Electrospinning of ultrafine cellulose fibers and fabrication of poly(butylene succinate) biocomposites reinforced by them

Han, Seong Ok,Son, Won Keun,Youk, Ji Ho,Park, Won Ho Wiley Subscription Services, Inc., A Wiley Company 2008 Journal of applied polymer science Vol.107 No.3

<P>In this study, electrospinning conditions for ultrafine cellulose fibers was systematically studied and poly(butylene succinate) biocomposites reinforced by the ultrafine cellulose fibers (cellulose/PBS biocomposite) were fabricated. The ultrafine cellulose fibers were electrospun from cellulose (DP = 700) solutions in N-methylmorpholine-N-oxide hydrate (85/15 w/w) at 100°C. The optimal electrospinning concentration of the cellulose solutions was determined to be 7 wt % and the average diameter of the resulting cellulose fibers was 560 nm. The cellulose I structure of the native cellulose was converted to the cellulose II structure after electrospinning. The ultrafine cellulose fibers showed a reinforcing effect in the cellulose/PBS biocomposite, suggesting that they have potential applications as reinforcement fibers for biocomposites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008</P>

TEAH/요소 용제에 용해된 셀룰로오스와 AKD를 이용한 소수성 셀룰로오스 비즈 제조

장민석,조병욱 한국펄프·종이공학회 2024 펄프.종이기술 Vol.56 No.2

. To expand the application of hydrophilic cellulose beads, we developed a technique to prepare hydrophobic cellulose beads with alkyl ketene dimer (AKD). The cellulose solution was prepared by dissolving chemical pulp in tetraethylammonium hydroxide (TEAH)/urea solvent, followed by the addition of AKD to disperse it at room temperature. Cellulose beads were prepared by dropwise addition of the cellulose-AKD suspension into acetic acid solution, followed by washing and drying. The effects of AKD addition on the cellulose- AKD suspension and the properties of the AKD-modified cellulose beads were investigated. It was confirmed that the cellulose beads were chemically modified by AKD, resulting in enhanced hydrophobicity. The addition of AKD to the TEAH/urea/cellulose solution led to a reduction in viscosity and surface tension. Compared to unmodified cellulose beads, AKD-modified cellulose beads exhibited lower water retention value (WRV) and water absorption capacity, as well as increased oil absorption. They also exhibited relatively higher strength (lower deformation) when swollen in water.

Site-directed mutagenesis of bacterial cellulose synthase highlights sulfur-arene interaction as key to catalysis

Sun, S.j.,Horikawa, Y.,Wada, M.,Sugiyama, J.,Imai, T. Elsevier Scientific Pub 2016 Carbohydrate research Vol.434 No.-

<P>Cellulose is one of the most abundant biological polymers on Earth, and is synthesized by the cellulose synthase complex in cell membranes. Although many cellulose synthase genes have been identified over the past 25 years, functional studies of cellulose synthase using recombinant proteins have rarely been conducted. In this study, we conducted a functional analysis of cellulose synthase with site-directed mutagenesis, by using recombinant cellulose synthase reconstituted in living Escherichia coil cells that we recently constructed (cellulose-synthesizing E. coli, CESEC). We demonstrated that inactivating mutations at an important amino acid residue reduced cellulose production. In this study, an interesting loss-of-function mutation occurred on Cys308, whose main chain carbonyl plays an important role for locating the cellulose terminus. Mutating this cysteine to serine, thus changing sulfur to oxygen in the side chain, abolished cellulose production in addition to other apparent detrimental, mutations. This unexpected result highlights that the thiol side-chain of this cysteine plays an active role in catalysis, and additional mutation experiments indicated that the sulfur arene interaction around Cys308 is a key in cellulose-synthesizing activity. Data obtained by CESEC shed light on the function of cellulose synthase in living cells, and will deepen our understanding of the mechanism of cellulose synthase. (C) 2016 The Authors. Published by Elsevier Ltd.</P>

Rheological and mechanical properties of oleogels based on castor oil and cellulosic derivatives potentially applicable as bio-lubricating greases: Influence of cellulosic derivatives concentration ratio

R. Sanchez,J.M. Franco,M.A. Delgado,C. Valencia,C. Gallegos 한국공업화학회 2011 Journal of Industrial and Engineering Chemistry Vol.17 No.4

