ASTM C1303/C1303M-23

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: C1303/C1303M − 23
Standard Test Method for
Predicting Long-Term Thermal Resistance of Closed-Cell
Foam Insulation
This standard is issued under the fixed designation C1303/C1303M; 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 1.5.1 To use the Prescriptive Method, the date of manufac-
ture must be known, which usually involves the cooperation of
1.1 This test method covers a procedure for predicting the
the manufacturer.
long-term thermal resistance (LTTR) of unfaced or permeably
faced rigid gas-filled closed-cell foam insulations by reducing
1.6 The values stated in either SI units or inch-pound units
the specimen thickness to accelerate aging under controlled
are to be regarded separately as standard. The values stated in
laboratory conditions (1-5).
each system are not necessarily exact equivalents; therefore, to
ensure conformance with the standard, each system shall be
NOTE 1—See Terminology, 3.2.1, for the meaning of the word aging
used independently of the other, and values from the two
within this standard.
systems shall not be combined.
1.2 Rigid gas-filled closed-cell foam insulation includes all
cellular plastic insulations manufactured with the intent to
1.7 This standard does not purport to address all of the
retain a blowing agent other than air.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
1.3 This test method is limited to unfaced or permeably
priate safety, health, and environmental practices and deter-
faced, homogeneous materials. This method is applied to a
mine the applicability of regulatory limitations prior to use.
wide range of rigid closed-cell foam insulation types, including
but not limited to: extruded polystyrene, polyurethane, 1.8 Table of Contents:
polyisocyanurate, and phenolic. This test method does not
Section
Scope 1
apply to impermeably faced rigid closed-cell foams or to rigid
Reference Documents 2
closed-cell bun stock foams.
Terminology 3
NOTE 2—See Note 8 for more details regarding the applicability of this
Summary of Test Method 4
test method to rigid closed-cell bun stock foams.
Significance and Use 5
Part A: The Prescriptive Method 6
1.4 This test method utilizes referenced standard test proce-
Applicability 6.1
dures for measuring thermal resistance. Periodic measurements
Qualification Requirements 6.1.1
Facing Permeability 6.1.2
are performed on specimens to observe the effects of aging.
Apparatus 6.2
Specimens of reduced thickness (that is, thin slices) are used to
Sampling 6.3
shorten the time required for these observations. The results of
Schedule 6.3.1
Specimen Preparation 6.4
these measurements are used to predict the long-term thermal
Goal 6.4.1
resistance of the material.
Schedule 6.4.2
Replicate Test Specimen Sets 6.4.3
1.5 The test method is given in two parts. The Prescriptive
Specimen Extraction 6.4.4
Method in Part A provides long-term thermal resistance values
Slice Flatness 6.4.5
on a consistent basis that can be used for a variety of purposes, Slice Thickness 6.4.6
Stack Composition 6.4.7
including product evaluation, specifications, or product com-
Storage Conditioning 6.5
parisons. The Research Method in part B provides a general
Test Procedure 6.6
relationship between thermal conductivity, age, and product Thermal Resistance Measurement Schedule 6.6.1
Thermal Resistance Measurements 6.6.2
thickness.
Product Density 6.6.3
Calculations 6.7
This test method is under the jurisdiction of ASTM Committee C16 on Thermal Part B: The Research Method 7
Insulation and is the direct responsibility of Subcommittee C16.30 on Thermal Background 7.1
TDSL Apparatus 7.2
Measurement.
Sampling Schedule 7.3
Current edition approved Nov. 1, 2023. Published November 2023. Originally
Specimen Preparation 7.4
approved in 1995. Last previous edition approved in 2022 as C1303/C1303M – 22.
Storage Conditioning 7.5
DOI: 10.1520/C1303_C1303M-23.
2 Test Procedure 7.6
The boldface numbers in parentheses refer to the list of references at the end of
Calculations 7.7
this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1303/C1303M − 23
2.3 ASTM Adjuncts:
Reporting 8
Reporting for Part A, the Prescriptive Method 8.1
Test Method for Predicting Long-Term Thermal Resistance
Reporting for Part B, the Research Method 8.2
of Closed-Cell Foam Insulation
Precision and Bias 9
Keywords 10
Mandatory Information – Qualification Annex 3. Terminology
A1
3.1 Definitions—For definitions of terms and symbols used
Specimen Preparation A1.1
Homogeneity Qualification A1.2
in this test method, refer to Terminology C168.
Thermal Conductivity Equivalence Test Procedure A1.3
3.2 Definitions of Terms Specific to This Standard:
Alternate Product Thickness Qualification A1.4
Example Calculations A1.5
3.2.1 aging, v—the change in thermophysical properties of
Mandatory Information-Preparation of Test Specimens for Annex
rigid closed–cell plastic foam with time, primarily due to
Spray-Foam Products A2
Effect Of TDSL Appendix changes in the composition of the gas contained within the
X1
closed cells.
