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Journal articles on the topic 'Equilibrium swelling'

Author: Grafiati

Published: 4 June 2021

Last updated: 9 February 2022

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1

Oberth, Adolf E. "Equilibrium Swelling of Polyurethane Elastomers." Rubber Chemistry and Technology 63, no. 1 (March 1, 1990): 56–65. http://dx.doi.org/10.5254/1.3538242.

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Abstract Equilibrium swelling of randomly crosslinked elastomers is in satisfactory agreement with a model that considers them to be aggregates of equivalent spheres whose diameter is proportional to Mc1/2. Solvation expands these spheres, the extent of expansion being proportional to the diameter and the strength of the solvent-polymer interaction, but is independent of the number of effective chains per volume unit of the elastomer. A potential mechanistic explanation assumes that the solvent molecules form a weak complex with the elements of the polymeric chain, which forces the segments out of their equilibrium position, thus creating a force that opposes further solvation. Both forces have a very short range and are effective only in the individual segment that has formed the polymer-solvent complex. The magnitude of the extension of the whole chain will be proportional to the number of chain segments undergoing solvation, which leads to the mathematical relationship that forms the basis of Equation (6). Since the swollen volume is many times the volume of the network rubber, it is clear that only a (comparatively) small fraction of the solvent molecules will interact directly with the polymer, many of which will just fill the space created by the expanding network. In weak solvents, or at very high levels of crosslinking, where the swelling volumes are small, the extent of swelling is likely to depend on the polymer content, and the presented mechanism does not apply.

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2

English, Anthony E., Salvador Mafé, José A. Manzanares, Xiahong Yu, Alexander Yu Grosberg, and Toyoichi Tanaka. "Equilibrium swelling properties of polyampholytic hydrogels." Journal of Chemical Physics 104, no. 21 (June 1996): 8713–20. http://dx.doi.org/10.1063/1.471560.

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3

Bell, Cristi L., and Nikolaos A. Peppas. "Equilibrium and dynamic swelling of polyacrylates." Polymer Engineering & Science 36, no. 14 (July 1996): 1856–61. http://dx.doi.org/10.1002/pen.10581.

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4

Liu, Jie, and Ke Yong Tang. "Effects of SiO₂ and In Situ Crosslinking on the Swelling and Thermal Properties of Poly(vinyl Alcohol)/SiO₂ Hybrid Films." Advanced Materials Research 266 (June 2011): 180–83. http://dx.doi.org/10.4028/www.scientific.net/amr.266.180.

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Poly(vinyl alcohol) (PVA)/SiO2 hybrid films were prepared through hydrolysis of tetraethoxysilane (TEOS) in the presence of PVA solution, followed by the in-situ crosslinking with formaldehyde (HCHO) in acidic circumstance. The swelling and thermal gravimetric (TG) analysis was employed to evaluate the influence of SiO2 and crosslinking on the properties of the hybrid films. The results indicate that SiO2 affects effectively the swelling property and thermal stability of the hybrid films because of both the filling and crosslinking effects of SiO2. With increasing the crosslinking time, the swelling ratio at equilibrium of the hybrid films decreases. The swelling ratio at equilibrium of the hybrid films is sensitive to the SiO2 content, which is similar to the swelling ratio at equilibrium (65~75%) for PVA and PVA/SiO2 hybrid films with enough crosslinking time (12h). Compared to the film without in-situ crosslinking, the crosslinked PVA/SiO2 film showed a lower swelling ratio at equilibrium and an increased diffusion coefficient at the initial stage of swelling.

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5

Ekanayake, Jagath C., and David J. Painter. "Gravitational Equilibrium Moisture Profiles in Swelling Soils." Water Resources Research 31, no. 10 (October 1995): 2497–502. http://dx.doi.org/10.1029/95wr01652.

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6

Sommer, Jens-Uwe, Ron Dockhorn, Petra B. Welzel, Uwe Freudenberg, and Carsten Werner. "Swelling Equilibrium of a Binary Polymer Gel." Macromolecules 44, no. 4 (February 22, 2011): 981–86. http://dx.doi.org/10.1021/ma1019363.

