scholarly journals Impact of the Enzyme Charge on the Production and Morphological Features of Cellulose Nanofibrils

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3238
Author(s):  
Sergio Henríquez-Gallegos ◽  
Gregory Albornoz-Palma ◽  
Andrea Andrade ◽  
Carolina Soto ◽  
Miguel Pereira
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Cell Wall ◽  
Aspect Ratio ◽  
Linear Relationship ◽  
Mechanical Treatment ◽  
Essential Role ◽  
Cellulose Nanofibrils ◽  
Degree Of Polymerization ◽  
Cnf Films

The available research does not allow specific relationships to be established between the applied enzymatic-mechanical treatment, the degree of polymerization, and the characteristics of the cellulose nanofibrils (CNFs) produced. This work aims to establish specific relationships between the intensity of enzymatic treatment, the degree of polymerization of the cellulose, the morphology of CNFs, and the tensile strength of the CNF films. It is determined that the decrease in the degree of polymerization plays an essential role in the fibrillation processes of the cell wall to produce CNFs and that there is a linear relationship between the degree of polymerization and the length of CNFs, which is independent of the type of enzyme, enzyme charge, and intensity of the applied mechanical treatment. In addition, it is determined that the percentage of the decrease in the degree of polymerization of CNFs due to mechanical treatment is irrespective of the applied enzyme charge. Finally, it is shown that the aspect ratio is a good indicator of the efficiency of the fibrillation process, and is directly related to the mechanical properties of CNF films.

scholarly journals Effect of The Enzyme Charge On The Production And Morphological Characteristics of Cellulose Nanofibrils

2021 ◽  
Author(s):  
Sergio Henríquez-Gallegos ◽  
Gregory Albornoz-Palma ◽  
Andrea Andrade ◽  
Carolina Soto ◽  
Miguel Pereira
Keyword(s):  
Tensile Strength ◽  
Cell Wall ◽  
Aspect Ratio ◽  
Mechanical Treatment ◽  
Cellulose Nanofibrils ◽  
Morphological Characteristics ◽  
Degree Of Polymerization ◽  
Maximum Value ◽  
Cnf Films ◽  
Available Information

Abstract The effect of cellulase enzymes on the degree of polymerization of cellulose and the mechanical fibrillation process has been widely reported. However, the available information does not allow to establish specific relationships between the applied enzymatic-mechanical treatment, the degree of polymerization, and the characteristics of the cellulose nanofibrils (CNFs) produced. This work aims to establish specific relationships between the intensity of enzymatic treatment, the degree of polymerization of the cellulose, the morphology of CNFs, and the tensile strength of the films. It was determined that the decrease in the degree of polymerization plays an important role in the fibrillation processes of the cell wall to produce CNFs and that there is a linear relationship between the degree of polymerization and the length of CNFs, which is independent of the type of enzyme, enzyme charge, and intensity of the applied mechanical treatment. In addition, it was determined that the percentage of decrease in the degree of polymerization of CNFs due to mechanical treatment is irrespective of the applied enzyme charge. Else ways, it was shown that the aspect ratio is a good indicator of the efficiency of the fibrillation process, and the degree of polymerization in not. Finally, it was shown that the resistance of CNF films is positively related to the degree of polymerization up to a maximum value which corresponds to the maximum of the aspect ratio.

Preparation and Properties of Optically Transparent Chitin Nanofibers Sheet by Different Simple Mechanical Methods

2013 ◽  
Vol 634-638 ◽  
pp. 2232-2237
Author(s):  
Qin Qin Hu ◽  
Da Gang Li ◽  
Ai Jun Li ◽  
Wen Biao Gu
Keyword(s):  
High Pressure ◽  
Tensile Strength ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Mechanical Treatment ◽  
High Pressure Homogenization ◽  
Flexible Composites ◽  
Mechanical Methods ◽  
Optically Transparent ◽  
Chitin Nanofibers

Chitin nanofibers were prepared from commercially available dried chitin powders by different simple mechanical methods under acid conditions after removal of minerals and proteins. The fibrillated chitin samples were observed by FE-SEM and there was a fine network structure formed by chitin nanofibes with a width of approximately 10-50 nm and high aspect ratio. The mechanical treatment under acid conditions was crucial to facilitate the fibrillation of chitin fibers into nanofibers. The high pressure homogenization in combination with grinding was used to obtain the most transparent chitin nanofibers sheet with a transmittance of 88.5% and tensile strength of 82.34MPa, and the sheet even had a Young’s modulus of 6.17GPa. Thus, chitin nanofibers provide excellent potential as reinforcement of transparent flexible composites to improve the properties of nanocomposites.

