The infrared spectrum displays a combination of aromatic C–H, ring‑skeletal, and aliphatic C–H bands that closely matches the multivariate loading pattern of polystyrene reported in the literature. An intense carbonyl envelope near 1735 cm⁻¹ and weaker features attributable to sulfate or amide‑related vibrations suggest the presence of oxygenated or sulfated comonomer/additive units. Because the library match is only weak (15 % confidence; leading hits include a flavonoid, a thiazolidinium, and a butadiene–styrene copolymer), a single definitive identity cannot be assigned FTIR In-Depth Interpretation was not selected for this task, so this section shows the library-search result only and no deep AI interpretation was run.