Scope:

This ASTM D6042 test method describes a liquid chromatographic separation approach for various polypropylene compounds currently in use. UV absorbance is measured for the compound at 200 nm and quantification is done using this standard procedure. Stabilizers utilized in polypropylene manufacturing are isolated and characterized for identifying the performance qualities of the polymer composition. In polypropylene samples, the ASTM D6042 test technique can detect the presence of erucamide slip, vitamin E, irgafos 168, irganox 3114, irganox 1010, and irganox 1076.

Other antioxidants, such as ultranox 626, ethanox 330, santonox R, and BHT, should be able to be determined using this test method, although the application of this test method for these antioxidants has not been examined. 

Procedure:

For ASTM D6042, the polypropylene (PP) sample is crushed to 20-mesh particle size (850  microns) and extracted by refluxing or ultrasonic bathing with a 75:25 methylene chloride:  cyclohexane combination. Liquid chromatography is then used to evaluate the solvent extract.  Using reverse-phase chromatography (C-18 column) with ultraviolet (UV) detection at 200 nm,  the additive concentrations are evaluated relative to an internal standard (included in the solvent).

Specimen size:

For the ASTM D6042 test procedure, crushed polypropylene of (5 ± 0.01)grams is used as a test specimen.

Data:

In ASTM D6042, the additive content of each sample is calculated from the following equation:

where,

A = area of the additive

R = response factor 

Cis = concentration of the internal standard 

V = volume of the extraction solvent in mL 

W = weight of the sample extracted, g, 

Ais = area in the internal standard

Conclusion:

This ASTM D6042 test method describes a liquid chromatographic separation approach for various polypropylene compounds currently in use.