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7

Drozdov, A. D., and J. deClaville Christiansen. "Equilibrium swelling of thermo-responsive copolymer microgels." RSC Advances 10, no. 70 (2020): 42718–32. http://dx.doi.org/10.1039/d0ra08619c.

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A model is developed for equilibrium swelling of thermo-responsive copolymer gels and is applied to predict the effect of molar fraction of comonomers on the volume phase transition temperature of macroscopic gels and microgels.

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8

Brannon-Peppas, Lisa, and Nikolaos A. Peppas. "Equilibrium swelling behavior of pH-sensitive hydrogels." Chemical Engineering Science 46, no. 3 (1991): 715–22. http://dx.doi.org/10.1016/0009-2509(91)80177-z.

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9

Klepko, V. V., and Yu B. Mel'nichenko. "Kinetics and equilibrium swelling of gelatine gels." Polymer 36, no. 26 (1995): 5057–59. http://dx.doi.org/10.1016/0032-3861(96)81636-3.

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10

Drozdov, A. D. "Equilibrium swelling of core–shell composite microgels." Meccanica 50, no. 6 (January 22, 2015): 1579–92. http://dx.doi.org/10.1007/s11012-015-0107-2.

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11

Lou, Yu, Wei Yao Zhu, Xue Ling Zhang, and Yun Qian Long. "Effect of Salinity and Temperature on Swelling Behavior of Nano/Micro Polymer Particle." Applied Mechanics and Materials 448-453 (October 2013): 3993–97. http://dx.doi.org/10.4028/www.scientific.net/amm.448-453.3993.

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Nano/micro polymer particles of acrylamide (AM), acrylic acid (AA), methyl methacrylate (MMA) are used to enhance oil recovery. Swelling kinetics of nano/micro polymer particles were investigated through experimental analysis and statistical analysis. The effect of salinity and temperature on swelling behavior over time is studied experimentally. The swelling kinetics of nano/micro polymer particle was described by second order kinetics. Equilibrium swelling ratio and swelling rate were obtained through nonlinear regression. The quantitative relationships between equilibrium swelling ratio and salinity, temperature were presented. Results show that the swelling ratio increases with increasing temperature or decreasing salt concentration. The study provides a direct perspective of swelling characteristics of nano/micro polymer particles for oil recovery enhancement.

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12

Hamzavi, N., A. D. Drozdov, Y. Gu, and E. Birgersson. "Modeling Equilibrium Swelling of a Dual pH- and Temperature-Responsive Core/Shell Hydrogel." International Journal of Applied Mechanics 08, no. 03 (April 2016): 1650039. http://dx.doi.org/10.1142/s1758825116500393.

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The equilibrium swelling of a dual stimuli-responsive core/shell hydrogel is studied by a thermodynamic model. This hydrogel shows thermo-sensitivity as well as pH-sensitivity. The model captures the inhomogeneous swelling of core/shell hydrogels and also, accounts for temperature and pH sensitivity. The predictions of this model are verified with the swelling experiments of a core/shell microgel comprising poly N-isopropyl acrylamide (pNIPAM) and acrylic acid (AAc). The model calculates the equilibrium swelling within the ionic core and the neutral shell. Simulation results can reproduce the equilibrium swelling-temperature curves of this microgel at different pH values considering the delay in the volume phase transition temperature (VPTT) of the ionic polymer gel (pNIPAM-co-AAc) in the core. Two transition points are found in the equilibrium swelling behavior of the hydrogel akin to the VPTTs of the core and shell domains at high pH values of bath solutions. Likewise, the degree of ionization in the core domain is predicted to have a two-step transition behavior corresponding to the VPTTs of the core and shell domains at high pH values of bath solutions. It is shown that the equilibrium swelling of the ionic core is mainly influenced by the electrostatic repulsion between bound charges rather than the ionic pressure. Furthermore, it is determined that the maximum radial stress occurs at the core/shell interface and reaches its maximum value about the VPTT of the core.

