Structure, Rheological Behavior, and in Situ Local Flow Fields of Cellulose Nanocrystal Dispersions during Cross-Flow Ultrafiltration

2019 ◽  
Vol 7 (12) ◽  
pp. 10679-10689 ◽  
Author(s):  
C. Rey ◽  
N. Hengl ◽  
S. Baup ◽  
M. Karrouch ◽  
E. Gicquel ◽  
...  
Keyword(s):  
Rheological Behavior ◽  
Cross Flow ◽  
Flow Fields ◽  
Cellulose Nanocrystal ◽  
Local Flow

scholarly journals Flow fields associated with in situ mineral leaching

1994 ◽  
Vol 36 (2) ◽  
pp. 133-151 ◽  
Author(s):  
Lawrence K. Forbes ◽  
Anthony M. Watts ◽  
Graeme A. Chandler
Keyword(s):  
Simple Model ◽  
Free Boundary ◽  
Numerical Method ◽  
Flow Rate ◽  
Recovery Rate ◽  
Flow Fields ◽  
Vertical Line ◽  
Rate Limiting ◽  
Mineral Leaching

AbstractA simple model for underground mineral leaching is considered, in which liquor is injected into the rock at one point and retrieved from the rock by being pumped out at another point. In its passage through the rock, the liquor dissolves some of the ore of interest, and this is therefore recovered in solution. When the injection and recovery points lie on a vertical line, the region of wetted rock forms an axi-symmetric plume, the surface of which is a free boundary. We present an accurate numerical method for the solution of the problem, and obtain estimates for the maximum possible recovery rate of the liquor, as a fraction of the injected flow rate. Limiting cases are discussed, and other geometries for fluid recovery are considered.

scholarly journals Injectable and Gellable Chitosan Formulations Filled with Cellulose Nanofibers for Intervertebral Disc Tissue Engineering

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1202 ◽  
Author(s):  
Ingo Doench ◽  
Maria Torres-Ramos ◽  
Alexandra Montembault ◽  
Paula Nunes de Oliveira ◽  
Celia Halimi ◽  
...  
Keyword(s):  
Intervertebral Disc ◽  
Rheological Behavior ◽  
Biomedical Application ◽  
Flow Behavior ◽  
Cellulose Nanofibers ◽  
Nanofibrillated Cellulose ◽  
The Body ◽  
Mechanical Reinforcement ◽  
Invasive Approach

The development of non-cellularized injectable suspensions of viscous chitosan (CHI) solutions (1.7–3.3% (w/w)), filled with cellulose nanofibers (CNF) (0.02–0.6% (w/w)) of the type nanofibrillated cellulose, was proposed for viscosupplementation of the intervertebral disc nucleus pulposus tissue. The achievement of CNF/CHI formulations which can gel in situ at the disc injection site constitutes a minimally-invasive approach to restore damaged/degenerated discs. We studied physico-chemical aspects of the sol and gel states of the CNF/CHI formulations, including the rheological behavior in relation to injectability (sol state) and fiber mechanical reinforcement (gel state). CNF-CHI interactions could be evidenced by a double flow behavior due to the relaxation of the CHI polymer chains and those interacting with the CNFs. At high shear rates resembling the injection conditions with needles commonly used in surgical treatments, both the reference CHI viscous solutions and those filled with CNFs exhibited similar rheological behavior. The neutralization of the flowing and weakly acidic CNF/CHI suspensions yielded composite hydrogels in which the nanofibers reinforced the CHI matrix. We performed evaluations in relation to the biomedical application, such as the effect of the intradiscal injection of the CNF/CHI formulation in pig and rabbit spine models on disc biomechanics. We showed that the injectable formulations became hydrogels in situ after intradiscal gelation, due to CHI neutralization occurring in contact with the body fluids. No leakage of the injectate through the injection canal was observed and the gelled formulation restored the disc height and loss of mechanical properties, which is commonly related to disc degeneration.

