ISO 7822:1990
Textile glass reinforced plastics; determination of void content; loss on ignition, mechanical disintegration and statistical counting methods

Standard No.

ISO 7822:1990

Release Date

1990

Published By

International Organization for Standardization (ISO)

Latest

ISO 7822:1990

Scope

This International Standard specifies three methods for the determination of the void content of textile glass reinforced plastics or composites, of which the constituents are of a solid nature. 1 Method A - Loss on ignition This method is applicable to composites for which the effects of the loss on ignition test on the materials are known. Most matrix resins and textile glass fibre reinforcements fall into this class. The method is not applicable to composites for which the ef-fects of the loss on ignition test on the resin, the reinforcement, and any fillers are unknown. This may include silicone resins, which do not burn off completely, and fillers consisting of ox-ides, carbonates, etc., which may gain or lose weight. Note that separate weight loss tests on individual materials will usually, but not necessarily, give the same result as when all the materials are combined. The accuracy of the method is ±2,5 % by volume. 2 Method B - Mechanical disintegration This method is applicable if the composite can be disintegrated in such a way, for example by crushing in a press, that all the enclosed voids are connected with the outside of the com-posite material. The method is destructive and has limited ap-plication if the matrix material shows ductile behaviour under compression, unless it can be made more brittle in an artificial way (for example by cooling). The method is especially suitable when the densities of the con-stituent materials are not known or not determinable. The method neglects the influence of any volatile constituents that could evaporate during and after disintegration. In this connection, the conditioning shall be chosen with care. The method also does not take into account any cut or exposed voids at the surface of the sample. The accuracy of the method is ±1 % by volume. 3 Method C - Statistical counting This method is applicable to composites having a void content less than or equal to 1 % by volume.

ISO 7822:1990 history

• 1990 ISO 7822:1990 Textile glass reinforced plastics; determination of void content; loss on ignition, mechanical disintegration and statistical counting methods