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Josef Breu - One of the best experts on this subject based on the ideXlab platform.
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transfer batch blending an innovative solvent solid assisted method for melt compounding to achieve good Dispersion Quality for polymer clay nanocomposites
Composites Science and Technology, 2015Co-Authors: Josef Hausner, Mazen Ziadeh, Bianca Fischer, Hussein Kalo, Jasmin Schmid, Raphael Kunz, Volker Altstädt, Josef BreuAbstract:Abstract The specific interface area between filler and matrix is of key importance for the performance of nanocomposites and therefore blending methods that deliver the best possible Dispersion Quality, while at the same time being technically benign, are sought-after. Transfer batch blending, as proposed here, utilizes an organic separator compound that is highly volatile at melt compounding temperatures allowing for its easy removal, while being solid at room temperature allowing for easy handling and processing. As judged by particle size distributions for redissolved nanocomposites and TEM micrographs, the Quality of Dispersion achieved by this transfer batch blending is of comparably high Quality as the Quality achieved by solution blending and is clearly superior to the Quality obtained by melt blending. Permeability was chosen as the nanocomposite property used to probe Dispersion Quality as achieved by the different blending methods. For both fillers applied, organically modified natural montmorillonites and synthetic hectorites, transfer batch blending consistently delivered significantly higher reductions of the permeability suggesting that higher effective aspect ratios are achieved via the improved Dispersion Quality by transfer blending as compared to melt blending.
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Transfer batch blending, an innovative solvent/solid assisted method for melt compounding to achieve good Dispersion Quality for polymer–clay-nanocomposites
Composites Science and Technology, 2015Co-Authors: Josef Hausner, Mazen Ziadeh, Bianca Fischer, Hussein Kalo, Jasmin Schmid, Raphael Kunz, Volker Altstädt, Josef BreuAbstract:Abstract The specific interface area between filler and matrix is of key importance for the performance of nanocomposites and therefore blending methods that deliver the best possible Dispersion Quality, while at the same time being technically benign, are sought-after. Transfer batch blending, as proposed here, utilizes an organic separator compound that is highly volatile at melt compounding temperatures allowing for its easy removal, while being solid at room temperature allowing for easy handling and processing. As judged by particle size distributions for redissolved nanocomposites and TEM micrographs, the Quality of Dispersion achieved by this transfer batch blending is of comparably high Quality as the Quality achieved by solution blending and is clearly superior to the Quality obtained by melt blending. Permeability was chosen as the nanocomposite property used to probe Dispersion Quality as achieved by the different blending methods. For both fillers applied, organically modified natural montmorillonites and synthetic hectorites, transfer batch blending consistently delivered significantly higher reductions of the permeability suggesting that higher effective aspect ratios are achieved via the improved Dispersion Quality by transfer blending as compared to melt blending.
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On the importance of specific interface area in clay nanocomposites of PMMA filled with synthetic nano-mica
Polymer, 2014Co-Authors: Mazen Ziadeh, Bianca Fischer, Jasmin Schmid, Volker Altstädt, Josef BreuAbstract:Abstract In clay nanocomposites, the specific interface area is the key factor determining potential improvements of properties. Nevertheless, in most systematic studies of nanocomposites little emphasis is put on assuring and characterizing Dispersion Quality. To probe the influence of Dispersion Quality, we compare nanocomposites filled with two layered silicates which were made by melt compounding and solution blending, respectively. Poly(methyl methacrylate) (PMMA) is chosen here as a thermoplastic model matrix which was compounded with a synthetic nano-mica (O-hect) and commercial Bentone with typical diameters of 5–7 μm and The Dispersion Quality was monitored by μ-computer tomography (μ-CT) and transmission electron microscopy (TEM). Moreover, gas barrier measurements proved to be an additional independent and very sensitive probe. Reductions of the oxygen permeation at ∼4 wt.% by 60% and 30% for solution blended and melt compounded samples directly evidence a mediocre Dispersion in the latter. Structure-property relationships were established by in-depth mechanical testing and the properties were correlated with the improved morphology. Significantly higher stiffness was achieved by enhanced Dispersion Quality for O-hect-filled nanocomposites without causing any embrittlement. Interestingly, a maximum increase of fracture toughness (63%) was obtained at filler content as low as 0.8 vol.% for the solution blended sample. A similar improvement of fracture toughness for the melt compounded sample afforded more than twice the clay content emphasising the crucial influence of specific surface area. This highlights the importance of the solution blending method to exploit the full potential of nanofillers and suggests that only samples with comparable Dispersion Quality may be compared.
