Residual Acrylonitrile Monomer in Styrene-Acrylonitrile Copolymer Resins & Nitrile-Butadiene Rubber ASTM D5508-16

Scope:

The ASTM D5508-16 test technique includes the detection of residual acrylonitrile monomer in styrene-acrylonitrile copolymer resins and nitrile-butadiene rubber by using headspace-capillary gas (HS-CGC). The residual acrylonitrile in nitrile rubbers (NBR), styrene-acrylonitrile (SAN) copolymers, and ABS resins can be measured to determine polymers’ appropriateness for various uses. This ASTM D5508-16 test technique is limited to dry rubbers and resins due to the presence of 3-hydroxypropionitrile in latices.

Procedure:

In the ASTM D5508-16 test procedure, for each polymer, two dispersions (in o-dichloro benzene) are made and sealed in headspace vials: one includes the polymer in solvent, and the other contains the polymer, solvent, and a known standard amount of acrylonitrile (AN). Under ambient circumstances, both vials are shaken for a set amount of time. The vials are thermally equilibrated in a constant-temperature bath after shaking.

Then, an aliquot of hot headspace gas from each vial is fed into a capillary gas chromatographic column when the timed equilibration is completed. The transfer takes place using an automated injection method. The chromatographic resolution needed to separate the AN from any other volatiles present will be provided by the capillary column. A nitrogen-specific detector is used to detect the AN response (NPD). Using a conventional addition calculation, the raw data signal is transformed into a relative RAN concentration.

Specimen size:

According to ASTM D5508-16, the polymer test unit (sample) that is submitted for analysis should be a 1¾ inch (45 mm) cube. 

Result:

As per ASTM D5508-16, the residual acrylonitrile monomer is reported in parts per billion (ng/g).