History of the Standard Appendix
X2 3.2.2 bias, n—a generic concept related to a consistent or
Theory of Foam Aging Appendix
systematic difference between a set of test results from the
X3
process (that is, the predicted thermal conductivity at 5 years)
References
and an accepted reference value of the property being mea-
1.9 This international standard was developed in accor-
sured (that is, the actual thermal resistance after 5 years of
dance with internationally recognized principles on standard-
full-thickness products taken from the same lot as the source of
ization established in the Decision on Principles for the
the thin slices).
Development of International Standards, Guides and Recom-
3.2.3 core slice, n—a thin-slice foam specimen that was
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. taken at least 5 mm [0.2 in.] or 25 % of the product thickness,
whichever is greater, away from the surface of the full-
2. Referenced Documents thickness product.
3.2.4 effective diffusion thickness, n—one-half of the geo-
2.1 ASTM Standards:
metric thickness minus the total thickness of damaged surface
C168 Terminology Relating to Thermal Insulation
layer(s) (TDSL).
C177 Test Method for Steady-State Heat Flux Measure-
ments and Thermal Transmission Properties by Means of
3.2.5 facing, n—a material adhered to the surface of foam
the Guarded-Hot-Plate Apparatus
insulation, including any foam product that has been suffused
C518 Test Method for Steady-State Thermal Transmission
into the facing material, but not inclusive of any skin formed
Properties by Means of the Heat Flow Meter Apparatus
by the foam insulation itself.
C578 Specification for Rigid, Cellular Polystyrene Thermal
3.2.6 homogeneous material, n—sufficiently uniform in
Insulation
structure and composition to meet the requirements of this test
C591 Specification for Unfaced Preformed Rigid Cellular
method (see A1.2).
Polyisocyanurate Thermal Insulation
3.2.7 long-term, adj—for the purposes of the Prescriptive
C1029 Specification for Spray-Applied Rigid Cellular Poly-
Method, long term refers to five years.
urethane Thermal Insulation
3.2.8 normalized service life, n—product service life di-
C1045 Practice for Calculating Thermal Transmission Prop-
vided by the square of the full product thickness, units of
erties Under Steady-State Conditions
time/length .
C1126 Specification for Faced or Unfaced Rigid Cellular
Phenolic Thermal Insulation
3.2.9 scaled time, n—time divided by the square of the
C1289 Specification for Faced Rigid Cellular Polyisocyanu-
specimen thickness.
rate Thermal Insulation Board
3.2.10 scaled service life, n—time necessary for a thin
D1622 Test Method for Apparent Density of Rigid Cellular
specimen to reach the same thermal conductivity that a full
Plastics
thickness specimen would reach at the end of its service life,
D6226 Test Method for Open Cell Content of Rigid Cellular
equals the product service life multiplied by the square of the
Plastics
ratio of the average slice thickness to the full product thickness,
2.2 Other Standards:
value has units of time.
CAN/ULC S770 Standard Test Method for Determination of
3.2.11 service life, n—the anticipated period of time that the
Long-Term Thermal Resistance of Closed-Cell Thermal
material is expected to maintain claimed thermophysical
Insulation Foams
properties, may be dependent on the specific end-use applica-
tion.
3.2.12 surface slice, n—a thin-slice foam specimen that was
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
originally adjacent to the surface of the full-thickness product
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
4 5
Underwriters Laboratory of Canada, 333 Pfingsten Road, Northbrook, IL Available from ASTM International Headquarters. Order Adjunct No.
60062-2096 USA,www.ulc.ca ADJC1303.
C1303/C1303M − 23
and that includes any facing that was adhered to the surface of 5.1.2 Physical gas diffusion phenomena occur in three
the original full-thickness product. dimensions. The one-dimensional form of the diffusion equa-
tions used in the development of this practice are valid only for
3.2.13 thickness of damaged surface layer (TDSL), n—the
planar geometries, that is, for specimens that have parallel
average thickness of surface cells, on one surface, that are
faces and where the thickness is much smaller than the width
either destroyed (ruptured or opened) during the preparation of
and much smaller than the length.
test specimens or were originally open due to the manufactur-
ing process.
NOTE 3—Please see Appendix X3 for a discussion of the theory of
accelerated aging via thin slicing.
3.3 Symbols:
NOTE 4—Theoretical and experimental evaluations of the aging of
insulation in radial forms, such as pipe insulation, have been made. (6)
F = fraction of the product thickness represented by
surface
However, these practices have not evolved to the point of inclusion in the
surface slice
test standard.
i = counter used in a summation
5.2 The change in thermal resistance due to the phenomena
k = thermal conductivity, W/(m·K)
described in 5.1 usually occurs over an extended period of
L = thickness, m
time. Information regarding changes in the thermal resistance
n = counter used in a summation
of these materials as a function of time is required in a shorter
N = number of cut planar surfaces
period of time so that decisions regarding formulations,
n = counter in a time series that corresponds to the
SL
production, and comparisons with other materials can be made.
service life.