Effect of Metakaolin and PVA Fibres on the Workability and Mechanical Properties of Concrete

2014 ◽  
Vol 935 ◽  
pp. 188-192 ◽  
Author(s):  
Sadaqat Ullah Khan ◽  
Muhd Fadhil Nuruddin ◽  
Nasir Shafiq ◽  
Tehmina Ayub
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Aspect Ratio ◽  
Volume Fraction ◽  
Splitting Tensile Strength

Locally produced metakaolin (MK) as the cement replacing material and PVA fibres has been used. The effect on workability and on the mechanical properties of concrete has been investigated. Total fifteen (15) mixes of concrete have been examined using MK 5 to 10% and PVA fibres of aspect ratio 45, 60, 90 and 120 with 1% volume fraction. Three (03) mixes without PVA fibre have been used as control mixes. For each mix, test for slump, cube compressive strength and splitting tensile strength has been performed. It has been found that MK and PVA fibres causes decrease in slump but use of MK and PVA fibres together improves the workability. The use of MK and PVA fibres has advantageous in increasing compressive strength and splitting tensile strength.

Effect of Polyethylene Glycol (PEG) on Molten Plasticized Cellulose Acetate (CA)

2013 ◽  
Vol 830 ◽  
pp. 172-175
Author(s):  
Cheng Zhi Chuai ◽  
Zhi Zhang
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Tensile Strength ◽  
Polyethylene Glycol ◽  
Flexural Strength ◽  
Cellulose Acetate ◽  
Flexural Modulus ◽  
Degree Of Polymerization ◽  
Maximum Elongation ◽  
Elongation At Break

Ethylene glycol (EG) and polyethylene glycol (PEG) were added as plasticizers to improve the processing performance of cellulose acetate (CA). The CA with 30% plasticizers were melted by HAAKE at 200 °C. The effects of EG and PEG (degree of polymerization in 200-800) on rheological properties and mechanical properties of CA were investigated. The results show that the plasticizing time, equilibrium torque and melt viscosity of the plasticizing system increase with the increase of PEG molecular weight, while the processing performance decreased. The tensile strength of the system decrease as the PEG molecular weight increased. The plasticizing system which contents 30% PEG-200(degree of polymerization is 200) shows the maximum elongation at break. The minimum values appeared in both flexural strength and flexural modulus in the CA/PEG-200 system.

Effects of mechanical fibrillation time by disk grinding on the properties of cellulose nanofibrils

TAPPI Journal ◽  
2016 ◽  
Vol 15 (6) ◽  
pp. 419-423 ◽  
Author(s):  
QIANQIAN WANG ◽  
J.Y. ZHU
Keyword(s):  
Energy Input ◽  
Cellulose Nanofibrils ◽  
Crystallinity Index ◽  
Degree Of Polymerization ◽  
Optical Transparency ◽  
Structure And Properties ◽  
Eucalyptus Pulp ◽  
Mechanical Fibrillation ◽  
Cnf Films ◽  
Grinding Time

Cellulose nanofibrils (CNF) were successfully produced from a bleach kraft eucalyptus pulp by a supermasscolloider. Effects of grinding time on structure and properties of CNF and the corresponding CNF films were investigated. Grinding time was important to increase the optical transparency of CNF suspensions. The degree of polymerization (DP) and crystallinity index (CrI) of CNF decreased linearly with the increase in CNF suspension transparency. This suggests optical transparency of a CNF suspension can be used to characterize the degree of fibrillation. Specific tensile strength and Young’s modulus of the CNF films made of CNF suspension with only 0.5 h grinding were increased approximately 30% and 200%, respectively, compared with conventional handsheets prepared by valley beating to 300 Canadian Standard Freeness (CSF). Energy input was only 1.38 kWh/kg for 0.5 h grinding. Grinding beyond 0.5 h produced negligible improvement in specific tensile and specific modulus. Opacity of CNF films decreased rapidly during the first 1.5 h of fibrillation and then plateaued.

scholarly journals Effect of carboxymethylated cellulose nanofibril concentration regime upon material forming on mechanical properties in films and filaments

Cellulose ◽  
2020 ◽  
Author(s):  
Karl M. O. Håkansson
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Cellulose Nanofibrils ◽  
Efficient Manner ◽  
Spatial Homogeneity ◽  
High Performing ◽  
Macro Scale ◽  
Protein Fibrils ◽  
Main Factors ◽  
Material Forming

Abstract It is predicted that the forest and materials from the forest will play an important role to enable the transformation from our linear present to a circular and sustainable future. Therefore, there is a need to understand the materials that can be extracted from the forest, and how to use them in an efficient manner. Here, carboxymethylated cellulose nanofibrils (CNF) from the forest are used to produce films and filaments with the aim to preserve the impressive mechanical properties of a single CNF in a macro-scale material. The mechanical properties of both the films (tensile strength of 231 MPa) and filaments (tensile strength of 645 MPa) are demonstrated to be maximized when the starting suspension is in a flowing state. This is a new insight with regards to filament spinning of CNF, and it is here argued that the three main factors contributing to the mechanical properties of the filaments are (1) the possibility to produce a self-supporting filament from a suspension, (2) the CNF alignment inside the filament and (3) the spatial homogeneity of the starting suspension. The results in this study could possibly also apply to other nanomaterials such as carbon nanotubes and silk protein fibrils, which are predicted to play a large part in future high performing applications. Graphic abstract

