Table 3.

µ-FTIR absorptions of the open- and closed-cell “Unaged” phenol formaldehyde (PF) foams investigated and their assignment according to the literature data [5,8,13,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39].

PF Foams
	Open-Cell		Closed-Cell
Bond Type	Gardol	Oasis	Balsa Foam Soft Density	Balsa Foam 5 PCF	Austrotherm	Lit. Data Range [5,8,13,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39]	Lit. Compound Type Assignment
	Wavenumber cm−1
O–H stretching	3374	3348	3386	3386	3387	3389–3100	Phenolic O–H [5,8,24,25,26,27,28] and methylol OH [5,24,26,29]
C–H stretching	3009	3014	3007	3009	3010	3300–3010	Phenolic ring C–H [5,24,27,28]
	2921; 2868	2924; 2855	2908; 2864	2911; 2867	2921; 2871	2953–2800	Methylene group –CH2– [5,24,25,27,28]
	O	O	2789	2791	O	2724	CH2 groups of formaldehyde (–CHO) [25]
C=O stretching and C–C stretching	1742.000	O	1751.000	1751.000	O	1755–1735	Arlyl carboxylic acid [35,38]/Tetra–substituted benzene ring C–C stretching [27,36]
C=O stretching	O	O	1722 (shoulder)	1721	O	1720	Hydroxy acids COOH [13]
	O	O	O	O	1709	1704	(Phenolic) C=O [34]
	O	O	1685 (shoulder)	O	O	1660–1690	Quinoid structures [13]
	1650	O	1651	1651	1653; 1648	1643	Formaldehyde monomer residue [8]/benzophenone by oxidation of methylene groups [13,27]/(Phenolic) C=O [34]
C=C stretching	1606	1606; 1594; 1558; 1504	1606; 1503 (weak shoulder)	1607; 1503 (weak shoulder)	1600; 1501	1633–1500	Phenolic ring C=C [5,8,24,25,26,28,29]
C–H bending and C=C stretching	1478	1478	1476	1478	1475	1480–1473	Scissor bending vibration of CH2 (o–p’ ) [31,32,33]
	1447	1442	1450 (shoulder)	1450 (shoulder)	1451 (weak shoulder)	1456–1450	Scissor bending vibration of CH2 (p–p’) [31,32,33] and C=C aromatic ring [28,29]
	O	O	O	O	1436	1437	Aliphatic CH3 [27]
O–H in plane bending and C–H bending	O	O	1377	1377	O	1378–1370	Phenolic O–H groups [5,24,25] /C–H deformation vibration of aliphatic hydrocarbons [27] / O–H in plane bending of carboxylic acids [39]
	1354	1353	1353	1353	1349	1360 –1340	Phenolic O–H groups [5,8,24,25,26,28] / C–H deformation vibration of aliphatic hydrocarbons [27]
C–H bending (overtone)	1326	O	1324	1326	O		CH2 groups
C–O stretching	O	O	1260 (shoulder)	1260 (shoulder)	1257 (shoulder)	1270–1260	Biphenyl ether C–O [28] / alkyl–phenol C–O [30] / carboxylic acids C–O [39]
	1223	1210	1235; 1223	1234; 1223	1208	1240–1210	Phenolic C–O [5,24,25,26,27,28,30] and ether bond [29]
C–H bending andC–O stretching	1167	O	1168	1168	O	1175–1160	Aromatic C–H in plane deformation [5,24,28]
	1146	1151	1143	1146	1138	1153–1147	Aromatic C–H in plane deformation [26,28] and dimethylerne ether C–O–C– bridges [29]
	1064	1124; 1102 (shoulders)	1077	1077	1098; 1077	1120–1060	Aromatic C–H in plane deformation [5,8,24,28] and dimethylene ether C–O–C [5,26,27]
C–O stretching	1031; 1006	1029; 1005	1012	1035; 1013	1032; 1011	1058–1010	Alcoholic C–O (methylol groups) [5,24,25,26,27,28,29]
C–H bending	O	O	992	992	O	997–960	Phenol with trisubstitution at 1,2,4 positions [25,28] / =C–H def. of aryl and/or a,b–unsaturated carboxylic acid [38]
	O	O	933	932	O	950–920	C–O–C ether alyphatic or aromatic C–O–O–C peroxide [32]; O–H out of plane of carboxylic acids [39]
	884	885	880	881	883	890–875	Phenol with tri–substitution at 1,2,4 positions (o,p) [5,13] and tetra–substitution at 1,2,4,6 positions (o,o',p) [5,24,25,26,28,30]
	818	828	822	820	822	826–814	Phenol with di–substitutions at 1,4 positions (p) [5,24,25,26,28,30] and tri–substitution at 1,2,4 positions (o,p) [13]
	779	O	775	778	777	790–780	Phenol with tri–substituions at 1,2,6 positions (o,o') [5,24,28]
	759	767	753	754	748	760 –756	Phenol with di–substituions at 1,2 positions (o) [5,24,25,28,31] and tri–substituions at 1,2,6 positions [30,31]
	O	O	714	714	O	–	CH2 rocking [32]
	685	695	680	680 (shoulder)	700	694–690	Monosubstituted ring [5,24,25,28]