R = thermal resistance, (m ·K)/W
5.3 Specifications C578, C591, C1029, C1126 and C1289
TDSL = average thickness of damaged surface layer, m
on rigid closed-cell foams measure thermal resistance after
ΔX = insulation thickness, m
conditioning at 23 6 1°C [73 6 2°F] for 180 6 5 days from
ΔX = effective diffusion thickness of thermal resistance
eff
the time of manufacture or at 60 6 1°C [140 6 2°F] for 90
specimen, m
days. This conditioning can be used for comparative purposes,
but is not sufficient to describe long-term thermal resistance.
4. Summary of Test Method
This requirement demonstrates the importance of the aging
4.1 Rigid gas-filled closed-cell foam insulation is thin-sliced
phenomena within this class of products.
to reduce the gas diffusion path length which accelerates the
5.4 The Prescriptive Method in Part A provides long-term
aging process. The resulting temporal acceleration is propor-
thermal resistance values on a consistent basis for a variety of
tional to the square of the ratio of the product use thickness to
purposes, including product evaluation, specifications, or prod-
the slice thickness.
uct comparisons. The consistent basis for these purposes is
4.2 Careful and precise slice preparation is necessary and
provided by a series of specific procedural constraints, which
the process is described in detail in 6.4.
are not required in the Research Method described in Part B.
4.3 In Part A, the Prescriptive Method, specific test dates are
The values produced by the Prescriptive Method correspond to
calculated and the thermal resistance of the thin slices is
the thermal resistance at an age of five years, which corre-
measured on those dates.
sponds closely to the average thermal resistance over a 15-year
4.3.1 Qualification tests are included to determine whether
service life (7, 8).
this method is applicable to a given material.
5.4.1 It is recommended that any material standard that
refers to C1303 to provide a product rating for long-term
4.4 In Part B, the Research Method, thermal conductivity is
thermal resistance specify the Part A Test Method of C1303.
measured for a series of time periods and extensive data
analysis is possible.
5.5 The Research Method in Part B provides a relationship
between thermal conductivity, age, and product thickness. The
5. Significance and Use
calculation methods given in Part B can be used to predict the
5.1 Rigid gas-filled closed-cell foam insulations include all resistance at any specific point in time as well as the average
cellular plastic insulations which rely on a blowing agent (or
resistance over a specific time period.
NOTE 5—The 5-year aged values produced in Part A can be derived
gas), other than air, for thermal resistance values. At the time of
from the Part B data only if all other Part A requirements are met.
manufacture, the cells of the foam usually contain their highest
percentage of blowing agent and the lowest percentage of 5.6 This test method addresses three separate elements
atmospheric gases. As time passes, the relative concentrations relating to the aging of rigid closed-cell plastic foams.
of these gases change due primarily to diffusion. This results in 5.6.1 Specimen Preparation—Techniques for the prepara-
a general reduction of the thermal resistance of the foam due to tion of thin flat specimens, including their extraction from the
an increase in the thermal conductivity of the resultant cell gas “as manufactured” product, and the measurement of specimen
mixture. These phenomena are typically referred to as foam thickness are discussed.
aging. 5.6.2 Measurement of the Thermal Resistance—Thermal
5.1.1 For some rigid gas-filled closed-cell foam insulation resistance measurements, taken at scheduled times, are an
products produced using blowing agent gases that diffuse very integral part of the test method.
rapidly out of the full-thickness foam product, such as ex- 5.6.3 Interpretation of Data—Procedures are included to
panded polystyrene, there is no need to accelerate the aging properly apply the theory and techniques to achieve the desired
process. goals.
C1303/C1303M − 23
6. Part A: The Prescriptive Method 6.2.2.3 The following two types of equipment have success-
fully been used to prepare thin slice specimens. Reference (12)
6.1 Applicability:
summarizes these techniques and compares their effectiveness.
6.1.1 Qualification Requirements—Before reporting the re-
(1) High Speed Band-saw, with a fine-tooth 1 tooth/mm [14
sults from a C1303 Part A aging test, the material must be
teeth/in.] blade, 0.6 mm [0.025 in.] blade thickness, and blade
qualified using the procedures given in Annex A1.
speed of about 6 m/s [1185 ft/min].
6.1.1.1 The qualification requirement tests must be per-
(2) Combination Lathe/Motor-driven Meat Slicer.
formed whenever a significant change that would affect the
6.2.2.4 Use of a hot-wire cutter is prohibited because it can
thermal resistance properties is made to the product.
produce a surface skin. For further discussion, please see 9.3
6.1.1.2 The qualification is valid for a period not to exceed
and Note 32.
two years.
