Effect of Hydration on Healthy Intervertebral Disk Mechanical Stiffness

2015 ◽  
Vol 137 (10) ◽  
Author(s):  
Semih E. Bezci ◽  
Aditya Nandy ◽  
Grace D. O'Connell
Keyword(s):  
Mechanical Behavior ◽  
Intervertebral Disk ◽  
Mechanical Stiffness ◽  
Swelling Properties ◽  
Compressive Stiffness ◽  
Intervertebral Disks ◽  
Swelling Capacity ◽  
Osmotic Loading ◽  
Wet Weight ◽  
Residual Strains

The intervertebral disk has an excellent swelling capacity to absorb water, which is thought to be largely due to the high proteoglycan composition. Injury, aging, degeneration, and diurnal loading are all noted by a significant decrease in water content and tissue hydration. The objective of this study was to evaluate the effect of hydration, through osmotic loading, on tissue swelling and compressive stiffness of healthy intervertebral disks. The wet weight of nucleus pulposus (NP) and annulus fibrosus (AF) explants following swelling was 50% or greater, demonstrating significant ability to absorb water under all osmotic loading conditions (0.015 M–3.0 M phosphate buffered saline (PBS)). Estimated NP residual strains, calculated from the swelling ratio, were approximately 1.5 × greater than AF residual strains. Compressive stiffness increased with hyperosmotic loading, which is thought to be due to material compaction from osmotic-loading and the nonlinear mechanical behavior. Importantly, this study demonstrated that residual strains and material properties are greatly dependent on osmotic loading. The findings of this study support the notion that swelling properties from osmotic loading will be important for accurately describing the effect of degeneration and injury on disk mechanics. Furthermore, the tissue swelling will be an important consideration for developing biological repair strategies aimed at restoring mechanical behavior toward a healthy disk.

scholarly journals Swelling Properties and Permeability of GMZ Bentonite-Sand Mixtures during Different Solutions Infiltration

2021 ◽  
Vol 13 (4) ◽  
pp. 1622
Author(s):  
Yu-Ping Wang ◽  
Zhe Wang ◽  
Yu Zhao ◽  
Fa-Cheng Yi ◽  
Bao-Long Zhu
Keyword(s):  
Swelling Pressure ◽  
Development Stage ◽  
Gmz Bentonite ◽  
Test Results ◽  
X Ray Diffraction ◽  
Swelling Properties ◽  
Swelling Capacity ◽  
Slow Expansion ◽  
Expansion Stage ◽  
Chemical Solutions

In China, Gaomiaozi (GMZ) bentonite is recognized as a barrier material for isolating nuclear waste. Different chemical solutions may change the hydraulic conductivity and swelling capacity of bentonite. Consequently, a series of swelling pressure and permeability experiments was carried out on bentonite-sand mixtures with various dry densities and infiltrating solutions. X-ray diffraction (XRD) and the field emission scanning electron microscope (FESEM) were carried out on the samples experiencing the tests to identify the influence of chemistry pore solutions upon the mineralogical and microstructure changes. The results show that the swelling pressure experienced rapid swelling, slow expansion, and the stable expansion stage for the specimens of infiltrating solutions except for NaOH. For the specimens infiltrated with NaOH solutions, the swelling pressure experienced rapid increases, slow decreases, and a stable development stage. With hyper-alkaline and hyper-salinity infiltration, the swelling pressure decreased, and the permeability increased. In addition, swelling pressure attained stability more quickly on contact with hyper-alkaline and hyper-salinity solutions. Comparing the test results, the results indicate that the influence of NaOH on the expansion and permeability was higher than NaCl-Na2SO4 at the same concentration.

Synthesis, Applications and Swelling Properties of Poly (Sodium Acrylate-Coacrylamide) Based Superabsorbent Hydrogels

2019 ◽  
Vol 41 (4) ◽  
pp. 668-668
Author(s):  
Saud Hashmi Saud Hashmi ◽  
Saad Nadeem Saad Nadeem ◽  
Zahoor Awan Zahoor Awan ◽  
Adeel ur Rehman Adeel ur Rehman ◽  
Ahsan Abdul Ghani Ahsan Abdul Ghani
Keyword(s):  
Rate Constant ◽  
Polymeric Materials ◽  
Water Soluble ◽  
Ion Concentration ◽  
Copolymer Composition ◽  
Swelling Properties ◽  
Swelling Capacity ◽  
Swelling Rate ◽  
Crosslinker Concentration ◽  
Superabsorbent Hydrogels