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13

Drozdov, Aleksey D. "Equilibrium Swelling of Biocompatible Thermo-Responsive Copolymer Gels." Gels 7, no. 2 (April 1, 2021): 40. http://dx.doi.org/10.3390/gels7020040.

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Biomedical applications of thermo-responsive (TR) hydrogels require these materials to be biocompatible, non-cytotoxic, and non-immunogenic. Due to serious concerns regarding potential toxicity of poly(N-isopropylacrylamide) (PNIPAm), design of alternative homo- and copolymer gels with controllable swelling properties has recently become a hot topic. This study focuses on equilibrium swelling of five potential candidates to replace PNIPAm in biomedical and biotechnological applications: poly(N-vinylcaprolactam), poly(vinyl methyl ether), poly(N,N-dimethyl amino ethyl methacrylate), and two families of poly(2-oxazoline)s, and poly(oligo(ethylene glycol) methacrylates). To evaluate their water uptake properties and to compare them with those of substituted acrylamide gels, a unified model is developed for equilibrium swelling of TR copolymer gels with various types of swelling diagrams. Depending on the strength of hydrophobic interactions (high, intermediate, and low), the (co)polymers under consideration are split into three groups that reveal different responses at and above the volume phase transition temperature.

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14

Vervoort, Liesbeth, Guy Van den Mooter, Patrick Augustijns, and Renaat Kinget. "Inulin hydrogels. I. Dynamic and equilibrium swelling properties." International Journal of Pharmaceutics 172, no. 1-2 (October 1998): 127–35. http://dx.doi.org/10.1016/s0378-5173(98)00200-2.

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15

Gusler, Gloria M., and Yoram Cohen. "Equilibrium Swelling of Highly Cross-Linked Polymeric Resins." Industrial & Engineering Chemistry Research 33, no. 10 (October 1994): 2345–57. http://dx.doi.org/10.1021/ie00034a014.

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16

Russ, Thomas, Rüdiger Brenn, and Mark Geoghegan. "Equilibrium Swelling of Polystyrene Networks by Linear Polystyrene." Macromolecules 36, no. 1 (January 2003): 127–41. http://dx.doi.org/10.1021/ma0211885.

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17

Chen, Wan-Lin, Kenneth R. Shull, Theodore Papatheodorou, Dmitrii A. Styrkas, and Joseph L. Keddie. "Equilibrium Swelling of Hydrophilic Polyacrylates in Humid Environments." Macromolecules 32, no. 1 (January 1999): 136–44. http://dx.doi.org/10.1021/ma981331n.

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18

Joseph, Mary, Tessymol Mathew, Devipriya S, Yu Chen, and Sunny Kuriakose. "Equilibrium swelling and solvation studies on crosslinked polyacrylamides." Polymer International 53, no. 6 (May 5, 2004): 794–801. http://dx.doi.org/10.1002/pi.1455.

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19

Rubinstein, Michael, Ralph H. Colby, Andrey V. Dobrynin, and Jean-Francois Joanny. "Elastic Modulus and Equilibrium Swelling of Polyelectrolyte Gels." Macromolecules 29, no. 1 (January 1996): 398–406. http://dx.doi.org/10.1021/ma9511917.

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20

Wu, Zhen, and Zheng Zhong. "Inhomogeneous Equilibrium Swelling of Core-Shell-Coating Gels." Soft Materials 11, no. 2 (April 2013): 215–20. http://dx.doi.org/10.1080/1539445x.2012.617644.

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21

Astashov, A. V., A. A. Belyi, and A. V. Bunin. "Quasi-equilibrium swelling and structural parameters of coals." Fuel 87, no. 15-16 (November 2008): 3455–61. http://dx.doi.org/10.1016/j.fuel.2008.04.027.

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22

Drozdov, Aleksey D., and Jesper deClaville Christiansen. "Equilibrium swelling of multi-stimuli-responsive copolymer gels." Journal of the Mechanical Behavior of Biomedical Materials 121 (September 2021): 104623. http://dx.doi.org/10.1016/j.jmbbm.2021.104623.

