scholarly journals Bio-Composites Consisting of Cellulose Nanofibers and Na+ Montmorillonite Clay: Morphology and Performance Property

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1448 ◽  
Author(s):  
Runzhou Huang ◽  
Xian Zhang ◽  
Huiyuan Li ◽  
Dingguo Zhou ◽  
Qinglin Wu
Keyword(s):  
Cellulose Nanofibers ◽  
Composite Films ◽  
Performance Property ◽  
Water Contact ◽  
Third Stage ◽  
Networking Ability ◽  
Apparent Activation Energies ◽  
And Performance ◽  
Cnf Films ◽  
Degradation Properties

This paper reports the usage of cellulose nanofibers (CNFs) as a continuous nanoporous matrix and nanoclay (NC) as additive to fabricate hybrid films. CNF/Cloisite Na+ nanoclay composite films containing 10–50 wt % of NC were prepared for the study. The effects of NC incorporation and its content on mechanical, wettability and thermal degradation properties were investigated. The results showed that the film had a multilayer structure with gradually deposited CNT-NC hybrid on the filter paper Pure CNF films had higher moduli compared with those from the composite films, as the incorporation of NC decreased hydrogen bonding and networking ability of CNFs, especially at the high NC loading levels. The composite films demonstrated self-extinguishing ability when being exposed to the open flame. Composites with over 35 wt % NC did not burn because of the formation of a protective barrier containing ordered NC platelets. The addition of montmorillonite NC led to increased surface water contact angle, showing enhanced hydrophobicity of the material. During the film’s thermal pyrolysis, the first process occurred between 100 and 200 °C, resulting mainly from the evaporation of absorbed water; the second, between 280 and 350 °C, indicated thermal decomposition of cellulose; and the slow third stage happened from the 350 to 600 °C, representing carbonization. The results demonstrate that the apparent activation energies for all the CNF/NC composites were higher than the pure CNF film. CNF/NC films fabricated in this process are a promising barrier material for packaging applications.

Comparison of morphological, structural and antibacterial properties of different Apocynum venetum poly (lactic acid)/nanocellulose nanofiber films

2019 ◽  
Vol 90 (5-6) ◽  
pp. 593-605 ◽  
Author(s):  
Lu Wang ◽  
Chenmeizi Wang ◽  
Qingle Zhang ◽  
Jianhua Liu ◽  
Xin Xia
Keyword(s):  
Lactic Acid ◽  
Cellulose Nanofibers ◽  
Antibacterial Properties ◽  
Poly Lactic Acid ◽  
Water Contact ◽  
Environment Friendly ◽  
Hydrolysis Method ◽  
Apocynum Venetum ◽  
Novel Material ◽  
Cnf Films

As new bio-based sustainable materials, this paper made a comparative study on the phloem and straw of Apocynum venetum. The cellulose nanofibers (CNFs) of Apocynum venetum phloem and straw were prepared by the acid hydrolysis method, and then different parts and proportions of poly (lactic acid) (PLA)/CNF films were prepared via electrospinning, respectively. The results revealed the CNF with longer length and finer diameter network structure can be separated by straw, while the short nanostructure of the rod-like structure can be separated by phloem. It was also shown that the wettability and permeability of PLA improved significantly by adding these two kinds of CNFs, the water contact angle of PLA decreased from 130° to 101° and the permeability was up to 4658 g/(m2•d). As for antibacterial properties, the antibacterial rate of CNF from straw proved slightly better than that from phloem against E.coli, reaching more than 90%. It proved that the CNF from straw showed excellent performance as phloem, providing a novel material for the preparation of CNFs, which can be naturally antibacterial and environment-friendly. The obtained PLA/CNF films could be potentially applied in antibacterial medical dressings.

scholarly journals Effect of pectin extraction method on properties of cellulose nanofibers isolated from sugar beet pulp

