ISO/TR 19032:2026

Plastics — Use of polyethylene reference film (PERF) for monitoring laboratory and outdoor weathering conditions

This document describes a method that demonstrates the use of polyethylene reference film (PERF) for monitoring laboratory and outdoor conditions as a weathering reference material in weathering tests used for plastics.

Plastiques — Utilisation d'un film de référence en polyéthylène (PERF) pour le contrôle des conditions de vieillissement climatique en laboratoire et en extérieur

General Information

• Status: Published
• Publication Date: 18-Jun-2026
• ICS: 83.080.01 - Plastics in general
• Technical Committee: ISO/TC 61/SC 6 - Ageing, chemical and environmental resistance
• Drafting Committee: ISO/TC 61/SC 6/WG 2 - Exposure to light
• Current Stage: 6060 - International Standard published
• Start Date: 19-Jun-2026
• Due Date: 28-Sep-2026
• Completion Date: 19-Jun-2026

Relations

• Revises: ISO/TR 19032:2019 - Plastics — Use of polyethylene reference specimens (PERS) for monitoring laboratory and outdoor weathering conditions
• Effective Date: 21-Oct-2023

Overview

ISO/TR 19032 is a technical report published by the International Organization for Standardization (ISO) that provides guidance on the use of polyethylene reference film (PERF) as a tool for monitoring laboratory and outdoor weathering conditions in plastics testing. This document describes the method and significance of utilizing PERF as a weathering reference material, enabling reliable assessment and comparison of environmental impacts-such as UV radiation and temperature-on plastics exposed to both natural and artificial conditions.

Key Topics

• Polyethylene Reference Film (PERF)
  • PERF serves as a standard reference material with known response characteristics when subjected to weathering.
  • Used to monitor and compare the ageing conditions in weathering tests on plastics.
• Weathering Conditions
  • Encompasses both laboratory-controlled (artificial) and outdoor (natural) environments.
  • Focuses predominantly on the combined effects of UV radiation and temperature.
• Carbonyl Index Measurement
  • PERF’s degradation is measured using the carbonyl index, calculated by FTIR spectroscopy, which reflects the formation of oxidized groups due to photo-oxidation.
  • The increase in the carbonyl index indicates the extent of polymer oxidation and ageing.
• Interlaboratory Comparisons
  • The standard highlights interlaboratory studies conducted to validate PERF’s sensitivity and reliability across different devices and conditions.

Applications

• Quality Control in Weathering Tests
  • Laboratories use PERF to ensure consistent exposure conditions in weathering chambers, providing a benchmark to compare artificial ageing rates.
• Outdoor Exposure Monitoring
  • PERF is deployed in field tests to monitor environmental effects on plastics, supporting product durability studies exposed to real-world weathering.
• Calibration and Device Verification
  • Testing facilities utilize PERF to calibrate weathering devices (xenon-arc lamp, fluorescent UV lamp, medium pressure mercury vapor lamp) and to detect deviations in operational parameters.
• Comparative Ageing Assessments
  • PERF enables manufacturers and researchers to compare the impact of different environments on plastic materials and to evaluate the performance of new formulations under accelerated ageing conditions.

Related Standards

• ISO 472: Plastics - Vocabulary
  Provides standard terminology for plastics, ensuring a common language for reference materials and weathering processes.
• ISO 4892 Series: Plastics - Methods of exposure to laboratory light sources
  Specifies exposure procedures for plastics under laboratory light sources such as xenon-arc and fluorescent UV lamps, frequently referenced for test conditions.
• ISO 877 Series: Plastics - Methods of exposure to direct weathering
  Outlines protocols for outdoor exposure testing, complementing the use of PERF in natural weathering assessments.
• ISO 10640: Practice for IR spectrometric analysis
  Details measurement methods including FTIR, relevant to assessing photo-oxidation in PERF.

Practical Value

Using ISO/TR 19032 and PERF elevates the reliability and comparability of weathering test results, making it easier for plastics professionals to:

• Monitor and verify environmental test conditions.
• Detect inconsistencies or faults in weathering equipment.
• Achieve harmonized reporting of plastics durability across different testing facilities and geographies.
• Support product R&D and regulatory compliance by providing traceable evidence of material performance under UV and temperature exposure.

