| 1. |
- Andersson Trojer, Markus, 1981, et al.
(författare)
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Synthesis and polymerisation of maleolyl-L-histidine monomers and addition of histidine to an ethylene-alt-maleic co-polymer
- 2012
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Ingår i: Journal of Polymer Research. - : Springer Science and Business Media LLC. - 1572-8935 .- 1022-9760. ; 19:2, s. 9821-9829
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Tidskriftsartikel (refereegranskat)abstract
- This work has investigated two routes of synthesising polymers containing L-histidine using maleimide chemistry; grafting of histidine onto an ethylene-alt-maleic anhydride copolymer and AIBN (azobisisobutyronitrile) initiated radical polymerisation of the monomer maleoyl-L-histidine. The grafting technique and monomer synthesis are utilising the maleimide formation between the primary amine of histidine and maleic anhydride. The reactions are conveniently carried out in one step with good yields. The copolymers containing L-histidine were prepared by reacting L-histidine or L-histidine methyl ester with poly(ethylene-alt maleic anhydride) in DMSO at 50 °C for 8–16 h with 80% yields independent of the degree of substitution. The monomer maleoyl-L-histidine was synthesised by reacting histidine and maleic anhydride in acetic acid and the monomer was subsequently polymerised by AIBN radical initiation in DMSO at 80 °C for 48 h to yield poly(N-histidyl maleimide). The resulting polymer had a different optical rotation ([α]D20 = −11) than the monomer ([α]D20 = +25), which is ascribed to the threo-diisotactic and/or threo-disyndiotactic stereoregularity of the polymer.
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| 2. |
- Badawi, Ali, et al.
(författare)
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Exploring the structural and optical properties of FeS filled graphene/PVA blend for environmental-friendly applications
- 2021
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Ingår i: Journal of Polymer Research. - : Springer Science and Business Media LLC. - 1022-9760 .- 1572-8935. ; 28
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the role of iron sulfide (FeS) content on the structural and optical properties of graphene/polyvinyl alcohol (Gr/PVA) blend has been examined for environmental-friendly applications. Gr/PVA blend filled with FeS (0 to 10 wt%) were equipped using the casting technique. The prepared samples were studied via a scanning electron microscope, X-ray diffractometer, FT-IR and UV–visible-NIR spectrophotometers. XRD analysis shows that the crystallinity increases with increasing FeS concentration in the host Gr/PVA blend. UV–visible-NIR analysis shows that the direct optical bandgap of composite blends shrinks from 5.37 to 4.68eV as FeS content is increased to 10 wt%. Also, it confirms that the refractive index and optical conductivity of Gr/PVA blend could be significantly enhanced via FeS filling. FeS filled Gr/PVA blends are recommended eco-friendly applications.
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| 3. |
- Baghaei, Behnaz, 1986-, et al.
(författare)
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Mechanical properties of all-cellulose composites from end-of-life textiles
- 2020
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Ingår i: Journal of polymer research. - : Springer. - 1022-9760 .- 1572-8935. ; 27:9
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports the recycling of end-of-life cellulose containing textiles by fabrication of all-cellulose composites (ACCs). Discharged denim fabrics were used as the reinforcement while dissolved cellulose from two different cellulose resources was used as the matrix phase. Virgin cotton fibres and recovered cotton from polyester/cotton (polycotton) waste fabrics were used to form the matrix phase. The process comprises preparing a 6 wt% cellulose solution by dissolving cellulose solution in a ionic liquid, 1-butyl-3-methyl imidazolium acetate ([BMIM][Ac]), this solution acted as a precursor for the matrix component. The denim fabrics were first embedded in the cellulose/IL solution followed by removal of the IL by washing to form the composite. The effect of reuse of the recovered IL by distillation was also investigated. The mechanical properties of the obtained ACCs were determined regarding tensile, impact and flexural properties. Fabricated ACC composite laminates were further characterised regarding structure by scanning electron microscopy.
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| 4. |
- Fagerland, Jenny, et al.
