ASTM F1634-95(2000)
(Practice)Standard Practice for In-Vitro Environmental Conditioning of Polymer Matrix Composite Materials and Implant Devices
Standard Practice for In-Vitro Environmental Conditioning of Polymer Matrix Composite Materials and Implant Devices
SIGNIFICANCE AND USE
The conditioning procedures covered in this practice provide methods for saturating PMC specimens in a liquid environment prior to conducting other tests for property evaluation.
The conditioning may affect geometric and dimensional changes in specimens. In some severe cases, chemical changes may occur in the fiber, polymer and fiber-polymer interphase and interface.
Caution must be taken if Procedure B (10.2, Procedure B—Accelerated Moisture Saturation at Elevated Temperature) is followed to condition PMC specimens at an elevated temperature. Physical and chemical reactions in materials are normally temperature dependent. An increase in experimental temperature may accelerate a desirable moisture diffusion process. However, elevated temperatures above 37°C may also cause undesirable reactions that do not represent appropriate responses of materials at 37°C. Consequently, a pilot study is recommended in Procedure B to determine if a selected elevated temperature can be used for accelerated conditioning. If the properties of materials are determined to be irreversibly affected by this pilot study at the selected elevated temperature, then either an appropriate lower elevated temperature should be determined by repeating the pilot study, or Procedure B should not be used.
SCOPE
1.1 This practice covers two procedures for conditioning non-absorbable polymer matrix composite (PMC) materials and implant devices in a liquid environment to obtain a state of saturation.
1.2 The purpose of this practice is to standardize methods and reporting procedures for conditioning PMC materials and implant devices (PMC specimens) in a user selected liquid environment prior to conducting subsequent tests. It is not the purpose of this practice to determine the diffusion coefficients or actual saturation levels of a given liquid into the materials and devices. For these determinations, other procedures, such as Test Method D 5229, may be followed.
1.3 Diffusion of liquid into a solid material is a slow process. While the time necessary to achieve saturation at 37°C may be sufficiently short for thin specimens, such as fracture fixation plates, it may be prohibitively long in thick sections, such as femoral components for hip arthroplasty. However, the diffusion process may be accelerated at an elevated temperature. Consequently, two separate procedures (Procedures A and B) are presented in this practice. Procedure A covers exposing the specimen to the desired conditioning environment at 37°C. Procedure B prescribes a method to accelerate the diffusion process by conditioning the specimen at a selected elevated temperature.
1.4 This practice does not specify the test environment to be used for conditioning. However, the pH value of immersion liquid shall be maintained at 7.4 ± 0.2 to simulate the in vivo environment.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Buy Standard
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:F1634–95 (Reapproved 2000)
Standard Practice for
In-Vitro Environmental Conditioning of Polymer Matrix
Composite Materials and Implant Devices
This standard is issued under the fixed designation F 1634; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope Insulation Materials for Testing
D 756 Practice for Determination of Weight and Shape
1.1 This practice covers two procedures for conditioning
Changes of Plastics Under Accelerated Service Condi-
non-absorbable polymer matrix composite (PMC) materials
tions
and implant devices in a liquid environment to obtain a state of
D 3878 Terminology of High-Modulus Reinforcing Fibers
saturation.
and Their Composites
1.2 The purpose of this practice is to standardize methods
D 5229/D 5229M Test Method for Moisture Absorption
and reporting procedures for conditioning PMC materials and
Properties and Equilibrium Conditioning of Polymer Ma-
implant devices (PMC specimens) in a user selected liquid
trix Composite Materials
environment prior to conducting subsequent tests. It is not the
purpose of this practice to determine the diffusion coefficients
3. Terminology
or actual saturation levels of a given liquid into the materials
3.1 Definitions:
and devices. For these determinations, other procedures, such
3.1.1 cumulative moisture content, M (%), n—the amount
t
as Test Method D 5229, may be followed.