By integrating PERF and the guidance in ISO/TR 19032 into routine weathering analysis, organizations can improve the integrity of plastics testing and accelerate innovation in materials designed for prolonged outdoor use.

Standards Content (Sample)

Technical
Report
ISO/TR 19032
Third edition
Plastics — Use of polyethylene
2026-06
reference film (PERF) for
monitoring laboratory and outdoor
weathering conditions
Plastiques — Utilisation d'un film de référence en polyéthylène
(PERF) pour le contrôle des conditions de vieillissement
climatique en laboratoire et en extérieur
Reference number
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 1
5 Background information . 1
6 Material. 2
6.1 Properties .2
6.2 Preparation .3
7 Method for measuring the carbonyl index of PERF . 3
8 Interlaboratory tests: exposure of PERF to laboratory light-sources. 4
8.1 General .4
8.2 Protocol for the artificial exposures .5
8.2.1 General .5
8.2.2 Xenon-arc lamp exposure .5
8.2.3 Fluorescent UV lamp exposure .5
8.2.4 Medium pressure mercury vapour lamp exposure.6
8.2.5 Measurement of the carbonyl index C .6
i
8.3 Outdoor exposure test of PERF .6
8.4 Results and discussion .6
8.4.1 Artificial exposures of PERF to laboratory light-source . .6
8.4.2 Exposure of PERF to natural outdoor conditions .17
8.5 Conclusion .19
Annex A (informative) History of polyethylene reference specimens (PERS) .21
Bibliography .23

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
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
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 6, Ageing,
chemical and environmental resistance.
This third edition cancels and replaces the second edition (ISO/TR 19032:2019), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— the reference material has been replaced;
— the physicochemical properties and the use of new PERF are described;
— results of interlaboratory tests with new PERF are detailed and commented.
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 physicochemical properties of polyethylene reference film (PERF) as well
as a method for using PERF as a weathering reference material to monitor the performance of natural or
artificial exposures. Under the action of UV radiation and heat, polyethylene materials undergo photo-
oxidation reactions leading to the formation and accumulation of various oxidation products. Among the
compounds formed during these photochemical processes, carboxylic acids end-groups are easily detected
by their specific infrared absorption in the carbonyl domain. Measuring the relative concentration of
carboxylic acids groups allows calculating a carbonyl index that reflects the polymer oxidation level. The
photo-oxidation rates being directly dependent on the environmental factors and especially UV radiation
and heat, determining the change in the carbonyl index of PERF during natural or artificial exposures allows
monitoring polymer ageing conditions.

v
Technical Report ISO/TR 19032:2026(en)
Plastics — Use of polyethylene reference film (PERF) for
monitoring laboratory and outdoor weathering conditions
1 Scope
This document describes a method that demonstrates the use of polyethylene reference film (PERF) for
monitoring laboratory and outdoor conditions as a weathering reference material in weathering tests used
for plastics.
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 472:2013, Plastics — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 472 and the following 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 https:// www .electropedia .org/
3.1
weathering reference material
material of known performance when exposed to solar radiation, heat, and moisture
Note 1 to entry: Weathering reference materials are used for weathering and irradiation testing.
Note 2 to entry: A weathering reference material is typically commercially available.
[1]
[SOURCE: ISO 4892-1:2024 , 3.5, modified – Note 2 to entry added]
4 Abbreviated terms
PERF Polyethylene reference film
PERS Polyethylene reference specimens
FTIR Fourier transform infrared
5 Background information
When subjected to natural or artificial environmental stresses (such as heat, light or humidity), polymer
[2]
materials are likely to degrade by photo-oxidative pathways. The rate of polymer photo-oxidation mainly
depends on two factors: spectral irradiance and temperature. However, the temperature dependence being
linked to an exponential law involving an activation energy (similar to an Arrhenius law), the influence of the
temperature on the global oxidation rate is the most important. Photo-initiated processes lead to thermally