Mathias Ulbricht - One of the best experts on this subject based on the ideXlab platform.
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Polymer Nanocomposite Ultrafiltration Membranes: the Influence of Polymeric Additive, Dispersion Quality and Particle Modification on the Integration of Zinc Oxide Nanoparticles into Polyvinylidene Difluoride Membranes.
Membranes, 2020Co-Authors: Thorsten Van Den Berg, Mathias UlbrichtAbstract:This study aims to improve the understanding of the influence of metal oxide nanofillers on polyvinylidene difluoride (PVDF) ultrafiltration membranes. Zinc oxide nanoparticles were chosen as the model filler material. The membranes were prepared by non-solvent induced phase separation from PVDF solutions in N-methylpyrrolidone. The influences of the addition of polyvinylpyrrolidone (PVP), the nanoparticle Dispersion Quality, and a surface modification of the ZnO particles with PVP on the nanofiller integration into the polymer matrix and the resulting membrane separation performance, were evaluated. Unmodified and PVP-modified nanoparticles were characterized by evaluation of their Hansen solubility parameters. The membranes were characterized by ultrafiltration experiments, scanning electron microscopy (SEM) and with respect to mechanical properties, while the dope solutions were analyzed by rheology in order to judge about Dispersion Quality. Pure water permeability and solute rejection data revealed that the dominant effect of the addition of pristine ZnO nanoparticles was a major decrease in permeability caused by pore blocking. In SEM analyses, it was seen that the plain nanofiller did not integrate well into the polymer matrix. Importantly, it was found that the surface modification of the nanofiller, as well as a high Dispersion Quality, can be strategically used to enhance the integration of the nanofiller and thus suppress pore blocking, leading to membranes with high ultrafiltration rejection and permeability simultaneously. Overall, the study provides relevant insights into a new approach to integrating nanofillers into polymer nanocomposite membranes for improving their properties and performance.
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Stable zinc oxide nanoparticle Dispersions in ionic liquids
Journal of Nanoparticle Research, 2014Co-Authors: Alexandra Wittmar, Devendraprakash Gautam, Carolin Schilling, Udo Dörfler, Wolfgang Mayer-zaika, Markus Winterer, Mathias UlbrichtAbstract:The influence of the hydrophilicity and length of the cation alkyl chain in imidazolium-based ionic liquids on the dispersability of ZnO nanoparticles by ultrasound treatment was studied by dynamic light scattering and advanced rheology. ZnO nanopowder synthesized by chemical vapor synthesis was used in parallel with one commercially available material. Before preparation of the Dispersion, the nanoparticles characteristics were determined by transmission electron microscopy, X-ray diffraction, nitrogen adsorption with BET analysis, and FT-IR spectroscopy. Hydrophilic ionic liquids dispersed all studied nanopowders better and in the series of hydrophilic ionic liquids, an improvement of the Dispersion Quality with increasing length of the alkyl chain of the cation was observed. Especially, for ionic liquids with short alkyl chain, additional factors like nanoparticle concentration in the Dispersion and the period of the ultrasonic treatment had significant influence on the Dispersion Quality. Additionally, nanopowder characteristics (crystallite shape and size as well as the agglomeration level) influenced the Dispersion Quality. The results indicate that the studied ionic liquids are promising candidates for absorber media at the end of the gas phase synthesis reactor allowing the direct preparation of non-agglomerated nanoparticle Dispersions without supplementary addition of dispersants and stabilizers.
Jonathan N. Coleman - One of the best experts on this subject based on the ideXlab platform.
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Quantitative comparison of ultracentrifuged and diluted single walled nanotube Dispersions; differences in Dispersion Quality
Chemical Physics Letters, 2009Co-Authors: Helen Cathcart, Jonathan N. ColemanAbstract:Abstract We have carried out a quantitative comparison of the Dispersion Quality for ultracentrifuged and diluted surfactant-stabilised single walled nanotube Dispersions. We have characterised these Dispersions at a fixed concentration of ∼30 μg mL −1 by absorption and photoluminescence spectroscopy as well as by statistical atomic force microscopy. Both the ultracentrifuged and the diluted samples contained significant quantities of bundles as well as individual nanotubes. The ultracentrifuged sample contained ∼4 times more individualised SWNTs than the diluted sample with partial concentrations of individual nanotubes of 4.8 and 1.1 μg mL −1 , respectively.