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23

Neppel, A. "Prediction of Equilibrium Swelling in Fuel and Lubricant Ingredients." Rubber Chemistry and Technology 59, no. 1 (March 1, 1986): 46–69. http://dx.doi.org/10.5254/1.3538188.

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Abstract In accord with the Porter equation, linear relationship has been found between the apparent and actual network-chain concentrations of DCP-cured NBR reference elastomers containing 18–39% ACN and 0–70 phr N550 black while Porter's k factors and, therefore, the extent of the restriction of swelling by the filler vary somewhat with the diluent. Taking this variation into account, a self-consistent relationship has been obtained between data on swelling in MEK (24 h) and those on equilibrium swelling in some fuel and lubricant ingredients (2 to 4 weeks). By using this relationship and the modified Flory-Rehner equation, the equilibrium swelling in fuel and lubricant ingredients of NBR test vulcanizates can be estimated from determining their nitrile content and from an MEK immersion test if these vulcanizates are filled with only N550 black, and if the only variables in their compositions are nitrile content, state of peroxide cure, and carbon black loading. The development of a similar technique to predict the swelling in mixed solvents of unknown NBR vulcanizates would probably involve serious difficulties which would stem from the presence of plasticizers, antioxidants, and fillers other than N550 black as well as from the assessment of the polymer-solvent interaction factor.

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24

Wang, Huiming, and Jianpeng Yang. "Quantifying the equilibrium swelling responses and swelling-induced snap-through of heterogeneous spherical hydrogels." Journal of Intelligent Material Systems and Structures 32, no. 1 (August 25, 2020): 113–23. http://dx.doi.org/10.1177/1045389x20951247.

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We employ the finite deformation theory to analyze the inhomogeneous large deformation of a heterogeneous spherical hydrogel subjected to chemo-mechanical loadings. The heterogeneous spherical hydrogel is composed of two concentric spherical hydrogel layers with different material properties. The Gent model is employed for the free energy function of the polymer stretching part in order to tackle the effect of the limiting chain extensibility. The heterogeneous spherical hydrogel is assumed to be perfectly bonded at the interface and is traction free at the external surface. At the internal surface, two boundary conditions are considered: one is internally fixed and the other is internally pressurized. Numerical examples are performed to describe the nonlinear behaviors of a heterogeneous spherical hydrogel when subjected to the swelling and mechanical loadings. For internally fixed case, numerical results show that the limiting chain extensibility and the initial swelling ratio have significant effect on the actuation deformation of a heterogeneous spherical hydrogel. For internally pressurized case, we find that the swelling-induced snap-through instability can be triggered under specified conditions. It is shown that the chemo-mechanical behaviors of the heterogeneous spherical hydrogels can be adjusted by tuning the material properties and the initial swelling ratios.

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25

Bhardwaj, Y. K., Virendra Kumar, and S. Sabharwal. "Swelling behavior of radiation-polymerized polyampholytic two-component gels: Dynamic and equilibrium swelling kinetics." Journal of Applied Polymer Science 88, no. 3 (February 19, 2003): 730–42. http://dx.doi.org/10.1002/app.12023.

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26

Zhou, Yu, and Lihua Jin. "Hydrolysis-induced large swelling of polyacrylamide hydrogels." Soft Matter 16, no. 24 (2020): 5740–49. http://dx.doi.org/10.1039/d0sm00663g.

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27

Kuhara, Kei, and Manabu Enoki. "Stress Analysis of the Swelling and Deswelling Process of Thermo-Responsive Gel." Key Engineering Materials 353-358 (September 2007): 2215–18. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.2215.

