As a renewable nanomaterial, cellulose nanocrystal (CNC) isolated from wood grants excellent mechanical properties in developing high performance nanocomposites. This study was undertaken to compare the reinforcing efficiency of two different CNCs, i.e., cellulose nanowhiskers (CNWs) and cellulose nanofibrils (CNFs) from hardwood bleached kraft pulp (HW-BKP) as reinforcing agent in polyvinyl alcohol (PVA)-based nanocomposite. The CNWs were isolated by sulfuric acid hydrolysis while the CNFs were isolated by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation. Based on measurements using transmission electron microscopy, the individual CNWs were about 6.96±0.87 nm wide and 178±55 nm long, while CNFs were 7.07±0.99 nm wide. The incorporation of CNWs and CNFs into the PVA matrix at 5% and 1% levels, respectively, resulted in the maximum tensile strength, indicating different efficiencies of these CNCs in the nanocomposites. Therefore, these results suggest a relationship between the reinforcing potential of CNCs and their physical characteristics, such as their morphology, dimensions, and aspect ratio.

본 연구의 목적은 지지체의 친수화가 압력지연삼투(Pressure retarded osmosis, PRO)막의 투과특성에 미치는 영향에 대해서 알아보고자 하였다. 소수성 지지체인 폴리에스테르를 친수성 고분자인 셀룰로오스 용액을 사용하여 친수화도를 조절하였다. 지지체의 친수화 특성만을 파악하기 위해서 지지층 없이 동일한 활성층을 사용하여 PRO 막 투과 특성을 비교하였다. 사용된 활성층은 1,4-dioxane과 cellulose tri-acetate (CTA, 13 wt%)를 사용하여 제조하였으며, 5 kgf/cm2 압력 하에서 행한 PRO 성능 평가의 경우 투과도가 친수화된 지지체를 사용한 경우와 친수화되지 않은 경우에 각각 1.2 L/m2hr와 0.8 L/m2hr로 친수화된 지지체를 사용할 경우 약 50% 투과량이 증가되는 특성을 보였다. 그러나 셀룰로오스 농도 변화에 따른 지지체의 친수화도 증가가 투과량 변화를 가져오지는 않았다. 이는 지지체를 친수화하기 위해 사용된 셀룰로오스의 농도가 증가함에 따라 지지체의 기공이 막히는 현상에 기인한 것으로 보인다. 이러한 결과를 통해 정삼투공정에서 투과유량을 높이기 위해서는 지지체로서 친수성 소재를 사용하여 분리막을 제조함과 동시에 지지체 기공을 유지하는 것이 중요함을 확인하였다.

This study examined the effect of the molecular weight, substitution degree, and substitution type of cellulose ether on the mechanical properties of dried rice noodles. When increasing the molecular weight of the hydroxypropyl methylcellulose (HPMC), the bending strength of the dried rice noodles also increased. However, the bending strength of the rice noodles with added HPMCs was still lower than that of the wheat noodles. Meanwhile, the bending elongation of the dried rice noodles was higher than that of the wheat noodles and was increased when decreasing the molecular weight of the HPMC. In conclusion, the bending strength and elongation of dried rice noodles is affected by the substitution degree and type of cellulose ether.

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±1.341 nm. 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 (Tp1 and Tp2), which suggested thermal decomposition of the nanocomposites to be a two steps-process. We think that Tp1 values from 219.6℃ to 235℃ resulted from the sodium carboxylate groups in the CNFs, and that Tp2 values from 267℃ to 273.5℃ 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 Tp2 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.

목적: 본 연구의 목적은 새롭게 개발하여 국산화한 안경테용 셀룰로오스 아세테이트(Cellulose Acetate; CA) 소재의 가공품질 및 생산성 향상을 위해 절삭성에 관한 연구를 수행하였다. 방법: 다양한 절삭 및 이송속도의 변화조건 하에서 절삭성이 평가되었다. CA 소재의 절삭실험은 절삭력, 표면조도 및 칩형상 등의 분석이 이루어졌으며, 이를 통해 절삭성을 평가하였다. 결과: 주축회전수 20,000과 30,000 rpm을 제외하고 고속영역에서 절삭력이 낮게 나타났으며, 고속회전 시 표면조도가 저속회전 조건 보다 우수하였다. 절삭력과 표면조도의 상관관계는 고속회전 조건에서는 크지 않은 것으로 나타났다. 결론: 국산화를 위해 새롭게 개발한 안경테용 CA 소재의 고품위 가공의 절삭성 평가를 수행한 결과 주축 회전수 20,000과30,000rpm을 제외하고 고속영역에서 절삭성이 양호하였으며, 표면조도는 날당이송 0.1mm 이외의 조건에서 주축회전수가 증가할수록 양호해졌고, 칩형상도 고속회전 및 저이송 조건으로 갈수록 균일 한 형태의 칩이 발생됨을 알 수 있었다. 이상과 같은 실험결과를 종합하여 새롭게 개발된 CA 소재의 절삭성을 평가할 수 있는 기초자료를 확보할 수 있었다.

