scholarly journals High Modulus Regenerated Cellulose Fibers Spun from a Low Molecular Weight Microcrystalline Cellulose Solution

2016 ◽  
Vol 4 (9) ◽  
pp. 4545-4553 ◽  
Author(s):  
Chenchen Zhu ◽  
Robert M. Richardson ◽  
Kevin D. Potter ◽  
Anastasia F. Koutsomitopoulou ◽  
Jeroen S. van Duijneveldt ◽  
...  
2018 ◽  
Vol 303 (5) ◽  
pp. 1800029 ◽  
Author(s):  
Chenchen Zhu ◽  
Anastasia F. Koutsomitopoulou ◽  
Stephen J. Eichhorn ◽  
Jeroen S. van Duijneveldt ◽  
Robert M. Richardson ◽  
...  

2016 ◽  
Vol 852 ◽  
pp. 1256-1264
Author(s):  
Jiao Jiao Miao ◽  
Yong Qi Yu ◽  
Li Ping Zhang

Tetrabutylammonium acetate, a new solvent, can dissolve cellulose (8 wt%) within 5 min at 40°C with dimethyl sulfoxide as coslovent without any pretreatment or inert gas atmosphere. The dissolution detail was recorded by Confocal Laser Scanning Microscope. And the viscosity of cellulose solution prepared from the new solvent was only 10% of that prepared from [BMIM]Cl. Moreover, the influence of molecular weight on the rheology of the cellulose solution was investigated. With the increase of the molecular weight, the viscosity was increasing and the cross-over point of the storage modulus (G′) and loss modulus (G′′) curves shifted to the lower angular frequency. The structure and mechanical properties of the fibers prepared from the cellulose solution were characterized by FT-IR, XRD, SEM and DSC. During the dissolution process, the crystalline region of the cellulose was destroyed and the celluloseIbecame amorphous. However, part of amorphous cellulose transformed into celluloseII by the wet spinning, indicated by FT-IR and XRD spectrum. SEM images showed that the resulting fibers were homogeneous with smooth surfaces and circular cross-sections. Meanwhile, the cellulose fibers had good thermal stability, measured by DSC. This work provided a promising way to prepare cellulose fibers with good physical properties, which was green, low cost and suitable for industrial production.


2020 ◽  
Vol 54 (24) ◽  
pp. 3611-3624 ◽  
Author(s):  
Lucas G P Tienne ◽  
Suellem B Cordeiro ◽  
Elisa B Brito ◽  
Maria de Fátima Vieira Marques

The use of cellulose fibers derived from renewable resources as reinforcement in polymeric composites provides positive environmental benefits with respect to disposal and raw material savings. Microcrystalline cellulose is a regenerated cellulose material that is free of lignin and hemicellulose, widely used in various applications. Recently, there has been enormous interest in producing polymer nanocomposites using cellulose nanofibers as reinforcement. Moreover, the steam explosion process is an ecofriendly method to modify cellulose fibers by inducing fibrillation, allowing the production of nanofibers. Fibrillation of microcrystalline cellulose using steam explosion process as the only cellulose treatment process was not yet studied in the literature. In the present work, steam explosion process was applied to commercial microcrystalline cellulose and the obtained fibers were characterized and employed in composites with polypropylene for evaluation of the thermal, mechanical, and morphological properties in relation to the matrix. The results showed that this process promoted partial fibrillation to nanosized diameter, and an increase in crystalline degree and thermal stability of the original fiber. As for the polypropylene/cellulose composites in the absence of compatibilizer, there was an increase of thermal degradation temperature and mechanical properties measured by dynamic-mechanical analysis in comparison with pure polypropylene.


Cellulose ◽  
2021 ◽  
Vol 28 (15) ◽  
pp. 9547-9566 ◽  
Author(s):  
Kaniz Moriam ◽  
Daisuke Sawada ◽  
Kaarlo Nieminen ◽  
Michael Hummel ◽  
Yibo Ma ◽  
...  

AbstractThe production of sustainable and high-performance fabrics requires high mechanical strength of the individual (staple) fibers. Although Ioncell fibers already exhibit higher fiber strength than commercial man-made cellulose fibers or cotton fibers, we further aimed to increase both strength and toughness to gradually approach synthetic fibers in these properties. Decisive factors for the achievable mechanical properties of the fibers were the pulp purity, the cellulose concentration in the spinning solution and length-to-diameter (L/D) ratio of the cylindrical part of the spinneret. The absence of low molecular weight fractions in combination with an increased average molecular weight had the highest impact on the achievement of both high strength and toughness. Using a spinneret with a high L/D ratio, it was possible to spin Ioncell fibers with a tensile strength of 925 MPa (61.5 cN/tex) and a modulus of toughness of 83.3 MPa (55.5 J/g). According to a fluid dynamic simulation, uniformly longer molecular cellulose chains in combination with a longer cylindrical capillary promoted an effective alignment of the cellulose molecules inside the spinneret capillary before entering the airgap, thus creating the conditions for a simultaneous increase in tensile strength and elongation i.e. toughness of the fiber. Mechanistically, high fiber toughness is caused by the structural parameters in longitudinal direction, in particular by a higher tilt angle, a longer periodicity of the lamellar plane and lower micro void orientation. In summary, we have developed lyocell-type fibers with high strength and toughness, which can potentially be used as a surrogate for synthetic fibers. Graphic abstract


2016 ◽  
Vol 18 (24) ◽  
pp. 6516-6525 ◽  
Author(s):  
Jean Buffiere ◽  
Patrik Ahvenainen ◽  
Marc Borrega ◽  
Kirsi Svedström ◽  
Herbert Sixta

A pathway to produce narrowly distributed low-molecular-weight cellulose by hydrolysis of microcrystalline cellulose using supercritical water.


Author(s):  
G.K.W. Balkau ◽  
E. Bez ◽  
J.L. Farrant

The earliest account of the contamination of electron microscope specimens by the deposition of carbonaceous material during electron irradiation was published in 1947 by Watson who was then working in Canada. It was soon established that this carbonaceous material is formed from organic vapours, and it is now recognized that the principal source is the oil-sealed rotary pumps which provide the backing vacuum. It has been shown that the organic vapours consist of low molecular weight fragments of oil molecules which have been degraded at hot spots produced by friction between the vanes and the surfaces on which they slide. As satisfactory oil-free pumps are unavailable, it is standard electron microscope practice to reduce the partial pressure of organic vapours in the microscope in the vicinity of the specimen by using liquid-nitrogen cooled anti-contamination devices. Traps of this type are sufficient to reduce the contamination rate to about 0.1 Å per min, which is tolerable for many investigations.


1998 ◽  
Vol 1 (5) ◽  
pp. 166-174 ◽  
Author(s):  
Evelyn R Hermes De Santis ◽  
Betsy S Laumeister ◽  
Vidhu Bansal ◽  
Vandana Kataria ◽  
Preeti Loomba ◽  
...  

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