Table 3.

¹H-NMR analysis of acetylated milled wood lignin from the cotton stalk at various degradation stages.

Chemical shift region (δ)	Type of protons	Percentage of protons (%)
		ck	30 day	60 day
7.3–6.8	Aromatic protons in guaiacyl units	0.59	0.29	0.32
6.8–6.3	Aromatic protons in syringyl units	0.49	0.12	0.08
6.3–5.6	Hα of β-O-4 and β-1 structures	0.01	0.03	0.2
5.6–5.2	Hα of β-5 structures	0.17	0.11	0.2
5.2–5.0	Hydrocarbon protons	0.17	0.1	0.16
4.9–4.5	Hα and Hβ of β-O-4 structures	0.51	0.38	0.38
4.5–4.2	Hα of β-β structures	0.29	0.18	0.46
4.2–3.0	H of methoxyl, methanol groups, and Hα in several structures	4.66	3.65	5.48
2.3–1.9	H of aromatic acetates	0.11	0.07	0.12
1.9–1.6	H of aliphstic acetates	0.13	0.08	0.13