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Table 2 Relative changes in poplar samples after dilute acid pretreatment by Fourier transform infrared spectroscopy

From: Effect of lignin content on changes occurring in poplar cellulose ultrastructure during dilute acid pretreatment

Band position

Assignment[[32]-[38]]

Pretreatment conditions

PL23-t0

PL23-t15

PL23-t35

PL19-t0

PL19-t15

PL19-t35

PL14-t0

PL14-t15

PL14-t35

3340

O-H stretching, related to cellulose-hydrogen bonds

1.7

1.6

1.5

2.1

1.9

2.2

2.1

1.8

2.3

2900

C-H stretching, related to biomass methyl/methylene group

0.8

0.8

0.9

0.9

0.8

1.0

0.9

0.8

1.1

1740

Carbonyl bonds ascribed to hemicelluloses

1.3

--

--

1.6

--

--

1.5

--

--

1595

Lignin aromatic ring stretch

0.7

0.8

0.8

0.6

0.7

0.7

0.5

0.5

0.7

1510

Lignin aromatic ring stretch

0.6

0.9

1.0

0.5

0.8

0.8

0.4

0.7

0.7

1424

CH2 scissor motion in cellulose

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1367

Aliphatic C-H stretch in CH3

1.1

0.9

0.8

1.3

1.1

1.1

1.4

1.2

1.1

1265

Ester absorption associated with uronic acid

--

1.1

1.2

--

1.2

1.1

--

1.3

1.2

1240

C-O absorption from acetyl group cleavage

1.6

1.3

1.2

2.2

1.1

1.0

2.0

1.2

1.1

1059

C-O stretch in secondary alcohol

5.0

3.6

3.4

--

4.0

4.3

--

5.3

4.9

1100/900

Crystalline to amorphous cellulose ration

3.0

4.4

4.5

2.9

3.7

4.5

2.7

4.1

4.4

750/710

Iα/Iβ

0.9

0.6

0.4

0.3

0.3

0.2

0.3

0.3

0.2

900

Amorphous cellulose

1.1

0.6

0.6

1.2

0.8

0.8

1.2

0.9

0.7

  1. Sample code with definition is in Table 1.