Fig. HSQC Spectrum of Aromatic Region for oven dried lignin reference sample 5-1
Fig. HSQC Spectrum of Aliphatic Region for oven dried lignin reference sample 5-1
•
Aromatic Region:
A noticeable decrease in peak intensity for G2, G5, and G6 units suggests thermal degradation and partial condensation of guaiacyl units under high-temperature oven drying conditions. This indicates a less reactive but more condensed lignin structure.
•
Aliphatic Region:
Methoxy (OMe) and β-O-4 peaks display moderate intensity reductions, signifying some level of ether bond cleavage and side-chain degradation. Oven drying appears to cause oxidative degradation, albeit less pronounced compared to dynamic drying.