Test Method
Standardized laboratory procedures are required to determine the exact proportion of bio-based carbon in solid, liquid, and gaseous materials. The protocols of astm d6866 utilize radiocarbon dating techniques to distinguish contemporary carbon from fossil carbon in polymeric blends. This standard provides a rigorous regulatory framework for verifying bio-based claims on apparel packaging and retail hangtags.
It defines the specific combustion and collection steps necessary for reproducible isotopic measurement.
Biomass Verification
Testing according to this standard calculates the ratio of modern carbon-14 to total carbon in the textile matrix. Fossil fuels do not contain any carbon-14, which has completely decayed over millions of years. Modern biomass, however, carries a predictable concentration of this isotope.
The measurement of this isotopic abundance allows the lab to compute the percentage of the material derived from agricultural or marine feedstocks.
Sample Cleaning
A critical preparatory stage must occur to strip away any surface-applied chemical finishes before combustion. Surface coatings, including flame retardants or plasticizers, often contain synthetic carbon that would distort the natural-to-synthetic ratio. Technical specialists extract these finishes using organic solvents like dichloromethane or ethanol.
After extraction, the remaining polymer is dried and prepared for conversion to gas, ensuring that only the structural fiber is measured. This treatment prevents false-positive results from temporary textile finishes.
Analytical Range
The method is designed specifically for carbon-based molecules and does not apply to inorganic fillers or metal accessories. The accuracy of the result relies on the precision of the mass spectrometer, which generally resolves bio-based percentages to within three percent. The standard does not differentiate between different types of bio-based feedstocks, only between fossil and non-fossil carbon.
It remains the primary benchmark for certifying the raw material origin of bio-polyester fabrics.