The aim of this study was to evaluate the status of consumption and consumer satisfaction of dietary fiber supplements. The survey was conducted using a self-recorded questionnaire developed to meet the purpose of this study. The characteristics of the subjects who have taken dietary fiber supplements in the past are as follows: distributions of socioeconomic variables showed that the highest-ranked group(the group that reported the highest consumption of dietary fiber supplements) was professionals with a college degree or higher degree. In addition, the highest-ranked group were the most healthy, nonsmokers and reported drinking habits of ‘1～2 times/week’. Regarding the health status of those surveyed, digestive disease and constipation were the most common complaints. The majority responded with ‘health concerns’ to the question that asked the reason for their purchase of the dietary fiber supplements. Three major places respondents could find dietary fiber supplements were ‘through the internet’, ‘the market’, ‘the pharmacy’ in descending order. The compositions of dietary fiber products varied. ‘konjac’, ‘cellulose’, ‘psyllium husks’ were the most popular components consumed by the subjects. The average duration of product consumption was less than one month. In terms of satisfaction levels(satisfaction was ranked from 1 to 5), ‘taste’ and ‘type’ scored the highest in satisfaction levels while ‘price’ ranked the lowest. When subjects were asked about self-awareness regarding the physiological efficacy of dietary fiber supplements, the responses were positive in ‘bowel movement’ and ‘weight loss’. Further research is required to improve the quality of dietary fiber supplements in order to assist consumers in selecting the appropriate products.

목 적: 본 연구는 안경테 소재용 셀룰로오스 아세테이트(Cellulose Acetate; CA)의 최적 가공조건을 규 명하여 안경테 전용 가공기의 설계조건 선정에 활용하고자 한다. 방 법: CA안경테 소재의 가공성 평가를 위해 절삭력, 표면조도 및 형상, 칩 형상 등을 분석하였다. 절삭 속도와 이송속도를 가공변수로 다양한 실험을 수행하여 적정 가공조건을 선정하였다. 결 과: CA안경테의 반경방향 절삭력은 절삭속도에 변화에 따른 영향이 미미한 반면, 이송방향 절삭력은 20,000과 30,000 rpm에서 증가하는 경향을 보였다. 표면조도는 날당 이송이 작은 0.05 mm 경우 절삭속도가 증가하면서 양호해지는 결과를 얻었다. 결 론: 안경테 소재용 CA의 가공성을 절삭력과 가공면의 상태를 고려하여 평가하였다. 절삭력을 고려했을 때 절삭속도가 25,000 rpm이 가장 적정한 조건으로 나타났다. 표면조도를 고려했을 경우에는 저 날당 이 송, 고 절삭속도가 최적 가공조건이었다. 따라서 이를 종합했을 때 절삭력은 전체적으로 낮은 값을 가지므로 표면조도를 주요 인자로 고려하여 날당 이송 0.05 mm, 절삭속도 20,000~ 30,000 rpm이 적정 가공조건으 로 나타났다.

셀룰로오스는 지구상에서 가장 풍부하게 존재하는 재생 가능한 천연 다당류로서 glucose의 β-1,4 결합에 의하여 이루어진 물질이자 고등식물의 주요 구성성분으로서 현재 제지, 펼프 및 방적산업을 비롯한 다양한 분야에서 사용되고 있다. 셀룰로오스의 소비가 급증함에 따라 그 원료로 사용되는 목재에 대한 수요도 갈수록 높아지고 있으나 원료공급과 환경문제로 인하여 제지 대체물질에 대한 연구가 절실한 형편이다(Sutherland 1998). 따라

Many basidiomycetes, especially mushroom species, thrive on saccharides that they obtain from the decomposition of cellulose, hemi-cellulose and or lignin. Cellulose is degraded by specific enzymes called cellulases. Cellulases play an important role in the biosphere by recycling cellulose, the most abundant carbohydrate produced by plants. Also cellulases have many potential biotechnologic and industrial applications. Detection of cellulose degrading activity is commonly performed on carboxymethylcellulose CMC medium in combination with a stain that reveals the degraded CMC. In order to efficiently screen the F. velutipes knockout library, obtained through Agrobacterium-mediated transformation (ATMT), for those important enzymes we compared two different staining methods i.e. Congo Red and Gram’s Iodine (as reported in R. C. Kasana et al 2008). The latter stain showed strongly enhanced detection in time and intensity, facilitating mass screening of our mutant database. Using Gram’s iodine and square petri dishes containing up to 9 colonies at a time we can now rapidly screen multiple mutants in a short period. We are going to find the genes. Inactivated genes of mutants with altered cellulase degradation activity will be identified and cloned for further analysis.