Nowadays the lubricating market is demanding new biodegradable or more environmentally acceptable products based on renewable resources as a consequence of progressively more strict environmental regulations. In this framework, this study deals with the design of gel-like dispersions potentially applicable as environmentally friendly lubricating greases. These dispersions were formulated using castor oil and ethyl cellulose/a-cellulose or ethyl cellulose/methyl cellulose blends. In particular, the influence of cellulosic derivatives concentration ratio on the linear viscoelasticity and mechanical stability of the resulting oleogel formulations was studied. The modification of ethyl cellulose/acellulose or ethyl cellulose/methyl cellulose weight ratios allows obtaining some formulations with suitable rheological characteristics and mechanical stability for potential lubricating applications. An important decrease in the values of the linear viscoelasticity functions down to a minimum value was found by increasing ethyl cellulose/a-cellulose or ethyl cellulose/methyl cellulose weight ratios (W) up to a critical value, which depends on both nature of the cellulosic derivatives employed and temperature. Above this critical value, the linear viscoelastic functions increase with W, at temperatures in the range 0–75 8C, and continuously decrease at higher temperatures, i.e. 125 8C. Thermal susceptibility is significantly dampened by reducing ethyl cellulose concentration. Gel-like dispersions formulated with ethyl cellulose/methyl cellulose blends showed appropriate mechanical stabilities to be used as biolubricating greases.

[Bmim]Cl-DMF 용제에 의한 HwBKP의 용해 및 이를 이용한 셀룰로오스 비즈 제조: 셀룰로오스 농도와 주사기 바늘 직경의 영향

이성규,오세영,조병욱 한국펄프.종이工學會 2022 펄프.종이기술 Vol.54 No.4

This study investigated the effects of cellulose concentration dissolved in 1-butyl-3- methylimidazolium chloride ([Bmim]Cl) and N,N-dimethylformamide (DMF) on the properties of cellulose solution and beads. Cellulose beads were prepared using the dropping method. The cellulose solution dissolved in [Bmim]Cl and DMF (mixing ratio=70:30) did not gel for 12 h and exhibited shear thinning behavior. Increasing the cellulose concentration increased the viscosity and surface tension of the cellulose solution. Cellulose beads, 600-1000 μm in size, were prepared by varying the cellulose concentration in the range of 2-4% and the syringe needle diameter in the range of 0.3-0.9 mm using the dropping method. The particle size of the beads increased with increasing cellulose concentration and diameter of the syringe needle. The cellulose concentration had no remarkable effect on the chemical structure, crystallinity, and thermal stability of cellulose. .

Properties of Bacterial Cellulose and Its Nanocrystalline Obtained from Pineapple Peel Waste Juice

Budiman Anwar,Bunbun Bundjali,Yayan Sunarya,I Made Arcana 한국섬유공학회 2021 Fibers and polymers Vol.22 No.5

Bacterial cellulose is a type of biopolymers and has a magnitude of applications in food, paper, and textileindustries, and as a biomaterial in cosmetics and medicine. Whilst, nanocrystalline cellulose is a kind of renewable andbiocompatible nanomaterials that can find the vast application in biotechnology, medicine, and various technical areas. Bacterial cellulose and its nanocrystalline can be obtained by utilizing the agricultural waste. This work is focused on thecharacterization of bacterial cellulose and its nanocrystalline isolated from bacterial cellulose produced by using pineapplepeel waste juice as a culture medium. Fourier-transform infrared analysis toward the original bacterial cellulose andnanocrystalline cellulose indicated that both have the same chemical composition, however they have differences incrystallinity. The X-ray diffraction showed that both bacterial cellulose and nanocrystalline cellulose have a polymorphstructure of cellulose I. The original BC has more the allomorph structure of Iα with crystallinity index of 74 %, but afterhydrolysis process to become nanocrystalline cellulose has more the allomorph structure of Iβ with crystallinity index of89 %. The nanocrystalline cellulose has a morphology of needle-like structure, with an average diameter and length of 25±11and 325±182 nm, respectively. The thermal stability of nanocrystalline cellulose is found to be higher than the originalbacterial cellulose.

