Bacterial Cellulose Aerogels Skeleton Strengthened by Regenerated Cellulose

Soft skeleton of bacterial cellulose aerogels (BCAs) was strengthened effectively by conformal coverage of regenerated cellulose to make sure the BCAs sustain more compression. After freeze drying, compression modulus of the strengthened sample is significantly higher than that of the BCAs, which endows the former more extensive applications. The regenerated cellulose solution was prepared by gelation of cellulose from aqueous alkali hydroxide/urea solution. Then the bacterial cellulose wet gels bulks were immersed in the regenerated cellulose solution with different contents to discuss the enhanced effect of the BCAs skeleton. The morphology of the enhanced BCAs was observed by scanning electron micrograph (SEM).The porous structure of the enhanced BCAs was investigated by Brunauer-Emmett-Teller (BET) instrument. The stress−strain curves of the enhanced BCAs were measured. The XRD pattern of the strengthened sample was also carried out. The results indicated that regenerated cellulose forms thin layers which conformally covered bacterial cellulose skeleton fibers and that had little effect on microstructure and crystal form of the bulk cellulose aerogels.

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Cellulose-Silica Composite Aerogels Prepared with Sodium Silicate by Freeze Drying Method

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.697.129 ◽

2016 ◽

Vol 697 ◽

pp. 129-133 ◽

Cited By ~ 1

Author(s):

Hua Zheng Sai ◽

Rui Fu ◽

Li Xing ◽

Jun Hui Xiang ◽

Zhen You Li ◽

...

Keyword(s):

Freeze Drying ◽

Sol Gel ◽

Cellulose Nanofibers ◽

Compression Modulus ◽

High Specific Surface Area ◽

Regenerated Cellulose ◽

Organic Precursor ◽

Silica Composite ◽

Composite Aerogels ◽

Solvent Replacement

The cellulose-silica composite aerogels (CAs) were fabricated through a permeation sol-gel process in the regenerated cellulose hydrogels followed by freeze drying. The precursor Na2SiO3 instead of traditional organic precursor was diffused in the cellulose matrix followed by permeating the catalyst into the cellulose nanofibers network gradually to promote the in situ condensation of Na2SiO3 to form a SiO2 gel skeleton from outside to inside. The obtained CAs displayed the interpenetrating network (IPN) structure of the regenerated cellulose nanofibers network and the SiO2 gel skeleton in nanoscale. In the IPN structure, the flexible cellulose nanofibers network was supported by the hard inorganic network effectively to sustain the compression and the silica gel skeleton protect the cellulose nanofibers to avoid the remodeling of their shape in the process of solvent replacement before freeze drying. Due to the synergic effects of the different network, the IPN structure endows the CAs with high compression modulus (as high as 15.48 MPa), high specific surface area (as high as 621 m2 g-1) and low density (less than 0.182 g cm-3).

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Lightweight, Flexible Cellulose-Derived Carbon Aerogel@Reduced Graphene Oxide/PDMS Composites with Outstanding EMI Shielding Performances and Excellent Thermal Conductivities

Nano-Micro Letters ◽

10.1007/s40820-021-00624-4 ◽

2021 ◽

Vol 13 (1) ◽

Author(s):

Ping Song ◽

Bei Liu ◽

Chaobo Liang ◽

Kunpeng Ruan ◽

Hua Qiu ◽

...

