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Sequential fractionation of lignin macromolecules with organic solvents and investigation of their potentials for lignin-PLA composites
유기용매를 이용한 리그닌 분획 및 분획물의 리그닌-PLA 복합재로써 활용 가능성 탐색

DC Field Value Language
dc.contributor.advisor윤혜정-
dc.contributor.author박신영-
dc.date.accessioned2017-07-14T06:33:37Z-
dc.date.available2017-07-14T06:33:37Z-
dc.date.issued2017-02-
dc.identifier.other000000142230-
dc.identifier.urihttps://hdl.handle.net/10371/125710-
dc.description학위논문 (석사)-- 서울대학교 대학원 : 산림과학부, 2017. 2. 윤혜정.-
dc.description.abstractMilled wood lignin (MWL), organosolv lignin (OL), and soda lignin (SL) were sequentially fractionated with ethyl acetate (F1), 2-butanone (F2), methanol (F3), acetone (F4), and dioxane/water (95:5 v/v, F5). Yields of the five MWL fractions were 11.7%, 11.7%, 15.3%, 11.8%, and 49.6%, and yields of OL fractions were 26.2%, 26.1%, 18.7%, 3.7%, and 25.4% where yields of SL fractions were 30.1%, 25.5%, 24.7%, 2.0%, 11.2%, and 6.5% of insoluble fraction (INS) was remained. GPC analysis showed that the molecular weights of lignin fractions increased from F1 to F5. The average molecular weight of F1 ranged from 1000 to 2400 Da. whereas that of F5 was above 10000 Da revealing that molecular weight of fractions increased from F1 to F5. According to functional group analysis, the contents of phenolic hydroxyl groups and methoxyl groups decreased gradually with increasing molecular weight. DFRC analysis revealed that the higher molecular weight fractions yielded larger amounts of DFRC monomers indicating that later fractions contain more aryl ether linkages than earlier fractions. According to Py-GC/MS analysis, main pyrolysis products of each fraction were analysed. S/G ratios obtained by DFRC and Py-GC/MS analysis showed difference since condensed structure of lignin might bias the result of DFRC. TG/DTG analysis suggested that the low molecular weight fractions generally have lower thermal stability than other fractions due to their high content of functional groups.
Native SL and SL fraction were individually grafted with L-lactide via ring-opening polymerization to produce lignin-grafted-poly(L-lactide) (lignin-g-PLLA). Conversion ratio of each fraction was calculated by 1H NMR and revealed that SL F1 which contains the largest amount of hydroxyl groups had the highest conversion ratio of 91.2% while SL F5 showed the lowest value of 88.3%. However, SLF1-g-PLLA showed the lowest molecular weight (Mn) where that of SLF5-g-PLLA was the highest indicating that SLF5-g-PLLA had the longest PLLA chain length. According to DSC analysis, it was revealed that SL-g-PLLA had the highest glass transition temperature due to its structural complexity. Surface characterization using scanning electron microscope suggested that surface of lignin grafted with PLLA had is smoother than that of native lignin, while SL F1, F3, and F5 had more smoother surface than SL and SLINS grafted with PLLA. Each copolymer was mixed with PLA 2002D to manufacture a lignin-PLA composite. Tensile strengths of composites were varied by chain lengths and surface properties of copolymers. In case of tensile modulus, the chain length of copolymer affected mainly.
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dc.description.tableofcontents1. Introduction 1
1.1. Lignin as an alternative to fossil fuel 1
1.2. Obstacles to lignin utilization 3
1.3. Lignin solvent fractionation 4
1.4. Lignin-grafted-polylactide (PLA) 6
1.4. Objectives 7
2. Literature review 8
2.1. Lignin solvent fractionation 8
2.2. Factors effect on lignin application 10
2.3. Utilization of fractionated lignin 12
2.4. Utilization of lignin into lignin-grafted-polylactide (PLA) copolymer 14
3. Materials and methods 15
3.1. Materials 15
3.2. Lignin preparation 16
3.3. Lignin solvent fractionation 17
3.4. Structural analysis of fractionated lignin 19
3.4.1. Gel permeation chromatography (GPC) 19
3.4.2. Nuclear magnetic resonance spectrometry (NMR) 19
3.4.3. Methoxyl group contents analysis 19
3.4.4. DFRC analysis 20
3.5. Thermal analysis of fractionated lignin 21
3.5.1. Pyrolysis Gas chromatography / Mass spectrometry (Py-GC/MS) 21
3.5.2. Thermogravimetric analysis (TGA) 21
3.6. Application of lignin fractions: Lignin-PLA grafting 22
3.6.1. Synthesis of Lignin-graft-poly(L-lactide) 22
3.6.2. Analysis of lignin-g-PLA 24
3.6.2.1. Analysis of conversion ratio of lignin-g-PLLA by 1H NMR 24
3.6.2.2. Analysis of thermal properties of lignin-g-PLLA 24
3.6.2.3. Investigation of surface of lignin-g-PLLA 24
3.6.2.4. Investigation of mechanical properties of lignin-g-PLLA 25
4. Results and discussion 26
4.1. Yields of lignin fractions 26
4.2. Molecular weight distributions of lignin fractions 28
4.3. Determination of functional group contents 30
4.4. Determination of S/G ratios of lignin fractions by DFRC 32
4.5. Pyrolytic analysis of lignin fractions by Py-GC/MS 34
4.6. Thermal decomposition characteristics of lignin fractions 40
4.7. Analyses of lignin-grafted-PLLA copolymers 45
4.7.1. Features of grafted PLLA onto lignin 45
4.7.2. Thermal properties of lignin-g-PLLA 48
4.7.3. Surface characterization of lignin-g-PLLA 51
4.7.4. Mechanical properties of lignin-g-PLLA 53
5. Conclusion 57
6. References 59
초록 64
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dc.formatapplication/pdf-
dc.format.extent1365392 bytes-
dc.format.mediumapplication/pdf-
dc.language.isoen-
dc.publisher서울대학교 대학원-
dc.subjectlignin-
dc.subjectsolvent fractionation-
dc.subjectfunctional groups-
dc.subjectlignin application-
dc.subjectPLA grafting-
dc.subjectlignin copolymer-
dc.subject.ddc634-
dc.titleSequential fractionation of lignin macromolecules with organic solvents and investigation of their potentials for lignin-PLA composites-
dc.title.alternative유기용매를 이용한 리그닌 분획 및 분획물의 리그닌-PLA 복합재로써 활용 가능성 탐색-
dc.typeThesis-
dc.description.degreeMaster-
dc.citation.pages63-
dc.contributor.affiliation농업생명과학대학 산림과학부-
dc.date.awarded2017-02-
Appears in Collections:
College of Agriculture and Life Sciences (농업생명과학대학)Dept. of Forest Sciences (산림과학부)Theses (Master's Degree_산림과학부)
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