About the FoamPyc Module

A FoamPyc option for measuring open and closed cell foam materials is available for both standard and temperature-controlled pycnometers. This unit can be ordered initially with the FoamPyc application installed, or can be upgraded from the standard AccuPyc with a software enhancement via USB media. Configuration options are:

  • 100 cm3 nominal cell volume (recommended)
  • 10 cm3 nominal cell volume

The FoamPyc option performs analyses on materials such as polystyrene, urethane, and rubber foams using five different methods:

  • Correction using cell dimensions. Measures the closed cell fraction and corrects for the cells 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‑6226‑15) 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 measurements. For the 2nd measurement, the sample is recut to double the amount of cut surface. 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 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 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 intended to be an exact measure of the volume compressibility.
  • Cell fracture test. A perfectly rigid foam is assumed. First, a P1,P2 cycle is performed at the 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 difference between the volume of the sample on the first measurement and on the third measurement is reported as the volume of fractured cells. It is assumed that cells fracture by exposure to the highest pressure (2nd 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.

The 100 cm3 AccuPyc II has been designed and tested to follow the procedure in ASTM Method D 6226 for FoamPyc analyses. The 10 cm3 and 350 cm3 units can be used for some types of foam materials; however, analyses on these AccuPycs will not conform to the ASTM method. The 1 cm3 AccuPyc II cannot be used to perform FoamPyc analyses.

The FoamPyc software also provides the capability to perform analyses in the Standard mode of operation. This is especially convenient for users who have upgraded to the FoamPyc method from the standard method. For example, a 100 cm3 AccuPyc on which FoamPyc analyses are performed and a 1 cm3 analysis module attached on which standard analyses are performed.

 
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