ASTM D8539-23

Standard Guide for Measurement of Polyolefin Properties Using TD-NMR Relaxometry

SIGNIFICANCE AND USE
5.1 This guide is intended to assist users how to determine polymer properties in polyolefins related to their morphology (2) using TD-NMR Relaxometry, for example, Xylene Solubles (XS) content in polypropylene (PP).  
5.2 The advantage of using TD-NMR Relaxometry lies in the fact that the method is rapid, non-destructive, cost effective, safe for the operator, environmentally friendly, and less dependent on operator consistency than traditional methods.  
5.3 These polymer properties are measured for Quality Assurance (QA), Quality Control (QC) (7) and process control, for example, certificates of analysis (CoA) or optimization of the reaction process (6). These properties are key indicators of performance characteristics and are therefore important in compounding and manufacturing of plastic products.  
5.3.1 This guide is applicable in a laboratory environment, continuous inspection as a quality control or as a research tool. It is also appropriate for use in commercial processes used to produce polyethylene and polypropylene.  
5.4 TD-NMR Relaxometry can measure crystallinity content and relaxation rates directly (4), (5). Polyolefin properties used in industry that are correlated with crystallinity can be quantified. In these cases, a calibration is necessary.  
5.5 As a secondary technique, results achieved by different TD-NMR Relaxometry systems, even from the same vendor, in different laboratories are not necessarily comparable and may result in biases. Therefore, the user is advised to perform measurement validation.
SCOPE
1.1 This guide is intended to provide suggested approaches and criteria for the determination of polyolefin properties via time-domain Nuclear Magnetic Resonance (TD-NMR) Relaxometry. Though any crystallinity or morphology related property can be determined using this method (1), (2)2, the focus of this guide is on the prediction of Xylene Solubles content for polypropylene and density (3) for polyethylene as these are the most commonly specified properties for polyolefin manufacturers. Please note that other properties such as flexural modulus, Izod, Charpy, intrinsic viscosity, decalin/hexane solubles and others can be determined as well.  
1.2 High-Level Purpose—The purpose of this guide includes:
(1) educating new users on the use of TD-NMR Relaxometry to determine properties of polyolefins in manufacturing plants and laboratories;
(2) providing a standard terminology that can be used by different vendors and end users;
(3) establishing minimum requirements for apparatus, data acquisition, analysis, calibration and validation;
(4) providing guidance for the specification, evaluation, cost justification, implementation, project management, training, and documentation of TD-NMR Relaxometers; and
(5) providing a functional requirements checklist for TD-NMR Relaxometers for use in polyolefin plants and laboratories that can be integrated with existing systems.  
1.3 Audience—This guide has been created with the needs of the following stakeholders in mind:
(1) end users of TD-NMR Relaxometers for use in polyolefin plants and laboratories,
(2) implementers of TD-NMR Relaxometers for use in polyolefin plants and laboratories,
(3) quality personnel,
(4) information technology personnel,
(5) vendors of TD-NMR Relaxometers for use in polyolefin plants and laboratories,
(6) individuals who approve funding of TD-NMR Relaxometers for use in polyolefin plants and laboratories,
(7) applications support specialists for TD-NMR Relaxometers used in polyolefin plants and laboratories, and
(8) software test/validation specialists.  
1.4 Information contained in this guide will benefit a broad audience of people who interact with a TD-NMR Relaxometer used in polyolefin plants and laboratories. New users can use this guide to understand the purpose and functions of TD-NMR Relaxometers for use in polyolefin plants and laboratories as well as the int...

General Information

• Status: Published
• Publication Date: 31-Oct-2023
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.70 - Analytical Methods

Relations

• Refers: ASTM D5492-17(2024) - Standard Test Method for Determination of Xylene Solubles in Propylene Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM D5492-17 - Standard Test Method for Determination of Xylene Solubles in Propylene Plastics
• Effective Date: 01-Aug-2017

Overview

ASTM D8539-23: Standard Guide for Measurement of Polyolefin Properties Using TD-NMR Relaxometry provides best practices and criteria for assessing the properties of polyolefins-such as polypropylene (PP) and polyethylene (PE)-using time-domain nuclear magnetic resonance (TD-NMR) relaxometry. This guide is intended to help users implement rapid, non-destructive, and environmentally friendly techniques for analyzing morphological and crystallinity-related characteristics in polyolefin materials. Key properties addressed include Xylene Solubles (XS) content in polypropylene and density in polyethylene, which are critical indicators for quality assurance, process control, and material performance in the plastics industry.

