| 15101. |
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Identities and Life Worlds : with Examples from Östmark and Ostmark
- 2009
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- This report is a collection of various texts on projects related to identities and life worlds. It consists of three papers: one theoretical and two dealing with special geographical study areas.The terminology ‘Local and Regional Identities’ has been used and is still frequently used by geographers and regional planners, but what is its relevance today? In the first paper both personal experiences and ongoing trends in the world are used in an attempt to theoretically discuss what it refers to, or what it could refer to. The focus is on the term ‘relational’, frequently used by other authors relating to space in different ways. The definition here is delimited to people and identities based on their relations to different regions, since this is mainly humanistic geography. Three different kinds of identities are defined: person identities, region (or landscape or place) identities and relational identities.The second paper is based on a field trip to a study area in Sweden, Östmark in the province of Värmland. Here life worlds and identities are communicated within the region and between two geographers from different parts of the world (Sweden and India).The third paper is based on a field trip to ‘Ostmark region’ in Meeker County in the US with a pilot study on identities. This region represents a region with inhabitants with ancestors from Östmark in Sweden. Many people from Östmark migrated to the US, beginning in the 1860s and continuing to the 1920s.
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| 15102. |
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| 15103. |
- Idris, Alamin, et al.
(författare)
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A review on predictive tortuosity models for composite films in gas barrier applications
- 2022
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Ingår i: JCT Research. - : Springer. - 1547-0091 .- 2168-8028. ; 19, s. 699-716
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Tidskriftsartikel (refereegranskat)abstract
- Different types of impermeable fillers are usually incorporated into polymeric coating film to enhance the gas barrier properties. For instance, impermeable fillers are commonly used in barrier coating due to their larger surface, which in turn serve as barrier inclusions restricting the penetrant gas to diffuse through a longer tortuous pathway. Modeling gas transport in barrier coating can help determine the shelf-life of packaged food and reduce product development resources and time. In this paper, related tortuosity-based models corresponding to different filler geometries are outlined. This review emphasizes the emerging trends in modeling the tortuous pathway and the respective relative permeability model to predict the gas barrier performance in composite films used for barrier coating applications. We review models incorporating a range of factors, including different shapes, geometries, angular orientations, alignments, randomness in distribution, stacking, interspacing, and the polydispersity of fillers. The approaches employed to develop the tortuosity-based phenomenological models starting with simplified filler geometry and orientations to more complex morphological features of the composite films are elaborated.
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| 15104. |
- Idris, Alamin, et al.
(författare)
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Effect of silane coupling agents on properties and performance of polycarbonate/silica MMMs
- 2019
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Ingår i: Polymer testing. - : Elsevier. - 0142-9418 .- 1873-2348. ; 73, s. 159-170
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Tidskriftsartikel (refereegranskat)abstract
- The choice of amine terminated silanes remain scarce although they have been used as coupling agents to enhance silica dispersion and interaction in polymer matrix. Functionalized silica particles were synthesized by co-condensing tetraethyl-orthosilicate with four types of silane agents in sol-gel process. These particles were characterized and incorporated into polycarbonate polymer matrix. The morphology, structure, thermal stability, mechanical strength and gas (N2, CH4, CO2) permeation properties of mixed matrix membranes (MMMs) were characterized by standard techniques. The functionalized silica particles were of various particle sizes and extent of functionalization. PC/Silica MMM produced by incorporating functionalized silica particles using (3-aminopropyl) trimethoxysilane exhibited better morphology. The corresponding MMM performance has improved (αCO2/N2 = 42.8 and αCO2/CH4 = 38) as compared to pure PC membrane (αCO2/N2 = 20.30 and αCO2/CH4 = 18.5) and other MMMs. Thus, low molecular weight single amine terminated silane agents are potential candidates for the development of PC/silica MMMs.
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| 15105. |
- Idris, Alamin, et al.