Cellulose ◽  
2021 ◽  
Author(s):  
Mohammad L. Hassan ◽  
Linn Berglund ◽  
Wafaa S. Abou Elseoud ◽  
Enas A. Hassan ◽  
Kristiina Oksman
Keyword(s):  
Mechanical Properties ◽  
Sugar Beet ◽  
Extraction Method ◽  
Cellulose Nanofibers ◽  
Degree Of Polymerization ◽  
Sugar Beet Pulp ◽  
Cellulose Content ◽  
Water Contact ◽  
Beet Pulp ◽  
Cnf Films

AbstractIn this study, the effect of pectin extraction method on the properties of cellulose nanofibers (CNFs) isolated from sugar beet pulp (SBP) was studied. Pectin was extracted by the industrially practiced method by sulfuric acid hydrolysis or by enzymatic hydrolysis using a cellulase/xylanase enzymes mixture. The CNFs were then isolated by high-pressure homogenization and investigated in terms of their chemical composition, crystallinity, size, degree of polymerization, and re-dispersion in water after freeze-drying. The mechanical properties and surface characteristics of CNF films were also studied. The results showed that fibrillation of the de-pectinated SBP was more efficient for the acid hydrolyzed SBP. CNFs from the acid-hydrolyzed SBP had a slightly wider diameter, higher crystallinity, viscosity, and α-cellulose content but a lower degree of polymerization than CNFs from the enzyme-hydrolyzed SBP. Owing to the presence of more residual hemicelluloses in the CNFs from the enzyme-hydrolyzed SBP, the CNFs had higher re-dispersion ability in water. CNF films from enzyme-hydrolyzed SBP displayed slightly better mechanical properties and higher water contact angle than acid-hydrolyzed CNF films. Graphic abstract

scholarly journals Improved Hydrophobicity of Macroalgae Biopolymer Film Incorporated with Kenaf Derived CNF Using Silane Coupling Agent

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2254
Author(s):  
Adeleke A. Oyekanmi ◽  
N. I. Saharudin ◽  
Che Mohamad Hazwan ◽  
Abdul Khalil H. P. S. ◽  
Niyi G. Olaiya ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Coupling Agent ◽  
Silane Coupling Agent ◽  
Cellulose Nanofibrils ◽  
Hydroxyl Groups ◽  
Water Contact ◽  
Silane Coupling ◽  
Cnf Films ◽  
Kenaf Bast ◽  
Thermal Stability Of

Hydrophilic behaviour of carrageenan macroalgae biopolymer, due to hydroxyl groups, has limited its applications, especially for packaging. In this study, macroalgae were reinforced with cellulose nanofibrils (CNFs) isolated from kenaf bast fibres. The macroalgae CNF film was after that treated with silane for hydrophobicity enhancement. The wettability and functional properties of unmodified macroalgae CNF films were compared with silane-modified macroalgae CNF films. Characterisation of the unmodified and modified biopolymers films was investigated. The atomic force microscope (AFM), SEM morphology, tensile properties, water contact angle, and thermal behaviour of the biofilms showed that the incorporation of Kenaf bast CNF remarkably increased the strength, moisture resistance, and thermal stability of the macroalgae biopolymer films. Moreover, the films’ modification using a silane coupling agent further enhanced the strength and thermal stability of the films apart from improved water-resistance of the biopolymer films compared to unmodified films. The morphology and AFM showed good interfacial interaction of the components of the biopolymer films. The modified biopolymer films exhibited significantly improved hydrophobic properties compared to the unmodified films due to the enhanced dispersion resulting from the silane treatment. The improved biopolymer films can potentially be utilised as packaging materials.

