Unraveling the structural characteristics of lignin in hydrothermal pretreated fibers and manufactured binderless boards from Eucalyptus grandis

Sustainable Chemical Processes

Table 3 Hydrogen bond intensity and cellulose crystallinity ratios

	HBI^a	FT-IR		XRD^d	NMR^e
	A₃₄₀₀/A₁₃₂₃	TCI (A₁₃₆₉/A₂₉₀₀)^b	LOI (A₁₄₂₃/A₈₉₉₎^c
Control	3.46	0.48	0.99	40.53	34.83
F1-a	3.79	0.54	2.01	42.62	37.90
F1-b	4.78	0.59	1.05	46.42	40.81
F8-a	3.84	0.55	1.83	44.82	39.41
F8-b	4.84	0.60	1.54	46.47	41.26
Q1-a	4.06	0.50	1.86	42.68	34.83
Q1-b	4.65	0.61	1.82	45.56	37.90
Q4-a	3.59	0.56	1.70	41.73	36.90
Q4-b	4.10	0.60	1.67	48.64	38.99

^aHBI – hydrogen bond intensity which is the ratio of A₃₄₀₀ cm⁻¹ and A₁₃₂₃ cm⁻¹ from FT-IR spectra.
^bTCI – total crystallinity index which is the ratio of A₁₃₆₉ cm⁻¹ and A₂₉₀₀ cm⁻¹ from FT-IR spectra.
^cLOI – lateral order index was determined as the ratio of two absorption bands of A₁₄₂₃ cm^–1 and A₈₉₉ cm^–1 from FT-IR spectra.
^dCrI was calculated based on the height of the peak corresponding to (002) lattice plane (I₀₀₂) and the minimum between 110 and 002 lattice planes (I_am) as below: CrI (%) = (I₀₀₂ – I_am) / I₀₀₂.
^eCrI was calculated from the ratio of the crystalline area over the total area, where separation of crystalline (86 – 92 ppm) and amorphous (80 – 86 ppm).