of absorbed moisture in a material at a given time t, expressed
1.3 Diffusion of liquid into a solid material is a slow
as a percentage of the weight of absorbed moisture divided by
process.Whilethetimenecessarytoachievesaturationat37°C
the initial specimen weight, as follows:
may be sufficiently short for thin specimens, such as fracture
W 2 W
fixation plates, it may be prohibitively long in thick sections,
i b
M,% 5 3 100 (1)
t
W
such as femoral components for hip arthroplasty. However, the
b
diffusion process may be accelerated at an elevated tempera-
where:
ture. Consequently, two separate procedures (ProceduresAand
W = current specimen weight, g, and
t
B) are presented in this practice. ProcedureAcovers exposing
W = initial (baseline) specimen weight at t = 0 and stan-
b
the specimen to the desired conditioning environment at 37°C.
dard laboratory atmosphere, g.
Procedure B prescribes a method to accelerate the diffusion
3.1.2 liquid, n—water, saline solution, calf serum, or any
process by conditioning the specimen at a selected elevated
other liquid solution that is used to condition PMC specimens.
temperature.
3.1.3 nominal saturated moisture content, M (%)—an ap-
s
1.4 This practice does not specify the test environment to be
proximationoftheamountofmoistureabsorbedbyaspecimen
used for conditioning. However, the pH value of immersion
at saturation, expressed as a percentage of the weight of
liquid shall be maintained at 7.4 6 0.2 to simulate the in vivo
absorbed moisture at approximate saturation divided by the
environment.
initial specimen weight, as follows:
1.5 This standard does not purport to address all of the
W 2 W
s b
safety concerns, if any, associated with its use. It is the
M,% 5 3 100 (2)
s
W
b
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
where:
bility of regulatory limitations prior to use.
W = specimen weight at approximate saturation, g, and
s
W = initial (baseline) specimen weight at t = 0 and stan-
b
2. Referenced Documents
dard laboratory atmosphere, g.
2.1 ASTM Standards:
3.1.4 standard laboratory atmosphere, n— a laboratory
D 618 Practice for Conditioning Plastics and Electrical
atmosphere having a temperature of 23 6 2°C and a relative
humidity of 50 6 10 %.
ThispracticeisunderthejurisdictionofASTMCommitteeF04onMedicaland
Surgical Materials and Devices and is the direct responsibility of Subcommittee
F04.15 on Material Test Methods. Annual Book of ASTM Standards, Vol 08.01.
Current edition approved May 10, 2000. Published January 1996. Annual Book of ASTM Standards, Vol 15.03.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F1634–95 (2000)
4. Summary of Test Method 6.7 Differential Scanning Calorimeter—An analytical sys-
tem capable of heating a specimen at a controlled rate while
4.1 In ProcedureA, a specimen is immersed in a liquid bath
measuring heat input and temperature.
at 37 6 1°C with a pH value of 7.4 6 0.2.
4.2 In Procedure B, conditioning occurs in a liquid bath at a
7. Sampling and Test Specimens
selected elevated temperature.
7.1 Preparation— Precaution shall be taken to avoid the
4.3 Weight change is monitored over time until specimens
entrapment of moisture in uneven surfaces, or delamination
reach the nominal moisture saturation content.
due to inappropriate machining and manufacturing processes.
4.4 Keep specimens in the conditioning bath for storage
7.2 Labeling—Label the specimen so as to be distinct from
prior to subsequent tests.
each other in a manner that will both be unaffected by the test
andnotinfluencethetestand,furthermore,willnotberemoved
5. Significance and Use
during conditioning.
5.1 The conditioning procedures covered in this practice
provide methods for saturating PMC specimens in a liquid
8. Measurements of Test Specimens
environment prior to conducting other tests for property
8.1 The following measurements shall be made on speci-
evaluation.
mens prior to immersion, after conditioning at the end of a test
5.2 The conditioning may affect geometric and dimensional
procedure, and at any intermediate stage as prescribed in the
changes in specimens. In some severe cases, chemical changes
test procedures:
may occur in the fiber, polymer and fiber-polymer interphase
8.1.1 Weight—The weight within 0.005 % of specimen
and interface.
weight.