(författare)
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Effects of Phase Separation Behavior on Morphology and Performance of Polycarbonate Membranes
- 2017
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Ingår i: Membranes. - : MDPI. - 2077-0375 .- 2077-0375. ; 7:2, s. 1-18
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Tidskriftsartikel (refereegranskat)abstract
- The phase separation behavior of bisphenol-A-polycarbonate (PC), dissolved in N-methyl-2-pyrrolidone and dichloromethane solvents in coagulant water, was studied by the cloud point method. The respective cloud point data were determined by titration against water at room temperature and the characteristic binodal curves for the ternary systems were plotted. Further, the physical properties such as viscosity, refractive index, and density of the solution were measured. The critical polymer concentrations were determined from the viscosity measurements. PC/NMP and PC/DCM membranes were fabricated by the dry-wet phase inversion technique and characterized for their morphology, structure, and thermal stability using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis, respectively. The membranes’ performances were tested for their permeance to CO2, CH4, and N2 gases at 24 ± 0.5 °C with varying feed pressures from 2 to 10 bar. The PC/DCM membranes appeared to be asymmetric dense membrane types with appreciable thermal stability, whereas the PC/NMP membranes were observed to be asymmetric with porous structures exhibiting 4.18% and 9.17% decrease in the initial and maximum degradation temperatures, respectively. The ideal CO2/N2 and CO2/CH4 selectivities of the PC/NMP membrane decreased with the increase in feed pressures, while for the PC/DCM membrane, the average ideal CO2/N2 and CO2/CH4 selectivities were found to be 25.1 ± 0.8 and 21.1 ± 0.6, respectively. Therefore, the PC/DCM membranes with dense morphologies are appropriate for gas separation applications.
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| 15106. |
- Idris, Alamin, et al.
(författare)
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Grindability and abrasive behavior of coal blends : analysis and prediction
- 2019
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Ingår i: International Journal of Coal Preparation and Utilization. - : Taylor & Francis. - 1939-2699 .- 1939-2702. ; , s. 1-27
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Tidskriftsartikel (refereegranskat)abstract
- Low-grade coals are blended with high-quality coals to meet economic, environmental, and quality specifications. Hence, the grindability and abrasiveness of coal blends are crucial economic and operational parameters. This work evaluates, analyzes, and predicts the grindability and abrasive behavior of coal blends. Three binary coal blends with common low-grade coal were first prepared at various ratios. Blends 1 and 2 were composed of identical and similar ranks, whereas Blend 3 was composed of different ranks. The blends were analyzed using proximate, ultimate analyzers, and a Bomb calorimeter. The grindability and abrasive behavior of the blends were measured using Hardgrove grindability index (HGI) and Yancey, Geer, and Price methods, respectively. Further, the coarser (+75 mu m) and finer (-75 mu m) fractions of HGI experiment were characterized using proximate, ultimate and heating value analyses. The additivity of HGI values was observed for Blend 1 and Blend 2, whereas, the non-additive behavior was observed in Blend 3. Further, the blends' mineral matter contents and abrasiveness index were found to be additive. Several existing models were found to be inaccurate for HGI predictions. Therefore, a new cross-validated model using multi-linear regression was proposed. The model exhibited better HGI predictions of coal blends with a coefficient of determination R-2 = 0.9416.
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| 15107. |
- Idris, Alamin, et al.
(författare)
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Investigation on particle properties and extent of functionalization of silica nanoparticles
- 2020
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 506
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Tidskriftsartikel (refereegranskat)abstract
- Quantification of the extent of functionalization on silica nanoparticle surface is crucial in a variety of applications. This work aims to evaluate particle properties and extent of functionalization on silica nanoparticles synthesized under acidic and basic conditions via co-condensation of tetraethyl orthosilicate with 3-aminopropyltrimethoxysilane in the sol-gel process. The silica nanoparticles properties were analyzed via field emission scanning electron microscope, transmission electron microscopy, dynamic light scattering, and Brunauer-Emmett-Teller methods; whereas, the extent of functionalization was evaluated using Fourier transform infrared spectroscopy, X-ray photoelectron spectrometer, and thermogravimetric analyzer. Results showed that the functionalized silica nanoparticles have a lower tendency to agglomerate and highly monodispersed as compared to unfunctionalized. The surface areas of acid and base-catalyzed nanoparticles were obtained as 618.8 and 514.7 m2/g, respectively. FTIR spectra, XPS scans, and TGA curves confirmed the presence of alkyl and amine functional groups on the functionalized surfaces. The extent of functionalization (N/Si) was obtained as 0.296 and 0.196, and the percentages of functional groups attached on the surface were found to be 6.80 and 5.92% for acid and base-catalyzed nanoparticles, respectively. The overall results suggest that acidic catalysis is a better approach for the synthesis of surface-modified or organofunctionalized silica nanoparticles.
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| 15108. |
- Idris, Alamin, et al.
