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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, ...
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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 ...
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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 ...
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Use of Design of Experiments (DoE) to Model the Sulphate Agent Amount of (Ultra)Finely Ground and Fast Hardening Portland Cement Clinker
(2021-09-25)
This paper presents a model to calculate the sulphate agent amount and sulphate agent ratio for fine grounded and fast hardening Portland cement clinker. Despite sufficient knowledge about the influence of calcium sulphate on the hydration process of cement, the sulphate agent amount is mostly adjusted empirically. As a result, often a wide and unfeasible experimental matrix has to be tested. In this work, Design of Experiments (DoE) was used in combination with in-situ X-ray diffraction (XRD) tests to accurately ...
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Measurement and analysis of residual stresses and warpage in fiber reinforced plastic and hybrid components
(2021-02-16)
Glass/carbon fiber reinforced plastic (GFRP/CFRP) and hybrid components have attracted increasing attention in lightweight applications. However, residual stresses induced in the manufacturing process of these components can result in warpage and, eventually, negatively affect the mechanical performance of the composite structures. In the present work, GFRP, CFRP, GFRP/steel and CFRP/steel hybrid components were manufactured through the prepreg-press-technology always employing the same process parameters. The residual ...
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Influence of hot deformation on the precipitation hardening of high-strength aluminum AA7075 during thermo-mechanical processing
(2021-04-21)
The aim of this work was to investigate the effect of hot deformation on the aging behavior of precipitation-hardenable aluminum alloy AA7075 within a novel thermo-mechanical forming process, in order to gain insight into its precipitation kinetics. For this purpose, the material was formed at 420 °C after undergoing solution treatment to different strain levels ranging from 2% to 10% to obtain different dislocation densities. After undergoing hot deformation, aging at 120 °C with different parameters was carried out ...
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Liquid Silicone Rubber Foams Made with Water as Blowing Agent
(2021-08-18)
Liquid silicone rubber (LSR) is primarily used in injection molding. Foamed molded parts made of LSR are almost nonexistent because the process reliability of LSR foam injection molding is currently not given. It makes sense to have suitable foaming processes for this material as well, because the density of this elastomer is about 1.15 g cm−3. With the injection molding process presented herein for foaming LSR, density reductions of up to 40% can be achieved. In this process, up to 3% by weight of water is added to ...
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A Critical Review on the Complex Potentials in Linear Elastic Fracture Mechanics
(2022-01-03)
Introducing a crack in an elastic plate is challenging from the mathematical point of view and relevant within an engineering context of evaluating strength and reliability of structures. Accordingly, a multitude of associated works is available to date, emanating from both applied mathematics and mechanics communities. Although considering the same problem, the given complex potentials prove to be different, revealing various inconsistencies in terms of resulting stresses and displacements. Essential information on ...