5.3 Caution must be taken if Procedure B (10.2, Procedure
8.1.2 Characteristic dimensions of specimens may be mea-
B—Accelerated Moisture Saturation at Elevated Temperature)
sured as a function of immersion time to determine the amount
is followed to condition PMC specimens at an elevated
of swelling induced by moisture absorption.
temperature. Physical and chemical reactions in materials are
normally temperature dependent. An increase in experimental
9. Visual Examination
temperature may accelerate a desirable moisture diffusion
9.1 Noticeable qualitative changes in surfaces, outline, and
process. However, elevated temperatures above 37°C may also
general appearance of the test specimen shall be recorded after
cause undesirable reactions that do not represent appropriate
each stage of the testing procedure. These changes include
responses of materials at 37°C. Consequently, a pilot study is
color, surface irregularities, odor, surface voids, delamination
recommended in Procedure B to determine if a selected
and cracking. The immersion liquid should also be observed
elevated temperature can be used for accelerated conditioning.
for evidence of material that has leached from specimens or
If the properties of materials are determined to be irreversibly
holders, and evidence of bacterial or fungal contamination. If
affectedbythispilotstudyattheselectedelevatedtemperature,
bacterial or fungal contamination is found, specimens should
then either an appropriate lower elevated temperature should
be removed from the solution, washed with detergent and
be determined by repeating the pilot study, or Procedure B
water, rinsed, and placed in fresh solution. If contamination is
should not be used.
a recurring problem, antibacterial or antifungal agents must be
added to the solution; minimal amounts should be used as they
6. Apparatus
may affect specimen properties.
6.1 Balance—An analytical balance capable of measuring
weight of specimens to within a resolution of at least 0.005 %
10. Procedures
of the total specimen weight.
10.1 Procedure A—Moisture Saturation Determination at
6.2 Conditioning Bath—A temperature-controlled liquid
37°C:
bath shall be capable of maintaining the required temperature
10.1.1 Specimen Preconditioning—Bringthetestspecimens
to within 61°C. The bath shall be monitored either on an
to a uniform 23 6 2°C after manufacturing process.
automated continuous basis or on a manual basis at regular
10.1.2 Moisture Absorption:
intervals.
10.1.2.1 Record the initial (baseline) weight, W .
b
6.3 Specimen Bag— A sealable, flexible, moisture-proof
10.1.2.2 Place the specimen in the conditioning bath, which
bag made of material suitable for exposure to specimens that
has previously reached the specified temperature 37 6 1°C.
have been removed from the conditioning bath for cooling
The pH value of immersion liquid used shall be maintained at
prior to weighing. Bags that meet the requirement of MIL-B-
7.4 6 0.2 throughout the conditioning process and monitored
131 have been found to be satisfactory for use in such
at least once a week. If the solution pH falls outside the
applications.
designated range, the solution should be changed. The pH
6.4 Absorbent Cloth— Clean, non-linting absorbent cloth
should not be maintained by repeatedly adding buffer to the
for use in wiping excess liquid from surface of specimens.
same solution. This will change solution composition and may
6.5 Gloves—Clean, non-linting gloves for use when han-
affect specimen properties. Evaporation losses should be made
dling specimens.
up with sterile deionized water if saline, serum, plasma, or
6.6 pH Measurement System—Ananalyticalsystemcapable other hydrous medium is used as the conditioning environ-
of measuring pH to within 60.1. ment.
F1634–95 (2000)
10.1.2.3 Monitor the weight gain of specimens over time.A match the intended post-conditioning test that the PMC speci-
suggested schedule is to weigh each specimen every 24 h for men will be conditioned for. If T influences the properties in
a
the first 120 h, then every 96 h. question, then a lower conditioning temperature must be
identified by repeating this procedure at selected lower tem-
10.1.2.4 At the end of each time interval, remove the
peratures in which the property is not influenced by condition-
specimens from the conditioning bath and place them in the
ing. If the property is determined to be not influenced by T ,
specimenbag.Sealthebagandallowthespecimenstocometo
a
then T can be used to accelerate the conditioning process for
laboratory standard temperature. Remove the specimens from
a
subsequent specimens.
