Elements in Polypropylene

    Application Note EDXRF1705

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    The measurement of trace levels of Al, Si, P, Cl, Ti, and Ca in polypropylene is demonstrated.


    In the production of polymers such as polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET, PETE) various additives and stabilizers are added, as well as Si (as SiO₂) as an anti-block. Trace levels of catalyst residues may also be present. To ensure proper quality control during the production process test, samples are made and the trace elements are measured. To meet this industry need, Applied Rigaku Technologies offers a full line of benchtop EDXRF analyzers. With simple, intuitive software interface and powerful, innovative design, Rigaku EDXRF systems make an excellent tool for quality control checks at several places along the polymer production process.

    NEX QC+ QuantEZ workstationModel: NEX QC+ QuantEZ


    Empirical calibration is used. Because all elements are at trace levels, X-ray absorption/enhancement effects are negligible and can be ignored for process quality control. Each calibration standard can include all elements dispersed independently, or series of single element standards can be used to make calibrations. Series of single element standards were used in this demonstration, with the calibration results summarized here.

    Element Number of standards Concentration range
    Al 3 76 – 230 ppm
    Si 5 0.018 – 0.097 mass%
    P 4 36 – 92 ppm
    Cl 5 24 – 103 ppm
    Ca 4 38 – 188 ppm
    Ti 2 3.7 – 9.2 ppm

    Repeatability (precision)

    Typical precision is shown here. Ten repeat analyses of each middle concentration sample were performed with the sample in static position.

    Element Units Assay value Average value Std. deviation % Relative
    Al ppm 109 114 11 10%
    Si mass % 0.0597 0.0584 0.0010 1.7%
    P ppm 51 55.2 2.4 4.7%
    Cl ppm 54 52.0 0.7 1.3%
    Ca ppm 74 73.8 1.1 1.5%
    Ti ppm 3.7 3.8 0.3 8.1%


    EDXRF provides a rapid, non- destructive means of semi- quantitative measurement for screening and identification, as well as elemental quantification of metals, solids, powder, pellets, thin films, and liquids. The NEX QC+ QuantEZ powerful yet simple and intuitive software gives the quality control lab and at-line technicians a fast means of making QC checks along the production process line in the manufacturing of polypropylene and other similar polymers.

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