Superabsorbent hydrogels constitute a group of polymeric materials with three-dimensional network structure, which can swell to absorb an enormous amount of water or aqueous solutions. This property enables various commercial applications of hydrogels such as water holding capability in agriculture and superabsorbent material for baby diapers. Several novel superabsorbent hydrogels based on acrylic acid-co-acrylamide copolymers were synthesized under variation of copolymer compositions through free radical polymerization. N,N’methylenebisacrylamide (MBA) was used as a water soluble crosslinker and potassium persulphate (KPS) as an initiator. Effect of varying the copolymer composition, change in crosslinker concentration, and effect of environmental parameters (pH, temperature, and ion concentration) on both swelling capacity and swelling rate were examined. These gel shows maximum swelling at neutral pH-7, whereas increasing salt concentration in water decrease the swelling capacity. It was found interesting that an increase in crosslinker concentration from 0.020% to 0.16%, the swelling capacity decreases up to 70% while the swelling rate increases from 0.007g water/g dry hydrogel sec to 0.024g water/g dry hydrogel sec, respectively because there is a compromise exists between entropic spring forces between network connection points and the hydrostatic pressure of the water diffusing into the gels. Dynamic swelling curve obtained were fitted to the three different kinetic models namely Peleg’s kinetic model, pseudo 1st order as proposed by Lagergen and pseudo 2nd order kinetics. All these models provided a good agreement with the experimental data; However on the bases of statistical parameters (RMSE, R2 and X2) the Peleg’s model was selected as the most appropriate model for this study. Analyzing rate constant for Peleg’s models at different swelling temperatures disclosed that increasing temperature could only increase the swelling rate without affecting the swelling capacity of the hydrogels. Experimental values for rate constant k1 of Peleg’s model at different temperature shows a sharp decrease from 0.57545 at 30 oC to 0.1535 at 75 oC that contemplated the rate of swelling at 75 oC was 65% faster than that of 30 oC. The diffusion mechanisms in hydrogels were proven to be tailorable by increasing cross-linker concentration and temperature, leading towards the Fickian type diffusion behavior. The synthesized superabsorbent hydrogels were also tested for water retention applications in agriculture.

scholarly journals A Novel Hydrogel Based on Renewable Materials for Agricultural Application

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Silvie Durpekova ◽  
Kateryna Filatova ◽  
Jaroslav Cisar ◽  
Alena Ronzova ◽  
Erika Kutalkova ◽  
...  
Keyword(s):  
Citric Acid ◽  
Water Uptake ◽  
Agricultural Product ◽  
Cellulose Derivatives ◽  
Gravimetric Analysis ◽  
Renewable Materials ◽  
Swelling Properties ◽  
Arable Farming ◽  
Swelling Capacity ◽  
The Stability

This study details the design and characterization of a new, biodegradable, and renewable whey/cellulose-based hydrogel (i.e., agricultural hydrogel). This was formulated from cellulose derivatives (carboxymethylcellulose (CMC) and hydroxyethylcellulose (HEC)) and acid whey cross-linked with citric acid, with the aim to obtain an agricultural product with a high swelling capacity to uphold the quality of soil and conserve water resources. With regard to the swelling behaviour of the prepared hydrogels, the authors initially assessed the swelling ratio and capacity for water uptake. Evaluating the chemical structure of the hydrogel and its thermal and viscoelastic properties involved performing Fourier transform infrared spectroscopy, differential scanning colorimetry, thermal gravimetric analysis, and rheological measurement of the hydrogel films. According to preliminary results, sufficient swelling capacity and stiffness were observed in a hydrogel prepared with 3% CMC and HEC, cross-linked with 5% citric acid. Moreover, the kinetics of water uptake revealed a promising capacity that was sustainable after 5 drying and swelling cycles. The results confirmed that the stability of the hydrogel was enhanced by the presence of the citric acid. As a consequence, it is necessary to utilize an appropriate cross-linking concentration and abide by certain conditions to ensure the swelling properties of the prepared hydrogel are sufficient. Further investigation of the topic, especially in relation to applications in soil, could confirm if the whey-cellulose-based hydrogel is actually suitable for agricultural use, thereby contributing to the advancement of sustainable arable farming.

Mapping of Intervertebral Disk Annulus Fibrosus Compressive Properties Is Sensitive to Specimen Boundary Conditions

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Sarah E. Duclos ◽  
Arthur J. Michalek
Keyword(s):  
Residual Strain ◽  
Annulus Fibrosus ◽  
Intervertebral Disk ◽  
Transverse Plane ◽  
The State ◽  
Compressive Properties ◽  
Spatial Homogeneity ◽  
Matrix Deposition ◽  
Residual Strains