6.3 Sampling:
NOTE 6—This test method is founded upon gas diffusion physical laws
6.3.1 Schedule—Specimens shall be collected between 7
that apply to homogeneous materials with free surface exposure to the
atmosphere as discussed more fully in Appendix X3 (2-4) and (9-11).
and 20 days after production. The specimen collection sched-
Although rigid closed-cell foam insulation may not rigorously meet these
ule must be coordinated with the specimen preparation time
homogeneity and exposure criteria, this test method has been shown to
requirement of 6.4.2.
provide useful information for a wide range of products. Recognizing that
none of the foam insulation products available today is perfectly
6.4 Specimen Preparation:
homogeneous, the qualification requirements determine whether the
6.4.1 Goal—The goal of this section is to produce thin
product is sufficiently homogeneous for this test method to produce
slices, that when aged, are representative of the aged perfor-
meaningful results. The user should also be aware that the material
characteristics of the thin specimens must approximate those of the mance of the full-thickness product.
material under investigation. The material characteristics that are of most
6.4.2 Schedule—The specimens shall be prepared between
importance are gas diffusion coefficients and initial cell gas content.
14 and 21 days after the production date.
One-dimensional diffusion must dominate in the full use thickness
6.4.3 Replicate Test Specimen Sets—The minimum number
material; by design, one-dimensional diffusion dominates in the thin slice.
NOTE 7—If two thicknesses of a particular foam product are manufac-
of replicate specimens, referred to as stacks, to be tested shall
tured from identical components and have identical foam morphology,
be selected so that there is confidence that the average results
then thin slices from one specimen will accurately predict the long-term
from these sliced specimens are representative of the material
aging behavior of the other. However, due to possible differences in the
undergoing testing. Depending upon the material, as described
foam morphology, the applicability of data derived from specimens taken
in 6.4.7, one, two, or three stacks shall be prepared.
from one product thickness to a different thickness of the same product is
currently a subject of research. The “alternate product equivalence test”
6.4.4 Specimen Extraction—Test specimens shall be ex-
qualification in Annex A1 is provided in Part A to allow this type of data
tracted either from full size product sheets or from specially
generalization.
prepared spray-product constructions.
NOTE 8—The age acceleration test method applies when one-
dimensional diffusion dominates in the full-use thickness material. In 6.4.4.1 Extraction of test specimens from full size product
bun-stock products, this condition does not exist during the time period
sheets:
between the initial foam production and the manufacturing process that
(1) Cut 300 by 300 mm 6 6 mm [12 by 12 in. 6 0.25 in.]
cuts the buns into flat sheets. Because this time is variable, it is not
full-thickness sections from two full-size product sheets. In no
possible to define a consistent initial time for the Prescriptive Method.
case shall these sections be taken within 15 cm [6 in.] of the
Also, because the sheets may be cut from the bun stock in different
orientations, the foam morphology may vary from one product sheet to product edge. The number of full-thickness sections needed
another.
will depend upon the equipment used to prepare the thin slices
and the number of replicate sets tested, as discussed in 6.4.3.
6.1.2 Facing Permeability:
6.1.2.1 Unfaced foam insulation meets the criteria of a free (2) Slice the 300 by 300 mm 6 6 mm [12 by 12 in. 6 0.25
in.] full-thickness specimens prepared in 6.4.4.1(1) to produce
exposure to the atmosphere so the test method is applicable.
6.1.2.2 Faced products, with the exception of those foil- stacks of thin slices. Surface slices shall include the product
skin or facing.
faced products that are Type 1 in Specification C1289, that pass
the homogeneity qualification test in Annex A1 meet the 6.4.4.2 The preparation and extraction of test specimens
criteria of this test method. from spray-foam product is described in Annex A2.
6.4.5 Slice Flatness:
6.2 Apparatus:
6.4.5.1 During the slicing process, the thickness of each
6.2.1 Thermal resistance test apparatus used for this test
individual slice shall be measured in eight locations distributed
method shall conform to all of the requirements of Test Method
evenly over the surface of the slice as shown in Fig. 1.
C518.
(1) These measurements shall be made using a digital
6.2.2 Specimen preparation equipment must produce slices
caliper or a digital length meter. Care shall be taken so that the
that are consistent in dimension and surface morphology.
contact between the caliper jaws or the length meter’s pressure
6.2.2.1 Surface Damage—Equipment for preparing thin
foot does not indent the foam surface.
specimens shall be selected based on the ability of the
6.4.5.2 Each of these eight measurements must be within
equipment to consistently limit the amount of surface damage
65 % of the average of the eight measurements.
(open cells) that occurs during the preparation process.
6.2.2.2 Thickness Uniformity—The equipment used to pre- 6.4.5.3 The average of these eight measurements shall be
pare specimens shall be capable of producing uniform thick- used to represent the thickness of the slice for the purposes of
ness slices able to meet the requirements of 6.4.5. 6.4.6.3.
C1303/C1303M − 23
NOTE 1—Lines show position of caliper jaws.
