High Molecular-Weight Thermoplastic Polymerization of Kraft Lignin Macromers with Diisocyanate
- Authors
- Le Dai Duong; Nam, Gi-Yong; Oh, Joon-Suk; Park, In-Kyung; Nguyen Dang Luong; Yoon, Ho-Kyu; Lee, Seong-Hoon; Lee, Youngkwan; Yun, Ju-Ho; Lee, Chong-Gu; Hwang, Suk-Ho; Nam, Jae-Do
- Issue Date
- 2014
- Publisher
- NORTH CAROLINA STATE UNIV DEPT WOOD & PAPER SCI
- Keywords
- Lignin; Lignin-based polyurethane; Eco-friendly; Dielectric analysis; Glass transition temperature
- Citation
- BIORESOURCES, v.9, no.2, pp.2359 - 2371
- Indexed
- SCIE
SCOPUS
- Journal Title
- BIORESOURCES
- Volume
- 9
- Number
- 2
- Start Page
- 2359
- End Page
- 2371
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/101066
- ISSN
- 1930-2126
- Abstract
- A high molecular-weight thermoplastic lignin-based polymer was successfully synthesized by adjusting the degree of polymerization while inducing linear growth of lignin macromers via methylene diphenyldiisocyanate. The thermoplastic lignin-urethane polymer was desirably achieved in a narrow range of reaction conditions of 2.5 to 3.5 h at 80 degrees C in this study, and the molecular weight of the resulting lignin-based polyurethanes (LigPU) reached as high as 912,000 g/mole, which is far above any reported values of lignin-based polymer derivatives. The thermal stability of LigPU was greatly improved by the urethane polymerization, giving the initial degradation temperature (T-2%) at 204 degrees C, which should be compared with T-2% = 104 degrees C of the pristine lignin. This was due to the fact that the OH groups in the lignin macromers, having low bond-dissociation energy, were replaced by the urethane bonds. In dielectric analysis, the synthesized LigPU exhibited a softening transition at 175 degrees C corresponding to a combinatorial dual process of the dry T-g,T-dry of the lignin macromers and the softening of methylenediphenyl urethane chains. This work clearly demonstrated that a high molecular weight of thermoplastic LigPU could be desirably synthesized, broadening the lignin application for value added and eco-friendly products through common melt processes of polymer blend or composites.
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