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Poly-N-isopropylacrylamide (PNIPA) gel is a typical thermo responsive gel which undergoes a large volume change from the low-temperature swollen phase to the high-temperature shrunken phase. In this study, the mechanical behavior of PNIPA gels was investigated by the experiment and simulation. The cylindrical shaped specimens of PNIPA gel were prepared and tensioned at various temperature. Swelling ratio at equilibrium state was calculated by diameter of swelling gels. Young modulus was obtained from stress-strain curve plotted using tensile load measured by semiconductor gauge. Also swelling and deswelling behavior of thermo sensitive gel were simulated by using finite element method. Polymer-solvent interaction parameter, χ was used as a function of temperature. Calculated swelling ratio at equilibrium was compared with experimental result and theoretical swelling curve. Furthermore, change of volume fraction and stress distribution in swelling process were evaluated.

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28

Kawai, Ryota, Hiro Tanaka, Seishiro Matsubara, Shohei Ida, Makoto Uchida, and Dai Okumura. "Implicit rule on the elastic function of a swollen polyacrylamide hydrogel." Soft Matter 17, no. 19 (2021): 4979–88. http://dx.doi.org/10.1039/d1sm00346a.

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A full understanding of the elastic properties of hydrogels under swelling is required for their practical application. Graphs show the distribution of the shear moduli and swelling factors in the as-prepared state and the equilibrium swelling state.

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29

Ji, Y. J., and X. Li. "The equilibrium time and deformation characteristic of sulfate saline soil in 1D saline expansion test." BULLETIN of L.N. Gumilyov Eurasian National University. Technical Science and Technology Series 135, no. 2 (2021): 58–63. http://dx.doi.org/10.32523/2616-7263-2021-135-2-58-63.

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The salt expansion disease is serious for the soil containing sodium sulfate in cold regions. This paper carried out one-dimensional swelling tests of saline soil, and numerical cooling tests of soil to explore the stability time of salt swelling deformation and determine the standard procedure of the salt swelling test method. The test results demonstrate that: (A) the temperature equilibrium and crystallization process are almost completed simultaneously in the one-dimensional (1D) salt expansion test; (B) Referring to the standard of consolidation test, a standard that the expansion rate is less than 0.02mm/h can be used in the salt expansion test; (C) The required time for temperature equilibrium of soil is quadratic to sample size and is much faster with liquid bath condition comparing to gas bath condition. Because the deformation and temperature are synchronized, the deformation stabilization time of different size samples in different cooling media is recommended.This can provide a reference for the deformation equilibrium time of the salt swelling test.

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30

Üzüm, Ömer Bariş, Semiha Kundakci, and Erdener Karadağ. "Equilibrium Swelling Studies of Highly Swollen Acrylamide/Thiosinamine Hydrogels." Polymer-Plastics Technology and Engineering 48, no. 2 (February 2, 2009): 152–57. http://dx.doi.org/10.1080/03602550802577338.

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31

Patel, Suman K., Shawn Malone, Claude Cohen, Jeffrey R. Gillmor, and Ralph H. Colby. "Elastic modulus and equilibrium swelling of poly(dimethylsiloxane) networks." Macromolecules 25, no. 20 (September 1992): 5241–51. http://dx.doi.org/10.1021/ma00046a021.

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32

Elouali, Fatima Zohra, and Ulrich Maschke. "Kinetics and Equilibrium Swelling Properties of Hydrophilic Polymethacrylate Networks." Macromolecular Symposia 303, no. 1 (May 2011): 71–77. http://dx.doi.org/10.1002/masy.201150510.

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33

Drozdov, Aleksey D., and Jesper deClaville Christiansen. "Mechanical response and equilibrium swelling of thermoresponsive copolymer hydrogels." Polymer International 69, no. 10 (June 23, 2020): 974–84. http://dx.doi.org/10.1002/pi.6051.

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34

Barr-Howell, Barbara D., and Nikolaos A. Peppas. "Dynamic and equilibrium swelling of DVB-crosslinked polystyrene particles." Journal of Applied Polymer Science 30, no. 12 (December 1985): 4583–89. http://dx.doi.org/10.1002/app.1985.070301206.