the bag and wipe the specimens free of surface moisture with
10.2.3 Accelerated Conditioning:
an absorbent lint-free cloth. Wait for 10 min and measure the
10.2.3.1 Follow the procedures outlined in 10.1.2 with the
weight of specimens to the required precision, and W, along
t
exception that the conditioning bath will be maintained at T 6
with the corresponding total elapsed time and the time interval
a
since the previous measurement. 1.0°C. The same time-measurement sequence as described in
10.1.2 should be used to determine the minimum time, t ,
10.1.2.5 Return the specimens to the conditioning bath. The min
when saturation is reached. The bath should be adequately
specimens shall not be out of the conditioning bath for more
sealedtominimizeevaporationlossandperiodicallymonitored
than 30 min and shall not be out of the specimen bag for more
to ensure adequate bath depth is maintained for complete
than 15 min.
immersion of samples. If the bath is physically sealed, a safe
10.1.2.6 Calculate cumulative moisture content, M (%),
t
mechanism of pressure relief (that is, pressure relief valve or
using Eq 1 at each time interval and plot versus time.
releasable lid seal) must be provided to prevent pressure
10.1.2.7 The minimum time, t , required to reach nominal
min
build-up if the oven is accidentally overheated. Evaporation
saturated moisture content, M , is the time at which the change
s
losses should be made up with sterile deionized water if saline,
in cumulative moisture content from the prior measurement is
serum, plasma, or other hydrous medium is used as the
less than 0.010 % of specimen weight for three consecutive
conditioning environment.
weighings with no less than 96 h of elapsed time between each
10.2.3.2 Following moisture saturation within the specified
consecutive weighing.
tolerance range, the specimen should be stored in a bath of the
10.1.2.8 Following moisture saturation within the specified
same fluid which is to be used for post-conditioning testing
tolerance range, the specimen should be stored in a bath of the
until the time the post-conditioning testing is conducted.
same fluid which is to be used for post-conditioning testing
until the time the post-conditioning testing is conducted.
11. Selection of Conditioning Procedure
10.2 Procedure B—Accelerated Moisture Saturation at El-
11.1 The choice between procedures should preferably be
evated Temperature:
based on the one that gives the most reproducible results.
10.2.1 Determination of Accelerated Temperature (T )
a
Level: 12. Report
10.2.1.1 Specimens should be first saturated in the condi-
12.1 Report the following information:
tioning environment at 37°C and then evaluated by differential
12.1.1 Description of the specimen or device being consid-
scanning calorimeter (DSC) evaluation over a temperature
ered (that is, material name, dimensions, part number, model
range of 37 to 120°C. The purpose of this is to determine if a
number, size designation).
material transition temperature (that is, glass transition or
12.1.2 The date of issue of this practice and the procedure
melting temperature), or a degradation temperature (such as an
used.
oxidation or thermal decomposition temperature), occurs
12.1.3 The date(s) and location(s) of the test.
within this temperature range. If the material is stable within
12.1.4 The name(s) of the test operator(s).
this range, then accelerated conditioning may be conducted at
12.1.5 Any variations to this practice, anomalies noticed
T = 95°C in a conditioning environment containing water. If a
a during testing or equipment problems occurring during testing.
transition or degradation temperature is found between 37 and
12.1.6 Description of the materials and fabrication method
120°C, then the maximum acceleration temperature to be used
used in preparing the specimen including: cure cycle, consoli-
should be at least 25°C below the lowest transition or decom-
dation method and a description of equipment used.
position temperature. If nonhydrous solutions are used
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:F1634–95 Designation: F 1634 – 95 (Reapproved 2000)
Standard Practice for
In-Vitro Environmental Conditioning of Polymer Matrix
Composite Materials and Implant Devices
This standard is issued under the fixed designation F 1634; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This practice covers two procedures for conditioning non-absorbable polymer matrix composite (PMC) materials and
implant devices in a liquid environment to obtain a state of saturation.
