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Current Research and Challenges in Bitumen Emulsion Manufacturing and Its Properties
(2022-03-09)
The global increase of road infrastructure and its impact on the environment requires serious attention to develop sustainable and environmentally friendly road materials. One group of those materials is produced by using bitumen emulsion. However, there are still scientific and technical obstacles standing against its regular application. The bitumen emulsion formulation process and compositional optimization are subjected to a high number of degrees of freedom. Consequently, obtaining the desired product is mostly ...
Aufsatz
Adsorption of PCE in alkali-activated materials analysed by fluorescence microscopy
(2021-10-18)
The realisation of high-performance concrete mixtures requires the use of superplasticizers to achieve a low water/binder ratio and thus high strengths. Polycarboxylate ethers (PCE) are mostly used as superplasticizers. The effectiveness of these superplasticizers depends on their chemical structure, the binders’ alkaline environment and the ions present in the pore solution of the binder. In high alkaline systems like some alkali-activated materials no effective superplasticizer have been found yet. To unravel the ...
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Simulation framework for crystallization in melt flows of semi-crystalline polymers based on phenomenological models
(2022-04-16)
Polymer components are shaped mostly out of the molten state. As in the case of semi-crystalline polymers, crystallization can be suppressed by shock cooling, thermal process design allows to influence the solid bodies properties. A simulation approach that enables to predict these properties based on a forecast of crystallinity is presented in this paper. The main effects to consider and possibilities of modeling and simulation are discussed. A detailed description of how to create an experimental foundation using ...
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Determination of Local Electrical Properties Using a Potential Field Measurement for Electrically Conductive Carbon Fiber Reinforced Plastics with Metal Contact Pins Joined via Injection Molding
(2022-07-09)
Carbon fiber reinforced plastics (CFRP) bear a high potential in terms of electrical conductivity and its potential applications. A locally resolved electrical measurement method for these anisotropic materials is a key prerequisite for understanding the structural and manufacturing process-related interrelationships. The aim of this paper is to develop a measurement method that allows this to be achieved and also to investigate areas of overmolded metal contact pins in detail. CFRP samples with polyamide 6 and ...
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Polyurethane-Based Gel Electrolyte for Application in Flexible Electrochromic Devices
(2022-06-28)
For the application in flexible electrochromic devices (ECDs) on plastic substrates, a new polyurethane-based gel electrolyte was manufactured. In this context, the curing behavior and the influence of the proportion of solvent and salt on the ion conductivity as well as the optical and mechanical properties were investigated. Furthermore, the stoichiometric ratio of the polyurethane matrix was varied to influence the ion conductivity. As an isocyanate component, the aliphatic difunctional polyisocyanate prepolymer, ...
Aufsatz
Liquid Silicone Rubber Foamed with Thermoplastic Expandable Microspheres
(2022-05-25)
To reduce the material costs as well as the density of Liquid Silicone Rubber (LSR), LSR foams can be produced in an injection molding process. Expandable thermoplastic microspheres can be used as blowing agents. This publication deals with the analysis of the cell structure of these LSR foams. For this purpose, cylindrical disks are injection molded and examined for their cell structure as a function of different proportions of microspheres using a scanning electron spectroscope. In addition, the density of the ...
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Adhesion of liquid silicone rubber (LSR) polypropylene (PP) composites after storage tests
(2022-07-15)
The objective of this study is the production of liquid silicone rubber (LSR) polypropylene (PP) composites. To create adhesion between LSR and thermoplastics, self-adhesive LSR types are available on the market. However, these materials are not effective for commodity thermoplastics, such as PP and no adhesion can be achieved between these two components. Therefore, the PP surface was activated by means of silicatization (flame treatment). Subsequently, the LSR was applied on the activated PP by an overmolding ...
Aufsatz
Demonstration of Hybrid Effect in Single Fiber Pull-Out Tests for Glass/Cellulose-Reinforced Polypropylene with Different Fiber–Matrix Adhesions
(2022-06-21)
In hybrid fiber reinforcement, the combination of glass and regenerated cellulose fibers is a promising combination because the different properties of the fibers can be combined. The properties of the regenerated cellulose fiber in combination with the absorption of energy by fiber pull-outs can thus significantly increase the toughness of the composite in the event of failure, while the glass fiber significantly increases the stiffness and strength due to its properties. In this study, the interaction of the two ...
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Dissimilar micro beam welding of titanium to Nitinol and stainless steel using biocompatible filler materials for medical applications
(2022-11-16)
In the present investigation, thin sheet geometries of commercially pure titanium (cp, grade 4) are butt-welded to AISI 316L stainless steel as well as Nitinol by means of micro electron beam welding using filler materials. In order to avoid mixing of the base materials, the refractory metals tantalum, niobium and hafnium are applied as intermediate layers. Owing to the biocompatibility of these filler materials, the final products are suitable for medical technology applications. In combination with low energy inputs ...
Aufsatz
Effect of Surfactants on the Flow Patterns of Horizontal Tube Bundles with a Falling Film
(2020-03-24)
The influence of two alcoholic surfactants on the flow patterns of falling film tube bundles is investigated. The flow patterns are measured in a single‐stage absorption chiller in the absence of surfactants. The surface tension of H2O/aqueous LiBr solution with different concentrations of 1‐octanol and 2‐ethylhexanol is measured at low pressure in a saturated atmosphere. Small quantities of surfactants in the aqueous solution do not have an influence on the flow patterns of the condenser and evaporator, while a shift ...