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35

Cohen, Noy. "Programming the equilibrium swelling response of heterogeneous polymeric gels." International Journal of Solids and Structures 178-179 (December 2019): 81–90. http://dx.doi.org/10.1016/j.ijsolstr.2019.06.023.

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36

Falcão, António N., Jan Skov Pedersen, Kell Mortensen, and François Boué. "Polydimethylsiloxane Networks at Equilibrium Swelling: Extracted and Nonextracted Networks." Macromolecules 29, no. 3 (January 1996): 809–18. http://dx.doi.org/10.1021/ma941014q.

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37

Rubinstein, Michael, and Ralph H. Colby. "Elastic Modulus and Equilibrium Swelling of Near-Critical Gels." Macromolecules 27, no. 12 (June 1994): 3184–90. http://dx.doi.org/10.1021/ma00090a011.

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38

Jeyanthi, R., and K. Panduranga Rao. "Equilibrium swelling behavior of collagen-poly(HEMA) copolymeric hydrogels." Journal of Applied Polymer Science 43, no. 12 (December 20, 1991): 2333–36. http://dx.doi.org/10.1002/app.1991.070431224.

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39

Drozdov, A. D., and J. deC Christiansen. "Structure-property relations for equilibrium swelling of cationic gels." European Polymer Journal 79 (June 2016): 23–35. http://dx.doi.org/10.1016/j.eurpolymj.2016.04.008.

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40

Drozdov, A. D., and J. deClaville Christiansen. "Mechanical response and equilibrium swelling of temperature-responsive gels." European Polymer Journal 94 (September 2017): 56–67. http://dx.doi.org/10.1016/j.eurpolymj.2017.06.045.

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41

Yan, Huixian, Bo Jin, Songhua Gao, and Liwei Chen. "Equilibrium swelling and electrochemistry of polyampholytic pH-sensitive hydrogel." International Journal of Solids and Structures 51, no. 23-24 (November 2014): 4149–56. http://dx.doi.org/10.1016/j.ijsolstr.2014.08.016.

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42

Han, Wei, and You Hong Tang. "Water-Swelling Rubber Containing Small Amount of Nanofillers with Enhanced Water Swelling Durability." Advanced Materials Research 774-776 (September 2013): 544–47. http://dx.doi.org/10.4028/www.scientific.net/amr.774-776.544.

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A series of water-swelling rubbers (WSR) were prepared by directly mixing room temperature vulcanization-2 components silicone rubber (RTV-2 SR) with superabsorbent polymer (SAP) and nanofiller (s) (halloysite nanotube or/and CaCO3). The effects of component on its mechanical behaviours and water-absorbent properties such as degree of swelling, swelling ratio, and weight loss ratio were investigated. The equilibrium swelling ratio increased with increasing amounts of water-absorbent resin. Well-dispersed nanofiller (s) increased the mechanical properties of WSR and prevented SAP breaking off from the elastomer network to effectively enhance the water-swelling durability of WSR.

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43

Yu, Yueqin, Yanshun Li, Chunjing Zhu, and Lingxiu Liu. "Synthesis and characterization of temperature-sensitive and biodegradable hydrogel based on N-isopropylacrylamide." Open Chemistry 8, no. 2 (April 1, 2010): 426–33. http://dx.doi.org/10.2478/s11532-009-0144-6.

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AbstractBased on a biodegradable cross-linker, N-maleyl chitosan (N-MACH), a series of Poly(N-isopropylacrylamide) (PNIPAAm) and Poly(N-isopropylacrylamide-co-acrylamide) [P(NIPAAm-co-Am)] hydrogels were prepared, and their lower critical solution temperature (LCST), swelling kinetics, equilibrium swelling ratio in NaCl solution, and enzymatic degradation behavior in simulated gastric fluids (SGF) were discussed. The LCST did not change with different cross-linker contents. By altering the NIPAAm/Am molar ratio of P(NIPAAm-co-Am) hydrogels, the LCST could be increased to 39°C. The LCST of the hydrogel was significantly influenced by the monomer ratio of the NIPAAm/Am but not by the cross-linker content. In the swelling kinetics, all the dry hydrogels exhibited fast swelling behavior, and the swelling ratios were influenced by the cross-linker content and NIPAAm/Am molar ratios. Equilibrium swelling ratio of all the hydrogels decreased with increasing NaCl solution concentration. In enzymatic degradation tests, the weight loss of hydrogels was dependent on the cross-linker contents and the enzyme concentration.