1.2 ThepurposeofthispracticeistostandardizemethodsandreportingproceduresforconditioningPMCmaterialsandimplant
devices (PMC specimens) in a user selected liquid environment prior to conducting subsequent tests. It is not the purpose of this
practice to determine the diffusion coefficients or actual saturation levels of a given liquid into the materials and devices. For these
determinations, other procedures, such as Test Method D 5229, may be followed.
1.3 Diffusion of liquid into a solid material is a slow process. While the time necessary to achieve saturation at 37°C may be
sufficiently short for thin specimens, such as fracture fixation plates, it may be prohibitively long in thick sections, such as femoral
components for hip arthroplasty. However, the diffusion process may be accelerated at an elevated temperature. Consequently, two
separate procedures (ProceduresAand B) are presented in this practice. ProcedureAcovers exposing the specimen to the desired
conditioning environment at 37°C. Procedure B prescribes a method to accelerate the diffusion process by conditioning the
specimen at a selected elevated temperature.
1.4 This practice does not specify the test environment to be used for conditioning. However, the pH value of immersion liquid
shall be maintained at 7.4 6 0.2 to simulate the in vivo environment.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D 618 Practice for Conditioning Plastics and Electrical Insulation Materials for Testing
D 756 Practice for Determination of Weight and Shape Changes of Plastics Under Accelerated Service Conditions
D 3878 Terminology of High-Modulus Reinforcing Fibers and Their Composites
D 5229/D 5229M Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix
Composite Materials
3. Terminology
3.1 Definitions:
3.1.1 cumulative moisture content, M (%), n—the amount of absorbed moisture in a material at a given time t, expressed as a
t
percentage of the weight of absorbed moisture divided by the initial specimen weight, as follows:
W 2 W
i b
M,% 5 3 100 (1)
t
W
b
where:
W = current specimen weight, g, and
t
W = initial (baseline) specimen weight at t = 0 and standard laboratory atmosphere, g.
b
3.1.2 liquid, n—water, saline solution, calf serum, or any other liquid solution that is used to condition PMC specimens.
3.1.3 nominal saturated moisture content, M (%)—an approximation of the amount of moisture absorbed by a specimen at
s
This practice is under the jurisdiction of ASTM Committee F-4F04 on Medical and Surgical Materials and Devices and is the direct responsibility of Subcommittee
F04.14F04.15 on Composite Materials. Material Test Methods.
Current edition approved Nov. 10, 1995. Published January 1996.
Annual Book of ASTM Standards, Vol 08.01.
Annual Book of ASTM Standards, Vol 15.03.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F 1634 – 95 (2000)
saturation, expressed as a percentage of the weight of absorbed moisture at approximate saturation divided by the initial specimen
weight, as follows:
W 2 W
s b
M,% 5 3 100 (2)
s
W
b
where:
W = specimen weight at approximate saturation, g, and
s
W = initial (baseline) specimen weight at t = 0 and standard laboratory atmosphere, g.
b
3.1.4 standard laboratory atmosphere, n— a laboratory atmosphere having a temperature of 23 6 2°C and a relative humidity
of 50 6 10 %.
4. Summary of Test Method
4.1 In Procedure A, a specimen is immersed in a liquid bath at 37 6 1°C with a pH value of 7.4 6 0.2.
4.2 In Procedure B, conditioning occurs in a liquid bath at a selected elevated temperature.
4.3 Weight change is monitored over time until specimens reach the nominal moisture saturation content.
4.4 Keep specimens in the conditioning bath for storage prior to subsequent tests.
5. Significance and Use
5.1 The conditioning procedures covered in this practice provide methods for saturating PMC specimens in a liquid
environment prior to conducting other tests for property evaluation.
5.2 The conditioning may affect geometric and dimensional changes in specimens. In some severe cases, chemical changes may
occur in the fiber, polymer and fiber-polymer interphase and interface.