activated oxidation reactions responsible for chain scissions of the polymer backbone and to the formation
[3],[4]
of a variety of oxidations products, including hydroperoxides, ketones, carboxylic acids, esters, lactones,
[5],[6]
etc. Some of these compounds are not retained by the polymer matrix because they are volatile whereas
other ones accumulate in the material as new functional groups linked to the polymer chains (often as end-
groups). Chain cleavages of polymer materials through oxidation reactions are often responsible for loss
of functional properties (such as aspect degradation or decrease in mechanical properties). Monitoring
the environmental conditions leading to these phenomena requires therefore precise and simultaneous
measurements of irradiance and temperature. Another way to evaluate environmental conditions consists
in monitoring the degradation of a suitable reference material whose oxidation rate was previously well
[7],[8],[9],[10]
characterized. This document refers to this approach and describes the properties and the use
of polyethylene reference film (PERF) to evaluate environmental ageing conditions resulting from the
combined effect of temperature and UV irradiance.
NOTE 1 The first and second edition of this document referred to PERS (polyethylene reference specimens) that
[7],[8],[9],[10]
were produced by the Japan Weathering Test Center. This material is no longer available (see Annex A).
NOTE 2 Relative humidity and wetness have no influence on PERF or this influence is unknown.
6 Material
6.1 Properties
Some physicochemical properties of PERF are reported in Table 1.
Table 1 — Physicochemical properties of PERF
Property Range of values Test method

a [27]
Relative infrared (IR) absorbance of vinylidene insaturations 0,6 to 0,8 ASTM E168
b [27]
Relative IR absorbance of carbonyl compounds (ketones) < 0,15 ASTM E168
3 [21]
Density 920 to 924 kg/m ISO 1183-1
[20]
Melt flow rate (temperature 190 °C, load 2,16 kg) 0,2 to 0,4 g/10 min ISO 1133-1
c [23]
Melting point 110-120 °C ISO 11357-3
c [23]
Crystallinity 20 to 40 % ISO 11357-3
d [25]
Number average molar mass (Mn) 25 000 g/mol to ISO 16014-4
40 000 g/mol
d [25]
Mass average molar mass (Mw) 400 000 g/mol to ISO 16014-4
600 000 g/mol
d [25]
Polydispersity index (PDI) 10 to 20 ISO 16014-4
e [26]
Thermal phenolic stabilizer content < 20 ppm ASTM D6953
[24]
Oxidation induction time (OIT) at 210 °C < 1 min ISO 11357-6
[22]
Film thickness 0,15 ± 0,02 mm ISO 4593
a
Determined by FTIR spectroscopy in transmission mode by calculating the ratio A /A , A corresponding to the
888 2 020 888
-1 -1
IR absorbance of vinylidene groups at 888 cm and A to the absorbance at 2020 cm of a polyethylene thickness correction
2 020
band.
b
Determined by FTIR spectroscopy in transmission mode by calculating the ratio A /A , A corresponding to the
1 723 2 020 1 723
-1 -1
IR absorbance of carbonyl compounds at 1 723 cm and A to the absorbance at 2020 cm of a polyethylene thickness
2 020 cm-1
correction band.
c
Determined by differential scanning calorimetry (DSC). The crystallinity was calculated using a heat of fusion of a 100 %
crystalline polyethylene of 293 J/g.
d
Determined by gel permeation chromatography (GPC) using a polystyrene calibration curve. The molar masses are therefore
expressed as “polystyrene-equivalent molecular weight”.
e
Determined by high-performance liquid chromatography (HPLC).