Surface modification of reverse osmosis membranes with zwitterionic polymer to reduce biofouling

2015 ◽  
Vol 15 (5) ◽  
pp. 999-1010 ◽  
Author(s):  
Ahmed E. Abdelhamid ◽  
Mahmoud M. Elawady ◽  
Mahmoud Ahmed Abd El-Ghaffar ◽  
Abdelgawad M. Rabie ◽  
Poul Larsen ◽  
...  
Keyword(s):  
Reverse Osmosis ◽  
Tap Water ◽  
Membrane Surface ◽  
Salt Content ◽  
Cross Flow ◽  
Membrane Properties ◽  
Cleaning Efficiency ◽  
Bacteria Growth ◽  
Cross Flow Filtration

The zwitterionic homopolymer poly[2-(methacryloyloxy)ethyl-dimethyl-(3-sulfopropyl) ammonium hydroxide was coated onto the surface of commercial polyamide reverse osmosis (RO) membranes. Aqueous solutions of the polymer at different concentrations were applied to modify the polyamide membranes through an in situ surface coating procedure. After membrane modification, cross-flow filtration testing was used to test the antifouling potential of the modified membranes. The obtained data were compared with experimental data for unmodified membranes. Each test was done by cross-flow filtering tap water for 60 hours. Yeast extract was added as a nutrient source for the naturally occurring bacteria in tap water, to accelerate bacteria growth. Fourier transform infrared spectroscopy, contact angle, scanning electron microscopy, atomic force microscopy, and permeation tests were employed to characterize membrane properties. The results confirmed that modifying the membranes enhanced their antifouling properties and cleaning efficiency, the fouling resistance to bacteria improving due to the increased hydrophilicity of the membrane surface after coating. In addition, the water permeability and salt rejection improved. This in situ surface treatment approach for RO membranes could be very important for modifying membranes in their original module assemblies as it increases water production and reduces the salt content.

Polycarbonate-based composites reinforced by in situ polytetrafluoroethylene fibrillation: Preparation, thermal and rheological behavior

2015 ◽  
Vol 132 (32) ◽  
pp. n/a-n/a ◽  
Author(s):  
Diego Antonioli ◽  
Katia Sparnacci ◽  
Michele Laus ◽  
Luca Boarino ◽  
Maria Cristina Righetti
Keyword(s):  
Rheological Behavior

scholarly journals Unexpected microphase transitions in flow towards nematic order of cellulose nanocrystals

Cellulose ◽  
2019 ◽  
Vol 27 (4) ◽  
pp. 2003-2014 ◽  
Author(s):  
Roland Kádár ◽  
Mina Fazilati ◽  
Tiina Nypelö
Keyword(s):  
Liquid Crystal ◽  
Shear Rate ◽  
Formation Process ◽  
Recovery Time ◽  
Continuous Process ◽  
Cellulose Nanocrystal ◽  
Nematic Order ◽  
Chiral Nematic ◽  
Macro Scale

Abstract Organization of nanoparticles is essential in order to control their light-matter interactions. We present cellulose nanocrystal suspension organization in flow towards a unidirectional state. Visualization of evolving polarization patterns of the cellulose nanocrystal suspensions is combined with steady and oscillatory shear rheology. Elucidation of the chiral nematic mesophase in a continuous process towards unidirectional order enables control of alignment in a suspension precursor for structural films and reveals thus far in situ unrevealed transition states that were not detectable by rheology alone. The coupled analytics enabled the suspensions of interest to be divided into rheological gels and rheological liquid crystal fluids with detailed information on the microtransition phases. Both populations experienced submicron organization and reached macro-scale homogeneity with unidirectional ordering in continued shear. We quantify the time, shear rate, and recovery time after shear to design an optimizing formation process for controlled wet structures as precursors for dry products. Graphic abstract

Rheological behavior and particle alignment of cellulose nanocrystal and its composite hydrogels during 3D printing

2021 ◽  
Vol 253 ◽  
pp. 117217
Author(s):  
Tao Ma ◽  
Linxiang Lv ◽  
Chengzheng Ouyang ◽  
Xinna Hu ◽  
Xiaojun Liao ◽  
...  
Keyword(s):  
3D Printing ◽  
Rheological Behavior ◽  
Cellulose Nanocrystal ◽  
Composite Hydrogels ◽  
Particle Alignment
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