5.3 Caution must be taken if Procedure B (10.2, Procedure B—Accelerated Moisture Saturation at Elevated Temperature) is
followed to condition PMC specimens at an elevated temperature. Physical and chemical reactions in materials are normally
temperature dependent.An increase in experimental temperature may accelerate a desirable moisture diffusion process. However,
elevated temperatures above 37°C may also cause undesirable reactions that do not represent appropriate responses of materials
at 37°C. Consequently, a pilot study is recommended in Procedure B to determine if a selected elevated temperature can be used
for accelerated conditioning. If the properties of materials are determined to be irreversibly affected by this pilot study at the
selected elevated temperature, then either an appropriate lower elevated temperature should be determined by repeating the pilot
study, or Procedure B should not be used.
6. Apparatus
6.1 Balance—An analytical balance capable of measuring weight of specimens to within a resolution of at least 0.005 % of the
total specimen weight.
6.2 Conditioning Bath—Atemperature-controlledliquidbathshallbecapableofmaintainingtherequiredtemperaturetowithin
61°C. The bath shall be monitored either on an automated continuous basis or on a manual basis at regular intervals.
6.3 Specimen Bag—Asealable,flexible,moisture-proofbagmadeofmaterialsuitableforexposuretospecimensthathavebeen
removed from the conditioning bath for cooling prior to weighing. Bags that meet the requirement of MIL-B-131 have been found
to be satisfactory for use in such applications.
6.4 Absorbent Cloth— Clean, non-linting absorbent cloth for use in wiping excess liquid from surface of specimens.
6.5 Gloves—Clean, non-linting gloves for use when handling specimens.
6.6 pH Measurement System—An analytical system capable of measuring pH to within 60.1.
6.7 Differential Scanning Calorimeter —An analytical system capable of heating a specimen at a controlled rate while
measuring heat input and temperature.
7. Sampling and Test Specimens
7.1 Preparation— Precaution shall be taken to avoid the entrapment of moisture in uneven surfaces, or delamination due to
inappropriate machining and manufacturing processes.
7.2 Labeling—Label the specimen so as to be distinct from each other in a manner that will both be unaffected by the test and
not influence the test and, furthermore, will not be removed during conditioning.
8. Measurements of Test Specimens
8.1 The following measurements shall be made on specimens prior to immersion, after conditioning at the end of a test
procedure, and at any intermediate stage as prescribed in the test procedures:
8.1.1 Weight—The weight within 0.005 % of specimen weight.
8.1.2 Characteristic dimensions of specimens may be measured as a function of immersion time to determine the amount of
swelling induced by moisture absorption.
9. Visual Examination
9.1 Noticeable qualitative changes in surfaces, outline, and general appearance of the test specimen shall be recorded after each
F 1634 – 95 (2000)
stage of the testing procedure. These changes include color, surface irregularities, odor, surface voids, delamination and cracking.
The immersion liquid should also be observed for evidence of material that has leached from specimens or holders, and evidence
ofbacterialorfungalcontamination.Ifbacterialorfungalcontaminationisfound,specimensshouldberemovedfromthesolution,
washed with detergent and water, rinsed, and placed in fresh solution. If contamination is a recurring problem, antibacterial or
antifungal agents must be added to the solution; minimal amounts should be used as they may affect specimen properties.
10. Procedures
10.1 Procedure A—Moisture Saturation Determination at 37°C:
10.1.1 Specimen Preconditioning—Bring the test specimens to a uniform 23 6 2°C after manufacturing process.
10.1.2 Moisture Absorption:
10.1.2.1 Record the initial (baseline) weight, W .
b
10.1.2.2 Place the specimen in the conditioning bath, which has previously reached the specified temperature 37 6 1°C. The
pH value of immersion liquid used shall be maintained at 7.4 6 0.2 throughout the conditioning process and monitored at least
onceaweek.IfthesolutionpHfallsoutsidethedesignatedrange,thesolutionshouldbechanged.ThepHshouldnotbemaintained
by repeatedly adding buffer to the same solution. This will change solution composition and may affect specimen properties.