Preparation and properties of polyurethane coatings modified by polysilazane

2019 ◽  
Vol 32 (6) ◽  
pp. 611-619 ◽  
Author(s):  
Xiaoli Liu ◽  
Zhen Ge ◽  
Wenguo Zhang ◽  
Yunjun Luo
Keyword(s):  
Mechanical Property ◽  
Photoelectron Spectroscopy ◽  
Composite Coatings ◽  
Composite Films ◽  
Dip Coating ◽  
Water Contact ◽  
Research Attention ◽  
Elongation At Break ◽  
Coating Method ◽  
Dip Coating Method

Due to their unique physicochemical properties, polysilazanes exhibit excellent performance when combined with some resin matrixes, which had drawn great research attention. In this article, polyurethane (PU) was firstly prepared by polytetrahydrofuran glycol, isophorone diisocyanate, and 1,4-butanediol as main materials. Then, the prepared PU was blended with polysilazane by mixing the two solutions together, which was cured to films via dip-coating method at room temperature. The structure, thermal stability, and surface properties of the composite coatings were investigated by Fourier-transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and X-ray photoelectron spectroscopy. The results demonstrated that after modification with polysilazane, the heat resistance, hydrophobicity, and mechanical property of the PU coatings were improved. When the content of polysilazane was 6 wt%, the mechanical property of the composite films was optimized, with a maximum tensile strength of 25.7 MPa and elongation at break of 797%. Meanwhile, the water contact angle of the composite film was 107° and the water absorption reached a minimum of 2.1%, which showed improved hydrophobicity and water resistance.

scholarly journals Complex Aerogels Generated from Nano-Polysaccharides and Its Derivatives for Oil–Water Separation

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1593 ◽  
Author(s):  
Hajo Yagoub ◽  
Liping Zhu ◽  
Mahmoud H. M. A. Shibraen ◽  
Ali A. Altam ◽  
Dafaalla M. D. Babiker ◽  
...  
Keyword(s):  
Guar Gum ◽  
Corn Oil ◽  
Cellulose Nanofibers ◽  
Aqueous Media ◽  
Three Dimensional ◽  
Absorption Capacity ◽  
Water Contact ◽  
Water Separation ◽  
Oil Water Separation ◽  
Oil Water

The complex aerogel generated from nano-polysaccharides, chitin nanocrystals (ChiNC) and TEMPO-oxidized cellulose nanofibers (TCNF), and its derivative cationic guar gum (CGG) is successfully prepared via a facile freeze-drying method with glutaraldehyde (GA) as cross-linkers. The complexation of ChiNC, TCNF, and CGG is shown to be helpful in creating a porous structure in the three-dimensional aerogel, which creates within the aerogel with large pore volume and excellent compressive properties. The ChiNC/TCNF/CGG aerogel is then modified with methyltrichlorosilane (MTCS) to obtain superhydrophobicity/superoleophilicity and used for oil–water separation. The successful modification is demonstrated through FTIR, XPS, and surface wettability studies. A water contact angle of 155° on the aerogel surface and 150° on the surface of the inside part of aerogel are obtained for the MTCS-modified ChiNC/TCNF/CGG aerogel, resulting in its effective absorption of corn oil and organic solvents (toluene, n-hexane, and trichloromethane) from both beneath and at the surface of water with excellent absorption capacity (i.e., 21.9 g/g for trichloromethane). More importantly, the modified aerogel can be used to continuously separate oil from water with the assistance of a vacuum setup and maintains a high absorption capacity after being used for 10 cycles. The as-prepared superhydrophobic/superoleophilic ChiNC/TCNF/CGG aerogel can be used as a promising absorbent material for the removal of oil from aqueous media.

scholarly journals Engineering the Surface and Mechanical Properties of Water Desalination Membranes Using Ultralong Carbon Nanotubes

Membranes ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 106 ◽  
Author(s):  
Yehia M. Manawi ◽  
Kui Wang ◽  
Viktor Kochkodan ◽  
Daniel J. Johnson ◽  
Muataz A. Atieh ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Aspect Ratio ◽  
Water Flux ◽  
Contact Angles ◽  
Water Desalination ◽  
Membrane Properties ◽  
Porous Membranes ◽  
Water Contact ◽  
And Performance