Predicting the mechanical behavior of the intervertebral disk (IVD) in health and in disease requires accurate spatial mapping of its compressive mechanical properties. Previous studies confirmed that residual strains in the annulus fibrosus (AF) of the IVD, which result from nonuniform extracellular matrix deposition in response to in vivo loads, vary by anatomical regions (anterior, posterior, and lateral) and zones (inner, middle, and outer). We hypothesized that as the AF is composed of a nonlinear, anisotropic, viscoelastic material, the state of residual strain in the transverse plane would influence the apparent values of axial compressive properties. To test this hypothesis, axial creep indentation tests were performed, using a 1.6 mm spherical probe, at nine different anatomical locations on bovine caudal AFs in both the intact (residual strain present) and strain relieved states. The results showed a shift toward increased spatial homogeneity in all measured parameters, particularly instantaneous strain. This shift was not observed in control AFs, which were tested twice in the intact state. Our results confirm that time-dependent axial compressive properties of the AF are sensitive to the state of residual strain in the transverse plane, to a degree that is likely to affect whole disk behavior.

scholarly journals Organic/Inorganic Superabsorbent Hydrogels Based on Xylan and Montmorillonite

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Shuang Zhang ◽  
Ying Guan ◽  
Gen-Que Fu ◽  
Bo-Yang Chen ◽  
Feng Peng ◽  
...  
Keyword(s):  
Compressive Modulus ◽  
Cross Linking ◽  
Swelling Properties ◽  
Ph Values ◽  
Swelling Capacity ◽  
Wide Ph Range ◽  
Grafting Copolymerization ◽  
Ph Range ◽  
Influence Of Ph ◽  
Superabsorbent Hydrogels

The unique organic/inorganic superabsorbent hydrogels based on xylan and inorganic clay montmorillonite (MMT) were prepared via grafting copolymerization of acrylic acid (AA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) withN,N-methylenebisacrylamide (MBA) as a cross-linking agent and potassium persulfate (KPS) as an initiator. The effect of variables on the swelling capacity of the hydrogels, such as the weight ratios of MMT/xylan, MBA/xylan, and AMPS/AA, was systematically optimized. The results indicated that the superabsorbent hydrogels comprised a porous cross-linking structure of MMT and xylan with side chains that carry carboxylate, carboxamide, and sulfate. The hydrogels exhibit the high compressive modulus (E), about 35–55 KPa, and the compression strength of the hydrogels increased with an increment of the MMT content. The effect of various cationic salt solutions (LiCl, CaCl2, and FeCl3) on the swelling has the following order: Li+> Ca2+> Fe3+. Furthermore, the influence of pH values on swelling behaviors showed that the superabsorbent composites retained around 1000 g g−1over a wide pH range of 6.0–10.0. The xylan-based hydrogels with the high mechanical and swelling properties are promising for the applications in the biomaterials area.

scholarly journals Investigation of superabsorbent polymer absorbency at reduced chemical potential of water

2019 ◽  
Vol 268 ◽  
pp. 04010 ◽  
Author(s):  
Ariel Melendres ◽  
Judy An Antang ◽  
Christian Jake Manacob
Keyword(s):  
Chemical Potential ◽  
Chloride Concentration ◽  
Crosslinking Density ◽  
Superabsorbent Polymer ◽  
Sodium Chloride Concentration ◽  
Swelling Properties ◽  
Superabsorbent Polymers ◽  
Swelling Capacity ◽  
Major Parameter ◽  
Different Types

Different types of superabsorbent polymers (SAP) exhibiting varied absorbency properties were investigated for their performances at varying concentrations of an electrolyte. Water chemical potential, which is a function of concentration and pressure, was interpreted as a major parameter for absorbency and swelling properties of SAP. Superabsorbent polymers that were investigated gave different values of permeability which was carried out in a layer of swelled superabsorbent polymer. This result revealed differences on the structure of the superabsorbent polymers particularly on the crosslinking density. SAP’s absorbency properties were further tested and a correlation between the quantity of absorption and the chemical potential of water in terms of sodium chloride concentration was developed using experimental data on free swelling capacity and absorption under pressure. Results showed decreasing quantity of absorption by the superabsorbent polymers with decreasing chemical potential of water with higher reduction in the absorbency at higher pressure applied on the swelled SAP.

scholarly journals Nanocrystalline Cellulose/Polyvinylpyrrolidone Fibrous Composites Prepared by Electrospinning and Thermal Crosslinking

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Katrina M. Hatch ◽  
Jana Hlavatá ◽  
Katherine Paulett ◽  
Tatsiana Liavitskaya ◽  
Sergey Vyazovkin ◽  
...  
Keyword(s):  
Morphological Changes ◽  
Fibrous Composite ◽  
Weight Ratio ◽  
Nanocrystalline Cellulose ◽  
Process Efficiency ◽  
Swelling Properties ◽  
Thermal Crosslinking ◽  
Swelling Capacity ◽  
Fibrous Membranes ◽  
Composite Fibrous Membranes

