Table 2. Correlation between the Absorption Difference Δν and the Extractability.

	C=O absorption banda (cm–1)			extractabilityd
plasticizer	νob	νc	|Δν̅| ↓	↑ (wt %)
DOP	1724	1720	4.0	14.1%
2,5-DBF	1724, 1709	1736, 1717	10.0	13.5%
2,5-DIAF	1724, 1709	1736, 1718	10.5	13.1%
2,3-DIAF	1712	1722	10.0	7.9%
2,3-DBF	1716	1730	14.0	5.4%

^aApparatus’ resolution: 4 cm^–1.

^bFrequency of unbound C=O stretching band (pure form, before mixing).

^cFrequency of interactive C=O stretching band (PVC-PLS 50%, after mixing).

^dExtraction resistance (ASTM D5227-13): the lower the value, the higher the polarity.