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Effects of Ambient Conditions on Solvent-Nanotube Dispersions: Exposure to Water and Temperature Variation
The Journal of Physical Chemistry C, 2009Co-Authors: Zhenyu Sun, Shane D Bergin, Ian O'connor, Jonathan N. ColemanAbstract:Dispersions of single walled nanotubes in N-methyl-2-pyrrolidone (NMP) have been exposed to water and variations in storage temperature. The subsequent degradation of Dispersion Quality has been monitored using sedimentation, UV-vis-NIR, and atomic force microscopy (AFM) measurements. Four parameters derived from AFM; the root-mean-square bundle diameter, the total number of dispersed objects (individuals and bundles) per unit volume of Dispersion, the number fraction of individual nanotubes, and the number of individual nanotubes per unit volume of Dispersion were used to quantitatively characterize the Dispersion Quality as a function of water content and storage temperature. In addition the positions of the nanotube absorption peaks were used to track Dispersion Quality, with redshifts taken as an indication of aggregation. It was found that water can rapidly shift the Dispersion to a new but more aggregated equilibrium state. In particular the population of individual nanotubes falls to zero for relatively low amounts of added water. The Dispersion Quality decreases with increasing water content, reaching a plateau for all metrics by 20 vol % added water. In addition, it was also identified that low temperature treatment, i.e. -16, -18, -20, and -22 °C (all above the freezing point of NMP) does not influence the Dispersion Quality and stability regardless of the treatment time. However, freezing (-80 °C) or heating (80 °C) the Dispersion leads to a substantial degradation of the Dispersion Quality and stability. 1.0. Introduction
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quantitative evaluation of surfactant stabilized single walled carbon nanotubes Dispersion Quality and its correlation with zeta potential
Journal of Physical Chemistry C, 2008Co-Authors: Valeria Nicolosi, David Rickard, Shane D Bergin, Damian Aherne, Jonathan N. ColemanAbstract:Stable Dispersions of single-walled carbon nanotubes in deionized water were prepared using six common surfactants: sodium dodecylbenzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), lithium dodecyl sulfate (LDS), tetradecyl trimethyl ammonium bromide (TTAB), sodium cholate (SC), and Fairy liquid (FL). For all nanotube Dispersions (CNT = 1 mg/mL), the optimum concentration of surfactant was found to be close to CSurf = 10 mg/mL by measuring the fraction of nanotubes remaining after centrifugation for a range of surfactant concentrations. The aggregation state of each nanotube−surfactant Dispersion was characterized as a function of nanotube concentration by AFM analysis of large numbers of nanotubes/bundles deposited onto substrates. The Dispersion Quality could then be quantified by four parameters: the saturation value (at low concentration) of the root-mean-square bundle diameter, the maximum value of the total number of dispersed objects (individuals and bundles) per unit volume of Dispersion, the ...
N.-m. Barkoula - One of the best experts on this subject based on the ideXlab platform.
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On the efficiency of UV–vis spectroscopy in assessing the Dispersion Quality in sonicated aqueous suspensions of carbon nanotubes
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2016Co-Authors: P. Alafogianni, Konstantinos G. Dassios, S. Farmaki, S.k. Antiohos, Theodore E. Matikas, N.-m. BarkoulaAbstract:Abstract The present study evaluates carbon nanotube (CNT) Dispersion Quality in sonicated aqueous suspensions assisted by two types of dispersive agents, an ionic surfactant commonly used in nanocomposite development and a plasticizer-type dispersant relevant to cementitious matter. Dispersion Quality is assessed by UV–vis spectroscopy and related to experimental parameters such as sonication duration/energy, dispersant type and concentration, and CNT loading. The results obtained from the versatile and straightforward methodology are compared to those obtained by the more complex and analytical Liquid Mode Laser Diffractometry (LMLD). The efficiency of UV–vis spectroscopy in effectively following the sonication process and in capturing its different stages is investigated and conclusions concerning the relation between surfactant concentration and sonication duration for achievement of monodisperse suspensions are drawn. The efficiency of the two assistive agents with regard to Dispersion Quality is compared and discussed in the text.
Mazen Ziadeh - One of the best experts on this subject based on the ideXlab platform.