In this work, novel polysulphone (PS) porous membranes for water desalination, incorporated with commercial and produced carbon nanotubes (CNT), were fabricated and analyzed. It was demonstrated that changing the main characteristics of CNT (e.g., loading in the dope solutions, aspect ratio, and functionality) significantly affected the membrane properties and performance including porosity, water flux, and mechanical and surface properties. The water flux of the fabricated membranes increased considerably (up to 20 times) along with the increase in CNT loading. Conversely, yield stress and Young’s modulus of the membranes dropped with the increase in the CNT loading mainly due to porosity increase. It was shown that the elongation at fracture for PS/0.25 wt. % CNT membrane was much higher than for pristine PS membrane due to enhanced compatibility of commercial CNTs with PS matrix. More pronounced effect on membrane’s mechanical properties was observed due to compatibility of CNTs with PS matrix when compared to other factors (i.e., changes in the CNT aspect ratio). The water contact angle for PS membranes incorporated with commercial CNT sharply decreased from 73° to 53° (membrane hydrophilization) for membranes with 0.1 and 1.0 wt. % of CNTs, while for the same loading of produced CNTs the water contact angles for the membrane samples increased from 66° to 72°. The obtained results show that complex interplay of various factors such as: loading of CNT in the dope solutions, aspect ratio, and functionality of CNT. These features can be used to engineer membranes with desired properties and performance.

scholarly journals Internationalization and Performance of Vietnamese Manufacturing Firms: Does Organizational Slack Matter?

2018 ◽  
Vol 8 (4) ◽  
pp. 64 ◽  
Author(s):  
Hien Thi Ngoc Huynh ◽  
Phuong V. Nguyen ◽  
Khoa T. Tran
Keyword(s):  
Emerging Market ◽  
Developed Countries ◽  
Organizational Slack ◽  
Optimum Level ◽  
International Expansion ◽  
Manufacturing Enterprises ◽  
Long Run ◽  
Third Stage ◽  
And Performance ◽  
Using Data

This paper aims to investigate the three-stage theory of international expansion in the long run from the perspective of firm behavior. Although this topic has been mostly explored using data from developed countries, this paper aims to fill the research gap in an emerging market by using an extensive unbalanced panel data of 12,704 unlisted Vietnam manufacturing enterprises from the General Statistics Office during 2007 to 2012. The findings illustrated a significant S-shaped relationship between internationalization and performance. Notably, the results depict significantly moderating effects of both high-discretion slacks and low-discretion slacks on the internationalization–performance relationship across three stages of global expansion as an enterprise enhances this relationship in the first and third stage although this worsens it in the middle stage. The empirical results suggest that firms should determine the optimum level of internationalization and slacks in addition to balancing their costs with their real gains.

Addition of Cellulose Nanofibers to Control Surface Roughness for Hydrophobic Ceramic Coatings

2021 ◽  
Vol 21 (8) ◽  
pp. 4492-4497
Author(s):  
Eun Ae Shin ◽  
Gye Hyeon Kim ◽  
Jeyoung Jung ◽  
Sang Bong Lee ◽  
Chang Kee Lee
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Surface Energy ◽  
Water Contact Angle ◽  
Ceramic Coating ◽  
Cellulose Nanofibers ◽  
Ceramic Coatings ◽  
Coating Material ◽  
Textured Surface ◽  
Water Contact

Hydrophobic ceramic coatings are used for a variety of applications. Generally, hydrophobic coating surfaces are obtained by reducing the surface energy of the coating material or by forming a highly textured surface. Reducing the surface energy of the coating material requires additional costs and processing and changes the surface properties of the ceramic coating. In this study, we introduce a simple method to improve the hydrophobicity of ceramic coatings by implementing a textured surface without chemical modification of the surface. The ceramic coating solution was first prepared by adding cellulose nanofibers (CNFs) and then applied to a polypropylene (PP) substrate. The surface roughness increased as the amount of added CNFs increased, increasing the water contact angle of the surface. When the amount of CNFs added was corresponding to 10% of the solid content, the surface roughness average of the area was 43.8 μm. This is an increase of approximately 140% from 3.1 μm (the value of the surface roughness of the surface without added CNFs). In addition, the water contact angle of the coating with added CNF increased to 145.0°, which was 46% higher than that without the CNFs. The hydrophobicity of ceramic coatings with added CNFs was better because of changes in the surface topography. After coating and drying, the CNFs randomly accumulated inside the ceramic coating layer, forming a textured surface. Thus, hydrophobicity was improved by implementing a rugged ceramic surface without revealing the surface of the CNFs inside the ceramic layer.

