| 1. |
- Aminlashgari, Nina, et al.
(författare)
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Degradation product profiles of melt spun in situ cross-linked poly(epsilon-caprolactone) fibers
- 2015
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Ingår i: Materials Chemistry and Physics. - : Elsevier BV. - 0254-0584 .- 1879-3312. ; 156, s. 82-88
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Tidskriftsartikel (refereegranskat)abstract
- In situ cross-linking of poly(epsilon-caprolactone) (PCL) fiber with bis-(epsilon-caprolactone-4-yl) (BCY) was shown to be a feasible approach to compensate for reduction in molar mass of PCL during melt-spinning. The effect of in situ cross-linking on the degradation profile of melt spun PCL fibers with different amounts of BCY was evaluated using electrospray ionization-mass spectrometry. Degradation of the cross-linked fibers was carried out in aqueous medium at 37 degrees C and 60 degrees C for different periods of time. The degradation profiles were then compared with uncross-linked fiber and 3D porous cross-linked film of PCL Interesting differences in the degradation product profiles with linear, cyclic or BCY-related low molar mass compounds were observed, clearly demonstrating the effect of cross-linking and processing on the degradation process and formation of water-soluble products. In addition the degradation product profiles demonstrated that in situ cross-linking is a feasible technique for counteracting degradation reactions during melt-spinning.
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| 2. |
- Kumar, Advitiya, et al.
(författare)
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Emulsion templated cellulosic porous scaffolds of superior oleophilicity
- 2023
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Ingår i: Cellulose. - : Springer Nature. - 0969-0239 .- 1572-882X. ; 30:14, s. 9047-9059
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Tidskriftsartikel (refereegranskat)abstract
- Oil spills and related environmental concerns have been dealt using various approaches including hydrophobic absorbents made of synthetic polymers. Disposal and secondary contamination from such polymeric absorbent however are issues due to non-degradable nature of synthetic polymers. A cellulose based oleophilic porous scaffold for oil sorption is thus fabricated in this work via emulsion templating. Pre-treated wood pulp cellulose based high internal phase emulsion was developed through judicious choice of solvent, emulsifiers, nature and volume fraction of dispersed phase, and crosslinker for cellulose. The scaffold showed a highly interconnected porous structure resulting in an oil sorption capacity up to 8.8 g/g for automobile engine oil (volumetric swelling of 30 ml/ml), matching with some of the previously reported hydrophobically modified cellulosic absorbents. The scaffold showed no structural disintegration or decline in sorption capacity during cyclic sorption-desorption test up to 5 cycles. The oleophilic character was introduced in the scaffold due to high surface area and interconnected macropores acting as microchannels and reservoir for oil sorption without any interaction of the hydrophilic cellulose with the oil. The efficiency of porous scaffold of a natural polymer for oil sorption can further be enhanced via hydrophobic functionalization and other vast applications.
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| 3. |
- Samanta, Pratick, et al.
(författare)
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Crystallization in PLLA-Based Blends, and Composites
- 2023
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Ingår i: Polymer Crystallization. - : Wiley. ; , s. 161-194
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Poly (lactic acid) (PLA) has gained attention due to its mechanical performance, optical transparency, renewability, biocompatibility and biodegradability in recent past. The slow crystallization kinetics, poor thermal stability, brittleness and process complexity limit its practical applications. Hence, crystallization behavior of PLA was studied enormously in past to improve its performance. Here, in particular, crystallization behavior of poly (l -lactic acid) (PLLA) and its different forms (in blends, in composites, and after adding nucleating agents, etc.) are described.
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| 4. |
- Samanta, Pratick, et al.
(författare)
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Fabrication and crystallization behavior of hollow poly(l-lactic acid) nanofibers
- 2020
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Ingår i: Polymer Crystallization. - : John Wiley and Sons Inc. - 2573-7619. ; 3:5
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a bundle of poly(l-lactic acid) (PLLA) hollow nanofibers was prepared through anodic aluminum oxide (AAO) membrane wetting method. The infiltrated PLLA in the nanopores of AAO membrane were isolated via etching of the membrane using phosphoric acid, preserving their original nanostructure. The outer diameter of isolated PLLA nanofibers and wall thickness were found to be 235 ± 17 nm and 38.5 ± 9 nm, respectively. The differential scanning calorimetry analysis showed that the hollow PLLA nanofibers exhibited lower melting and crystallization temperatures than the bulk PLLA sample. Furthermore, the wide-angle X-ray diffraction measurement suggested that PLLA crystallized preferentially along the 110/200 plane direction due to confinement effect of the AAO walls. Such hollow PLLA nanofibers may have potential application as a drug delivery system.
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| 5. |
- 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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| 6. |
- Skrifvars, Mikael, 1962-, et al.
(författare)
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Electrospun composite matrices from tenside-free poly(caprolactone)-grafted acrylic acid/hydroxyapatite oil-in-water emulsions
- 2017
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Ingår i: Journal of Materials Science. - : Springer Science and Business Media LLC. - 0022-2461 .- 1573-4803. ; 52:4, s. 2254-2262
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Tidskriftsartikel (refereegranskat)abstract
- Composite matrices of poly(ε-caprolactone)-grafted acrylic acid (PCL-g-AA) and hydroxyapatite (HA) were prepared via electrospinning of oil-in-water emulsions. Grafting of varying amounts of AA on PCL was carried out in a twin-screw compounder using benzoyl peroxide as an initiator under inert atmosphere. A solution of PCL-g-AA in toluene, containing HA, comprised the oil phase of the emulsion, while the aqueous phase contained poly(vinyl alcohol) (PVA) as a template polymer. No emulsifier was used in making such emulsions which were found to be stable for more than a month at room temperature. Secondary interactions of AA group of PCL-g-AA with HA and PVA at the oil–water interface provided stability to the emulsion. Uniform composite fibrous matrices were produced from the resultant emulsions under controlled electrospinning conditions. The composite matrices, thus developed using minimal organic solvent, are free from emulsifiers and have high potential to be used in applications including tissue engineering
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