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transfer batch blending an innovative solvent solid assisted method for melt compounding to achieve good Dispersion Quality for polymer clay nanocomposites
Composites Science and Technology, 2015Co-Authors: Josef Hausner, Mazen Ziadeh, Bianca Fischer, Hussein Kalo, Jasmin Schmid, Raphael Kunz, Volker Altstädt, Josef BreuAbstract:Abstract The specific interface area between filler and matrix is of key importance for the performance of nanocomposites and therefore blending methods that deliver the best possible Dispersion Quality, while at the same time being technically benign, are sought-after. Transfer batch blending, as proposed here, utilizes an organic separator compound that is highly volatile at melt compounding temperatures allowing for its easy removal, while being solid at room temperature allowing for easy handling and processing. As judged by particle size distributions for redissolved nanocomposites and TEM micrographs, the Quality of Dispersion achieved by this transfer batch blending is of comparably high Quality as the Quality achieved by solution blending and is clearly superior to the Quality obtained by melt blending. Permeability was chosen as the nanocomposite property used to probe Dispersion Quality as achieved by the different blending methods. For both fillers applied, organically modified natural montmorillonites and synthetic hectorites, transfer batch blending consistently delivered significantly higher reductions of the permeability suggesting that higher effective aspect ratios are achieved via the improved Dispersion Quality by transfer blending as compared to melt blending.
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Transfer batch blending, an innovative solvent/solid assisted method for melt compounding to achieve good Dispersion Quality for polymer–clay-nanocomposites
Composites Science and Technology, 2015Co-Authors: Josef Hausner, Mazen Ziadeh, Bianca Fischer, Hussein Kalo, Jasmin Schmid, Raphael Kunz, Volker Altstädt, Josef BreuAbstract:Abstract The specific interface area between filler and matrix is of key importance for the performance of nanocomposites and therefore blending methods that deliver the best possible Dispersion Quality, while at the same time being technically benign, are sought-after. Transfer batch blending, as proposed here, utilizes an organic separator compound that is highly volatile at melt compounding temperatures allowing for its easy removal, while being solid at room temperature allowing for easy handling and processing. As judged by particle size distributions for redissolved nanocomposites and TEM micrographs, the Quality of Dispersion achieved by this transfer batch blending is of comparably high Quality as the Quality achieved by solution blending and is clearly superior to the Quality obtained by melt blending. Permeability was chosen as the nanocomposite property used to probe Dispersion Quality as achieved by the different blending methods. For both fillers applied, organically modified natural montmorillonites and synthetic hectorites, transfer batch blending consistently delivered significantly higher reductions of the permeability suggesting that higher effective aspect ratios are achieved via the improved Dispersion Quality by transfer blending as compared to melt blending.
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On the importance of specific interface area in clay nanocomposites of PMMA filled with synthetic nano-mica
Polymer, 2014Co-Authors: Mazen Ziadeh, Bianca Fischer, Jasmin Schmid, Volker Altstädt, Josef BreuAbstract:Abstract In clay nanocomposites, the specific interface area is the key factor determining potential improvements of properties. Nevertheless, in most systematic studies of nanocomposites little emphasis is put on assuring and characterizing Dispersion Quality. To probe the influence of Dispersion Quality, we compare nanocomposites filled with two layered silicates which were made by melt compounding and solution blending, respectively. Poly(methyl methacrylate) (PMMA) is chosen here as a thermoplastic model matrix which was compounded with a synthetic nano-mica (O-hect) and commercial Bentone with typical diameters of 5–7 μm and The Dispersion Quality was monitored by μ-computer tomography (μ-CT) and transmission electron microscopy (TEM). Moreover, gas barrier measurements proved to be an additional independent and very sensitive probe. Reductions of the oxygen permeation at ∼4 wt.% by 60% and 30% for solution blended and melt compounded samples directly evidence a mediocre Dispersion in the latter. Structure-property relationships were established by in-depth mechanical testing and the properties were correlated with the improved morphology. Significantly higher stiffness was achieved by enhanced Dispersion Quality for O-hect-filled nanocomposites without causing any embrittlement. Interestingly, a maximum increase of fracture toughness (63%) was obtained at filler content as low as 0.8 vol.% for the solution blended sample. A similar improvement of fracture toughness for the melt compounded sample afforded more than twice the clay content emphasising the crucial influence of specific surface area. This highlights the importance of the solution blending method to exploit the full potential of nanofillers and suggests that only samples with comparable Dispersion Quality may be compared.