FIG. 1 Location of Eight Measuring Points for Slice Thickness on a 300 by 300 mm [12 by 12 in.] Slice
6.4.5.4 It is possible that a apparatus and cutting technique 6.4.6.4 The average of the foam portion of the slice thick-
adjustments will be necessary to meet the requirements of this
ness within the stack will be used later in 6.7.1 to determine
section and those of 6.4.6.3. Practice is recommended.
appropriate testing periods. This is called the Average Slice
6.4.6 Slice Thickness:
Thickness in Eq 1 in 6.7.1.
6.4.6.1 Each core slice shall be a minimum of 8 mm [0.32
NOTE 9—The presence of a damaged layer of cells on every cut surface
in.] thick.
introduces errors into both the calculated testing period (causing it to be
6.4.6.2 The foam portion of each surface slice shall be a
overestimated) and the thermal resistance (causing the measured value to
minimum of 8 mm [0.32 in.] thick. The total thickness of each
be less than the true value). The 8 mm [0.32 in.] minimum thickness was
surface slice shall be a minimum of 8 mm [0.32 in.] plus the
selected based upon the magnitude of these errors (discussed in Appendix
thickness of any facing material. If the facing thickness is not
X1) and a desire to limit the controllable error sources associated with this
known, the facing shall be removed from an edge portion of the test method to no more than the uncertainty of Test Method C518. There
have been numerous experiments that show results from accelerated aging
product sheet and the thickness measured with a caliper or
with 10 mm [0.39] slices are in good agreement with full-thickness aged
digital length meter to the nearest 0.1 mm [0.004 in.]. If the
values, as discussed more fully in Section 9. The C1303/C1303M
facing thickness is less than 2 % of the total slice thickness, it
ruggedness test established good agreement between full-thickness aged
shall be considered negligible in all succeeding calculations
values and the accelerated aging predictions for slices between 8 mm
and the total slice thickness shall be used to represent the
[0.32 in.] and 12 mm [0.47 in.] for PIR and XPS boardstock products.
thickness of the foam portion of the surface slice.
NOTE 10—If foam product morphology is changed by the introduction
6.4.6.3 Slice uniformity within each stack: The thickness of
of new materials or manufacturing processes, the manufacturer may wish
the foam portion of every slice (from 6.4.5.3) must be within to pursue the TDSL investigation described in the Part B test method to
determine whether the slice thickness should be increased to keep the
65 % of the average of the foam portion of all the slices used
TDSL errors within the uncertainty of Test Method C518.
within that stack.
C1303/C1303M − 23
NOTE 11—Errors in both the calculated testing period and the measured
6.4.8 Stack Type Selection:
thermal resistance have the greatest effect for thermal resistance measure-
6.4.8.1 The stack types allowed for PIR and XPS board-
ments made in the earlier portion of the aging curve. Therefore, when
stock are based upon the results of a ruggedness test described
predicting aged values for thicker products, for example, 75 or 100 mm [3
or 4 in.] products, users may wish to elect slice thicknesses greater than in 9.5(14). Similar data are not yet available for other insula-
the 8 mm [0.32 in.] minimum to extend the test time interval. This will
tion products; so all three physical stack types are required for
improve the accuracy by: (1) reducing the effect of any small variation in
all other insulation products. That is, prepare three stacks
the test time period and (2) reducing the magnitude of errors introduced
using: four core slices, four surface slices, and a mixed stack of
into the calculated testing period due to the smaller relative fraction of
core and surface slices.
TDSL (as discussed more fully in Appendix X1).
6.4.8.2 For PIR boardstock, select one of the five options
6.4.7 Stack Composition:
listed here:
6.4.7.1 All thermal resistance measurements are made using
(1) If a product less than 75 mm [3 in.] thick is used to
stacks of slices in order to avoid errors (often referred to as the
predict the long-term aged value for products of that same
“thickness effect”) introduced by radiation heat transfer phe-
thickness, prepare a mixed stack.
nomena at small specimen thicknesses (13).
6.4.7.2 Depending upon the material, as described in 6.4.8, (2) If a product less than 75 mm [3 in.] thick is used to
one, two, or three stacks shall be prepared. These three stack predict the long-term aged value for products of that same
types are: four core slices, four surface slices, and a mixed thickness, prepare a core stack.
stack of core and surface slices. (3) If a product less than 75 mm [3 in.] thick is used to
predict the long-term aged value for products of that same
NOTE 12—For background and rationale regarding the use of these
thickness, prepare both core and surface stacks. These will
three stacks, please see X2.2.
provide data required to evaluate the results for a mathematical
(1) Slice uniformity among multiple stacks: The average
equivalent stack.
slice thickness of each of the multiple stacks (that value
(4) If a product with an original thickness between 45 and
calculated in 6.4.6.4 and used in 6.7.1 for each stack) must
55 mm [1.8 and 2.2 in.] is used to predict the long-term aged
agree within 61 mm [60.04 in.].
value for products between 22 and 103 mm [0.9 and 4.1 in.],
6.4.7.3 For a stack of surface slices, the slices shall be
prepare a core stack.
organized so that every skin or facing faces upward, as shown
(5) If a product with an original thickness between 45 and
in Fig. 2.
