• Journal of the Korean Wood Science and Technology
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• 제43권6호
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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.

• Composites Research
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• 제35권3호
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• pp.153-160
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• 2022

목재 섬유 기반의 셀룰로오스 나노피브릴(cellulose nanofibrils, CNF)은 생체적합특성이 우수하여 조직 공학용 스캐폴드, 약물 운반체, 상처 치유용 겔 등의 생체 의료 분야에서 많은 관심을 받고 있다. 하지만, 셀룰로오스 나노피브릴은 상대적으로 약한 기계적 강도를 나타내기 때문에 높은 기계적 특성을 요구하는 응용 분야에 사용되기 어렵다는 한계를 가지고 있다. 따라서 본 연구에서는 셀룰로오스 나노피브릴의 기계적 강도를 향상시키기 위해 TEMPO (2,2,6,6-tetramethylpiperidin-oxyl) 산화 처리된 셀룰로오스 나노피브릴에 금속 양이온을 도입하여 금속-카르복실레이트 배위 결합을 가지는 하이드로겔을 제조하였다. 또한, 큰 진폭 진동 전단(large amplitude oscillatory shear) 측정과 Live/Dead 세포 시험을 통해 하이드로겔의 비선형 점탄성 거동과 세포 생존 능력을 분석하였다. 특히, 첨가된 금속염의 종류에 따라 세포의 증식 및 생존 능력이 변화하였고, 이는 하이드로겔들의 유변 물성 특성에도 영향을 미쳤다.

• 펄프종이기술
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• 제48권2호
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• pp.91-98
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• 2016

Cellulose nanofibrils (CNF) was made from oil palm trunk (OPT) with soda-anthraquinone pulping, chlorine dioxide bleaching, carboxymethylation, followed by mechanical grinding. Size of this CNF was 16-40 nm of width confirmed by TEM. To evaluate CNF from OPT as cosmetics raw materials for moisturizing component, water holding properties was compared with hyaluronic acid and collagen. CNF from OPT had better water holding property than collagen or hyaluronic acid whether phenoxyethanol was added as antiseptic or without additive.

• 폴리머
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• 제38권4호
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• pp.464-470
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• 2014

A chemo-mechanical method was used to prepare lignin-containing cellulose nanofibrils(L-CNF) from unbleached woodpulps dispersed uniformly in an organic solvent. L-CNF/PLA composites were obtained by solvent casting method. The effects of L-CNF concentration on the composite performances were characterized by tensile test machine, contact angle machine, scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR). The tensile test results indicated that the tensile strength and elongation-at-break increased by 50.6% and 31.8% compared with pure PLA. The contact angle of PLA composites decreased from $79.3^{\circ}$ to $68.9^{\circ}$. The FTIR analysis successfully showed that L-CNF had formed intermolecular hydrogen bonding with PLA matrix.

• 펄프종이기술
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• 제47권2호
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• pp.42-52
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• 2015

In this study, cellulose nanofibrils (CNF) were modified through carboxymethylation or TEMPO-mediated oxidation and their effects on ionicity and characteristics of sheet, film, and foam were investigated. Carboxymethylation was carried out on pulp fibers as a pre-treatment before preparation of CNF. The gel-like and translucent CNF hydrogel was obtained by grinding of carboxymethylated cellulose fibers. Carboxymethylated CNF film and freeze dried sheet showed higher transparency than that of untreated CNF. The CNF sheet with high strength and the CNF foam without large ice crystals were obtained by using the carboxymethylated CNF. TEMPO-mediated oxidation was carried out as a post-treatment of CNF. The zeta potential and charge demand of TEMPO-oxidized CNF were increased with an increase in oxidation time and addition amount of NaClO. The density of sheet made of TEMPO oxidized CNF was increased with the amount of oxidizing agent. The TEMPO oxidized cellulose nanofiber (TOCN) which was obtained from supernatant after centrifugation could be converted to transparent film.

• 펄프종이기술
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• 제46권6호
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• pp.78-86
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• 2014

Since cellulose nanofibrils (CNF) has large specific surface area and high water holding capacity, it is very difficult task to remove water from the CNF suspension. However, dewatering of CNF suspension is a prerequisite of following processes such as mat forming and drying for the application of CNF. In this study, we evaluated the drainage of cellulose fibers suspension under vacuum and pressure conditions depending on the number of grinding passes. Also, the effect of the addition of cationic polyelectrolyte on dewatering ability of CNF suspension was investigated. Regardless of dewatering condition, the total drained water amount as well as the drainage rate were decreased with an increase in the number of grinding passes. Pressure dewatering equipment enables us to prepare wet CNF mat with relatively higher grammage. The cationic polyelectrolytes improved the dewatering ability of CNF suspension by controlling the zeta potential of CNF. The fast drainage was obtained when CNF suspension had around neutral zeta potential.

• Journal of the Korean Wood Science and Technology
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• 제43권5호
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• pp.613-627
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• 2015

Simple methods of conductometric titration and infrared spectroscopy were used to quantify the surface carboxyl content of cellulose fibrils isolated by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation. The effects of different cellulose sources, post or assisted-sonication oxidation treatment, and the amount of sodium hypochlorite addition on the carboxyl content of cellulose were reported. This study showed that post sonication treatment had no influence on the improvement of surface carboxyl charge of cellulose macrofibrils (CMFs). However, the carboxyl content increased for the isolated cellulose nanofibrils (CNFs). Thus the carboxyl content of CNFs is different from those of their corresponding bulk oxidized cellulose and CMFs. Filter paper as a CNF source imparted a higher surface charge than did hardwood bleached kraft pulp (HWBKP) and microcrystalline cellulose (MCC). It was considered that the crystallinity and microstructure of the initial cellulose affected oxidation efficiency. In addition, the carboxyl content of cellulose was successfully controlled by applying sonication treatment during the oxidation reaction and adjusting the amount of sodium hypochlorite.

• 멤브레인
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• 제31권6호
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• pp.384-392
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• 2021

현재 우리 산업의 가속화된 발전으로 인해 다양하고 많은 양의 오염이 만들어지기 시작하고 있다. 특히 폐수의 경우 석유, 금속 및 유기물로 오염되는 강과 바다가 늘고 있으며, 빠른 조치가 필요해 보인다. 이러한 오염에 대응하기 위해 폐수에서 분리막을 이용한 깨끗한 물의 여과가 비용적으로 유리하고 친환경적인 기술로 떠오르고 있다. 재생 자원으로 만들어진 막여과 기법들이 환경오염의 원인 중 하나인 합성고분자 분리막들을 대체하기 위해 많이 사용되고 있다. 박테리아 셀룰로오스(Bacterial Cellulose / BC)는 순수하고 뚜렷한 형태의 셀룰로오스 나노섬유(Cellulose nanofibrils / CNF)이다. CNF에서 제조된 나노페이퍼는 각기 다른 용도로 한외여과막과 나노여과막으로 사용된다. BC의 높은 결정성으로 인해 폐수 처리 막의 필수 기준인 우수한 기계적 성질을 가질 수 있다. 본 리뷰 논문에서는 염료, 오일 및 중금속 등 폐수의 오염물질들을 걸러내기 위해 사용될 수 있는 BC 기반 분리막들에 대해 논의한다.

• Journal of the Korean Wood Science and Technology
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• 제42권2호
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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.

• 공업화학
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• 제32권1호
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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.