활엽수크라프트펄프 및 박테리아 셀룰로오스부터 제조한 종이의 물성

조남석,김영신,박종문,민두식,안드레레오노비치 한국펄프종이공학회 1997 펄프.종이기술 Vol.29 No.4

Most cellulose resources come from the higher plants, but bacteria also synthesize same cellulose as in plants. Many scientists have been widely studied on the bacterial cellulose, the process development, manufacturing, even marketing of cellulose fibers. The bacterial celluloses are very different in its physical and morphological structures. These fibers have many unique properties that are potentially and commercially beneficial. The fine fibers can produce a smooth paper with enchanced its strength property. But there gave been few reports on the mechanical properties of the processing of bacterial cellulose into structural materials. This study were performed to elucidate the mechanical properties of sheets prepared from bacterial cellulose. Also reinforcing effect of bacterial cellulose on the conventional pulp paper as well as surface structures by scanning electron microscopy were discussed. Paper made from bacterial cellulose is 10 times much stronger than ordinary chemical pulp sheet, and the mixing of bacterial cellulose has a remarkable reinforcing effect on the papers. Mechanical strengthes were increased with the increase of bacterial cellulose content in the sheet. This strength increase corresponds to the increasing water retention value and sheet density with the increase of bacterial cellulose content. Scanning electron micrographs were shown that fine microfibrills of bacterial celluloses covered on the surfaces of hardwood pulp fibers, and enhanced sheet strength by its intimate fiber bonding.

셀룰로오스-NMMO 수화물 용액의 압출가공 조건에 따른 셀룰로오스 분자량과 알파 셀룰로오스 함량 변화에 대한 연구

김동복(Dong Bok Kim) 한국고분자학회 2013 폴리머 Vol.37 No.3

새로운 방법에 의하여 제조된 셀룰로오스-NMMO pre-dope를 이용한 셀룰로오스 섬유 및 필름 제조를 위한 압출가공 시 열분해 및 기계적 분해에 따른 셀룰로오스의 분자량 및 알파 셀룰로오스 함량 변화에 대하여 고찰하였다. 고속분쇄에 의해 제조된 pre-dope를 압출기에 통과시켜 용액으로 제조할 때 가공온도, 셀룰로오스의 농도 및 체 제시간에 따라 셀룰로오스의 분자량 및 알파 셀룰로오스 함량 변화가 다양하게 나타났다. 셀룰로오스의 분자량과 알파 셀룰로오스 함량은 셀룰로오스의 농도가 낮을수록 온도가 높을수록 감소하였다. 셀룰로오스 농도 15% 및 짧은 체제시간 영역에서 알파 셀룰로오스 함량은 높은 전단으로 인해 온도가 높을수록 가장 큰 변화를 보였다. 다양 한 가공조건으로부터 알파 셀룰로오스 함량변화 거동은 분자량 변화와 다른 거동을 보였으며 셀룰로오스 용액 제조를 위한 압출가공조건이 중요 요인임을 알 수 있었다. During extruder processing to manufacture cellulose fiber and film using cellulose-NMMO pre-dope produced by a new method, it seems to occur the changes of molecular weight and α-cellulose content of cellulose upon thermal and mechanical degradation. In an extruder making cellulose solutions from the pre-dope obtained by high-speed mixer, the changes of cellulose molecular weight and α-cellulose content resulted with the variations of processing temperature, concentration of cellulose, and residence time. The molecular weight and α-cellulose content of cellulose decreased with decreasing cellulose concentration and increasing processing temperature. At 15% concentration and short residence time region, the change of α-cellulose content was so high due to high-shear with an increase in temperature. From these processing conditions, the variations of α-cellulose content and molecular weight showed different behaviors, and these processing conditions for making cellulose solution were found to be important factors.

Proposal on the Cellulose Degradation Model for the Domestic 1st Phase Underground Repository

Hyun Woo Song,Moonoh Kim,Sang June Park,Sungjun Kim,Jun-gi Yeom 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1

With the recent concern regarding cellulose enhancing radionuclide mobility upon its degradation to ISA, disposal of cellulosic wastes is being held off until the disposal safety is vindicated. Thus, a rational assessment should be conducted, applying an appropriate cellulose degradation model considering the disposal environment and cellulose degradation mechanisms. In this paper cellulose degradation mechanisms and the disposal environment are studied to propose the best-suitable cellulose degradation model for the domestic 1st phase repository. For the cellulose to readily degrade, the pH should be greater than 12.5. As in the case of SKB, 1BLA is excluded from the safety assessment because the pH of 1BLA remains below 12.5. Furthermore, despite cellulose degradation occurring, it does not always produce ISA. At low Ca2+ concentration, the ISA yield rate is around 25%, but at high Ca2+ concentration, the ISA yield rate increases up to 90%. Thus, for the cellulose to be a major concern, both pH and Ca2+ concentration conditions must be satisfied. To satisfy both conditions, the cement hydration must be in 2nd phase, when the porewater pH remains around 12.5 and a significant amount of Ca2+ ion is leaching out from the cement. However, according to the safety evaluation and domestic research, 2nd phase of cement hydration for silo concrete would achieve a pH of around 12.4, dissatisfying cellulose degradation condition like in 1BLA. Thus, cellulose degradation would be unlikely to occur in the domestic 1st phase repository. To derive waste acceptance criteria, a quantitative evaluation should be conducted, conservatively assuming cellulose is degraded. To conduct a safety evaluation, an appropriate degradation model should be applied to determine the degradation rate of cellulose. According to overseas research, despite the mid-chain scission being yet to be seen in the experiments, the degradation model considering mid-chain scission is applied, resulting in an almost 100% degradation rate. The model is selected because the repositories are backfilled with cement, achieving a pH greater than 13, so extensive degradation is reasonably conservative. However, under the domestic disposal condition, where cellulose degradation is unlikely to occur, applying such model would be excessively conservative. Thus, the peeling and stopping model derived by Van Loon and Haas, which suggests 10~25% degradation rate, is reasonably conservative. Based on this model, cellulose would not be a major concern in the domestic 1st phase repository. In the future, this study could be used as fundamental data for planning waste acceptance criteria.

