ASTM D6226-21 Open Cell Content of Rigid Cellular Plastics

Scope:

The ASTM D6226-21 test method determines the porosity of cellular plastics. It describes the roles of closed and open cells in retaining gases, reducing water absorption, and maintaining thermal conductivity, respectively.  It defines a standard to control the quality of rigid cellular materials, especially plastics.  It characterizes rigid cellular plastics and is applicable for research purposes. The role of different cells is specified, and the performance of plastics is determined. This helps specify the reliability and application of various rigid cellular plastics. 

Procedure:

The apparatus consisting of gas pycnometer, sample chamber, gauge pressure transducer, pressure relief valve, filter, flow control toggles, two-way selector valve, digital meter, cutting device, and a vernier calliper is set up. The method deals with determining the porosity of cellular plastics by measuring volume through Boyle’s Law. The two chambers are connected through a valve, and one of them is filled with the specimen letting in helium or nitrogen from a valve. The pressure in the sample chamber rises, and the differences in the pressure of both chambers are noted. The value of the pressure leads to the measurement of the volume of the sample chamber. The open cell volume is detected due to the difference between the volume of the sample chamber and the volume of the specimen.

Specimen Size:

The nominal dimension of the specimen is 2.5 by 2.5 by 2.5 cm.   

Data:

The cell wall volume percentage is calculated as Wv ꞊ [m/ (sg ×V)] × 100
Where: m = the mass of the specimen, g,
sg = the specific gravity of the material in solid form, g/cm ³, and
V = the geometric volume of the specimen, cm ³
The closed-cell volume percentage is calculated with the equation: Cv = 100 – Ov – Wv