New Test Method for Evaluation of the Extent of Oxidation in Polyolefin Piping by Using Infrared Spectroscopy to Determine a Ketone Carbonyl Index.
1. Scope
Infrared spectroscopy has been utilized to evaluate oxidation of polyolefin materials. This method covers a procedure for quantifying oxidation of polyolefin piping materials through the determination of a ketone carbonyl index. The material is analyzed by fourier transform infrared spectroscopy (FTIR). The intensity of the carbonyl absorption attributed to the formation of ketone carbonyl groups in the polymer by oxidation, found in the range from 1715 to 1720 cm-1, is used as a measure of the extent of oxidation of the polymer. The absorbance of the ketone carbonyl peak is determined by the height of that peak when the infrared spectrum is presented in absorbance mode. The Ketone Carbonyl Index is calculated by dividing the ketone peak absorbance by the absorbance (peak height) of the methylene bending peak at approximately 1460 cm-1. This normalizes the result to account for the samples thickness.
Keywords
polyolefin; oxidation; FTIR; ketone carbonyl index
Rationale
Evaluation of polyolefins for oxidation by FTIR spectroscopy is commonly done. However, neither existing methods for specific products, like ASTM F2102, nor a general carbonyl index method under development in Subcommittee D20.70 generate a result that has ever been applied to the impact that such oxidation can have on long term polyolefin pipe performance. This proposed new standard will be based on a method that has been utilized for over 40 years to quantify oxidation in polyolefin piping products that yields a result which decades of research correlates with the impact of such oxidation on performance.
WK74970 - New Test Method for Evaluation of the Extent of Oxidation in Polyolefin Piping by Using Infrared Spectroscopy to Determine a Ketone Carbonyl Index. | ASTM