6.2 Preparation
PERF are made of a free-radical polymerized low-density polyethylene produced by a high-pressure
autoclave process. The films are obtained by blown film extrusion at 200 °C.
NOTE 1 The only known supplier of PERF at the time of publication of this document is the National Centre for
Evaluation of Photoprotection (Centre National d’Evaluation de Photoprotection, CNEP) in France. This information
is given for the convenience of users of this document and does not constitute an endorsement by ISO of the product
named. Equivalent products may be used if they can be shown to lead to the same results.
NOTE 2 Former PERS were obtained from a high-density polyethylene material polymerized with molybdenum
dioxide as a catalyst containing trans-form vinylene groups. The specimens were produced by a compression process.
The physicochemical properties as well as the production method being different, results obtained with former PERS
described in the first and second edition of this document are not comparable to the ones obtained with the new
material of this edition of this document (see Annex A).
7 Method for measuring the carbonyl index of PERF
[11]
An FTIR spectrophotometer is used in accordance with ISO 10640. The FTIR spectrum of PERF is
recorded in transmission mode after natural or artificial exposure in a range comprising at least the interval
–1 –1
(2 200 cm to 1 600 cm ).
A scanning speed suitable for a quantitative analysis is used and all preliminary steps for reliable FTIR
analyses (such as an atmosphere baseline acquisition) are performed prior to the measurements. The FTIR
-1 -1
spectrum of the exposed PERF is then used to measure the IR absorbance at 2 020 cm and 1 715 cm . The
–1
IR absorption at 2 020 cm is employed as an internal standard to correct potential thickness variations
–1
of the film while the IR band at 1 715 cm corresponds to the content of carboxylic groups formed in the
film by the photo-oxidation processes. A theoretical IR spectrum of an oxidized PERF (after exposure)
is shown in Figure 1. The absorbance of the two infrared bands is determined by a tangent method that
-1 -1
consists in measuring the absolute absorbance at each wavenumber, i.e. 2 020 cm and 1 715 cm , and in
subtracting the absorbance of a hypothetic baseline corresponding to each band. The baseline is a straight
-1 -1
line connecting the values of the spectrum comprised between 1 850 cm and 1 660 cm for the band at
-1 -1 -1 -1
1 715 cm , and between 2 100 cm and 1 980 cm for the band at 2 020 cm (see Figure 1).

Key
−1
X wavenumber (cm )
Y FTIR absorbance
−1
1 IR absorption at 2 020 cm
−1
2 IR absorption at 1 715 cm
-1
3 IR absorption at 2 100 cm
-1
4 IR absorption at 1 980 cm
-1
5 IR absorption at 1 850 cm
-1
6 IR absorption at 1 660 cm
Figure 1 — Theoretical FTIR spectrum of photo-oxidized PERF
The carbonyl index, C , is calculated according to Formula (1):
i
A
C = (1)
i
A
where
C is the carbonyl index;
i
-1
A is the absorbance at 1 715 cm determined by a tangent method:
1 715
A = I − B ;
1 715 1 715 1 715
-1
A is the absorbance at 2 020 cm determined by a tangent method:
2 020
A = I − B ;
2 020 2 020 2 020
-1 -1
I and I are the absolute values of absorbance measured at 1 715 cm and 2 020 cm , re-
1 715 2 020
spectively;
-1
B and B are the absorbance of a baseline corresponding to the bands at 1 715 cm and
1 715 2 020
-1
2 020 cm , respectively.
8 Interlaboratory tests: exposure of PERF to laboratory light-sources
8.1 General
As previously mentioned, PERF are designed to monitor artificial or natural ageing conditions leading to
thermally activated photo-oxidative pathways. Although the polyethylene chemical oxidation follows an
exponential development likely to lead to important oxidation levels, the oxidation rate of PERF must be high
enough to rapidly obtain oxidation levels that can be detected by FTIR spectroscopy with good reliability.