Key Topics

• TD-NMR Relaxometry Fundamentals
  • Utilizes low-field, pulsed NMR technology for the direct measurement of crystallinity and relaxation rates in polyolefins.
  • Offers rapid analysis with minimal to no sample preparation and is less operator-dependent than traditional solvent-based or physical testing methods.
  • Enables non-destructive testing, preserving the sample for further analysis if needed.
• Target Properties Measured
  • Xylene Solubles (XS) content in polypropylene, an indicator of polymer fraction and process consistency.
  • Density in polyethylene, correlating with polymer crystallinity and structural integrity.
  • Additional properties measurable include flexural modulus, impact resistance, intrinsic viscosity, and solubility in non-xylene solvents.
• Quality Control and Validation
  • Emphasizes the need for calibration and periodic measurement validation to ensure reliable, traceable results.
  • Addresses challenges with direct comparison of results across different instrument platforms or laboratories, hence the importance of measurement validation and system checks.
• Stakeholder Relevance
  • Relevant for laboratory analysts, process engineers, quality assurance personnel, vendors, software specialists, and decision makers involved in polyolefin manufacturing and testing.

Applications

• Quality Assurance and Quality Control
  • TD-NMR relaxometry enables ongoing monitoring of polymer properties during manufacturing, supports batch-to-batch consistency, and informs certificates of analysis (CoA).
• Process Optimization
  • Rapid feedback on key properties such as crystallinity and solubles facilitates timely process adjustments, improving reaction efficiency and product uniformity.
• Research and Development
  • Provides a robust, versatile tool for developing and validating new polyolefin grades or formulations.
• Commercial Manufacturing
  • Applicable to in-line, at-line, and off-line use in industrial environments for both polyethylene and polypropylene production.
• Training and Implementation
  • The standard includes guidance for specification, project management, training, and integration with laboratory information systems, helping organizations streamline deployment and user adoption of TD-NMR relaxometers.

Related Standards

For comprehensive evaluation and method validation, ASTM D8539-23 references several related standards:

• ASTM D5492 – Test method for determination of Xylene Solubles in propylene plastics.
• ASTM D792 / D1505 – Test methods for density measurement in plastics.
• ASTM D4808 / D5227 / D7171 – Test methods for hydrogen and extractable content using NMR/spectroscopy.
• ISO 16152, ISO 6427, ISO 1183-1/2, ISO 24076 – International standards covering xylene solubles, density, and tacticity determination in polyolefins.

Common keywords associated with this standard include TD-NMR, polyolefin analysis, NMR relaxometry, polypropylene, polyethylene, Xylene Solubles, and polymer crystallinity.