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44

Kalagasidis-Krusic, Melina, Biljana Nikolic, and Jovanka Filipovic. "Semi-interpenetrating polymer networks based on polyacrylamide and poly[itaconic acid]." Chemical Industry 57, no. 11 (2003): 543–46. http://dx.doi.org/10.2298/hemind0311543k.

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The effect of pH and temperature on the equilibrium swelling properties of PIA/PAAm semi-IPNs were investigated.Semi-IPNs based on polyacrylamide (PAAm) and poly(itaconic acid) (PIA) were prepared by two different techniques, by polymerizing itaconic acid in the presence of polyacrylamide gel (Semi-IPNs-l) and by making the polyacrylamide gel in the presence of previously synthesized poly(itaconic acid) (Semi-IPNs-ll), with different PIA/PAAm mass ratios. The equilibrium swelling degree of an ionic network depends very much on the concentration of ionisable groups. The addition of a small amount of itaconic acid dramatically changes the swelling behavior of PAAm. Increase of the ionic monomer (IA) produces swelling degrees that increase to a high extent when the pH of the buffer solution is higher than the nominal pKa values of the acid groups. Gels with higher IA content swell less than PAAm gels in low pH buffers. At low pH, when complexation due to hydrogen bonding occurs between the carboxylic groups and amide groups of acrylamide, the polymer network collapses and the swelling ratio is low. The presence of hydrogen bonds in the complexes causes additional constraints in the network, acting as a physical crosslinking and makes the network less hydrophilic, because the carboxylic groups on the PIA are occupied in the complexes. As opposed to this, the equilibrium swelling degrees change very little with pH of the solution in nonionic PAAm gel.Hydrogels exhibit continuous changes in water content as a function of temperature. The swelling degree increases with increasing temperature due to gel expansion upon warming.

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45

Seii, Miyu, Tomoki Harano, Masao Doi, and Yoshimi Tanaka. "Competition between Osmotic Squeezing versus Friction-Driven Swelling of Gels." Gels 7, no. 3 (July 14, 2021): 94. http://dx.doi.org/10.3390/gels7030094.

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Some types of hydro-gels have almost the same equilibrium swelling volume in water and in ethylene glycol (EG), a highly viscous liquid completely miscible with water. Experiments showed that when a gel fully swollen with EG is immersed into a large amount of water, it temporarily swells up and then relaxes to the equilibrium volume in water. The temporary swelling is explained by the friction force exerted on the gel network from the outward EG flux In this paper, we experimentally show that the temporary swelling is suppressed by adding linear PEG (polyethylene glycol) in the outer water. Although the suppression seems to be explained by the osmotic pressure (i.e., by the same mechanism as the conventional osmotic squeezing), our theoretical analysis reveals that the effect of PEG is much stronger than that expected from the equilibrium osmotic pressure, implying that the PEG chains are condensed on the gel surface.

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46

Ndaji, Francis E., and K. Mark Thomas. "Effects of solvent steric properties on the equilibrium swelling and kinetics of solvent swelling of coal." Fuel 74, no. 6 (June 1995): 842–45. http://dx.doi.org/10.1016/0016-2361(95)00011-s.

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47

Zdravkovic, Aleksandar, Ljubisa Nikolic, Snezana Ilic-Stojanovic, Vesna Nikolic, Sasa Savic, and Agnes Kapor. "The evaluation of temperature and pH influences on equilibrium swelling of poly(n-isopropylacrylamide-co-acrylic acid) hydrogels." Chemical Industry 71, no. 5 (2017): 395–405. http://dx.doi.org/10.2298/hemind161018001z.