This prerequisite raises the important question of PERF sensitivity, in terms of photo-oxidizability, when
subjected to natural or artificial ageing conditions. Interlaboratory tests (hereafter called ILT) involving
artificial or natural exposures of PERF to different photochemical conditions were therefore conducted. The
main objective of these ILT was to evaluate the photochemical sensitivity of PERF under various photo-
oxidative conditions. The repeatability of the results was also studied, although this property can be also
strongly affected by the internal operating conditions of the artificial weathering device, potentially leading
to some deviations between several similar devices. The interpretation of these ILT was therefore focused
on the photochemical behaviour of PERF, and not on a comparison of several weathering devices of similar
or different types.
8.2 Protocol for the artificial exposures
8.2.1 General
A set of 4 specimens (50 mm × 50 mm) was provided to each participant to the ILT. The artificial exposure of
these specimens can be performed in any condition described in 8.2.2, 8.2.3 or 8.2.4. The participants were
asked to:
— expose the 4 specimens (50 mm × 50 mm) without any backing;
— pick up specimens after specified exposure durations (comprised between 50 h and 400 h, depending on
the artificial weathering device);
— indicate the exposed side and exposure duration on each specimen;
— rigorously respect the methods and corresponding International standard mentioned in 8.2.2, 8.2.3 and
8.2.4;
— check that all necessary maintenance and calibration steps were carried out prior to the test.
NOTE Without backing means that the specimen holder is an open frame. Nevertheless, there is always some sort
of background behind the specimen which can influence the UV reflection in the vicinity of the sample.
8.2.2 Xenon-arc lamp exposure
[12]
The tests were performed according to the conditions of ISO 4892-2:2013 + AMD 1:2021 shown in Table 2.
Table 2 — Exposure conditions for xenon-arc lamp
Filter Daylight filter type II according to ISO 4892-2:2013/Amd 1:2021, Annex C
2 2
Irradiance 0,51 W/(m ·nm) at 340 nm or 60 W/m in the range 300 nm to 400 nm
BST (65 ± 3) °C
Chamber temperature (38 ± 3) °C
Wetting 18 min water spray (light on) every 102 min of exposure in dry conditions
Relative humidity (50 ± 10) %
Exposure durations 100 h, 200 h, 300 h and 400 h
8.2.3 Fluorescent UV lamp exposure
[13]
The tests were performed according to the conditions of ISO 4892-3:2016 shown in Table 3.

Table 3 — Exposure conditions for fluorescent UV lamp
Lamp type UVA-340
Irradiance 0,76 W/m /nm at 340 nm
BST (60 ± 3) °C during UV exposure and (50 ± 3) °C during condensation cycles
Wetting 4 h condensation (light off) every 8 h of exposure in dry conditions
Relative Humidity Not controlled
Exposure durations 100 h, 200 h, 300 h and 400 h (total durations including the condensation cycles)
8.2.4 Medium pressure mercury vapour lamp exposure
[14]
The tests were performed in accordance with EN 16472:2014 in the experimental conditions shown in
Table 4.
Table 4 — Exposure conditions for medium pressure mercury vapour lamp
Filter No additional filter or a filter simulating daylight exposures
Irradiance 95 W/m in the range 300 to 400 nm
60 °C at the surface of the sample, controlled either by a BST/CHT system set at
Temperature
64 °C/54 °C, or by a white thermometer set at 65 °C or by a platinum sensor set at 60 °C
Wetting No
Relative Humidity Not controlled
Exposure durations 50 h, 75 h, 100 h and 125 h
8.2.5 Measurement of the carbonyl index C
i
The carbonyl index, C , was measured after each exposure duration by three different French laboratories
i
(A, B and C) according to the method described in Clause 7. These three analyses allowed checking the
repeatability of the FTIR measurements (in transmission mode). Average evolutions as well as standard
deviations were then calculated for each test.
8.3 Outdoor exposure test of PERF
Besides studying the photo-oxidative sensitivity of PERF under artificial weathering conditions, the carbonyl
index evolution of PERF when exposed to outdoor conditions was also characterized in order to evaluate the
relevancy of PERF for monitoring natural ageing conditions.
PERF was therefore exposed to natural outdoor conditions (45° tilted to the South, no backing), according
[15] [16]
to ISO 877-1:2009 and ISO 877-2:2009 for one year, from 1 July 2021 to 1 July 2022, on the Bandol site
(France). The carbonyl index was measured every month according to the method detailed in Clause 7.
NOTE The same type of backing is recommended if the intention is to compare artificial and outdoor exposure.
8.4 Results and discussion
8.4.1 Artificial exposures of PERF to laboratory light-source
8.4.1.1 Xenon-arc lamp exposure
The exposures to xenon-arc lamp were performed with nine devices from seven comp
...