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By providing standardized approaches for the use of TD-NMR relaxometry, ASTM D8539-23 ensures reliable, efficient, and sustainable measurement of vital polyolefin properties across laboratory and industrial environments, fostering improved quality, process control, and innovation in plastic material production.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D8539 − 23
Standard Guide for
Measurement of Polyolefin Properties Using TD-NMR
Relaxometry
This standard is issued under the fixed designation D8539; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope (4) information technology personnel,
(5) vendors of TD-NMR Relaxometers for use in poly-
1.1 This guide is intended to provide suggested approaches
olefin plants and laboratories,
and criteria for the determination of polyolefin properties via
(6) individuals who approve funding of TD-NMR Relax-
time-domain Nuclear Magnetic Resonance (TD-NMR) Relax-
ometers for use in polyolefin plants and laboratories,
ometry. Though any crystallinity or morphology related prop-
(7) applications support specialists for TD-NMR Relaxom-
erty can be determined using this method (1), (2) , the focus of
eters used in polyolefin plants and laboratories, and
this guide is on the prediction of Xylene Solubles content for
(8) software test/validation specialists.
polypropylene and density (3) for polyethylene as these are the
most commonly specified properties for polyolefin manufac-
1.4 Information contained in this guide will benefit a broad
turers. Please note that other properties such as flexural
audience of people who interact with a TD-NMR Relaxometer
modulus, Izod, Charpy, intrinsic viscosity, decalin/hexane
used in polyolefin plants and laboratories. New users can use
solubles and others can be determined as well.
this guide to understand the purpose and functions of TD-NMR
1.2 High-Level Purpose—The purpose of this guide in- Relaxometers for use in polyolefin plants and laboratories as
cludes: well as the interactions between these tools with external
(1) educating new users on the use of TD-NMR Relaxom- systems. The guide might also help prospective users in
etry to determine properties of polyolefins in manufacturing understanding terminology, configurations, features, design,
plants and laboratories; benefits, and costs of these analyzers. Individuals who are
(2) providing a standard terminology that can be used by purchasing TD-NMR Relaxometers for use in polyolefin plants
different vendors and end users;
and laboratories may also use this guide to identify functions
(3) establishing minimum requirements for apparatus, data
that are recommended for specific laboratory environments.
acquisition, analysis, calibration and validation;
Research and development staff of different commercial labo-
(4) providing guidance for the specification, evaluation,
ratory informatics system vendors may use the guide as a tool
cost justification, implementation, project management,
to evaluate, identify, and potentially improve the capabilities of
training, and documentation of TD-NMR Relaxometers; and
their products. The vendors’ sales staff may use the guide to
(5) providing a functional requirements checklist for TD-
represent functions of their laboratory informatics products to
NMR Relaxometers for use in polyolefin plants and laborato-
prospective customers in more generic and product-neutral
ries that can be integrated with existing systems.
terms.
1.3 Audience—This guide has been created with the needs
1.5 This standard does not purport to address all of the
of the following stakeholders in mind:
safety concerns, if any, associated with its use. It is the
(1) end users of TD-NMR Relaxometers for use in poly-
responsibility of the user of this standard to establish appro-
olefin plants and laboratories,
priate safety, health, and environmental practices and deter-
(2) implementers of TD-NMR Relaxometers for use in
mine the applicability of regulatory limitations prior to use.
polyolefin plants and laboratories,
NOTE 1—There is no known ISO equivalent to this standard guide.
(3) quality personnel,
1.6 This international standard was developed in accor-
dance with internationally recognized principles on standard-
This test method is under the jurisdiction of ASTM Committee D20 on Plastics
and is the direct responsibility of Subcommittee D20.70 on Analytical Methods.
ization established in the Decision on Principles for the
Current edition approved Nov. 1, 2023. Published November 2023. DOI:
Development of International Standards, Guides and Recom-
10.1520/D8539-23
2 mendations issued by the World Trade Organization Technical
The boldface numbers in parentheses refer to a list of references at the end of
this standard. Barriers to Trade (TBT) Committee.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D8539 − 23
2. Referenced Documents experiment. A pulse sequence is often defined in a file or a
3 parameter set on the NMR instrument.
