title: Investigation of structural modification and thermal characteristics of lignin after heat treatment.
abstract: Milled wood lignin was subjected to heat treatment between 150 and 300°C to understand the pattern of its structural modification and thermal properties. When the temperature was elevated with interval of 50°C, the color of the lignin became dark brown and the lignin released various forms of phenols from terminal phenolic groups in the lignin, leading to two physical phenomena: (1) gradual weight loss of the lignin, up to 19% based on dry weight and (2) increase in the carbon content and decrease in the oxygen content. Nitrobenzene oxidation and (13)C NMR analyses confirmed a cleavage of β-O-4 linkage (depolymerization) and reduction of methoxyl as well as phenolic hydroxyl group were also characteristic in the lignin structure during heat treatment. Simultaneously with lignin depolymerization, GPC analysis provided a possibility that condensation between lignin fragments could also occur during heat treatment. TGA/DTG/DSC data revealed that thermal stability of lignin obviously increased after heat treatment, implicating the structural rearrangement of lignin to reduction of β-O-4 linkage as well as accumulation of CC bonds.
authors: Department of Forest Sciences and Research Institute for Agriculture and Life Science, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul, 151-921, Republic of Korea.
authors: Jae-Young
authors: JY
authors: Kim
authors: Department of Forest Sciences and Research Institute for Agriculture and Life Science, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul, 151-921, Republic of Korea.
authors: Hyewon
authors: H
authors: Hwang
authors: Department of Forest Sciences and Research Institute for Agriculture and Life Science, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul, 151-921, Republic of Korea.
authors: Shinyoung
authors: S
authors: Oh
authors: Division of Wood Chemistry & Microbiology, Korea Forest Research Institute, 57 Hoegi-ro, Dongdaemun-gu, Seoul, 130-712, Republic of Korea.
authors: Yong-Sik
authors: YS
authors: Kim
authors: Department of Plant & Environmental New Resources, College of Life Science, KyungHee University, Yongin-si, Kyunggi-do, 446-701, Republic of Korea.
authors: Ung-Jin
authors: UJ
authors: Kim
authors: Department of Forest Sciences and Research Institute for Agriculture and Life Science, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul, 151-921, Republic of Korea. Electronic address: cjw@snu.ac.kr.
authors: Joon Weon
authors: JW
authors: Choi
mesh_terms: D002244:Carbon / Q000737:chemistry; D006358:Hot Temperature; D008031:Lignin / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D010636:Phenols / Q000737:chemistry; D058105:Polymerization; D014934:Wood / Q000737:chemistry
chemical_list: D010636:Phenols; D002244:Carbon; D008031:Lignin; D010100:Oxygen
keywords: Condensation; Depolymerization; Heat treatment; Lignin; TGA/DSC; β-O-4 linkage