55 mm [1.8 and 2.2 in.] is used to predict the long-term aged
6.4.7.4 For the mixed stack, the core and surface slices shall
value for products between 22 and 103 mm [0.9 and 4.1 in.],
be prepared at a uniform slice thickness that represents the
prepare both core and surface stacks. These will provide data
reassembled full cross-section of the product except for small
needed to evaluate the results for a mathematical equivalent
amounts destroyed in the slice-cutting process and excluding
stack.
any remainder less than 8 mm [0.32 in.] in thickness. The
6.4.8.3 For XPS boardstock, select one of the three options
slicing shall be organized so that any such remainder comes
listed here:
from a non-surface section of the foam and both surfaces shall
(1) If a product is used to predict the long-term aged value
be included as the outward facing layers of the stack. The
for products of that same thickness, prepare a mixed stack.
number of core sections in the mixed stack will vary according
(2) If a product is used to predict the long-term aged value
to the product thickness, as shown in Fig. 2.
6.4.7.5 Each stack shall be marked to assure that the for products of that same thickness, prepare both core and
surface stacks. These will provide data required to evaluate the
specimens are placed in the same top to bottom order for every
thermal measurement. Each stack shall be marked to assure results for a mathematical equivalent stack.
(3) If a product with an original thickness between 45 and
that the stacks are oriented in the thermal measurement
apparatus in the same direction for every measurement. Fig. 3 55 mm [1.8 and 2.2 in.] is used to predict the long-term aged
value for products between 22 and 103 mm [0.9 and 4.1 in.],
is one example of an effective marking scheme.
6.4.7.6 A mathematical equivalent stack is constructed us- prepare both core and surface stacks. These will provide data
ing the results from the core and surface stacks as described in required to evaluate the results for a mathematical equivalent
6.7.4. stack.
FIG. 2 Surface Stack Arrangement (left) and Mixed Stack Arrangement (right)
C1303/C1303M − 23
FIG. 3 Examples of Useful Specimen Stack Marking Techniques
6.5 Storage Conditioning:
First December 20, 2010 Measured thermal
test date (5 days before) (check, 5 conductivity
6.5.1 Specimens shall be stored during the extended time
< 7) = 0.0307 W/m-K
periods between thermal conductivity measurements in a
Calculated December 25, 2010 Interpolated thermal
conditioned space, at a temperature of 22°C [72°F] (65°C
test date conductivity
[10°F]) and relative humidity between 40 and 70 %.
= 0.0307+(5/9)(.0310-.0307)
= 0.0309
NOTE 13—The long-term storage conditioning requirements defined
here are separate from the specimen conditioning requirements of Test
Second December 29, 2010 Measured thermal
Methods C518 and C177. test date (4 days after, 9 days conductivity
after the = 0.0310 W/m-K
6.5.2 Specimens shall be stored so that each surface of each
first test)(check, 4 < 7)
slice is exposed to free air circulation.
6.6.2 Thermal Resistance Measurements—All thermal con-
ductivity and resistance measurements shall be made according
NOTE 14—One method used to assure such exposure is to stand the
to Test Method C518 or C177, used in conjunction with
slices like books on a shelf with small spaces between each adjacent slice.
Practice C1045. Of these test methods, the heat flow meter
6.6 Test Procedure:
apparatus, Test Method C518, is recommended.
6.6.1 Thermal Resistance Measurement Schedule:
6.6.2.1 The mean test temperature shall be 24 6 2°C [75 6
6.6.1.1 Calculate the testing period(s) corresponding to the 4°F] with a temperature difference of 22 6 2°C [40 6 4°F].
6.6.2.2 It is important to eliminate any air gaps between
desired product thickness(es), as described in 6.7. Add the
testing period to the slicing date to determine the test date for slices within the stack and between the stack and the controlled
each product thickness. temperature plates. Therefore, if the apparatus offers the option
of automatically positioning the plates and determining the
6.6.1.2 Measure the thermal resistance of the stack on the
specimen thickness, that option shall be used.
test dates determined in 6.6.1.1 within 624 h. If the test cannot
6.6.2.3 If the apparatus does not include an automatic
be performed within that 3-day period (test date minus 24 h to
positioning feature, the user must ensure that there are no air
test date plus 24 h), make a linear interpolation between two
gaps within the specimen stack or between the stack and the
test measurements made before and after the test date. Each
controlled temperature plates.
measurement used for interpolation shall be taken within a time
interval before and after the test date determined in 6.6.1.1,
NOTE 16—The thermal conductivity reported by Test Method C518 or
corresponding to the lesser of 7 days or 15% of the calculated C177 apparatus is directly proportional to the distance between the
controlled-temperature plates. If the apparatus reports the temperature
testing period. The linear interpolation shall be based on the
difference and heat flux rather than the thermal conductivity, then the stack
number of days the first test was made before the calculated
thickness used to calculate the thermal conductivity must equal the
test date, the number of days between the two tests, and the
distance between the plates. This is not likely to be the sum of the
measured thermal conductivity on both days.
individual slice thicknesses because of the pressure applied by the plate
positioning apparatus within the device.
