Meaning
Analytical ratios that measure the proportion of carbon-14 in a polymer sample compared to a modern reference standard determine the bio-based content of the material. The modern carbon fraction governs the validation of renewable resource claims for bioplastics and blended resins. This measurement establishes the boundary between fossil-derived carbon, which contains no carbon-14, and recent biomass-derived carbon.
It applies to any organic polymer compound and is independent of the mechanical or thermal history of the plastic.
Biomass Measurement
Radiocarbon analysis of the carbon-14 isotopes allows laboratories to calculate the exact percentage of plant-based resin mixed into a compound. This modern carbon fraction is used to verify that a supplied biopolymer meets the environmental specifications required by the customer or by green labeling schemes. When a compound combines bio-based polyamide with traditional glass fibers, the test isolates the organic carbon portion to determine the bio-fraction.
This analysis protects buyers from false green marketing claims and ensures that the material matches the technical datasheet.
Supplier Verification
Brand owners often require this test to confirm that a supplier has not diluted expensive bio-resins with cheaper, fossil-based equivalents during compounding. A low modern carbon fraction indicates that the material contains more petroleum-derived resin than the contract allows. This measurement is required when sourcing materials that must comply with government purchasing mandates for bio-based products.
The test results provide a clear chemical proof that holds up in commercial disputes or regulatory audits.
Combustion Method
Testing laboratories use accelerator mass spectrometry to measure the isotope levels according to standards such as ASTM D6866. This procedure burns a small sample of the polymer to produce carbon dioxide gas, which is then analyzed for its carbon-14 signature. The resulting modern carbon fraction is converted into a bio-based carbon content percentage by adjusting for the atmospheric carbon levels of the current year.