Nanocellulose/polyvinylpyrrolidone (nCel/PVP) fibrous composite materials containing rod-like nanocrystalline cellulose particles with the lengths varying in the range from 100 to 2000 nm were prepared by using DC electrospinning. The particle size had a strong effect on the precursor viscosity, process efficiency, and resulting fiber diameter. The thermal crosslinking of nCel/PVP composite nanofibers with up to 1.0 :  8.0 nCel/PVP weight ratio resulted in fibrous membranes with textural, air transport, and mass swelling properties varying significantly with the size of cellulose particles. The presence of nCel particles increased the oxidation resistance of PVP during the crosslinking and affected the morphological changes of nCel/PVP fibrous membranes in aqueous solutions. Particles with the smallest size improved the strength of the membrane but decreased its mass swelling capacity, whereas the larger particles led to a more porous and flexible, but mechanically weaker, membrane structure with a higher swelling ability. Thus, by using the nCel particles of different size and shape, the properties of nCel/PVP composite fibrous membranes can be tailored to a specific application.

scholarly journals Mechanical Behavior of Shale Rock under Uniaxial Cyclic Loading and Unloading Condition

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Baoyun Zhao ◽  
Dongyan Liu ◽  
Ziyun Li ◽  
Wei Huang ◽  
Qian Dong
Keyword(s):  
Cyclic Loading ◽  
Mechanical Behavior ◽  
Creep Behavior ◽  
Peak Stress ◽  
Creep Model ◽  
Cycle Number ◽  
Shale Rock ◽  
Cyclic Loading And Unloading ◽  
Residual Strains ◽  
Loading And Unloading

In order to investigate the mechanical behavior of shale rock under cyclic loading and unloading condition, two kinds of incremental cyclic loading tests were conducted. Based on the result of the short-term uniaxial incremental cyclic loading test, the permanent residual strain, modulus, and damage evolution were analyzed firstly. Results showed that the relationship between the residual strains and the cycle number can be expressed by an exponential function. The deformation modulus E50 and elastic modulus ES first increased and then decreased with the peak stress under the loading condition, and both of them increased approximately linearly with the peak stress under the unloading condition. On the basis of the energy dissipation, the damage variables showed an exponential increasing with the strain at peak stress. The creep behavior of the shale rock was also analyzed. Results showed that there are obvious instantaneous strain, decay creep, and steady creep under each stress level and the specimen appears the accelerated creep stage under the 4th stress of 51.16 MPa. Based on the characteristics of the Burgers creep model, a viscoelastic-plastic creep model was proposed through viscoplastic mechanics, which agrees very well with the experimental results and can better describe the creep behavior of shale rock better than the Burgers creep model. Results can provide some mechanics reference evidence for shale gas development.

Changes in Intervertebral Disk Mechanical Behavior During Early Degeneration

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Cornelis P. L. Paul ◽  
Kaj S. Emanuel ◽  
Idsart Kingma ◽  
Albert J. van der Veen ◽  
Roderick M. Holewijn ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Intervertebral Disk ◽  
Exponential Fitting ◽  
Stretched Exponential ◽  
Disk Degeneration ◽  
Histological Sections ◽  
Biomechanical Behavior ◽  
Recovery Behavior ◽  
Ivd Degeneration ◽  
Disk Height

Intervertebral disk (IVD) degeneration is commonly described by loss of height and hydration. However, in the first stage of IVD degeneration, this loss has not yet occurred. In the current study, we use an ex vivo degeneration model to analyze the changes in IVDs mechanical behavior in the first phase of degeneration. We characterize these changes by stretched-exponential fitting, and suggest the fitted parameters as markers for early degeneration. Enzymatic degeneration of healthy lumbar caprine IVDs was induced by injecting 100 μL of Chondroïtinase ABC (Cabc) into the nucleus. A no-intervention and phosphate buffered saline (PBS) injected group were used as controls. IVDs were cultured in a bioreactor for 20 days under diurnal, simulated-physiological loading (SPL) conditions. Disk deformation was continuously monitored. Changes in disk height recovery behavior were quantified using stretched-exponential fitting. Disk height, histological sections, and water- and glycosaminoglycan (GAG)-content measurements were used as gold standards for the degenerative state. Cabc injection caused significant GAG loss from the nucleus and had detrimental effects on poro-elastic mechanical properties of the IVDs. These were progressive over time, with a propensity toward more linear recovery behavior. On histological sections, both PBS and Cabc injected IVDs showed moderate degeneration. A small GAG loss yields changes in IVD recovery behavior, which can be quantified with stretched-exponential fitting. Parameters changed significantly compared to control. Studies on disk degeneration and biomaterial engineering for degenerative disk disease (DDD) could benefit from focusing on IVD biomechanical behavior rather than height and water-content, as a marker for early disk degeneration.

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