Evaporation losses should be made up with sterile deionized water if saline, serum, plasma, or other hydrous medium is used as
the conditioning environment.
10.1.2.3 Monitor the weight gain of specimens over time. A suggested schedule is to weigh each specimen every 24 h for the
first 120 h, then every 96 h.
10.1.2.4 Attheendofeachtimeinterval,removethespecimensfromtheconditioningbathandplacetheminthespecimenbag.
Seal the bag and allow the specimens to come to laboratory standard temperature. Remove the specimens from the bag and wipe
the specimens free of surface moisture with an absorbent lint-free cloth. Wait for 10 min and measure the weight of specimens to
the required precision, and W, along with the corresponding total elapsed time and the time interval since the previous
t
measurement.
10.1.2.5 Return the specimens to the conditioning bath. The specimens shall not be out of the conditioning bath for more than
30 min and shall not be out of the specimen bag for more than 15 min.
10.1.2.6 Calculate cumulative moisture content, M (%), using Eq 1 at each time interval and plot versus time.
t
10.1.2.7 The minimum time, t , required to reach nominal saturated moisture content, M , is the time at which the change in
min s
cumulative moisture content from the prior measurement is less than 0.010 % of specimen weight for three consecutive weighings
with no less than 96 h of elapsed time between each consecutive weighing.
10.1.2.8 Following moisture saturation within the specified tolerance range, the specimen should be stored in a bath of the same
fluid which is to be used for post-conditioning testing until the time the post-conditioning testing is conducted.
10.2 Procedure B—Accelerated Moisture Saturation at Elevated Temperature:
10.2.1 Determination of Accelerated Temperature (T ) Level:
a
10.2.1.1 Specimensshouldbefirstsaturatedintheconditioningenvironmentat37°Candthenevaluatedbydifferentialscanning
calorimeter (DSC) evaluation over a temperature range of 37 to 120°C. The purpose of this is to determine if a material transition
temperature (that is, glass transition or melting temperature), or a degradation temperature (such as an oxidation or thermal
decomposition temperature), occurs within this temperature range. If the material is stable within this range, then accelerated
conditioning may be conducted at T = 95°C in a conditioning environment containing water. If a transition or degradation
a
temperature is found between 37 and 120°C, then the maximum acceleration temperature to be used should be at least 25°C below
the lowest transition or decomposition temperature. If nonhydrous solutions are used as the conditioning environment (that is, pure
lipid), then a similar procedure can be followed except the temperature would now be governed by the boiling or decomposition
temperature of the given environment and specimen combination.
10.2.2 Effect of Accelerated Temperature Conditioning:
10.2.2.1 Once T is determined from 10.2.1.1, at least five samples representative of the specimen being evaluated should be
a
conditioning at both T and 37°C and then tested to check for conditioning temperature induced differences. Because conditioning
a
may influence different material properties of PMC specimens in different ways, the test implemented to check for differences
between T and 37°C should closely match the intended post-conditioning test that the PMC specimen will be conditioned for. If
a
T influences the properties in question, then a lower conditioning temperature must be identified by repeating this procedure at
a
selected lower temperatures in which the property is not influenced by conditioning. If the property is determined to be not
influenced by T , then T can be used to accelerate the conditioning process for subsequent specimens.
a a
10.2.3 Accelerated Conditioning:
10.2.3.1 Follow the procedures outlined in 10.1.2 with the exception that the conditioning bath will be maintained at T 6
a
1.0°C. The same time-measurement sequence as described in 10.1.2 should be used to determine the minimum time, t , when
min
saturation is reached. The bath should be adequately sealed to minimize evaporation loss and periodically monitored to ensure
adequate bath depth is maintained for complete immersion of samples. If the bath is physically sealed, a safe mechanism of
pressure relief (that is, pressure relief valve or releasable lid seal) must be provided to prevent pressure build-up if the oven is
accidentally overheated. Evaporation losses should be made up with sterile deionized water if saline, serum, plasma, or other
hydrous medium is used as the conditioning environment.
F 1634 – 95 (2000)
10.2
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.