Mechanical Properties of TPNR-MWNTs-OMMT Hybrid Nanocomposites

2012 ◽  
Vol 501 ◽  
pp. 194-198 ◽  
Author(s):  
Mou'ad A. Tarawneh ◽  
Sahrim H. Ahmad ◽  
A.R. Shamsul Bahri ◽  
Yu Lih Jiun
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Aspect Ratio ◽  
Interfacial Adhesion ◽  
Hybrid Nanocomposites ◽  
X Ray Diffraction ◽  
Elongation At Break ◽  
X Ray ◽  
Maximum Value ◽  
The Matrix

This paper discusses the processing of a hybrid of TPNR-MWNTs-OMMT nanocomposites with different percentages of filler to determine the optimum mechanical properties of the hybrid nanocomposites. Three types of hybrid nanocomposites with various MWNTs-OMMT compositions (1%wt MWNTs+3%wt OMMT), (2%wt MWNTs+2%wt OMMT) and (3%wt MWNTs+1%wt OMMT) were prepared. The OMMT layers were found to be separated further with higher nanotubes content as exhibited by X-ray diffraction. The result of tensile test showed that tensile strength and Young's modulus increase in the presence of nanotubes and maximum value were obtained for the nanocomposites with highest nanotubes (3%wt) which increased about 33% and 36%, respectively compared with pure TPNR matrix. On other hand, the elongation at break considerably decreased with increasing the percentage of MWNTs. TEM micrographs revealed aspect ratio and fillers orientation in the TPNR matrix also promoted strongly to interfacial adhesion between fillers and the matrix which contributed significantly to the improvement of the mechanical properties

The effect of (induced) dislocations on the tensile properties of individual Norway spruce fibres

Holzforschung ◽  
2008 ◽  
Vol 62 (1) ◽  
pp. 77-81 ◽  
Author(s):  
Michaela Eder ◽  
Nasko Terziev ◽  
Geoffrey Daniel ◽  
Ingo Burgert
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Cell Wall ◽  
Wood Cell Wall ◽  
Tensile Tests ◽  
Pulp And Paper ◽  
Living Tree ◽  
Wood Processing ◽  
Compressive Stresses ◽  
Different Levels

Abstract Axial compressive stresses can cause distortion of the cellulose fibril alignment in the wood cell wall. These deformations are thought to occur in the living tree and/or to develop during wood processing and seem to adversely affect the mechanical properties of pulp and paper and other fibre-based products. To characterise the influence of dislocations on the mechanical properties of the unmodified cell wall, dislocations were artificially created by applying high compression loads to wood blocks parallel to the fibre axis. Mechanically isolated fibres containing different levels of dislocations were then subjected to tensile tests. Comparison between micromechanical properties of reference fibres and fibres that were artificially loaded in compression revealed the importance of dislocations for the mechanics of both earlywood and latewood. However, the tensile strength (decrease ∼19% for earlywood and ∼26% for latewood) was less affected than expected from structural observations of the pre-compressed zones.

scholarly journals Bacterial Cellulose - Properties and Its Potential Application

2021 ◽  
Vol 50 (2) ◽  
pp. 493-505
Author(s):  
Izabela Betlej ◽  
Sarani Zakaria ◽  
Krzysztof J. Krajewski ◽  
Piotr Boruszewski
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Literature Review ◽  
Bacterial Cellulose ◽  
Review Paper ◽  
Physical And Mechanical Properties ◽  
Degree Of Polymerization ◽  
High Tensile Strength ◽  
Electronic Industry ◽  
Pure Cellulose

This review paper is related to the utilization on bacterial cellulose in many applications. The polymer produced from bacterial cellulose possessed a very good physical and mechanical properties, such as high tensile strength, elasticity, absorbency. The polymer from bacterial cellulose has a significantly higher degree of polymerization and crystallinity compared to those derived from plant. The collection of selected literature review shown that bacterial cellulose produced are in the form pure cellulose and can be used in many of applications. These include application in various industries and sectors of the economy, from medicine to paper or electronic industry.

Comparison of Textile Mechanical Properties of Cotton in Crosslinking with Dimethylolethyleneurea and Formaldehyde

1976 ◽  
Vol 46 (11) ◽  
pp. 813-817 ◽  
Author(s):  
U. Meyer ◽  
K. Müller ◽  
H. Zollinger
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Crosslinking Agent ◽  
Strength Loss ◽  
Cotton Fabrics ◽  
Degree Of Polymerization ◽  
Cure Process ◽  
Recovery Angle ◽  
Varied Concentration ◽  
Very High

Cotton fabrics were crosslinked with dimethylolethyleneurea (DMEU) and with formaldehyde by the pad-dry-cure process. The following parameters were varied: concentration of catalyst (MgCl2) and crosslinking agent, reaction time, and temperature. The crosslinked fabrics were characterized by dry and wet crease-recovery angles, tensile strength, and degree of polymerization. The results show that with DMEU a significantly better dry crease-recovery angle/tensile strength relation is obtainable. This difference is due entirely to a greater degradation of cellulose by hydrolysis in treatments with formaldehyde. Furthermore, in the case of DMEU the effect/strength loss relation can be improved by using very high resin concentrations in the padding liquor.

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