Molecular sorption mechanism of solvent diffusion in polymers

Nuclear magnetic resonance (NMR) imaging is sensitive to the mobile protons of solvent molecules and, as such, is well suited for studying the solvent diffusion in polymers. The fundamentals of NMR imaging are described, providing a platform for application of NMR imaging to diffusion processes in polymers. The constraints on the imaging experiment imposed by the diffusion process are discussed with respect to sample geometry and the rate of diffusion. A fast imaging scheme known as FLASH is described as an alternative method which reduces the influence of the diffusion rate and NMR relaxation parameters. Example images are given with regard to each of the constraints. An example of the successful application of NMR imaging to the study of Case II diffusion in PMMA is also given. The advantages and disadvantages of NMR imaging as applied to diffusion in polymers, as well as examples of the diffusion process that NMR imaging is uniquely qualified to study, are given in the conclusion.

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Formulation and evaluation of thymol loaded ethyl cellulose microparticles using solvent diffusion and nanoprecipitation methods: A comparative factorial design approach.

International Journal of Pharmaceutical Research ◽

10.31838/ijpr/2018.10.03.058 ◽

2018 ◽

Vol 10 (03) ◽

Keyword(s):

Factorial Design ◽

Ethyl Cellulose ◽

Design Approach ◽

Solvent Diffusion

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Modified Exfoliated Carbon Nanoplatelets as Sorbents for Ammonium from Natural Mineral Waters

Molecules ◽

10.3390/molecules26123541 ◽

2021 ◽

Vol 26 (12) ◽

pp. 3541

Author(s):

Ion Ion ◽

Daniela Bogdan ◽

Monica Maria Mincu ◽

Alina Catrinel Ion

Keyword(s):

Natural Waters ◽

Mineral Waters ◽

Aqueous Samples ◽

Sorption Mechanism ◽

Characteristic Parameters ◽

Sorption Characteristic ◽

Natural Mineral ◽

Maximum Sorption Capacity ◽

Ammonium Removal ◽

Maximum Sorption

In this manuscript an improved sorbent based on modified exfoliated carbon nanoplatelets, applied in the removal of ammonium from aqueous samples, is presented. This sorbent showed better efficiency in comparison with the previous one obtained in our group for ammonium removal, the values of the maximum sorption capacity being improved from 10 to 12.04 mg/g. In terms of kinetics and sorption characteristic parameters, their values were also improved. Based on these results, a sorption mechanism was proposed, taking into account ion-exchange and chemisorption processes at the surface of the oxidized exfoliated carbon nanoplatelets. Future applications for simultaneous removal of other positive charged contaminants from natural waters might be possible.

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Study on the sorption mechanism of middle‐low temperature sorption thermal storage materials from the microscale simulation: A review

International Journal of Energy Research ◽

10.1002/er.6495 ◽

2021 ◽

Author(s):

Yuxiang Zhou ◽

Ting Yan ◽

Weiguo Pan

Keyword(s):

Low Temperature ◽

Thermal Storage ◽

Sorption Mechanism ◽

Storage Materials

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Solvent diffusion mechanism of PMMA/ acetone coated glass fiber fabric during curing process

Journal of Industrial Textiles ◽

10.1177/15280837211036214 ◽

2021 ◽

pp. 152808372110362

Author(s):

Zhenrong Zheng ◽

Yuejiao Bi ◽

Lihuan Tong ◽

Yalan Liu

Keyword(s):

Glass Fiber ◽

Diffusion Mechanism ◽

Coating Film ◽

Curing Process ◽

Curing Time ◽

Solvent Concentration ◽

Solvent Diffusion ◽

Coated Glass ◽

Drying Model ◽

Fiber Fabric

Fabric it is not an impermeable substrate because of fiber porosity. To study the solvent diffusion mechanism of coated fabric in the curing process, the drying model of PMMA/acetone coated glass fiber fabric was established. This drying model was verified by confocal Raman spectroscopy. Finally, the impact of fabric structure, thickness and porosity on the solvent diffusion process in coated fabrics was studied by the model. It was shown that the predicted solvent concentrations by the model were consistent with the experimental values. This model can be used to quantitatively calculate the solvent concentration at any position and at any time inside the coating film during the drying process. Moreover, it can also predict the curing time and residual solvent concentration of the coating fabric required to reach drying equilibrium. Compared with coated 3/1 twill, 5/3 satin and 2/1 twill, the solvent diffusion of coated plain fabric was faster during curing. Under the same environmental conditions, the thinner the fabric was and the greater the porosity was, the shorter the curing time was. The fitting equations for fabric thickness, fabric porosity and drying time were obtained, which can provide a theoretical guidance for the preparation, performance research and drying conditions optimization of PMMA coated textile materials.

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Sorption Mechanism of Carbon-14 by Hardened Cement Paste

MRS Proceedings ◽

10.1557/proc-412-435 ◽

1995 ◽

Vol 412 ◽

Cited By ~ 5

Author(s):

K. Noshita ◽

T. Nishi ◽

M. Matsuda ◽

T. Izumida

Keyword(s):

Electrostatic Force ◽

Cementitious Materials ◽

Hardened Cement ◽

Sorption Mechanism ◽

Carbon 14 ◽

Adsorption Sites ◽

Radioactive Waste Repositories ◽

Waste Repositories ◽

Positively Charged

AbstractCarbon-14 sorption by cementitious materials should be enhanced to ensure the long term safety of radioactive waste repositories. The sorption mechanism of inorganic C- 14 (CO32- was investigated using batch sorption experiments and zeta potential measurements. The results suggested that C-14 was adsorbed onto the cement surface by an electrostatic force, due to the reaction between SiO2 and CaO contained in the cementitious composition. That is, SiO2 was originally negatively charged (SiO-) in cement, but became positively charged through the interaction of Ca2+. These positive sites on the SiO2 surface adsorbed inorganic C-14. Ordinary Portland cement (OPC) did not contain enough SiO2 compared with its CaO content to produce sufficient numbers of C-14 adsorption sites. The C-14 distribution coefficient (Kd) was increased from 2,000 to 7,000 mL/g by adding SiO2 to OPC.

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