(författare)
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Mapping the synthesis and the impact of low molecular weight PLGA-g-PEG on sol-gel properties to design hierarchical porous scaffolds
- 2013
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Ingår i: Journal of polymer research. - : Springer Science and Business Media LLC. - 1022-9760 .- 1572-8935. ; 21:1, s. 337-
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Tidskriftsartikel (refereegranskat)abstract
- Bone morphogenetic protein 2 (BMP-2)-functionalized poly(l-lactide-co-epsilon-caprolactone) (PLCL) porous scaffolds have shown promising results in bone tissue regeneration studies. It is believed that even better results are achieved by hierarchical porous scaffolds and a designed sequential release of growth factors. We therefore synthesized (l-lactide-co-glycolide)-g-poly(ethylene glycol) (PLGA-g-PEG) oligomers which could be injected into PLCL porous scaffolds. They were synthesized by ring-opening polymerization and carefully characterized by nuclear magnetic resonance spectroscopy (NMR), matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and size exclusion chromatography (SEC). The sol-gel transition temperature, pH, and functional life were determined and correlated with the molecular structure of PLGA-g-PEG. We found that low molecular weight PLGA-g-PEG was obtained and poly(l-lactide-co-glycolide-co-poly(ethylene glycol) methyl ether) (PLGA-MPEG) appeared to contribute to gelation. It was possible to design a system that formed a hydrogel within 1 min at 37 A degrees C with a pH between 6 and 7 and with a functional life of around 1 month. These low molecular weight thermosensitive PLGA-g-PEG oligomers, which can be injected into PLCL scaffolds, appear promising for bone tissue engineering applications.
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| 5. |
- Gonzalez-Perez, Alfredo, et al.
(författare)
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Polymersomes mimic biofilms fractal growth
- 2016
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Ingår i: Journal of Polymer Research. - : Springer Science and Business Media LLC. - 1022-9760 .- 1572-8935. ; 23:9
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Tidskriftsartikel (refereegranskat)abstract
- We have mimicked the biofilm formation with highly stable biocompatible poly(2-methyl-2-oxazoline)-based polymersomes by simple spreading-drying of a droplet of the sample solution onto a glass support. The diffusion-limited aggregation process of polymersomes onto the surface was analyzed within a fractal framework. The different examples analyzed and presented together indicate one means by which the aggregation process can be controlled and predicted. The anti-bacterial adhesion properties of poly(2-methyl-2-oxazoline) allow potential uses in surface modification for biofouling prevention improving stability and response time. [Figure not available: see fulltext.]
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| 6. |
- Kang, Jian, et al.
(författare)
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Understanding in the morphology and tensile behavior of isotactic polypropylene cast films with different stereo-defect distribution
- 2014
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Ingår i: Journal of polymer research. - : Springer Science and Business Media LLC. - 1022-9760 .- 1572-8935. ; 21:6, s. 485-
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Tidskriftsartikel (refereegranskat)abstract
- In this study, two iPP resins with similar molecular weight and average isotacticity but different uniformities of stereo-defect distribution were used in the production of cast films. The crystalline morphology and orientation, and tensile behavior during room temperature stretching of the cast films were investigated by scanning electronic microscopy (SEM), 2D-wide angle X-ray diffraction (2D-WAXD) and 2D-small-angle X-ray scattering (2D-SAXS). It was found that under fixed processing condition, iPP with more uniform stereo-defect distribution (PP2) favors the formation of row nucleated lamellar structure during cast film production, and therefore exhibiting hard-elastic deformation behavior during stretching; meanwhile, the sample with less uniform stereo-defect distribution (PP1) shows un-oriented spherulitical morphology in the cast film, and typical plastic deformation behavior during stretching. The crystallization and rheological analysis on the iPP raw materials revealed that, the uniformity of stereo-defect distribution determines the ability of nucleation and crystallization, and further influences the response of the crystalline morphology to the elongation effect of cast film production process, which is of great importance in the structure-property design in the production of iPP membranes.
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| 7. |
- Karlsson, Kristina, 1988, et al.
