Micromeritics ACCUPYC III Operator's Manual page 56

2 About the Software
FoamPyc
FoamPyc capability is used for measuring open and closed cell foam materials and is included in
both standard and temperature-controlled pycnometers. Five different techniques are available
for analyses on materials such as polystyrene, urethane, and rubber foams.
Correction using cell dimensions. Measures the closed cell fraction and corrects for the
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cells that were damaged while cutting the sample to the necessary size and shape. This is
accomplished by using either the average cell diameter or the cell chord length (as defined in
ASTM method D-6226) and the measurements of the sample to determine the volume of the
cut cells. This volume is deducted from the total volume of the open cells measured by the
pycnometer.
Correction by recutting sample. Corrects for the cut cells by using two separate meas-
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urements. For the second measurement, the sample is recut to double the amount of cut sur-
face. The observed difference in cut open cell volume is applied as a correction to the initial
measured volume. This method offers the distinct advantage that no assumptions are needed
about the relative amounts of open and closed cells.
No correction. Does not correct for cut cells. It is used for materials with predominantly open
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cells where good accuracy can be achieved without correction. The accuracy level deteriorates
as the percentage of closed cells increases.
Compressibility test. The fill pressure is increased incrementally over the sample with each
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repeat of the P1, P2 cycle (where P1 is the initial pressure to which the sample is charged, and
P2 the final pressure after expansion). The apparent variation of the measured sample volume
with the average pressure is determined.This test is an approximate indication. It is not inten-
ded to be an exact measure of volume compressibility. If you want to see whether com-
pressibility is reversible for your sample, use sample fill direction. If not, reference fill direction is
recommended.
Cell fracture test. A perfectly rigid foam is assumed. First, a P1, P2 cycle is performed at the
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lower of two specified P1 pressures, and the results stored. A second cycle is performed at a
higher specified value of P1, then a third cycle identical to the first cycle is performed.The dif-
ference between the volume of the sample on the first measurement and on the third meas-
urement is reported as the volume of fractured cells. It is assumed that cells fracture by
exposure to the highest pressure (second cycle) so that when the third measurement is made,
the measured sample volume has decreased from the first cycle by the amount of the closed
cell volume which was fractured.
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The 100 cm AccuPyc III has been designed and tested to follow the procedure in ASTM Method
D-6226 for FoamPyc analyses. The 10 cm
however, analyses on these AccuPycs will not conform to the ASTM method.
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unit can be used for some types of foam materials;
135-42800-01 (Rev -) — Nov 2023
AccuPyc III Operator Manual