2.1 Xylene Soluble Content:
D5492 Test Method for Determination of Xylene Solubles in 3.1.4 reference result—the measurement of a physical or
chemical property by a primary technique (such as ASTM
Propylene Plastics
2.2 Density: D5492 in the case of Xylene Solubles content) that is used as
a reference input for the calibration generation.
D792 Test Methods for Density and Specific Gravity (Rela-
tive Density) of Plastics by Displacement
3.1.5 regression—the application of a univariate or multi-
D1505 Test Method for Density of Plastics by the Density-
variate regression technique, which establishes a mathematical
Gradient Technique
relationship between extracted parameters and the reference
2.3 Others:
results. Once this relationship is established, the NMR instru-
D4808 Test Methods for Hydrogen Content of Light
ment can be used to predict/measure properties of interest.
Distillates, Middle Distillates, Gas Oils, and Residua by
3.1.6 signal processing—any operation directly applied to
Low-Resolution Nuclear Magnetic Resonance Spectros-
the raw NMR signal such as: magnitude correction, Inverse
copy
Laplace transformation, amplitude normalization, etc.
D5227 Test Method for Measurement of Hexane Extractable
Content of Polyolefins
4. Summary of Guide
D7171 Test Method for Hydrogen Content of Middle Dis-
tillate Petroleum Products by Low-Resolution Pulsed 4.1 The samples to be analyzed are typically polyolefin
powders or pellets, that is, polyethylenes (HDPE, LLDPE or
Nuclear Magnetic Resonance Spectroscopy
LDPE) or polypropylenes (homopolymers or co-polymers).
2.4 Xylene Solubles Content:
They are introduced into the NMR Relaxometer with minimal
ISO 16152 Plastics—Determination of Xylene Soluble mat-
sample preparation or none at all, and analyzed at an
ter in polypropylene
instrument-specific temperature. Sample conditioning as de-
ISO 6427 Plastics—Determination of Matter Extracted by
scribed in 8.3 is required and has to be always consistent,
Organic Solvents (Conventional Methods) Annex B Stan-
representative and repeatable.
dard Method of Test for Determination of Polypropylene
Solubility in Cold Xylene
4.2 NMR acquisition yields a signal known as Free Induc-
tion Decay (FID) which represents intensity versus time. In
2.5 Density:
TD-NMR Relaxometry this time-domain signal is not Fourier
ISO 1183-1 Plastics—Methods for determining the density
transformed as the analysis is performed on the FID itself. The
of non-cellular plastics—Part 1: Immersion method, liquid
analysis itself is automated and yields a measure of crystallin-
pycnometer method and titration method
ity (4), (5). For the measurement of crystallinity, no calibration
ISO 1183-2 Plastics—Methods for determining the density
is needed as NMR is a primary method for analysis of this
of non-cellular plastics—Part 2: Density gradient column
property. Since polyolefin manufacturers require properties to
method
be measured that are relevant for process control (6) and
2.6 Others:
quality control (7), typically a calibration is needed to measure
ISO 24076 Plastics—Polypropylene—Determination of iso-
tacticity, for example, via Xylene Solubles content (polypro-
tactic index by low-resolution nuclear magnetic resonance
pylene) or density (polyethylene); (3). Typically, most or all
spectrometry
steps of the measurements are automated and computer con-
trolled.
3. Terminology
3.1 Definitions:
5. Significance and Use
3.1.1 calibration—a series of mathematical operations
5.1 This guide is intended to assist users how to determine
which translates the raw FID response into a meaningful
polymer properties in polyolefins related to their morphology
measurement. These processes include, but are not limited to:
(2) using TD-NMR Relaxometry, for example, Xylene
signal pre-processing, parameter extraction, and regression
Solubles (XS) content in polypropylene (PP).
versus reference results.
5.2 The advantage of using TD-NMR Relaxometry lies in
3.1.2 parameter extraction—any operation that is used to
the fact that the method is rapid, non-destructive, cost effective,
generate x-inputs for the regression analysis. These processes
safe for the operator, environmentally friendly, and less depen-
include: curve fitting, integration, deconvolution, etc.
dent on operator consistency than traditional methods.
3.1.3 pulse sequence—a series of radio-frequency (RF)
5.3 These polymer properties are measured for Quality
pulses (B ) used to elicit a response from a sample in an NMR
Assurance (QA), Quality Control (QC) (7) and process control,
for example, certificates of analysis (CoA) or optimization of
the reaction process (6). These properties are key indicators of
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
performance characteristics and are therefore important in
Standards volume information, refer to the standard’s Document Summary page on
compounding and manufacturing of plastic products.
the ASTM website.
5.3.1 This guide is applicable in a laboratory environment,
