木质素
甲醛
光谱学
材料科学
脲醛
苯酚
主成分分析
化学
胶粘剂
制浆造纸工业
有机化学
纳米技术
计算机科学
物理
量子力学
工程类
人工智能
图层(电子)
作者
Sofia Gonçalves,Jorge Martins,Nádia Paiva,Diana Paiva,Luísa Carvalho,Fernão D. Magalhães
出处
期刊:Polymers
[MDPI AG]
日期:2022-12-30
卷期号:15 (1): 178-178
标识
DOI:10.3390/polym15010178
摘要
Out of the 50 to 70 million tons of lignin that are produced annually, only 1 to 2% are used for value-added products. Currently, 90% of the total market of this compound corresponds to lignosulphonates (LS). The most successful industrial attempts to use lignin for wood adhesives rely on using it as a partial substitute in phenol-formaldehyde or urea-formaldehyde resins. However, lignin's aromatic ring presents a low number of reactive sites. Several methods have been proposed to improve its reactivity, such as prior methylolation with formaldehyde. Off-line methods are commonly applied to monitor this reaction's progress, but this introduces a significant delay in the analysis. This study proposes a new method for in-line monitoring of the methylolation reaction using visible spectroscopy. In order to monitor the reaction progress, principal component analysis was applied to the spectra, and the obtained scores were analyzed. When these results were plotted against those obtained by the off-line methods, a satisfactory regression was obtained at 50 °C (R2 = 0.97) and 60 °C (R2 = 0.98) for two different LS samples. Therefore, it was concluded that visible spectroscopy is a promising technique for studying lignin methylolation.
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