| 1. |
- Achtel, Christian, et al.
(författare)
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Surprising Insensitivity of Homogeneous Acetylation of Cellulose Dissolved in Triethyl(n-octyl)ammonium Chloride/Molecular Solvent on the Solvent Polarity
- 2018
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Ingår i: Macromolecular materials and engineering. - : Wiley-VCH Verlag. - 1438-7492 .- 1439-2054. ; 303:5
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Tidskriftsartikel (refereegranskat)abstract
- The homogeneous acetylation of microcrystalline cellulose (MCC) by acetyl chloride and acetic anhydride in triethyl(n-octyl)ammonium chloride (N2228Cl)/molecular solvents (MSs) is investigated. The reaction with both acylating agents shows the expected increase of the degree of substitution (DS) on reaction temperature and time. Under comparable reaction conditions, however, DS is surprisingly little dependent on the MS employed, although the MSs differ in empirical polarity by 7 kcal mol−1 as calculated by use of solvatochromic probes. The empirical polarities of (MCC + N2228Cl + MS) differ only by 0.8 kcal mol−1. The formation a polar electrolyte sheath around cellulose chains presumably contributes to this “leveling-off†of the dependence DS on the polarity of the parent MS employed. N2228Cl recovery and recycling is feasible. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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| 2. |
- Gabrielsson, Erik, et al.
(författare)
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Spatiotemporal Control of Amyloid-Like A Plaque Formation Using a Multichannel Organic Electronic Device
- 2016
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Ingår i: Macromolecular materials and engineering. - : WILEY-V C H VERLAG GMBH. - 1438-7492 .- 1439-2054. ; 301:4, s. 359-363
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Tidskriftsartikel (refereegranskat)abstract
- We herein report on an iontronic device to drive and control A1-40 and A1-42 fibril formation. This system allows kinetic control of A aggregation by regulation of H+ flows. The formed aggregates show both nanometer-sized fibril structure and microscopic growth, thus mimicking senile plaques, at the H+-outlet. Mechanistically we observed initial accumulation of A1-40 likely driven by electrophoretic migration which preceded nucleation of amyloid structures in the accumulated peptide cluster.
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| 3. |
- Jedvert, Kerstin, et al.
(författare)
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Adsorption Studies of Amino Cellulose on Cellulosics
- 2017
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Ingår i: Macromolecular materials and engineering. - : Wiley. - 1438-7492 .- 1439-2054. ; 302:7
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Tidskriftsartikel (refereegranskat)abstract
- Adsorption of a typical example of a new class of amino cellulose, namely 6-deoxy-6-(2-aminoethyl)amino cellulose at different pH-values and in the presence of electrolytes, onto cellulose model substrates is studied with surface plasmon resonance and quartz crystal microbalance with dissipation monitoring. Unexpectedly, adsorption is consistently higher at a higher pH-value of 10, indicating that solubility and interactions between amine moieties and cellulose are more important than electrostatic interactions. The findings are highly relevant for the process to modify material surfaces with amino cellulose in water-based systems as a universal tool for changing the surface properties and chemistry. Potential applications for an antimicrobial all biobased material could be found, e.g., as medical textiles or in the biotechnology sector.
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| 4. |
- Meszynska, Anna, et al.
(författare)
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Effect of Oligo-Hydroxyalkanoates on Poly(3-Hydroxybutyrate-co-4-Hydroxybutyrate)-Based Systems
- 2015
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Ingår i: Macromolecular materials and engineering. - : Wiley. - 1438-7492 .- 1439-2054. ; 300:6, s. 661-666
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Tidskriftsartikel (refereegranskat)abstract
- This study presents the utilization of oligo-hydroxyalkanoates obtained from controlled degradation of poly(3-hydroxybutyrate) as additives in a poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymer matrix (P(3HB-co-4HB)). These oligomers are compared to a conventional biobased plasticizer, used as reference, based on a monoglyceride acetate obtained from hydrogenated castor oil. Different multiphase systems are elaborated with these additives and characterized. Thermal and mechanical properties demonstrate that the monoglyceride acetate is as an efficient plasticizer increasing the elongation of the P(3HB-co-4HB) films while decreasing their maximum strength and elastic modulus. On the contrary, the addition of oligo-PHB results in an increased crystallinity of the matrix, thus improving the maximum strength and elastic modulus of the corresponding films. The oligomers act as an efficient reinforcing agent. Mobility brought by the oligomers induces a rearrangement of the P(3HB-co-4HB) with an increase of the chain rearrangement. Interestingly, the simultaneous addition of both additives results in significantly reduced T-g and improved elongation at break, as expected from an efficient plasticizer, but it also leads to P(3HB-co-4HB) films retaining relatively high strength and modulus values, thanks to the reinforcement ability of the oligo-PHB additive. Thermal characterization finally demonstrated that such mixed additives system results in greatly improved thermal stability of the polyhydroxyalkanoate copolymer matrix.