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org. continuous inspection as a quality control or as a research tool.
D8539 − 23
It is also appropriate for use in commercial processes used to homopolymer, co- or terpolymer materials, composed of
produce polyethylene and polypropylene. ethylene, propylene, and higher alpha-olefins (7). Samples may
either be exclusively polymer materials, or could additionally
5.4 TD-NMR Relaxometry can measure crystallinity con-
contain additives such as anti-oxidants or filler materials, such
tent and relaxation rates directly (4), (5). Polyolefin properties
as talc, fibers, etc. There could also be impurities.
used in industry that are correlated with crystallinity can be
7.1.2 No reagents are required for this analysis.
quantified. In these cases, a calibration is necessary.
7.2 Test Specimen:
5.5 As a secondary technique, results achieved by different
7.2.1 Samples typically consist of powders, pellets or
TD-NMR Relaxometry systems, even from the same vendor, in
granules, but could also be analyzed in the form of flakes,
different laboratories are not necessarily comparable and may
films, fibers, cutouts from a dogbone (10), etc. For a given
result in biases. Therefore, the user is advised to perform
calibration model, they should always be in the same form
measurement validation.
since the physical form might affect results.
7.2.1.1 Powders sampled immediately after the reaction are
6. Apparatus
ideal candidates for process optimization and reactor control in
6.1 Nuclear Magnetic Resonance Relaxometer:
a manufacturing plant.
6.1.1 This guide describes the use of a low-field pulsed
7.2.1.2 Pellets sampled post extrusion are typically analyzed
NMR relaxometer capable of measuring a nuclear magnetic
for quality control and results can be used for certificates of
resonance free-induction decay (FID) signal due to hydrogen
analysis (CoA) and other purposes.
atoms in the sample. The instrument consists of the following
7.2.2 The sample volume affects results, so it is strongly
parts:
suggested to use the same filling volume every time. Sample
6.1.1.1 Permanent magnet to provide the necessary static
volumes for a given instrument are specific to that instrument.
magnetic field for the NMR experiments.
The maximum sample size is determined by magnet bore
6.1.1.2 NMR probe (sample compartment) which is a radio
diameter, sample tubes and probe filling heights. A typical
frequency (RF) transceiver coil for excitation and detection of
amount ranges from 100mg to 30g.
hydrogen nuclei relaxation as the FID signal.
7.2.3 It is important to ensure representative sampling as
6.1.1.3 Electronic units to control and monitor the reso-
outlined in 8.2.
nance condition involving magnet temperature control, pulse
7.2.4 The sample temperature also affects results, since the
sequence timing (8), RF generation, signal amplification,
NMR signal will change with temperature. In order to compare
signal digitization, and optionally the field offset coils.
results, NMR relaxometry experiments should be performed at
6.1.2 This guideline recommends that the relaxometer in-
a consistent sample temperature. The sample is therefore
strument is equipped with the ability to equilibrate samples
typically tempered prior to an experiment.
within the probe at a constant temperature (typically 40 °C - 80
7.2.5 There are several other temperature effects that might
°C with a tolerance of 60.1 °C; (7).
affect results: Reactor resin (powder) samples should only be
6.2 Sampling equipment suitable for offline, at-line, online
analyzed once by NMR Relaxometry, since annealing effects
(9) or inline use, that is, manual, semi-automatic or fully
(11), (12) cause changes in the polyolefin morphology, so
automatic. Options include:
prediction results change when experiments are repeated with
6.2.1 Sample changer to hold and load samples into the
the same aliquot. In the case of pelletized materials, additives
NMR probe.
and processing techniques may stabilize the material.
6.2.2 Sample delivery system which conveys sample from
However, the user should verify sample stability over repeated
the process to the NMR system. The system can be manual or
heating and cooling cycles before relying on multiple measure-
automatic.
ments of the same aliquot for control chart generation. Heating
any samples above their melting temperatures might cause
6.3 Active sample conditioning apparatus internal to the
further changes in the morphology.
NMR equipment or an external system in the form of a dry
7.2.6 Certain grades also become sticky when heated, so
block, bath, or other temperature conditioning device into
cleaning sample tubes might become difficult.
which the sample is inserted to control and stabilize sample
temperature (typically at 40 °C - 80 °C with a tolerance of
8. Procedure: TD-NMR Methodology
60.2 °C).
8.1 Analysis Flow-Chart—A typical sequence of events
6.4 A test chamber which is typically a glass tube with an
starting from collecting the sample to be
...