(författare)
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Hot-mould foaming of modified hemicelluloses and hydroxypropyl methylcellulose
- 2019
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Ingår i: Journal of Polymer Research. - : Springer Science and Business Media LLC. - 1572-8935 .- 1022-9760. ; 26:8
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Tidskriftsartikel (refereegranskat)abstract
- Plastics are a material group which have revolutionized the materials industry during the past century. However, the often fossil origin and littering of the material is problematic. Therefore, this study aims at exploring natural polymers, such as cellulose derivatives and hemicelluloses from different botanical origins, and demonstrate the possibility to use these polymers in a foaming application. The hemicelluloses were chemically treated in order to enhance their performance and foams with ratios as high as 4:1 of hemicellulose and the cellulose derivative, respectively, were successfully produced by a hot-mould foaming technique. The foams were found to be thermally stable up to about 280 degrees C. The chemical modifications were confirmed by Fourier transform infrared (FTIR) spectra and the foams were evaluated with regard to their liquid absorption capacity as well as their density. After 1 min the best foam absorbed 12.5 g/g of liquid and after 30 min soak time and centrifugation the foams had absorption capacities between 2 and 5 g/g. All foams exhibited densities below 0.1 g/cm(3). In both the absorption test and density evaluation, the foams produced from mainly hemicellulose performed in a similar way as the reference foams based only on the cellulose derivative, which is considered an impressive result since cellulose is often reported to have superior properties to hemicelluloses.
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| 8. |
- Lee, Ching-Hwa, et al.
(författare)
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A study on development of alternative biopolymers based proton exchange membrane for microbial fuel cells and effect of blending ratio and ionic crosslinking on bioenergy generation and COD removal
- 2019
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Ingår i: Journal of polymer research. - : Springer. - 1022-9760 .- 1572-8935. ; 26:12
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Tidskriftsartikel (refereegranskat)abstract
- The use of biopolymers as alternative proton exchange membranes (PEMs) is receiving significant attention in microbial fuel cells (MFCs) due to their attractive and competitive physico-chemical properties, eco-friendly behavior and biodegradable nature. In this study we developed the biopolymer-based blend PEMs using chitosan (Cs) alginate (Alg) for bioelectricity production and simultaneous wastewater treatment and also investigated the effect of blending ratio of the membrane and ionic crosslinking between the two biopolymers on MFC performance. The membranes of Cs:Alg were fabricated in volume ratio of 100:0, 80:20, 60:40, 50:50, 40:60, 20:80, and 0:100 via a solution casting and solvent evaporation method followed by crosslinking with phosphoric acid to avoid excess swelling of the hydrophilic polymers and increase the mechanical strength. Among these, the 50:50 ratio membranes exhibited the highest power generation (115 mW/m(2)) with 1340% water uptake, however the membrane with 40:60 ratio displayed maximum COD removal (78.6%) compared to other membranes. The structure and surface morphology of obtained membranes were examined using Infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX), Sorption and cation exchange capacity, and tensile strength. Sorption, cation exchange capacity and mechanical properties of Cs membranes increased with the addition of Alg with near to stoichiometric ratio.
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| 9. |
- Saleem, Anjum, et al.
(författare)
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Mechanical performance of hybrid bast and basalt fibers reinforced polymer composites
- 2020
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Ingår i: Journal of polymer research. - : SPRINGER. - 1022-9760 .- 1572-8935. ; 27:3
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Tidskriftsartikel (refereegranskat)abstract
- With increasing limitation of petrochemical resources, there is a growing demand for the replacement of nonrenewable fiber-reinforced polymer composites by renewable polymer composites. Therefore, the aim of this research work was to improve the mechanical properties of bast (plant) fibers reinforced polymer composites without reducing their renewable material content. To achieve this goal, basalt fibers (natural mineral fibers) were used to partially substitute the amount of bast fibers in the polymer composites. The applied fibers were processed to semi-finished materials by carding and needle punching and processed further by afterwards press-molding. An intense optimization of the carding process led to the production of homogeneous fabrics based on various types of fibers (bast, basalt and PP). The homogeneity of the fabrics was confirmed by scanning electron microscopy (SEM) analysis of the composites. Several composites based on polypropylene and acrylate thermoset resin, reinforced with merely bast fibers, were prepared as reference. In the next steps, the bast fiber content of the reference compositions was partially replaced by basalt fibers. The compression-molded samples were tested for their flexural, tensile, and impact energy properties. The very positive finding was that the addition of basalt fibers not just improved significantly the strength and stiffness of the composites, but simultaneously increased the properties of the composites regarding energy absorption, a key requirement in the automotive industry. The fracture surface analysis confirmed a better fiber matrix adhesion in thermoset composites compared to thermoplastic composites. The tested renewable hybrid polymer composites have great potential to replace nonrenewable fiber-reinforced polymer composites.