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| 5. |
- Naue, Ingo F. C., et al.
(författare)
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A new high sensitivity system to detect instabilities during the extrusion of polymer melts
- 2015
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Ingår i: Macromolecular Materials and Engineering. - : Wiley. - 1439-2054 .- 1438-7492. ; 300:11, s. 1141-1152
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Tidskriftsartikel (refereegranskat)abstract
- This publication is concerned with the development of a novel high sensitivity instability detection die for a laboratory size extruder. The high sensitivity detection system consists of piezoelectric transducers placed along the die length to monitor local pressure fluctuations, having temporal and pressure resolutions of up to ∆t ~ 10−3 s and ∆p ~ 10−5 bar, at a nominal pressure of 500 bar. The system is tested on short chain branched polyethylenes, namely on the detection and characterization of the sharkskin instability. It is shown that the determined instabilities are related to characteristic peaks in the corresponding in-situ pressure Fourier-transform spectra and that other peaks are caused by different, but defined, sources. The in situ results obtained are validated through optical image analysis of the instabilities. The implementation of high sensitivity detection systems on industrial processing equipment could lead to new methods for online process optimization, specifically maximum processing throughput at minimum energy consumption, and additionally in quality control.
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| 6. |
- Sun, Yang, et al.
(författare)
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Reinforced Degradable Biocomposite by Homogenously Distributed Functionalized Nanodiamond Particles
- 2015
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Ingår i: Macromolecular materials and engineering. - : Wiley. - 1438-7492 .- 1439-2054. ; 300:4, s. 436-447
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Tidskriftsartikel (refereegranskat)abstract
- Severe phase separation was observed in blending nanodiamond particle (n-DP) in poly (L-lactide-co-e-caprolactone) (poly(LLA-co-CL)) scaffold. In this study we optimized the scaffold by the addition of 1-50% (w/w) polylactide modified n-DP (n-DP-PLA) or benzoquinone-modified n-DP (n-DP-BQ). Composed by 10% n-DP-PLA, composite had 6 times higher E-modulus in tensile test, whereas the maximum reinforcement can be higher than 15 times. However, n-DP-BQ composites conserved the mechanical properties, and thermal properties of the polymer substrate. The attachment, spreading and growth of UE7T13 cells on modified n-DP composites were similar to poly(LLA-co-CL), and independent to n-DP concentrations. In summary, a proper modified n-DP is the key to reinforce poly(LLA-co-CL) for tissue engineering.
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| 7. |
- Träger, Andrea, et al.
(författare)
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Interpenetrated Networks of Nanocellulose and Polyacrylamide with Excellent Mechanical and Absorptive Properties
- 2018
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Ingår i: Macromolecular materials and engineering. - : Wiley. - 1438-7492 .- 1439-2054. ; 303:5
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Tidskriftsartikel (refereegranskat)abstract
- Composites based on interpenetrating networks (IPNs) of cellulose nanofibril (CNF) aerogels and polyacrylamide are prepared and exhibit robust mechanical, water retaining, and re-swelling capacities. Furthermore, their swelling behavior is not affected by an increased ionic strength of the aqueous phase. These unprecedented IPNs combine the water retaining capacity of the polyacrylamide with the mechanical strength provided by the CNF aerogel template. The CNF aerogel/polyacrylamide composites exhibit a compressive stress at break greater than 250% compared with a neat polyacrylamide hydrogel. Furthermore, the composites retain their wet compression properties after drying and re-swelling, whereas the neat polyacrylamide hydrogels fail at a significantly lower stress and strain after drying and re-swelling. These composite materials highlight the potential of CNF aerogels to strengthen the mechanical properties and reduce the number of fracture defects during the drying and re-swelling of a hydrogel. These composites show the potential of being optimized for a plethora of applications, especially in the hygiene field and for biomedical devices.
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