Keyword(s):

Graphene Oxide ◽

Reduced Graphene Oxide ◽

Freeze Drying ◽

Carbon Aerogel ◽

Urea Solution ◽

Cellulose Solution ◽

Emi Shielding ◽

Excellent Thermal Stability ◽

Reduced Graphene ◽

Shielding Composites

AbstractIn order to ensure the operational reliability and information security of sophisticated electronic components and to protect human health, efficient electromagnetic interference (EMI) shielding materials are required to attenuate electromagnetic wave energy. In this work, the cellulose solution is obtained by dissolving cotton through hydrogen bond driving self-assembly using sodium hydroxide (NaOH)/urea solution, and cellulose aerogels (CA) are prepared by gelation and freeze-drying. Then, the cellulose carbon aerogel@reduced graphene oxide aerogels (CCA@rGO) are prepared by vacuum impregnation, freeze-drying followed by thermal annealing, and finally, the CCA@rGO/polydimethylsiloxane (PDMS) EMI shielding composites are prepared by backfilling with PDMS. Owing to skin-core structure of CCA@rGO, the complete three-dimensional (3D) double-layer conductive network can be successfully constructed. When the loading of CCA@rGO is 3.05 wt%, CCA@rGO/PDMS EMI shielding composites have an excellent EMI shielding effectiveness (EMI SE) of 51 dB, which is 3.9 times higher than that of the co-blended CCA/rGO/PDMS EMI shielding composites (13 dB) with the same loading of fillers. At this time, the CCA@rGO/PDMS EMI shielding composites have excellent thermal stability (THRI of 178.3 °C) and good thermal conductivity coefficient (λ of 0.65 W m-1 K-1). Excellent comprehensive performance makes CCA@rGO/PDMS EMI shielding composites great prospect for applications in lightweight, flexible EMI shielding composites. Graphic abstract

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Filter made of cuprammonium regenerated cellulose for virus removal: a mini-review

Cellulose ◽

10.1007/s10570-021-04319-2 ◽

2021 ◽

Author(s):

Shoichi Ide

Keyword(s):

Membrane Filtration ◽

Hollow Fiber Membrane ◽

Membrane Filter ◽

Three Dimensional ◽

Protein Solutions ◽

Regenerated Cellulose ◽

Cellulose Solution ◽

Virus Removal ◽

Biological Products ◽

Molecular Weights

AbstractIn 1989, Asahi Kasei commercialized a porous hollow fiber membrane filter (Planova™) made of cuprammonium regenerated cellulose, making it possible for the first time in the world to “remove viruses from protein solutions by membrane filtration”. Planova has demonstrated its usefulness in separating proteins and viruses. Filters that remove viruses from protein solutions, i.e., virus removal filters (VFs), have become one of the critical modern technologies to assure viral safety of biological products. It has also become an indispensable technology for the future. The performance characteristics of VFs can be summarized in two points: 1) the virus removal performance increases as the virus diameter increases, and 2) the recovery rate of proteins with molecular weights greater than 10,000 exceeds the practical level. This paper outlines the emergence of VF and its essential roles in the purification process of biological products, requirements for VF, phase separation studies for cuprammonium cellulose solution, comparison between Planova and other regenerated cellulose flat membranes made from other cellulose solutions, and the development of Planova. The superior properties of Planova can be attributed to its highly interconnected three-dimensional network structure. Furthermore, future trends in the VF field, the subject of this review, are discussed.

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A Facile Way for Preparation of Cellulose Beads With High Homogeneity, Low Crystallinity, and Tunable - Internal Structure

10.21203/rs.3.rs-673294/v1 ◽

2021 ◽

Author(s):

Yuanyuan Xia ◽

Xinping Li ◽

Yue Yuan ◽

Jingshun Zhuang ◽

Wenliang Wang

Keyword(s):

Crystal Form ◽

Energy Storage Materials ◽

Regenerated Cellulose ◽

Protein Chromatography ◽

Green Materials ◽

Coagulation Mechanism ◽

Structures And Properties ◽

Water Holding ◽

Water Alcohol ◽

Low Crystallinity

Abstract The preparation of cellulose beads has attracted more and more attention in the application of advanced green materials. To obtain uniform and controllable cellulose beads, the dissolving pulp was dissolved in NMMO, and the cellulose beads were regenerated in various coagulation baths (water, alcohol, acid, NMMO, etc.) by phase conversion method. Results show that the crystal form of regenerated cellulose changes from cellulose I to cellulose II. NMMO swelling cellulose beads present low crystallinity and low water holding capacity. The coagulation mechanism of cellulose beads was clarified by a laser confocal microscopy. It is found that the whole coagulation process was from outside to inside gradually. It is a green and facile method for preparing cellulose beads with different structures and properties, which can be widely used in biomedicine, energy storage materials, and protein chromatography.

