Song-Yi Han

Characteristics of carbon nanofibers produced from lignin/polyacrylonitrile (PAN)/kraft lignin-g-PAN copolymer blends electrospun nanofibers

Abstract Lignin-based electrospun nanofibers (eNFs) were prepared and thermally stabilized at 250°C and subsequently carbonized at 1400°C. The starting blend was prepared in dimethyl formamide (DMF) solution with lignin and polyacrylonitrile (PAN), while a lignin-grafted-PAN (L-g-PAN) copolymer served as compatibilizer. The viscosity was highest of the DMF solution with PAN, and decreased for the lignin/PAN blends and additionally in presence of L-g-PAN. The uniform eNFs with clean surfaces dispose of diameters between 400 nm and 1 μm. The average diameter of eNFs decreased by the thermal treatment and at higher lignin contents in the blends. Remarkable shrinkage by carbonization was observed in all nanofibers. The successful carbonization of all electrospun carbon nanofibers (eCNFs) was confirmed by Fourier transform-infrared (FT-IR) spectroscopy. The specific tensile strength and elastic modulus of the eCNF mats from lignin/PAN blends were improved by the addition of L-g-PAN, and it can be safely concluded that it acts as a compatibilizer between lignin and PAN.

Effect of Nanocellulose and Aminated Starch on Tensile and Thermal Properties of Plasticized Starch Film

This study investigated the effect of nanocellulose, such as microfibrillated cellulose (MFC) and cellulose nanocrystal (CNC), and aminated starch on tensile property and thermal stability of plasticized starch film. Glycerol (23 wt%) was used as a plasticizer and nanocelluloses of 1-30 parts per hundred parts of resin (phr) in the basis of plasticized starch were added. Tensile strength and elastic modulus increased with increasing nanocellulose addition amount, whereas elongation at break decreased. Tensile properties of MFC-reinforced starch film were higher than those of CNC-reinforced film. Optimum addition amount of aminated starch, which is commonly used for paper sizing, to improve tensile property of film, was found to be 5%. And 1% addition of aminated starch showed the best effect in the improvement of tensile property of the film. Thermal stability was improved with the addition of MFC to plasticized starch film with and without aminated starch.

Overview of the Preparation Methods of Nano-scale Cellulose

A wide range of research on the science and technology of nano-scale cellulose, mainly cellulose nanofibrils (CNF) and cellulose nanocrystals (CNC), has been conducted worldwide because of nanocellulose’s unique distinguishing properties for various application fields. Nanocellulose can be produced from any type of lignocellulosic biomass and, so far, various production methods have been introduced. Recently, industries and institutes worldwide have attempted to scale-up the production of nanocelullose to produce it in large quantities to support its research and applications development. This review provides a short summary of previously published research and review papers on the preparation methods of nanocellulose, targeting the research activities of our interest.

Size Fractionation of Cellulose Nanofibers by Settling Method and Their Morphology

The cellulose nanofibers (CNFs) were prepared by wet disk-milling (WDM) and fractionated by settling method into supernatant, middle and sediment fractions. The diameter and its distribution of the fractionated CNFs were investigated. With increasing WDM passing number, precipitation became delayed. Weight fraction at sediment fraction was decreased, whereas those at supernatant and middle fractions were increased with increasing WDM passing number. Diameter distribution of CNFs at supernatant fraction was narrowest and became broaden at middle and sedi- ment fraction. Filtration time was longer in order of supernatant, middle and sediment fraction.

Effect of The Addition of Various Cellulose Nanofibers on The Properties of Sheet of Paper Mulberry Bast Fiber

본 연구는 셀룰로오스 나노섬유를 닥나무 인피섬유 시트의 제조시 첨가하여, 닥나무 인피섬유 시트의 특성에 미치는 영향을 조사하였다. 형태학적 및 화학적 성질이 다른 5종류의 셀룰로오스 나노섬유, 즉 리그노셀룰로오스 나노섬유 (lignocellulose nanofiber, LCNF), 홀로셀룰로오스 나노섬유(holocellulose nanofiber, HCNF), 알칼리처리 홀로셀룰로오스 나노섬유(alkali-treated HCNF, AT-HCNF), TEMPO-산화 나노섬유(TEMPO-oxidated nanofiber, TEMPO-NF), 셀룰로오스 나노크리스탈(cellulose nanocrystal, CNC)을 제조하였으며, 각 나노섬유의 종류 및 첨가량이 닥나무 인피섬유시트 제조시의 여수시간 및 시트의 투기도, 평활도, 인장강도 특성에 미치는 영향을 조사하였다. 여수시간은 모든 나노섬유에 있어서 첨가량이 증가함으로서 길어졌으며, 5%의 첨가량에서 HCNF가 가장 여수시간이 길었다. 또한, 셀룰로오스 나노섬유 첨가량이 증가할수록 시트의 평활도, 인장강도 특성이 향상되었으며, 특히 0.1%의 극히 적은양의 나노섬유 첨가로도 비인장강도 및 탄성계수가 크게 향상되는 것을 알 수 있었다. 이러한 특성 향상은 닥나무 인피섬유 간에 교차적으로 적층되어 있는 셀룰로오스 나노섬유의 충전 효과에 기인하는 것을 전자현미경 사진을 통해 확인할 수있었다.