• 제목/요약/키워드: cellulose nanofibril

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Preparation, structure, and properties of cellulose nanofibril/silk sericin composite film

  • Jang, Mi Jin;Park, Byung-Dae;Kweon, HaeYong;Jo, You-Young;Um, In Chul
    • International Journal of Industrial Entomology
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    • v.31 no.1
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    • pp.1-6
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    • 2015
  • Recently, sericin has attracted increasing attention in biomedical and cosmetic research because of its useful properties including acceleration of wound healing, improvement of cell attachment, and inhibition of ultraviolet-B induced apoptosis. However, sericin films have poor mechanical properties, which restricts the application to those fields. In this study, cellulose nanofibril (CNF)/sericin composite films were fabricated by solvent casting, and the effects of ultrasonication time and CNF content on the solution turbidity, molecular conformation, and film mechanical properties of sericin film were examined. As the ultrasonication time increased, the turbidity of the CNF/sericin suspension decreased. Conversely, as the CNF content increased, the turbidity increased. However, ${\beta}$-sheet crystallization and mechanical properties remained almost unchanged by varying the ultrasonication time and CNF content, indicating that CNF is not effective to improve the mechanical properties of sericin films.

Preparation and Characterization of Cellulose Nanofibril/Polyvinyl Alcohol Composite Nanofibers by Electrospinning

  • Park, Byung-Dae;Um, In Chul;Lee, Sun-Young;Dufresne, Alain
    • 목재공학
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    • v.42 no.2
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    • pp.119-129
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    • 2014
  • This work undertook to prepare nanofibers of cellulose nanofibrils (CNF)/polyvinyl alcohol (PVA) composite by electrospinning, and characterize the electrospun composite nanofibers. Different contents of CNFs isolated from hardwood bleached kraft pulp (HW-BKP) by 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO)-mediated oxidation were suspended in aqueous polyvinyl alcohol (PVA) solution, and then electrospun into CNF/PVA composite nanofibers. The morphology and dimension of CNFs were characterized by transmission electron microscopy (TEM), which revealed that CNFs were fibrillated form with the diameter of about $7.07{\pm}0.99$ nm. Morphology of the electrospun nanofiber observed by field-emission scanning electron microscopy (FE-SEM) showed that uniform CNF/PVA composite nanofibers were manufactured at 1~3% CNF contents while many beads were observed at 5% CNF level. Both the viscosity of CNF/PVA solution and diameter of the electrospun nanofiber decreased with an increase in CNF content. The diameter and its distribution of the electrospun nanofibers helped explain the differences observed in their morphology. These results show that the electrospinning method was successful in preparing uniform CNF/PVA nanofibers, indicating a great potential for manufacturing consistent and reliable cellulose-based nanofibrils for scaffolds in future applications.

Tensile Properties and Thermal Stability of Cellulose Nanofibril/Clay Nanocomposites

  • Park, Byung-Dae;Singh, Adya P.;Um, In Chul
    • Current Research on Agriculture and Life Sciences
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    • v.31 no.1
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    • pp.18-24
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    • 2013
  • This work attempted to fabricate organic/inorganic nanocomposite by combining organic cellulose nanofibrils (CNFs), isolated by 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO)-mediated oxidation of native cellulose with inorganic nanoclay. The morphology and dimension of CNFs, and tensile properties and thermal stability of CNF/clay nanocomposites were characterized by transmission electron microscope (TEM), tensile test, and thermogravimetry (TG), respectively. TEM observation showed that CNFs were fibrillated structure with a diameter of about $4.86{\pm}1.341nm$. Tensile strength and modulus of the hybrid nanocomposite decreased as the clay content of the nanocomposite increased, indicating a poor dispersion of CNFs or inefficient stress transfer between the CNFs and clay. The elongation at break increased at 1% clay level and then continuously decreased as the clay content increased, suggesting increased brittleness. Analysis of TG and derivative thermogravimetry (DTG) curves of the nanocomposites identified two thermal degradation peak temperatures ($T_{p1}$ and $T_{p2}$), which suggested thermal decomposition of the nanocomposites to be a two steps-process. We think that $T_{p1}$ values from $219.6^{\circ}C$ to $235^{\circ}C$ resulted from the sodium carboxylate groups in the CNFs, and that $T_{p2}$ values from $267^{\circ}C$ to $273.5^{\circ}C$ were mainly responsible for the thermal decomposition of crystalline cellulose in the nanocomposite. An increase in the clay level of the CNF/clay nanocomposite predominately affected $T_{p2}$ values, which continuously increased as the clay content increased. These results indicate that the addition of clay improved thermal stability of the CNF/clay nanocomposite but at the expense of nanocomposite's tensile properties.