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Hydrogels are synthesized by the method of radical polymerization of monomers: N-isopropylacrylamide (NIPAM) and acrylic acid (AA). Characterization of poly(N-isopropylacrylamide- co-acrylic acid) hydrogels, p(NIPAM/AA), has been performed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and by determination of the swelling behaviour in aqueous solutions at different temperatures (25, 31 and 37?C) and pH values (2.2, 4.5, 6 and 6.8). After lyophilisation in the solution at pH 6 and temperature of 25?C, p(NIPAM/AA) hydrogels have rapidly reached equilibrium degree of swelling, ?e, in comparison to non-lyophilized samples. The mechanism of solvent transport within matrix in lyophilized samples corresponds to less Fickian diffusion, whereas Super case II diffusion is characteristic for non-lyophilized samples. p(NIPAM/AA) hydrogel with 1.5 mol% of ethylene glycol dimethacrylate (EGDM) at the temperature of 25?C and pH 6.8, has reached the highest swelling equilibrium degree, ?e = 259.8. The results of swelling studies have shown that p(NIPAM/AA) hydrogels can be classified as superabsorbent polymers (SAPs). For the evaluation of pH and temperature influences on synthesized hydrogels swelling, a full three-level experimental design has been used. Two-factor interaction model (2FI) is the most optimal model of a full three-level experimental design for representing the swelling equilibrium degree of p(NIPAM/AA) hydrogels as a function of investigated parameters, i.e., temperature and pH.

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48

Patil, Pushkar N., Kathi Sudarshan, Pradeep K. Pujari, and Dhanadeep Dutta. "Effect of Crosslinkers on the Microstructure and Swelling Properties of the N-Isopropyl Acrylamide Gels: A Positron Annihilation Study." Materials Science Forum 733 (November 2012): 155–58. http://dx.doi.org/10.4028/www.scientific.net/msf.733.155.

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The Poly N-Isopropyl acrylamide (PNIPA) gels were prepared in different synthesis media by crosslinking with acrylate monomers with varying chain length. The microstructural characterization in terms of the free volume fractions and distributions were studied using positron annihilation lifetime spectroscopy (PALS). The equilibrium swelling of the PNIPA in distilled water was measured. An attempt has been made to understand the correlations between microscopic free volumes and the equilibrium swelling of the gels. The free volume fraction of the gels prepared in Dimethyl formamide (DMF) was directly correlated with swelling while it varied inversely with chain length of the crosslinker. The microstructure of the gels was found to be very sensitive to the solvent/medium used for polymerization. Our studies show that the swelling property is influenced by the free volumes, chain relaxation as well as the chemical nature of the cross linkers.

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49

Varghese, Siby, Baby Kuriakose, Sabu Thomas, and Kuruvilla Joseph. "Effect of Adhesion on the Equilibrium Swelling of Short Sisal Fiber Reinforced Natural Rubber Composites." Rubber Chemistry and Technology 68, no. 1 (March 1, 1995): 37–49. http://dx.doi.org/10.5254/1.3538730.

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Abstract Solvent swelling of natural rubber composites, containing both untreated and acetylated short sisal fiber, has been investigated in a series of normal alkanes such as pentane, hexane, heptane and octane. The restriction on elastomer swelling exerted by sisal fiber as well as the anisotropy of swelling of the composite have been confirmed by this study. The results showed that increased fiber content and the addition of bonding agent reduced the swelling considerably. It has been demonstrated that with improved adhesion between short fiber and rubber, the factor, (VI−VF)/VI, decreases, where VI and VF are the volume fraction of rubber in dry and swollen samples, respectively.

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50

Young, T. S., J. A. Hunt, D. W. Green, and G. P. Willhite. "Study of Equilibrium Properties of Cr(III)/Polyacrylamide Gels by Swelling Measurement and Equilibrium Dialysis." SPE Reservoir Engineering 4, no. 03 (August 1, 1989): 348–56. http://dx.doi.org/10.2118/14334-pa.

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