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Bidirectional anisotropic polyimide/bacterial cellulose aerogels by freeze-drying for super-thermal insulation

Chemical Engineering Journal ◽

10.1016/j.cej.2019.123963 ◽

2020 ◽

Vol 385 ◽

pp. 123963 ◽

Cited By ~ 14

Author(s):

Xiang Zhang ◽

Xingyu Zhao ◽

Tiantian Xue ◽

Fan Yang ◽

Wei Fan ◽

...

Keyword(s):

Bacterial Cellulose ◽

Thermal Insulation ◽

Freeze Drying

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Preparation, Characterization and Hemostatic Properties of Chitosan Caffeates

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.814.365 ◽

2019 ◽

Vol 814 ◽

pp. 365-371

Author(s):

Si Tong Lu ◽

Dong Ying Zhang ◽

Zhang Hu ◽

Si Dong Li ◽

Pu Wang Li

Keyword(s):

Caffeic Acid ◽

Freeze Drying ◽

Water Solubility ◽

Crystal Form ◽

Positive Control ◽

Mass Ratio ◽

X Ray Diffraction ◽

X Ray ◽

Yunnan Baiyao ◽

Better Than

In this paper, chitosan and caffeic acid were used as starting materials to prepare chitosan caffeates by reflux-heating and freeze-drying. The structures of chitosan caffeates were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and potentiometric titration. At the same time, the physical properties of chitosan caffeates were tested and the hemostatic properties were evaluated. The results showed that four chitosan caffeates with different mass ratios of chitosan and caffeic acid (1:1, 1:2, 1:4, 1:6) had been successfully prepared, which enhanced the water solubility. FTIR analysis demonstrated that caffeic acid had been successfully grafted onto chitosan chains. XRD showed that the crystal form of chitosan changed to some extent and the chain had some regularity in some directions, but its crystallinity reduced. Chitosan caffeates, particularly mass ratio of 1:1, showed excellent hemostatic properties and even better than chitosan and the positive control (Yunnan Baiyao), which were expected to be developed as an effective biomaterial for hemostasis.

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Actuation of Carbon Nanofiber Reinforced Electro-Active Paper Actuators

Volume 2: Biomedical and Biotechnology ◽

10.1115/imece2012-87159 ◽

2012 ◽

Author(s):

Nargis A. Chowdhury ◽

Ahmed A.-Jumaily ◽

Maximiano V. Ramos ◽

Afsar Uddin ◽

John Robertson

Keyword(s):

Ionic Liquid ◽

Solid State ◽

Maximum Stress ◽

Carbon Nanofiber ◽

Low Voltage ◽

Liquid Electrolyte ◽

Nanocomposite Films ◽

Regenerated Cellulose ◽

Cellulose Solution ◽

Ionic Liquid Electrolyte

Actuation of two types of electro-active paper actuators composed of functionalized carbon nanofiber, polypyrrole, and regenerated cellulose (FCNF/PPy/RC) and functionalized carbon nanofiber, ionic liquid, and regenerated cellulose (FCNF/IL/RC) is evaluated for different preparation processes. FCNF/PPy/RC nanocomposite films are prepared by dispersing functionalized carbon nanofiber and polypyrrole into cellulose solution in DMAC/LiCl, and then casting the solution onto glass. FCNF/IL/RC nanocomposite films are fabricated simply by adopting a bimorph configuration with a regenerated cellulose-supported internal ionic liquid electrolyte layer sandwiched by electrode layers with a view to getting quick and long-lived operation in air at low applied voltage. The electrode layers include functionalized carbon nanofiber, ionic liquid and regenerated cellulose. The results indicate that the bending displacement decreases with increasing frequency and increases with increasing voltage for both types of actuators. These low voltage driven solid state actuators show maximum stress and strain of 12.73 MPa and 3.0%, respectively, which are comparable with other low-voltage driven solid-state electro-active polymer actuators. The advantages of these types of actuators are their ability to perform well in air and easy process of fabrication.

