Enhancement of the mechanical properties of electrospun lignin-based nanofibers by heat treatment

Cho, Mijung; Karaaslan, Muzaffer A.; Renneckar, Scott; Ko, Frank

doi:10.1007/s10853-017-1160-0

Cited by 49 publications

(46 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…33,49 Nanocrystalline cellulose (NCC) was produced by authors as described in the published procedure. 48 Poly(ethylene oxide) (PEO) with average molecular weight of 1 × 10 6 g/mol was obtained from Sigma-Aldrich and used as received. N , N -Dimethylformamide (DMF), methanol, methylene chloride, and sulfuric acid of 98% were all ACS reagent grade and cellulose filter papers (Whatman No 1001-110) were also purchased from Fisher Scientific and used as received.…”

Section: Methodsmentioning

confidence: 99%

Impact of Thermal Oxidative Stabilization on the Performance of Lignin-Based Carbon Nanofiber Mats

Cho

Renneckar

2019

ACS Omega

Self Cite

View full text Add to dashboard Cite

Lignin is a renewable biopolymer considered as a potential precursor for low-cost carbon materials. Thermal oxidative stabilization (TOS) is an important processing step to maintain fiber geometry during carbonization, yet the impact of TOS on the properties of lignin-based carbon materials has not been clearly identified in the literature. Yield, change in fiber diameter/distribution, elemental composition, and mechanical properties were explored for both stabilized and carbonized lignin fibers. Vibrational spectroscopy and solid-state 13 C nuclear magnetic resonance spectroscopy were used to analyze the changes in lignin molecular structure after exposure to various heating conditions during the TOS steps. Further, studies were focused on the effects of TOS conditions on the resulting carbon structure of fiber mats through Raman spectroscopy measurements and electrical conductivity analysis. Although TOS conditions influenced the properties of the oxidized lignin fiber mats, properties of the carbonized samples were invariant to the TOS procedures used in this study over most of the conditions. As a result, there was flexibility for the parameters (time and temperature) in the TOS process when conditioning softwood lignin materials for carbon fibers.

show abstract

Section: Methodsmentioning

confidence: 99%

Impact of Thermal Oxidative Stabilization on the Performance of Lignin-Based Carbon Nanofiber Mats

Cho

Renneckar

2019

ACS Omega

Self Cite

View full text Add to dashboard Cite

show abstract

“…AFM images were captured using RTESPA, Veeco Inst. With a silicon cantilever, scan rate of 0.383 Hz and a scan size of 20 × 20 μm (Cho et al, 2017).…”

Section: Methodsmentioning

confidence: 99%

Aqueous Dispersions of Esterified Lignin Particles for Hydrophobic Coatings

et al. 2019

Self Cite

View full text Add to dashboard Cite

An aqueous biopolymer dispersion coating system was synthesized utilizing softwood kraft lignin and a long chain organic acid. The chemical treatment of lignin was a two-step procedure, which first consisted of hydroxyethylation of the phenolic groups on lignin utilizing ethylene carbonate and an alkaline catalyst. This first step resulted in the lignin containing more than 80% aliphatic hydroxyl functionality ( 1 H NMR). Following this step, oleic acid was reacted with hydoxyethyl lignin in order to form ester derivatives. With nearly a total reduction in absorbance in the hydroxyl stretching region, FT-IR analysis showed the majority of the hydroxyl groups was esterified forming an ethyl oleate derivative. Semi-quantitative 13 C NMR analysis of the lignin revealed 88% substitution of the lignin hydroxyl groups. This derivative was soluble in organic solvent such as toluene and tetrahydrofuran. Solutions of lignin derivatives were slowly precipitated through dialysis, resulting in a stable dispersion of lignin microparticles in distilled water. The 1–2 μm average diameter size of the precipitated particles was found with dynamic light scattering of the suspensions. Spray and spin coating were used to apply the lignin derivative dispersion to different surfaces. For both coating methods, the lignin-based particles enhanced the hydrophobicity of all the substrates tested, resulting in increased water contact angles for glass, kraft pulp sheets and solid wood. Benign reagents involved in the coating synthesis utilized natural compounds that are known to repel water in nature. Combined with the avoidance of volatile organic solvents during application, this process provided a low environmental footprint solution for synthesis of hydrophobic coatings.

show abstract

“…Commercially available kra lignin (Indulin-AT), organosolve lignin (Alcell™) were reported to be used for the production of carbon bers by many researchers. 10,[38][39][40][41][42] In most of these studies, lignin samples were sequentially acid cleaned, fractionated with methanol and methanol-dichloromethane mixtures. [38][39][40][41] A few other studies reported extensive desalting and acid washing, 10 fractionation with methyl isobutyl ketone (MIBK), ethanol and sulfuric acid.…”

Section: Introductionmentioning

confidence: 99%

“…10,[38][39][40][41][42] In most of these studies, lignin samples were sequentially acid cleaned, fractionated with methanol and methanol-dichloromethane mixtures. [38][39][40][41] A few other studies reported extensive desalting and acid washing, 10 fractionation with methyl isobutyl ketone (MIBK), ethanol and sulfuric acid. 42 The above-mentioned articles reported tensile strength of 5-8 MPa and elastic modulus of 500-700 MPa for lignin bers, and tensile strength of 30-700 MPa and elastic modulus of 2-40 GPa for carbon bers.…”

Section: Introductionmentioning

confidence: 99%