• Top library match: POLYESTER #12708

• The carbonyl peak position (1797 cm ¹) is shifted relative to the most common polyester C=O absorption (~1720 cm ¹); this could be due to anhydride formation or electron‑withdrawing ester linkages, but does not rule out the polyester classification.
• The 1030 cm ¹ band cannot be assigned with certainty to a specific functional group from the current data; both C-O stretching (ester/alcohol) and sulfoxide S=O are possible, the latter suggested by one literature source [2].
• The exact nature of the polyester backbone (e.g., aromatic amide sequence, possible vinyl ester comonomer) would benefit from additional analyses such as pyrolysis‑GC/MS or NMR.

Recommended next steps: Confirm the base polymer by dissolving or extracting the filler (acid digestion) and re‑recording the FTIR spectrum of the organic fraction. Perform thermogravimetric analysis (TGA) coupled with FTIR to resolve the carbonate content and identify the thermal degradation signature of the polymer. Acquire Raman or X‑ray diffraction data to verify the polymorph of calcium carbonate (calcite vs. aragonite).