| 1. |
- Altuna, Facundo I., et al.
(author)
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Effect of an Anhydride Excess on the Curing Kinetics and Dynamic Mechanical Properties of Synthetic and Biogenic Epoxy Resins
- 2019
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In: International Journal of Polymer Science. - : HINDAWI LTD. - 1687-9422 .- 1687-9430.
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Journal article (peer-reviewed)abstract
- This work analyzes the effect of the anhydride excess on the nonisothermal curing kinetics and on the final properties of synthetic and biobased epoxy resins. Diglycidyl ether of bisphenol A (DGEBA) and epoxidized soybean oil (ESO) were crosslinked using methyltetrahydrophthalic anhydride (MTHPA) as a curing agent and 1-methylimidazole (1MI) as an initiator. It was shown that the ESO/MTHPA/1MI system reacts slower than the DGEBA/MTHPA/1MI system, giving place to a more significant evaporation of the curing agent during the reaction. As a result, an excess of anhydride improves the final thermal properties of the ESO/MTHPA/1MI network, contrary to the behavior observed for DGEBA/MTHPA/1MI. The knowledge of the kinetics of the curing process and the optimal amount of the curing agent for each system is of critical importance for a more efficient processing of these materials.
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| 2. |
- Atari Jabarzadeh, Sevil, et al.
(author)
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Image Analysis Determination of the Influence of Surface Structure of Silicone Rubbers on Biofouling
- 2015
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In: International Journal of Polymer Science. - : Hindawi Limited. - 1687-9422 .- 1687-9430.
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Journal article (peer-reviewed)abstract
- This study focuses on how the texture of the silicone rubber material affects the distribution of microbial growth on the surface of materials used for high voltage insulation. The analysis of surface wetting properties showed that the textured surfaces provide higher receding contact angles and therefore lower contact angle hysteresis. The textured surfaces decrease the risk for dry band formation and thus preserve the electrical properties of the material due to a more homogeneous distribution of water on the surface, which, however, promotes the formation of more extensive biofilms. The samples were inoculated with fungal suspension and incubated in a microenvironment chamber simulating authentic conditions in the field. The extent and distribution of microbial growth on the textured and plane surface samples representing the different parts of the insulator housing that is shank and shed were determined by visual inspection and image analysis methods. The results showed that the microbial growth was evenly distributed on the surface of the textured samples but restricted to limited areas on the plane samples. More intensive microbial growth was determined on the textured samples representing sheds. It would therefore be preferable to use the textured surface silicone rubber for the shank of the insulator.
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| 3. |
- Bátori, Veronika, 1980-, et al.
(author)
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Production of Pectin-Cellulose Biofilms: A New Approach for Citrus Waste Recycling
- 2017
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In: International Journal of Polymer Science. - : Hindawi Limited. - 1687-9422 .- 1687-9430. ; 2017, s. 1-9
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Journal article (peer-reviewed)abstract
- While citrus waste is abundantly generated, the disposal methods used today remain unsatisfactory: they can be deleterious for ruminants, can cause soil salinity, or are not economically feasible; yet citrus waste consists of various valuable polymers. This paper introduces a novel environmentally safe approach that utilizes citrus waste polymers as a biobased and biodegradable film, for example, for food packaging. Orange waste has been investigated for biofilm production, using the gelling ability of pectin and the strength of cellulosic fibres. A casting method was used to form a film from the previously washed, dried, and milled orange waste. Two film-drying methods, a laboratory oven and an incubator shaker, were compared. FE-SEM images confirmed a smoother film morphology when the incubator shaker was used for drying. The tensile strength of the films was 31.67 ± 4.21 and 34.76 ± 2.64 MPa, respectively, for the oven-dried and incubator-dried films, which is within the range of different commodity plastics. Additionally, biodegradability of the films was confirmed under anaerobic conditions. Films showed an opaque appearance with yellowish colour.
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| 4. |
- Bergstrand, Anna, 1974, et al.
(author)
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Permeability of Porous Poly(3-hydroxybutyrate) Barriers of Single and Bilayer Type for Implant Applications
- 2014
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In: International Journal of Polymer Science. - : Hindawi Limited. - 1687-9430 .- 1687-9422. ; 2014, s. Art. no. 958975-
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Journal article (peer-reviewed)abstract
- Poly(3-hydroxybutyrate) (PHB) is a polyester which shows excellent biocompatibility and a PHB material is therefore considered suitable for many biomedical applications. A highly porous PHB material may be designed to facilitate the transport of small molecules and body fluids or serve as a biocompatible temporary barrier. In this study, PHB films with varying degree of porosity and pore interconnectivity were made by solvent casting using water-in-oil emulsion templates of varying composition. The morphology was characterized by SEM and the water permeability of the films was determined. The results show that an increased water content of the template emulsion resulted in a film with increased porosity. A fine tuning of the film morphology of the casted films was achieved by varying the salt content of the water phase of the template emulsion. It was concluded that the major determinant of the water permeability through these films is the pore interconnectivity. Furthermore, we report on the formation and water permeability of bilayer PHB films consisting of a porous layer combined with a dense backing layer.