NOTE 15—Linear interpolation example: Slice date July 30, 2010,
6.6.3 Product Density—For product identification and re-
calculated test date December 25, 2010. 15 % of the calculated test period
porting purposes, the product apparent density shall be mea-
of 148 days is 22 days, so the 7-day limit on interpolation test dates would
apply. sured in accordance with Test Method D1622.
C1303/C1303M − 23
6.6.3.1 The density of interest is that of the foam. Therefore, 7.2 TDSL Apparatus—Apparatus used to measure the effec-
for faced products, the facing shall be removed before the tive diffusion thickness of the specimen shall be as specified in
product density is measured. Test Method D6226 or shall have demonstrated equivalent
performance. See Ref (15) for a description of an acceptable
6.7 Calculations:
alternative apparatus.
6.7.1 The equation used to determine each testing period (in
days) is shown in Eq 1.
NOTE 19—Test Method D2856 has been withdrawn. However, labora-
tories that have the apparatus described in that test method are allowed to
AverageSliceThickness
use that apparatus following the withdrawn test method.
TestTime 5 × 1826 (1)
F G
ProductThickness
7.3 Sampling Schedule—It is acceptable to prepare the
6.7.1.1 The Average Slice Thickness is that value calculated
specimens from products where the production date is
in 6.4.6.4. The constant 1826 represents the number of days in
unknown, but every effort must be made to acquire the foam
a 5-year period. Be sure to state the Average Slice Thickness
soon after its production.
and the Product Thickness in the same set of units.
7.3.1 Data analysis must address the question of initial age
6.7.2 Use Eq 1 to determine the test time for each product
using the aging theory found in Appendix X3 and Refs (4, 8).
thickness of interest, subject to the limitations of Annex A1 and
7.3.2 Other resources, including data from the manufacturer
6.4.8.
and the pertinent material standard, shall be consulted to
6.7.3 For the purpose of this calculation, the average slice
determine whether the estimated initial age is reasonable.
thickness for surface slices shall not include the thickness of
7.4 Specimen Preparation:
any facing material.
7.4.1 Stack Composition—The choice of core, surface,
6.7.4 The results for a mathematical equivalent stack de-
mixed, or mathematical equivalent stacks, or a combination
scribed in 6.4.8 are calculated using the standard series
thereof is acceptable in the Research Method. However, data
resistance expression to weight the measured values from the
for each stack shall be kept independent from data for any other
core and surface stacks to represent the overall product
stack.
structure, as shown in Eq 2.
NOTE 20—The effects of facers and density gradients on the accuracy
L Δx 2L
product surface
R 5 5 R 5 5
S D and applicability of the accelerated aging test method are of great interest.
total ( (
k k k
effective surface
Researchers may select alternative stacking compositions in order to
L 2 2L
investigate these phenomena.
product surface
1 (2)
S D
k
core
7.4.2 It is acceptable to vary the extraction of specimens
described in 6.4.4 if necessary to meet research goals. In no
2L
surface
forF 5 ,
case shall these sections be taken within 15 cm [6 in.] of the
surface
L
product
product edge.
1 F 1 2 F
7.4.3 It is acceptable to reduce the slice thickness below the
surface surface
R 5 5 1
S D S D
effective
k k k
minimum specified for Part A in 6.4.6. See 7.6.5 and Appendix
effective surface core
X1.
7. Part B: The Research Method
7.4.4 If the TDSL is measured, prepare the TDSL test
specimens using the same slicing equipment as was used for
7.1 Background—In general, the prescriptive procedure de-
the thermal test specimens. Prepare test specimens with dimen-
scribed in Section 6 shall be followed. Modifications made to
sions that are required for the closed-cell volume measurement
meet research needs must be carefully documented when
apparatus described in Test Method D6226. Prepare these
reporting the results and must be based on a clear understand-
specimens from sample material taken adjacent to the thermal
ing of the gas diffusion physics that form the foundation of the
specimen sections.
accelerated aging theory. (See Appendix X3.)
7.1.1 Data taken using the Research Method shall not be
7.5 Storage Conditioning—In order to investigate the effect
used for product rating purposes unless all the requirements of
of environmental conditions on product aging, it is acceptable
the Prescriptive Method in Section 6 are satisfied.
to use environmental conditions other than those specified in
7.1.2 The qualification tests of Annex A1 are not required,
6.5. If other conditions are used, they shall be recorded on a
but are recommended. monthly basis.
