and mCal their masses; units of area and mass in calibration and measurement must be the same; with a significant difference between the specific heat capacities of the solid and liquid states, special baselines (e.g. sigmoidal) can improve the result. Precision (11): not known, no interlaboratory data. Test report (12): according to ISO 11357-1 plus the characteristic temperatures of each peak in °C and the enthalpy change ΔHf or ΔHc of each peak in kJ/kg (or J/g), to one decimal place; the peak separation technique, if applied.

STATUS (PKN catalogue cards as of 02.10.2026). The card of PN-EN ISO 11357-3:2025-12 (English version, published 04-12-2025, 20 pages, price group K) has no “Withdrawn” header: Chemical Sector, KT 141 Plastics, ICS 83.080.01, “Introduces: EN ISO 11357-3:2025 [IDT], ISO 11357-3:2025 [IDT]”, “Replaces: PN-EN ISO 11357-3:2018-06 – English version”. The card of PN-EN ISO 11357-3:2018-06 (English version, 18 pages) has the header “Withdrawn and replaced by PN-EN ISO 11357-3:2025-12”: withdrawal date 04-12-2025, “Replaces: PN-EN ISO 11357-3:2013-06”. The PKN search engine (query “PN-EN ISO 11357-3”, 02.10.2026) shows the 2013-06, 2018-06 and 2025-12 editions, all in English. EVS: ISO 11357-3:2025 valid from 29.05.2025, with ISO 11357-3:2018 in its history. What changed for the result: the scope of the 2025 edition specifies that the method concerns conventional DSC according to ISO 11357-1, not fast scanning DSC according to ISO 23976; we do not know other changes of the 2025 edition, as we do not have its text.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, data up to 17.09.2026, read 02.10.2026). The number 11357-3 appears in 7 records of 7 laboratories: AB 128, AB 163, AB 1376, AB 1447, AB 1490, AB 1882, AB 1907. In the current scopes on the PCA website (read 02.10.2026, issues from 03.04.2025 to 02.07.2026) AB 163, AB 1447 and AB 1907 cite the 2025-12 edition, AB 1882 — ISO 11357-3:2025 and PN-EN ISO 11357-3:2025-12, AB 1376 — the withdrawn 2018-06 edition, AB 128 — “PN-EN ISO 11357-3” without a date, and AB 1490 — “PN-EN-ISO 11357-3” without a date. The “Laboratories” tab: “PN-EN ISO 11357-3” — 6 laboratories (AB 128, AB 163, AB 1376, AB 1447, AB 1882, AB 1907), “ISO 11357-3” — 2 (AB 1882 and 1 Czech) — checked with queries of the tab on the labcoda.pl production server on 02.10.2026.

WHAT THE LABORATORIES TEST (PCA entries). “Temperature and enthalpy of melting and crystallization” (AB 163, AB 1376, AB 1882, AB 1907) or of melting alone (AB 1447) in plastics and plastic products, including thermoplastics (AB 1907); temperature ranges: (0–300) °C (AB 1376), (30.0–400.0) °C (AB 1907), (35–450) °C (AB 1882); “Melting point and glass transition temperature”, up to 400 °C (AB 128, alongside ISO 11357-2); calorimetric DSC tests: enthalpy and temperature of melting and crystallization and glass transition temperature, from −40 °C to +500 °C (AB 1490, alongside ASTM D3418 and parts 1 and 2 of the series).

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. With thermal history: the result is taken from the second heating; data from the first are allowed only for a reactive material or a specially pre-conditioned specimen and must be recorded in the test report (9.4.3). With the rate: a rate other than 10 K/min or 20 K/min changes the size of the effect and the resolution, which is why it requires agreement between the parties (9.4.1). With the mass: for polymer compounds the mass refers to the matrix polymer, not to the whole specimen (9.2) — an enthalpy calculated on the whole mass comes out lower. With the baseline: with multiple peaks the baseline covers all peaks, and the separation technique is stated in the test report (10.1). With mass loss: without reweighing it is not known whether the specimen lost mass during the measurement (9.4.9). With the glass transition: this part concerns melting and crystallization (scope) — the glass transition temperature is in the entries of AB 128 and AB 1490, alongside which ISO 11357-2 is cited, while AB 163 and AB 1376 have the glass transition as a separate entry according to PN-EN ISO 11357-2:2020-09. With the edition: AB 1376 has in its scope the 2018-06 edition, withdrawn on 04-12-2025.

WHAT WE DO NOT GIVE. We do not have the text of ISO 11357-1 (principle, apparatus, crucibles, gas, calibration and calibration materials, conditioning), or the text of the 2025 edition — so we give no apparatus requirements, calibration materials or differences between the 2018 and 2025 editions beyond the scope. The standard gives no precision (Clause 11).

Method principle

A plastic specimen in a crucible and a reference crucible are heated and cooled in a controlled way while the heat flow rate is recorded. Melting gives an endothermic peak, crystallization an exothermic one. After a first heating that erases the thermal history, the specimen is cooled and heated again; temperatures are read from the peaks, and the enthalpy of transition is calculated from the peak area above the baseline by comparing it with the peak area of a calibration material of known enthalpy, taking the masses of both specimens into account.

Applications

• Melting and crystallization temperatures and heats of transition of crystalline and partially crystalline plastics (e.g. thermoplastics) — 7 laboratories in PCA scopes
• Plastic products and composites — comparison of the crystalline state of the material with the requirement of a material standard or specification
• Polymer compounds and filled plastics — enthalpy referred to the mass of the matrix polymer

Key parameters

Standard

Standard number

PN-EN ISO 11357-3:2025-12 (wersja angielska; EN ISO 11357-3:2025 IDT, ISO 11357-3:2025 IDT)

Title (PL)

Tworzywa sztuczne — Różnicowa kalorymetria skaningowa (DSC) — Część 3: Oznaczanie temperatury oraz entalpii topnienia i krystalizacji

Title (EN)

Plastics — Differential scanning calorimetry (DSC) — Part 3: Determination of temperature and enthalpy of melting and crystallization

Step-by-step procedure

1. Preparation

   Apparatus, specimen, conditioning and calibration according to ISO 11357-1; specimen preferably 5–10 mg, for compounds referred to the matrix polymer. PN-EN ISO 11357-3:2025-12 current (PKN cards as of 02.10.2026).

2. First heating

   5 min nitrogen pre-purge; heating (recorded) preferably at 10 or 20 K/min to approx. 30 K above Tef,m to erase the thermal history; hold for 5 min.

3. Cooling

   Cooling (recorded) preferably at 10 or 20 K/min to approx. 50 K below Tef,c (when evaluating the glass transition — 50 K below Tg); hold for 5 min.

4. Second heating and specimen check

   Heating (recorded) at the same rate to approx. 30 K above Tef,m; after cooling down, inspection of the crucible and reweighing.

5. Evaluation of results

   Baseline from Ti to Tf, peak ≥ 25 % of scale; Tp,m from the second heating, Tei,c and Tp,c from the cooling; enthalpy from the peak area according to Formula (1); temperatures in °C, ΔH in kJ/kg or J/g to one decimal place.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• The standard contains no safety warnings in the text read; when heating plastics above the melting temperature, decomposition of the material must be taken into account (9.4.4: a longer hold only without degradation of the polymer)
• TECHNICAL NOTE: data from the first heating are not a result according to the standard unless the material is reactive or a specially pre-conditioned specimen is tested — the deviation is recorded in the test report

Frequently asked questions