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| 5. |
- Cho, Sung-Woo, et al.
(author)
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Wheat Gluten-Laminated Paperboard with Improved Moisture Barrier Properties : A New Concept Using a Plasticizer (Glycerol) Containing a Hydrophobic Component (Oleic Acid)
- 2012
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In: International Journal of Polymer Science. - : Hindawi Limited. - 1687-9422 .- 1687-9430. ; , s. 454359-
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Journal article (peer-reviewed)abstract
- This paper presents a novel approach to reduce the water vapor transmission rate (WVTR) and water absorbance of wheat gluten/paperboard laminates by introducing a hydrophobic component (oleic acid (OA)) into the hydrophilic plasticizer (glycerol). Whereas the paperboard showed immeasurably high WVTR, the laminate with gluten/glycerol yielded finite values. More importantly, by incorporating 75wt.% OA into the plasticizer, the WVTR and water absorbance were reduced by, respectively, a factor of three and 1.5-2. Of particular interest was that the mechanical properties were not changing dramatically between 0 and 50 wt.% OA. The results showed clear benefits of combining a gluten film with paperboard. Whereas the paperboard provided toughness, the WG layer contributed with improved moisture barrier properties. In addition, WVTR indicated that the paperboard reduced the swelling of the outer gluten/glycerol layer in moist conditions; a free standing gluten/glycerol film would yield infinite, rather than finite, WVTR values.
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| 6. |
- Jabbari, Mostafa, et al.
(author)
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New Solvent for Polyamide 66 and Its Use for Preparing a Single-Polymer Composite-Coated Fabric
- 2018
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In: International Journal of Polymer Science. - : Hindawi Limited. - 1687-9422 .- 1687-9430.
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Journal article (peer-reviewed)abstract
- Polyamides (PAs) are one of the most important engineering polymers; however, the difficulty in dissolving them hinders their applications. Formic acid (FA) is the most common solvent for PAs, but it has industrial limitations. In this contribution, we proposed a new solvent system for PAs by replacing a portion of the FA with urea and calcium chloride (FAUCa). Urea imparts the hydrogen bonding and calcium ion from the calcium chloride, as a Lewis acid was added to the system to compensate for the pH decrease due to the addition of urea. The results showed that the proposed solvent (FAUCa) could readily dissolve PAs, resulting in a less decrease in the mechanical properties during the dissolution. The composite prepared using the FAUCa has almost the same properties as the one prepared using the FA solution. The solution was applied on a polyamide 66 fabric to make an all-polyamide composite-coated fabric, which then was characterized. The FAUCa solution had a higher viscosity than the one prepared using the neat FA solvent, which can be an advantage in the applications which need higher viscosity like preparing the all-polyamide composite-coated fabric. A more viscous solution makes a denser coating which will increase the water /gas tightness. In conclusion, using the FAUCa solvent has two merits: (1) replacement of 40% of the FA with less harmful and environmentally friendly chemicals and (2) enabling for the preparation of more viscous solutions, which makes a denser coating.
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| 7. |
- Zaman, Muhammad, et al.
(author)
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Application of Nanoprecipitation Technique to Develop Poloxamer-407 Facilitated Solid Lipid Nanoparticles for the Controlled Delivery of Tacrolimus
- 2023
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In: International Journal of Polymer Science. - : HINDAWI LTD. - 1687-9422 .- 1687-9430. ; 2023
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Journal article (peer-reviewed)abstract
- Currently, the solid lipid nanoparticles (SLNs) are utilized as a novel approach for the controlled drug delivery system (CDDS). Tacrolimus (TCM), a lipophilic drug, can easily be encapsulated in the hydrophobic core of these SLNs using nanoprecipitation technique. The current aim was to develop the controlled release Poloxamer (PLX) facilitated TCM loaded SLNs (PLX/TCM-SLNs), followed by their physicochemical evaluations, including chemical compatibility, particle size, surface charge, surface morphology, nature of SLNs, loading efficiency (LE), entrapment efficiency (EE), in vitro drug release studies, release kinetic modeling, and statistical evaluation. Here we also evaluate physicochemical properties of TCM and investigate solubility profile for improvement and dissolution rate of PLX/TCM-SLNs. PLX was used in the process as a polymer due to its low toxicity and weak immunogenic properties. The prepared formulation was characterized by scanning electron microscopy (SEM) images, and Fourier transform infrared spectroscopy (FTIR) has confirmed the compatibility of the selected ingredients, whereas particle size analysis showed that prepared PLX/TCM-SLNs were of nanosized (120:6 +/- 9nm) having zeta potential of - 21.3 Mv. On the other hand, SEM had revealed the smooth and uniform surface of the particle, while X-ray diffraction (XRD) confirmed the uniform surface as crystalline structure of TCM in PLX/TCM-SLNs masked. A satisfactory level of EE (94:5 +/- 2:74%) has also been noticed. Furthermore, in vitro drug release studies have explored the controlled release of drug during 8 hours, following zero order release kinetics and diffusion type of release mechanism. Outcomes of the studies have advocated the successful preparation of SLNs, as controlled release PLX/TCM-SLNs have been prepared efficiently.
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| 8. |
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