| 1. |
- Arasteh, Rouhollah, et al.
(author)
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Effects of Fiber Spinning on the Morphology, Rheology, Thermal, and Mechanical Properties of Poly(trimethylene terephthalate)/Poly(ethylene terephthalate) Blends
- 2014
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In: Advances in Polymer Technology. - : Wiley. - 0730-6679 .- 1098-2329. ; 33:S1, s. 21443-
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Journal article (peer-reviewed)abstract
- The morphology, thermal behavior, rheological, and mechanical properties of poly(trimethylene terephthalate) (PTT)/poly(ethylene terephthalate) (PET) blend fibers were investigated. The scanning electron microscopy studies revealed the formation of a microfibrillar network of the PET within the PTT matrix after the fiber-spinning process. Differential scanning calorimetry results demonstrated that although the thermal characteristics of the amorphous phase were unaffected by the fiber-spinning process, the melting and crystallization behavior of the blends was altered by the elongation flow imposed during the melt spinning. The viscoelastic behavior of the PTT/PET blends was also studied by a steady shear rate and dynamic sweep rheological experiments before and after the spinning process. The induced morphology and crystallization reordering resulting from the fibrillation process are shown to have a remarkable effect on the complex viscosity profile of the PTT/PET fibers, particularly in the blend containing 30 wt% PET. The mechanical testing showed that tenacity and Young's modulus of the PTT fibers increased with the addition of PET up to 30 wt%.
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| 2. |
- Kang, J., et al.
(author)
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Investigation on the Tensile Behavior and Morphology Evolution of Isotactic Polypropylene Films Polymerized with Different Ziegler-Natta Catalysts
- 2015
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In: Advances in Polymer Technology. - : Wiley. - 0730-6679 .- 1098-2329.
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Journal article (peer-reviewed)abstract
- Stereodefect distribution is very important in determining the morphology and properties of isotactic polypropylene (iPP). In this study, two iPPs (PP-A and PP-B) with different uniformities of stereodefect distribution were prepared. The tensile behavior and morphology evolution of their cast films were studied. The morphology study of the cast films showed that compared with PP-B, PP-A with less uniform distribution of stereodefects has smaller spherulites and spheruilitic boundaries and higher degree of crystallinity. In uniaxial tensile measurements, PP-A exhibited higher yield strength and lower elongation at break. When strain was 500%, PP-A exhibits totally transparent appearance and highly oriented structures without cavities, whereas PP-B shows opaque appearance and mass of both nanometer- and micrometer-sized cavities. Moreover, calculation of rigid amorphous fraction (RAF) indicated that PP-B cast film has a higher amount of RAF, which might be the reason for the different morphology evolutions and tensile behaviors of the samples.
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| 3. |
- Kheirabadi, Malihe, et al.
(author)
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Improvement in Mechanical Performance of Anionic Hydrogels Using Full-Interpenetrating Polymer Network Reinforced with Graphene Oxide Nanosheets
- 2016
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In: Advances in Polymer Technology. - : Wiley. - 0730-6679 .- 1098-2329. ; 35:4, s. 386-395
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Journal article (peer-reviewed)abstract
- Weak mechanical possession is one of the limiting factors in application of hydrogels. To modify this inherent disadvantage, different approaches have been studied including synthesizing interpenetrating polymer network (IPN) and nanocomposite hydrogels. So, this study has focused on preparation of a novel full-IPN structure based on anionic monomers of 2-acrylamido-2-methylpropane sulfonic acid/acrylic acid-sodium acrylate via facile solution polymerization technique in an aqueous media with incorporation of graphene oxide (GO) nanosheets. Mechanical performance of materials in the as-prepared condition and swollen state was characterized via tensile, compression, and rheology tests, respectively. Significant improvement of both elastic and storage modulus (ca. four times higher than pure hydrogel) is observed in this approach. Also dynamic mechanical thermal analysis results revealed that incorporation of high GO content (0.5 wt%) can suppress formation of full-IPN structure, whereas low GO content has not such an effect, interestingly. Moreover, these novel hydrogels could easily be stretched or compressed followed by full recovery after unloading.
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| 4. |
- Kronberg, Simon, et al.
(author)
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Transforming Polycotton Textile Waste into New Bicomponent Fibers: An Investigative Study
- 2024
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In: Advances in Polymer Technology. - 0730-6679 .- 1098-2329. ; 2024:1
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Journal article (peer-reviewed)abstract
- This study aimed to develop an innovative recycling method for end-of-life polycotton textiles, eliminating the need for component separation. The use of 1-ethyl-3-methylimidazolium acetate ([EMIM][Ac]) as an ionic liquid solvent facilitated the dissolution of cotton, enabling the creation of a spinning dope containing cellulose and polyester fibers. Successful spinning of bicomponent fibers ensued, followed by comprehensive fiber evaluation. The dissolution of cotton was achieved with [EMIM][Ac], and spinning trials were conducted to devise a suitable method for regenerated cellulose. Tensile tests on the produced cellulosic fibers clearly demonstrated an increase in tensile strength with higher cellulose concentration. The introduction of polyester fibers to the spinning dope, comprising [EMIM][Ac] and cotton, posed challenges to the entire spinning process. Tensile tests on the resulting bicomponent fibers revealed a decrease in tensile strength compared to pure regenerated cellulose fibers. This reduction was attributed to increased voids and irregular polyester fiber distribution, corroborated by microscopy images and a wicking test. It was concluded that the quantity and length of polyester fibers significantly influenced the tensile strength of the bicomponent fibers, with lower concentrations and shorter fibers resulting in higher strength.
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| 5. |
- Rezaei, Babak, et al.
(author)
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Multifactorial modeling and optimization of solution and electrospinning parameters to generate superfine polystyrene nanofibers
- 2018
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In: Advances in Polymer Technology. - : John Wiley & Sons. - 0730-6679 .- 1098-2329. ; 37:8, s. 2743-2755
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Journal article (peer-reviewed)abstract
- This study was conducted to provide a quantitative understanding of the influence of the different solution and electrospinning variables on the morphology and the mean diameter of electrospun polystyrene nanofibers. In this regard, the effect of different solvents and ionic additives on the electrical conductivity, viscosity, and surface tension of the electrospinning solutions and thereby the morphology of nanofibers were examined. The results indicated that the morphology of the fibers is extremely dependent on the solvent’s properties, especially volatility and electrical conductivity, and the ionic characteristics of additives. Finally, to estimate the optimal electrospinning conditions for production of nanofibers with minimum possible diameter, modeling of the process was undertaken using the response surface methodology. Experimentally, nanofibers with the finest diameter of 169 ï¿œ 21 nm were obtained under the optimized conditions, and these could be considered promising candidates for a wide practical range of applications ranging from biosensors to filtration.
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