(författare)
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Modified Bruggeman models for prediction of CO2 permeance in polycarbonate/silica nanocomposite membranes
- 2017
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Ingår i: The Canadian Journal of Chemical Engineering. - : John Wiley & Sons. - 0008-4034 .- 1939-019X. ; 95:12, s. 2398-2409
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Tidskriftsartikel (refereegranskat)abstract
- Abstract The polycarbonate membranes performances are improved by the incorporation of silica nanoparticles into the polymer matrix. Prepared PC/silica nanocomposite membranes with various silica content are considered and the experimental relative permeance of CO2 gas at 200 kPa (2 bar) feed pressure are used as reference in the predictions using the existing theoretical models such as Maxwell-Wagner-Sillar, Bruggeman, Lewis-Nielsen, Pal, and modified Pal models. TEM and BET analysis were used to characterize the silica nanoparticles; FESEM was used to characterize the morphology of the nanocomposite membranes. The TEM image of the silica nanoparticles reveals that the nanoparticles are mostly spherical. BET results reveal that the surface area and pore diameter of the silica nanoparticles are 618.8 m2/g and 0.28 nm, respectively. The existing models have resulted in poor predictions with errors AARE % of 26.52 to 28.02 %. Observation by FESEM image shows that the dispersed particles are surrounded by interfacial voids and rigidified polymer layer. Modified Bruggeman models that consider the interfacial volume show appreciable prediction with AARE 4.59 % being obtained with the pseudo-two-phase Bruggeman model. Moreover, when the model considered pseudo-three-phase morphology, the AARE % value reduced to 3.92 %. Thus, the contribution due to the interfacial rigidified layer was minimal.
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| 15109. |
- Idris, Alamin, et al.
(författare)
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Modified Higuchi Model Applied to Permeation Prediction of Nanocomposite Membranes
- 2016
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Ingår i: Proceeding of 4th international conference on process engineering and advanced materials (ICPEAM 2016). - : Elsevier. ; , s. 208-214
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Konferensbidrag (refereegranskat)abstract
- In this work, the existing Higuchi models were used for the prediction of gas permeability through the nanocomposite membranes. Predicted values were compared with experimental results of permeability for polycarbonate/silica nanocomposite membranes. Based on the critical analysis of the models predictions and its deviations, the parameter that influences the permeation behavior has been identified. The results revealed that for any particular gas, the change of empirical Higuchi parameter exhibited a direct impact on the accuracy the model. Thus, a modified parameter was incorporated on the modified Higuchi model relating to the intrinsic properties of the penetrant gas. With the new proposed Higuchi model, appreciable predictions of gas permeability through polycarbonate/silica nanocomposite membranes were achieved. The calculated absolute average relative error for CO2, N2 and CH4 gas permeability were found to be 7.18%, 6.07%, and 6.14%, respectively. Their corresponding standard deviations were obtained as 2.53, 1.53 and 0.73 Comparing the existing Higuchi models predictions, the new proposed Higuchi model has resulted to a reduction in relative errors by 6.3% for CO2, 70.66% for N2, and 65.25% for CH4.
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| 15110. |
- Idris, Alamin, et al.
(författare)
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Oxygen Barrier Performance of Poly (Vinyl Alcohol) Coating Films with Different Induced Crystallinity and Model Predictions
- 2021
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Ingår i: Coatings. - : MDPI AG. - 2079-6412. ; 11, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- The presence of the crystalline regions in poly(vinyl alcohol) coating films acts as barrier clusters forcing the gas molecules to diffuse in a longer pathway in the amorphous region of the polymer, where diffusivity and solubility are promoted in comparison. Evaluating the influence of crystalline regions on the oxygen barrier property of a semi-crystalline polymer is thus essential to prepare better coating films. Poly(vinyl alcohol) coating films with varying induced crystallinity were prepared on a polyethylene terephthalate (PET) substrate by drying at different annealing temperatures for 10 min. The coating films were first delaminated from the PET substrate and then characterized using Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and X-ray diffraction (XRD) techniques to determine and confirm the induced percentage of crystallinity. The barrier performance of the coating films, i.e., the oxygen transmission rate (OTR), was measured at room temperature. Results showed a decrease in the OTR values of poly(vinyl alcohol) film with an increase in the degree of crystallinity of the polymer matrix. Tortuosity-based models, i.e., modified Nielsen models, were adopted to predict the barrier property of the semi-crystalline PVOH film with uniform or randomly distributed crystallites. A modified Nielsen model for orderly distributed crystallites with an aspect ratio of 3.4 and for randomly distributed crystallites with an aspect ratio of 10.4 resulted in a good correlation with the experimental observation. For the randomly distributed crystallites, lower absolute average relative errors of 4.66, 4.45, and 5.79% were observed as compared to orderly distributed crystallites when the degree of crystallinity was obtained using FTIR, DSC, and XRD data, respectively.
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