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| 10. |
- Samanta, Pratick, et al.
(författare)
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Non-isothermal crystallization kinetics of confined poly (ethylene oxide) in electrospun nanofibers prepared from polystyrene/ poly (ethylene oxide) blends
- 2022
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Ingår i: Journal of polymer research. - : Springer Nature. - 1022-9760 .- 1572-8935. ; 29:4
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Tidskriftsartikel (refereegranskat)abstract
- Study on non-isothermal crystallization kinetics of polymer is relevant for both fundamental as well as application perspective. Hence, the non-isothermal crystallization kinetics of bulk and confined poly(ethylene oxide) (PEO) in electrospun nanofibers was investigated using DSC. The nanofibers were prepared from polystyrene (PS)/PEO immiscible blends where PEO weight fraction was varied upto 0.4. It was found that the Avarmi and Jeziorny models successfully predict the nucleation nature of PEO chains and its growth behavior. However, the Ozawa model was not found to be suitable for the confined system. Nevertheless, the Mo's method, which is the combination of Avrami and Ozawa models, effectively described the non-isothermal crystallization behavior of PEO in confined domains. The Kissinger and Takhor methods showed that activation energy for crystallization of PEO chains increased with reduction of PEO weight fraction in the nanofibers. This was plausibly due to the geometrical restriction on the mobility of PEO chains. The present study is the first report on non-isothermal crystallization behavior of confined polymer in electrospun nanofibers systems.
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| 11. |
- Yang, Jiaojiao, et al.
(författare)
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Enhanced UV protection and water adsorption properties of transparent poly(methyl methacrylate) films through incorporation of amorphous magnesium carbonate nanoparticles
- 2021
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Ingår i: Journal of polymer research. - : Springer Nature. - 1022-9760 .- 1572-8935. ; 28:8, s. 281-
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Tidskriftsartikel (refereegranskat)abstract
- A simple solution casting approach was used to obtain transparent and flexible poly(methyl methacrylate) (PMMA) films incorporated with 1 – 4% by weight amorphous magnesium carbonate nanoparticles. Optical transparency was retained in visible wavelengths, while transmittance in the UV-B region was reduced by 22% at 310 nm and 58% at 256 nm with the addition of 4 wt. % nanoparticles. Furthermore, the incorporation of the nanoparticles was shown to provide protection for the films under UV-C irradiation (254 nm wavelength, 5 mW cm−2), with the amount of UV degradation decreasing with increasing concentration of nanoparticles. Films with incorporated nanoparticles were also shown to be able to retain adsorbed moisture much better than neat PMMA films; whereas neat PMMA films did not retain moisture, approximately 50% of the adsorbed moisture was retained in films containing 4 wt. % nanoparticles. These enhanced properties of PMMA are of great interest in applications such as flexible and transparent screens for personal electronic devices that require protection from both UV light and moisture.
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| 12. |
- Zhu, Yanji, et al.
(författare)
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Nano SiC enhancement in the BN micro structure for high thermal conductivity epoxy composite
- 2021
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Ingår i: Journal of polymer research. - : Springer. - 1022-9760 .- 1572-8935. ; 28:10
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Tidskriftsartikel (refereegranskat)abstract
- Improving the heat dissipation efficiency of electronic products is the key to the design of many modern electronic and mechanical systems. Herein, we combined the 3D network fabricating with the way of micron-nano reinforcement to prepare high thermal conductivity and excellent thermal stability composites. Epoxy resin was used as the matrix, while the silicon carbide foam (f-SiC) as skeleton and the BN/nano-SiC as thermally conductive fillers. The thermal conductivity of the EP/f-SiC/BN/nano-SiC composite reaches 3.5 W·m− 1·K− 1, which is about 16.6 times higher than that of pure epoxy resin. The characterization results of TC and infrared thermography images indicate that the EP/f-SiC/BN/nano-SiC composite possess superior heat transport performance. Meantime, the EP/f-SiC/BN/nano-SiC composite have excellent thermal stability, the THRI of EP/f-SiC/BN/nano-SiC reaches 195.8℃, which is 21.3℃ higher than that of pure EP. This work would provide a new strategy for improving the TC of polymers by using other 3D skeletons and micron-nano fillers, and is conducive to the development of high thermal conductivity and excellent thermal stability materials.
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