Effect of Dimethyl Sulfoxide in Hydrophobic Modification of Cotton Filter Cloth by ARGET-ATRP Mechanism

2020 ◽  
Vol 993 ◽  
pp. 1407-1416 ◽  
Author(s):  
Zheng Li ◽  
Zi Jian He ◽  
Ying Cheng Zhou ◽  
Yi Tang ◽  
Yu Fang Chen ◽  
...  
Keyword(s):  
Dimethyl Sulfoxide ◽  
Crystal Form ◽  
Surface Roughening ◽  
Hydrophobic Modification ◽  
Filter Cloth ◽  
Water Contact ◽  
Grafting Reaction ◽  
Hydrophobically Modified ◽  
Arget Atrp ◽  
And Performance

In this paper, Dimethyl sulfoxide (DMSO) was used in the activating process of cotton filter cloth to improve its further hydrophobic modification reaction between cotton fabric and 1-octadecene via an electron transfer (ARGET) atom transfer radical polymerization (ATRP) mechanism. The major influences of DMSO on ARGET-ATRP process was discussed, and meanwhile, the microstructure changes, morphology feature and performance characteristics of cotton filter cloth during the reaction was explored by the SEM, AFM, EDS, XRD and TGA techniques.The result shows that DMSO can leads to cotton fibers adhesion and surface roughening under the ARGET-ATRP grafting reaction conditions, but has little changes on the crystal form, crystallinity and thermal properties of cellulose. At a DMSO dosage of 10%, the hydrophobically modified cotton filter cloth has a water contact angle (CA) of up to 141°. While naturally placed for 1 hour, the CA of hydrophobically modified cotton filter cloth can be stable at 116° with a decay rate of 17.5%, which proves that the hydrophobic stability of cotton filter cloth has been improved markedly. Furthermore, a better improvement for the hydrophobic stability of cotton filter cloth will significantly enhance the application of hydrophobic functional modified cellulosic materials.

scholarly journals Preparation and Properties of Corn Starch/Chitin Composite Films Cross-Linked by Maleic Anhydride

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1606
Author(s):  
Peng Yin ◽  
Jinglong Liu ◽  
Wen Zhou ◽  
Panxin Li
Keyword(s):  
Maleic Anhydride ◽  
Corn Starch ◽  
Composite Films ◽  
Water Vapor Permeability ◽  
Contact Angles ◽  
Vapor Permeability ◽  
Water Contact ◽  
Elongation At Break ◽  
Shrimp Shell ◽  
Starch Films

To improve the functional properties of starch-based films, chitin (CH) was prepared from shrimp shell powder and incorporated into corn starch (CS) matrix. Before blending, maleic anhydride (MA) was introduced as a cross-linker. Composite CS/MA-CH films were obtained by casting-evaporation approach. Mechanical property estimation showed that addition of 0–7 wt % MA-CH improved the tensile strength of starch films from 3.89 MPa to 9.32 MPa. Elongation at break of the films decreased with the addition of MA-CH, but the decrease was obviously reduced than previous studies. Morphology analysis revealed that MA-CH homogeneously dispersed in starch matrix and no cracks were found in the CS/MA-CH films. Incorporation of MA-CH decreased the water vapor permeability of starch films. The water uptake of the films was reduced when the dosage of MA-CH was below 5 wt %. Water contact angles of the starch films increased from 22° to 86° with 9 wt % MA-CH incorporation. Besides, the composite films showed better inhibition effect against Escherichia coli and Staphylococcus aureus than pure starch films.

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