조리방법에 따른 채소의 불용성 식이섬유 함량 변화에 관한 연구

계수경 한국식품영양학회 1995 韓國食品營養學會誌 Vol.8 No.2

최근 영양 생리적으로 중요성이 인정된 식이섬유가 인체내에서 나타내는 생리기능은 식이섬유의 각 구성성분들의 함량과 특성에 의해 영향을 받으므로 각 성분들을 분별 측정할 필요가 있으나 국내에서는 식이섬유의 함량을 측정한 연구가 미흡한 실정이며 특히 가열조리시 조리 전후에 있어서 식이섬유 함량이 어떻게 변화하는가에 대해서는 검토된 바 없다. 그러므로 본연구에서는 한국인이 상용하는 채소 15종(근채류 3종, 과채류 3종, 경채류 2종, 엽채류 7종)에 대해, 식이섬유 각 구성성분의 함량을 측정 비교하였으며, 각종 조리방법과 김치발효에 따른 식이섬유의 함량 변화를 조사하였다. 이 상의 결과를 요약하면 다음과 같다. 각종 채소의 불용성 식이섬유 함량은 건물 기준으로 총 불용성 식이섬유인 Neutral detergent fiber(NDF)는 11.8 ∼ 31.9 %, acid detergent fiber(ADF)는 10.9 ∼ 25.4 %, cellulose는 8.8 ∼ 23.8%, hemicellulose는 0.6 ∼ 10.6 %, lignin은 1.0 ∼ 5.2 % 범위였으며 특히 고추류에서 총 불용성 식이섬유함량이 높았다. Cellulose는 총불용성 식이섬유인 NDF의 63%정도를 차지하여 본 실험에 사용된 채소들의 경우 불용성 식이섬유의 대부분이 cellulose로 구성되어 있음을 알 수 있었다 조리시 NDF, ADF, cellulose 함량은 원료시료보다 증가했으며 이들 성분들의 변화는 cellulose의 함량변화에 기인했다. 그러나 hemicellulose와 lignin 함량은 일정한 경향을 보이지 않았다. 발효 시 NDF, ADF, cellulose 함량은 원료시료보다 약간 증가했으나, hemicellulose와 lignin은 일정한 경향을 보이지 않았다. 조리나 발효와 같은 처리에 의해 불용성 식이섬유 분획 중 cellulose만이 크게 영향을 받는 것으로 나타났다. Recently, interests of dietary fiber associated with critical physiological effects have been rising in Korea. However, there are still little studies on exact contents of dietary fiber components which have distintive physiological effect in the body. In the present study, the contents of fiber components in 15 kinds of vegetables being consumed commonly in Korea were investigated, and the effects of various treatments(cook-ing and Kimchi fermentation) on fiber were studied. The results are summarized as follows. Fiber contents of vegetables were 11.8∼31.9% of neutral detergent fiber(NDF), total insoluble dietary fiber, 10.9∼25.4% of acid detergent fiber(ADF), 8.8∼23.8% of cellulose, 0.6∼10.6% of hemicellulose and 1.0∼5.2% of lignin, on dry weight basis. Especially, peppers had higher contents of NDF than the other vegetables. In the vegetables used in the present study, it was found that a great portion of NDF, total insoluble dietary fiber, was composed of cellulose because cellulose covered 63% of NDF. Cooking increased the NDF, ADF and cellulose contents, and most change was due to the change of cellulose. The values of hemicellulose and lignin showed an irregular pattern upon cooking. Fermentation slightly increased NDF, ADF and cellulose, while hemicellulose and lignin showed irregular pattern.