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Effect of Spray-drying Condition and Surfactant Addition on Morphological Characteristics of Spray-dried Nanocellulose

  • Park, Chan-Woo;Han, Song-Yi;Namgung, Hyun-Woo;Seo, Pureun-Narae;Lee, Seung-Hwan
    • Journal of Forest and Environmental Science
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    • v.33 no.1
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    • pp.33-38
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    • 2017
  • In this study, spray-drying yield and morphological characterization of spray-dried cellulose nanofibril (CNF) and TEMPO-oxidized nanocellulose (TONC) depending on spray-drying condition and surfactant addition was investigated. As spray-drying temperature increased, the yield of spray-dried CNF was increased. The highest spray-drying yields in both nanocelluloses were found at didecyl dimethyl ammonium chloride (DDAC) addition of 2.5 phr at all investigated temperatures. The spray-dried CNF was the sphere-like particle, but the spray-dried TONC showed both rod and sphere-like morphology. The average diameter of spray-dried CNF was decreased with increasing DDAC addition amount, resulting in the increase of specific surface area.

표면 개질된 나노피브릴화 셀룰로오스를 이용한 에멀젼 안정화 및 고분자 입자 제조 (Surface-modified Cellulose Nanofibril Surfactants for Stabilizing Oil-in-Water Emulsions and Producing Polymeric Particles)

  • 김보영;문지연;유명재;김선민;김정아;양현승
    • 공업화학
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    • v.32 no.1
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    • pp.110-116
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    • 2021
  • In this work, the surface of hydrophilic cellulose nanofibrils (CNFs) was modified precisely by varying amounts of cetyltrimethylammonium bromide (CTAB) to produce CNF-based particle surfactants. We found that a critical CTAB density was required to generate amphiphilic CTAB-grafted CNF (CNF-CTAB). Compared to pristine CNF, CNF-CTAB was highly efficient at stabilizing oil-in-water Pickering emulsions. To evaluate their effectiveness as particle surfactants, the surface coverage of oil-in-water emulsion droplets was determined by changing the CNF-CTAB concentration in the aqueous phase. Furthermore, styrene-in-water stabilized by CNF-CTAB surfactants was thermally polymerized to produce CNF-stabilized polystyrene (PS) particles, offering a great potential for various applications including pharmaceuticals, cosmetics, and petrochemicals.

Changes of Micro- and Nanoscopic Morphology of Various Bioresources by Different Milling Systems

  • Jang, Jae-Hyuk;Lee, Seung-Hwan;Lee, Min;Lee, Sang-Min;Kim, Nam-Hun
    • 목재공학
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    • v.45 no.6
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    • pp.737-745
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    • 2017
  • This study was carried out to investigate the changes in micro- and nanoscopic morphology of cellulose nanofibrils (CNFs) from various bioresources by investigating various mechanical milling systems. Mechanical milling in herbaceous bioresources was more effective than in woody bioresources, demonstrating lower energy consumption and finer morphology. The milling time to reach nanoscopic size was longer in woody bioresources than in herbaceous bioresources. Furthermore, at the same level of wet disk milling time, CNFs from herbaceous bioresources showed more slender morphology than those from woody bioresources. Tensile properties of nanopaper prepared from CNFs of herbaceous bioresources were higher than those of woody bioresources. The highest tensile strength was found to be 77.4 MPa in the nanopaper from Evening prim rose.

