Void Content of Reinforced Plastics ASTM D2734

Void content testing of reinforced plastics according ASTM D2734.

Intertek conducts void measurement testing of polymers and composites material, using ASTM method D2734.

Void content of reinforced plastics ASTM D2734 (Test Method A):
Void Content measures the voids in reinforced polymers and composites. Information on void content is useful because high void contents can significantly reduce the composites' strength. Monitoring lot-to-lot void contents can also act as a measure of the consistency of the composites' manufacturing process.

Void measurement test procedure:
The measured density of the material is determined by dry / wet weight method ASTM D792 Method A. For void content it is necessary to have theoretical densities of both the resin and the reinforcing material to determine the theoretical density. The individual densities are normally obtained from the supplier of the resin and reinforcing material.

After the actual density of the material is determined the weighed sample is placed into a weighed crucible and burned in a 600°C muffle furnace in air until only the reinforcing material remains. The crucible is cooled and weighed. The resin content (ignition loss) can be calculated as a weight percent from the available data. By comparing the actual density to the theoretical density, void content is calculated.

Specimen size:
The size is normally 1” by 1” x thickness.

Data: 

T = Theoretical Density
T_d = theoretical composite density
R = Resin weight %
r = Reinforcement weight %
 
T = 100 / ( R / D + r / d )

V = Void content ( volume % )
M_d = measured composite density
D = Density of resin
d = Density of reinforcement
V = ( T_d - M_d ) / T_d