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Fabrication Of Carbon Aerogels From Coir For Oil Adsorption

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/964/1/012033 ◽

2022 ◽

Vol 964 (1) ◽

pp. 012033

Author(s):

Hieu M Nguyen ◽

Khoi A Tran ◽

Tram T N Nguyen ◽

Nga N H Do ◽

Kien A Le ◽

...

Keyword(s):

Freeze Drying ◽

Oil Spills ◽

Sol Gel ◽

Urea Solution ◽

Carbon Aerogels ◽

Low Density ◽

High Porosity ◽

Motor Oil ◽

Sol Gel Process ◽

Oil Adsorption

Abstract Coir, known as coconut fibers, are an abundant cellulosic source in Vietnam, which are mostly discarded when copra and coconut water are taken, causing environmental pollution and waste of potential biomass. In this research, carbon aerogels from chemically pretreated coir were successfully synthesized via simple sol-gel process with NaOH-urea solution, economical freeze-drying, and carbonization. The samples, including pretreated coir, coir aerogels, and carbon aerogels, are characterized using FTIR spectroscopy, SEM, XRD spectroscopy, and TGA. The carbon aerogels exhibit low density (0.034–0.047 g/cm3), high porosity (97.63–98.32 %), and comparable motor oil sorption capacity (22.71 g/g). The properties of carbon aerogels are compared with those of coir aerogels, indicating such better values than those of coir aerogels. Coir-derived carbon aerogels is a potential replacement for the hydrophobically-coated cellulose aerogels in term of treating oil spills.

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Morphology and thermal stability of bacterial cellulose/collagen composites

Open Chemistry ◽

10.2478/s11532-014-0545-z ◽

2014 ◽

Vol 12 (9) ◽

pp. 968-975 ◽

Cited By ~ 12

Author(s):

Mădălina Albu ◽

Zina Vuluga ◽

Denis Panaitescu ◽

Dumitru Vuluga ◽

Angela Căşărică ◽

...

Keyword(s):

Thermal Stability ◽

Bacterial Cellulose ◽

Freeze Drying ◽

Collagen Gel ◽

Positive Influence ◽

Mechanical Tests ◽

Mechanical And Thermal Properties ◽

Force Microscopy ◽

Collagen Solution ◽

Thermal Stability Of

AbstractThe aim of this paper was to prepare composites of bacterial cellulose (BC) and collagen to evaluate both the effect of collagen on the morphological, mechanical and thermal properties of BC and the effect of BC on the thermal stability of collagen for designing composites with increased potential biomedical applications. Two series of composites were prepared, the first series by immersing BC pellicle in solutions of collagen obtained in three forms, collagen gel (CG), collagen solution (CS) and hydrolysed collagen (HC), followed by freeze drying; and the second series of composites by mixing BC powder in solutions of collagen (CG, CS and HC), also followed by freeze drying. The properties of obtained composites were evaluated by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), mechanical tests, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results revealed that BC acts as a thermal stabilizer for CS matrix, while with CG matrix it interacts synergistically leading to composites with improved properties. On the other hand, the BC sheet impregnated with collagen has a significantly improved thermal stability. Collagen (as HC, CS or CG) has also a positive influence on the mechanical properties of lyophilized BC sheet. A four times increase of modulus was observed in BC/HC and BC/CG composites. and an increase of 60 times for BC/CS. The spectacular increase of elastic modulus and tensile strength in the case of BC/CS composite was explained by the easier penetration of collagen solution in the BC network and impregnation of BC fibrils as revealed by SEM and AFM analyzes.

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