Hydroxypropyl cellulose/TEMPO-산화 처리된 셀룰로오스 나노섬유를 이용한 복합필름의 기계적 및 열적 특성 (Mechanical and Thermal Properties of Hydroxypropyl Cellulose/TEMPO-oxidized Cellulose Nanofibril Composite Films)

  • 조유정;조혜정;전상진;이선영
    • 목재공학
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    • v.43 no.6
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    • pp.740-745
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    • 2015
  • 본 연구에서는 HPC (hydroxypropyl cellulose)와 TEMPO 산화된 셀룰로오스 나노섬유(Tempo-oxidized cellulose nanofibrils, TOCN)가 보강된 복합필름을 제조하였다. 복합필름의 기계적, 열적 특성을 관찰하기 위해 인장강도 및 열중량 분석기(TGA)를 측정하였다. HPC/TOCN 복합필름에서 TOCN의 함량이 1 wt%에서 5 wt%까지 증가할수록 인장강도와 인장탄성계수는 직선적으로 증가하는 경향을 보였다. 그러나 TGA 분석 결과, TOCN의 함량에 관계없이 HPC/TOCN 복합필름의 열 안정성은 거의 차이가 없었다.

Preparation of Cellulose Nanofibril/Regenerated Silk Fibroin Composite Fibers

  • Lee, Ji Hye;Bae, Chang Hyun;Park, Byung-Dae;Um, In Chul
    • International Journal of Industrial Entomology
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    • v.26 no.2
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    • pp.81-88
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    • 2013
  • Wet-spun silk fibers have attracted the attention of many researchers because of 1) the unique properties of silk as a biomaterial, including good biocompatibility and cyto-compatability and 2) the various methods available to control the structure and properties of the fiber. Cellulose nanofibrils (CNFs) have typically been used as a reinforcing material for natural and synthetic polymers. In this study, CNF-embedded silk fibroin (SF) nanocomposite fibers were prepared for the first time. The effects of CNF content on the rheology of the dope solution and the characteristics of wet-spun CNF/SF composite fibers were also examined. A 5% SF formic acid solution that contained no CNFs showed nearly Newtonian fluid behavior, with slight shear thinning. However, after the addition of 1% CNFs, the viscosity of the dope solution increased significantly, and apparent shear thinning was observed. The maximum draw ratio of the CNF/SF composite fibers decreased as the CNF content increased. Interestingly, the crystallinity index for the silk in the CNF/SF fibers was sequentially reduced as the CNF content was increased. This phenomenon may be due to the fact that the CNFs prevent ${\beta}$-sheet crystallization of the SF by elimination of formic acid from the dope solution during the coagulation process. The CNF/SF composite fibers displayed a relatively smooth surface with stripes, at low magnification (${\times}500$). However, a rugged nanoscale surface was observed at high magnification (${\times}10,000$), and the surface roughness increased with the CNF content.

셀룰로스 나노피브릴을 이용한 재활용 탄소섬유 습식부직포의 기계적 물성 연구 (Research for Mechanical Properties of Wet Nonwoven Fabric Based on Recycled Carbon Fiber Using Cellulose Nanofibrils)

  • 윤철민;배영환;김우식;여상영
    • 한국섬유공학회지
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    • v.58 no.1
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    • pp.40-47
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    • 2021
  • Carbon fiber is an advanced material widely used in high-tech industries because of its light weight, heat resistance, chemical resistance, excellent mechanical properties, and electrical and thermal conductivity. However, carbon fibers also have high production costs and limited disposal methods (e.g., landfills). Research is being conducted to address these problems through the recycling of carbon fibers. Among the representative recycled carbon fiber products, wet nonwoven fabrics have limitations in their mechanical properties because their structure simply consists of stacked microsized-diameter carbon fibers and a binder. In this study, the tensile strength was improved by adding cellulose nanofibrils (CNFs) during the manufacturing of wet nonwoven fabrics by mixing short-cut carbon fibers and a binder (short-cut PVA fibers). CNF bundles improve the mechanical properties by forming a complex structure via the crosslinking of carbon fibers and short PVA fibers. The tensile strength of nonwoven fabrics consisting of short carbon fibers and PVA fibers was determined to be 92 gf. On the other hand, the tensile strength of the nonwoven fabric with 10% CNF added to the binder increased by approximately 20 times to 1,808 gf. The composite with nanofiber was confirmed to be effective in forming a structure with high mechanical properties when fabricating microfiber-based nonwoven fabrics.