The genes encoding cellulases, which belong to glycosyl hydrolase families have been cloned from the basidiomycetous mushrooms. The transcripts of cellulase genes are strongly induced when the mycelia are grown in medium containing crystalline cellulose, and they are not expressed in medium containing glucose, but how insoluble substrates such as microcrystalline cellulose are recognized by these fungal cells is not clear. The polypore mushroom Polyporus arcularius is a wood-decomposing basidiomycete that produces at least three types (I, II, and IIIa) of carboxymethyl cellulase (CMCase) when the medium contains crystalline cellulose as the sole carbon source and produced mainly cellobiose in the medium. The genomic and cDNA clones encoding the family 12 endoglucanase (CMCase IIIa) gene (cel3A) of P. arcularius have been sequenced, and Cel3A has been expressed as an active enzyme in Escherichia coli. To determine the role and function of each type of cellulase in the degradation of crystalline cellulose by basidiomycetous mushrooms, the structure of all of the cellulase genes should be investigated, but the nucleotide sequences of the other cellulase genes in P. arcularius have not yet been reported. In the current study, the genomic and cDNA clones encoding the endoglucanases (cel4), and the two cellobiohydrolases (cel1 and cel2) of P. arcularius sequenced and characterized. The predicted amino acid sequence of Cel1 Cel2, Cel3a and Cel4 are similar to glycosyl hydrolase family 7, 6 12 and 5 protein, respectively. The expressions of the all cellulase genes (cel1 cel2, cel3a and cel4) were induced by Avicel (microcrystalline cellulose) and cellopentaose but repressed by glucose, cellobiose, cellotriose, and cellotetraose. There was a low level of transcription of both genes regardless of the carbon source. These results suggest that P. arcularius cells constitutively express a very low level of cellulase that can degrade insoluble crystalline cellulose and that the transcription of celluases in the cells is induced by products produced by these endoglucanases such as cellooligosaccharides. From our findings, we propose a possible mechanism for the recognition and degradation of insoluble crystalline cellulose by fungal cells.

Regenerated cellulose fibers were prepared from three pulps containing different degree of polymerization(DP) and α-cellulose contents by dry-jet wet spinning technique with cellulose dope in N-methylmorpholin N-oxide (NMMO). The effect of antioxidant, n-propyl gallate (PG) on the properties of different regenerated celluloses was studied using X-ray diffraction, copper number calculation, and viscometry. The degradaqtion of regenerated cellulose from pulp containing higher DP and lower α-cellulose content was occurred more seriously. The tensile strength and initial modulus of regenerated cellulose fiber obtained from NMMO dope with PG were higher than those of fiber obtained from NMMO dope without PG. All fibers showed the round shape cross section and typical cellulose II crystalline structure.

Regenerated cellulose was prepared from Buckeye wood pulp V60 via dissolution in N-methylmorpholin N-oxide (NMMO) solvent system. The effect of antioxidants such as, n-propylgallate (PG), tris(nonylphenyl) phosphite (TRIS), ethylenediamine tetraacetic acid disodium salt (EDTA), and magnesium sulfate on the properties of regenerated cellulose was studied using X-ray diffraction, copper index calculation, and viscometry. Only addition of more than 0.01% of PG into NMMO solvent was effective to avoid the reduction of the degree of polymerization(DP) of regenerated cellulose during dissolution at 110℃. However, the early stage(within 0.5h of dissolution process) degradation of cellulose was not prevented eventhough up to 0.5% PG was appled to hot NMMO system. In addition, to recover the expensive NMMO after cellulose regenerating process, the washing filtrate was studied using simple techniques, such as refractive index, pH, and conductivity measurements. Through conductivity measurement result, 4-time of washing was enough to remove the NMMO completely from regenerated cellulose.

Cellulose triacetate (CTA) was prepared from cotton linter and pulps which contain various contents of α-cellulose. CTA which contains 2.8 of degree of substitution (DS) and 222 of degree of polymerization (DP) was obtained from V-81 pulp under the heterogeneous system. The DS was measured by the titration method, and the DP was obtained by measurement of viscosity. FT-IR spectometer (FT-IR 6300, JASCO) was used to analyze the chemical structure of raw materials and cellulose triacetate, and X-ray diffractometer (X-pert MPD PW3040, Philips) was used to confirm the crystal structure and to calculate the relative crystallinity index (RCI). As α-cellulose content in pulp increased, the acetylation yield increased. Besides with a kind of pulp, it contains insoluble residue which was mainly formed due to the formation of glucomannan triacetate and xylan diacetate during the esterification.