NOTE 17—For research purposes, such as to benchmark numerical 7.6 Test Procedure:
analysis methods, it may be desirable to perform thin slicing age
7.6.1 Start an initial thermal conductivity measurement as
acceleration of specimens known to be highly non-homogeneous.
soon as possible but no more than 6 h after the slicing
NOTE 18—This method applies when one-dimensional diffusion domi-
procedure begins. Record the time elapsed between this mea-
nates in the full-use thickness material. In bun-stock products, this
surement and the slicing procedure to the nearest hour.
condition does not exist during the time period between the initial foam
production and the manufacturing process that cuts the buns into flat
7.6.2 A series of subsequent thermal conductivity measure-
sheets. Also, because the sheets may be cut from the bun stock in different
ments shall be adequate to provide data for the integration
orientations, the foam morphology may vary from one sheet to another.
calculation procedure described in 7.7. The precise timing on
Therefore, if this type of product is tested using the Research Method,
these measurements is flexible, but it is important that the test
extensive information regarding the specimen source and extraction must
be provided. schedule recognize that the foam aging progresses at a more
C1303/C1303M − 23
rapid rate in the earliest portion of the aging period. Measure- simple interpolation and trapezoidal integration techniques.
ments need to continue until a steady state condition has been Note that thermal conductivity is used throughout this section.
reached. Steady state conditions can be recognized when The thermal resistance is calculated only after all other
thermal conductivity measurements, taken over a period of at calculation steps are complete. All the necessary equations are
least 100 days, agree within 62 %, and show no trend. See given here and are also available in an Excel spreadsheet.
7.7.2.
7.7.2 Extrapolate data with the greatest caution. These
products typically reach a steady-state value at some point in
NOTE 21—A suggested test schedule for 10 mm [0.4 in.] thick slices
time. However, if the last two data points are unequal, any
from a 25 mm [1 in.] product would include measurements at 5 days, 10
extrapolation using the linear data analysis methods given here
days, 30 days, 60 days, 100 days, 150 days, 210 days, 365 days, and 480
days.
will falsely show a product eventually reaching infinite or zero
NOTE 22—If a more accurate representation of the earliest aging period
thermal conductivity.
is desired, slice thickness should be increased to extend the time period
7.7.3 Organize the data in two columns, the first showing
over which this phenomenon occurs.
the test date and the second the measured thermal conductivity.
7.6.3 It is acceptable to make thermal conductivity measure-
Convert the test dates to elapsed test time periods in days,
ments at other mean test temperatures and temperature differ-
measured from the day of slicing. Create a column of normal-
ences.
ized test times corresponding to each elapsed test time period
according to Eq 3.
NOTE 23—Gas diffusion rates increase at elevated temperatures. Re-
peated thermal conductivity measurements made at elevated mean tem-
7.7.3.1 The Average Slice Thickness comes from 6.4.6.4
peratures may therefore change the very aging behavior that is the subject
and does not include the facing thickness for surface slices. See
of the study. The thin slice adjacent to the hottest surface during the
7.7.6 for adjustments related to slice thickness and TDSL.
thermal conductivity measurement is the most likely to be affected. It may
7.7.4 The average effective thermal conductivity of a given
be necessary to rotate the slice stacking order, or to use a smaller number
of measurements on a larger number of specimen stacks, in order to limit
product over a projected service life can be determined by
the exposure of any particular specimen to the higher temperatures.
performing an integration of thermal conductivity versus time,
and then dividing by the service life. The time scale used in this
7.6.4 It is acceptable to make the apparent specimen density
equation is real, not normalized, time. The concept is shown in
in accordance with Test Method D1622 on the same test
Eq 4.
schedule as the thermal conductivity.
7.6.5 Use Test Method D6226 to measure the TDSL and 7.7.5 Several time scales are used in this section. The Scaled
effective diffusion thickness if necessary. Service Life has units of time, usually days, and is comparable
to the “elapsed time period” scale in the thin-slice test data. The
NOTE 24—The accuracy of the measured TDSL from either method is
integration is accomplished in this time scale. The Normalized
strongly influenced by the proportion of closed cells in the body, because
2 2
Service Life has units of time per length , usually days/cm ,
any open cells that are connected to the surface will be counted in the
TDSL volume. and is comparable to the normalized test time scale. The
interpolation is accomplished in this normalized time scale.
7.6.5.1 The slice thickness, slice preparation method, and
The normalized time scale is also used to determine the thermal
foam morphology shall be considered in making this determi-
conductivity of a given thickness product at any specific point
nation. If the foam morphology varies from foam products
in time.
previously tested, or if the slice thickness is decreased such that
7.7.5.1 The service life integral can be approximated using
the TDSL will potentially comprise more than 4 % of the slice
a numerical trapezoidal integration based upon thin-slice test
thickness, the TDSL shall be measured.
data taken over a much shorter time period. This shorter time
NOTE 25—The specimen preparation techniques employed by this test
period corresponds to the Scaled Service Life. (Other integra-
method destroy the closed cell integrity of the surface cells. For thinner
tion techniques were tested and found to offer results very
specimens, these damaged surface cells may account for an appreciable
similar to this simple
...