Methyl methacrylate(MMA) was grafted onto microcrystalline cellulose(MCC) with ceric ammonium nitrate(CAN) as a redox initiator at the various conditions. The cellulose triacetate(CTA) composite films added MCC and MMA-grafted MCC powders were prepared on a glass plate. The graft yield(GY) and graft efficiency(GE) of the grafted MCC were calculated with the simple equations by the weight balance method. The double bond of C=O on the grafted MCC surfaces was confirmed by the fourier transform infrared spectroscopy with attenuated total reflection(FT-IT ATR) spectrophotometer. After grafting, the degree of crystallinity of cellulose powders was decresed by judging from x-ray diffraction(XRD) data. Scanning electron microscope(SEM) photos showed the only solvent and CAN solution could change the roughness of MCC powders and the effect of powder dispersions in composite matrix. The tensile strength of MCC/CTA composite films was decreased with increase of MCC powder contents. When 5% grafted MCC was added, the tensile strength of grafted MCC/CTA composite films was increased from 82.3 MPa to 97.2 MPa. The thermal property of powders was also analyzed by the thermogravimetric analysis(TGA).

Cellulose nanofibers from microfibril cellulose (MFC) was prepared by hydrobromic acid (HBr) treatment at different concentrations. Polyvinyl alcohol (PVA) composite films at various loading level of nanofibers were manufactured by a film casting method. The analysis of degree of polymerization (DP), crystallinity (Xc) and molecular weight (Mw) of cellulose after acid treatment was conducted. The mechanical and thermal properties of the cellulose nanofibers reinforced PVA films were characterized using tensile tests and thermogravimetric analysis (TGA). The DP and Mw of MFC by HBr hydrolysis considerably decreased, but Xc showed no significant change. After acid hydrolysis, the diameter of cellulose nanofibers was in the range of 100 to 200 nm. The thermal stability of the films was steadily improved with the increase of nanofiber loading. There was a significant increase in the tensile strength of PVA composite films with the increase in MFC loading. Finally, 5 wt.% nanofiber loading exhibited the highest tensile strength and thermal stability of PVA composite films.

In order to develop a protective carrier scaffolder for the external usage of medical and hygienic materials, three essential protective elements existing in nature, i.e., algin, cellulose, and calcium phosphate apatite, were investigated. The algin is a main skeletal component of sea weeds, the cellulose is of vegetables, and the calcium phosphate apatite is of vertebral animals. In the present study we select the agarose which is a derivative from algin, the cellulose fiber obtained from skin of sea squirt, calcium oxide purified from shell powder, and tricalcium phosphate apatite purchased commercially. Consequently, the agarose-cellulose hybrid was made by the hydrogen bonds intermediating the calcium phosphate apatite between agarose and cellulose molecules. As the calcium phosphate apatite is formed by the addition of calcium hydroxide into tricalcium phosphate solution, we used calcium oxide to accelerate the hybridization between the agarose and calcium phosphate apatite and also between the cellulose and calcium phosphate apatite. In the phase contrast microscopic observation the agarose-cellulose hybrid showed more compact matrix structure than the mixture of agarose and cellulose. The agarose-cellulose hybrid showed increased storage modulus but decreased loss modulus in Rheometer test compared to those of the other materials tested in this study, representing that the agarose-cellulose hybrid has the highest elasticity among them and similar water capacity to agarose. The agarose-cellulose hybrid showed the strongest antimicrobial effect in bacteria killing assay than the other materials, and also it showed a potent blood clotting effect but no immunological hypersensitivity on the human skin. From the above results we presumed that the nobel material, agarose-cellulose hybrid, is a compact scaffolding matrix which has proper elasticity, high capacity to hold substrates, and antimicrobial and blood clotting property potent enough to carry the bio-medical and hygienic materials for external treatment safely.

전 세계적으로 물 부족 문제를 해결하기 위한 한 가지 대안으로서 해수 담수화 기술이 높은 관심을 받고 있다. 본 연구에서는 해수 담수화를 위한 고효율 저에너지 소모 공정으로 떠오르고 있는 역삼투막의 제조를 위해 cellulose triacetate(CTA)의 적용 가능성을 살피고자 하였다. 염소에 대한 안정성과 유기물에 대한 저항성을 가지는 CTA를 사용하여 막을 제조할 시 아세틸화도, 용매, 첨가제와 같은 제막 조성의 변화가 막의 성능에 미치는 것으로 나타난다. 높은 아세틸화도와 CTA의 용매인 다이옥산과 아세톤의 비에서 다이옥산의 함량이 높을수록 높은 유량과 염 제거율을 가지는 막의 제조가 가능하다. 첨가제로는 acetic acid와 maleic acid가 선호된다. 실제 해수 담수화 플랜트에 상용화된 CTA 막(HOLLOSEPⓇ)을 적용해 본 결과 다른 화학적 처리 없이 계속적인 염소 처리만으로 장기간 안정된 유량과 수질을 나타낸다.