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MK-Spritzguss mit Flüssigsilikonkautschuk (LSR) und Acrylnitril-Butadien-Styrol (ABS) für die Medizintechnik
Das Mehrkomponentenspritzgießen von Flüssigsilikonkautschuken (LSR) mit Thermoplasten, wie PBT oder Polyamid ist Stand der Technik und wird bei vielen Bauteilen in der Automobilindustrie und im Bereich der Sanitärtechnik im Herstellungsprozess angewendet. Standardthermoplaste, wie z. B. Acrylnitril-Butadien-Styrol (ABS) lassen sich wegen ihrer niedrigen Erweichungstemperatur bisher nicht mit Silikonkautschuken im Spritzgießverfahren verbinden. In diesem Beitrag wird anhand von medizintechnisch zugelassenen ABS-Typen gezeigt, wie man mit einer dynamischen Werkzeugbeheizung und verschiedenen Vorbehandlungsmethoden für die Thermoplast-Oberflächen ABS-LSR Probekörper herstellen kann. Zudem wird aufgezeigt, welchen Einfluss die Sterilisation solcher Bauteile auf den Haftverbund hat.Weiterlesen...
Development of tribological Properties of PMMA Dental Resins reinforced with CNTs
The current research aims to improve the accuracy of results obtained from a pin-on-disc tribometer by using stepper motors and linear actuators. Additionally, the research focuses on enhancing the tribological properties of PMMA by reinforcing it with 0.1, 0.2 and 0.3 wt% SWCNT or MWCNT. The researchers prepared cylindrical-shaped nanocomposite samples and subjected them to friction and wear tests using a pin-on-disc tribometer with stainless steel disks as counterparts. The results showed that the PMMA matrix containing 0.2 wt% of SWCNT and 0.1 wt% of MWCNT exhibited the best tribological properties with reduced friction coefficient and wear rate.Weiterlesen...
Determination of the Degree of cross-linking of Rubber Sheets based on their acoustic resonance Frequency
With a test rig developed at the IKV, the resonance frequency of small sheets of rubber can be measured in seconds. The measuring principle has the potential to be used to monitor the degree of cross-linking on-line. In order to evaluate the suitability of the resonance frequency for this measurement task, the hardness, compression set, static spring constant and loss factor were measured on pressed sheets in addition to the resonance frequency, and anisothermal relaxation tests were carried out. The tests confirm the applicability of the resonance frequency to determine the degree of cross-linking.Weiterlesen...
Using Projectile Injection Technology in the Elastomer Injection Moulding Process
Projectile injection technology (PIT) is a new approach for the production of hollow rubber parts that is already used in thermoplastics processing. However, there have been very few investigations on the PIT processing behaviour of rubber compounds. The flow and curing behaviours are mainly responsible for the surface quality achievable and residual wall thickness. Different compounds were chosen according to the projected applications.Weiterlesen...
Wie Krabbenabfälle biogene Pigmente in Druckfarben werden
Dem Fraunhofer IPA ist es zusammen mit der Uni Paderborn und Siegwerk gelungen, biogene Pigmente aus Chitin und biobasierte Farbstoffe herzustellen.Weiterlesen...
A coarse grained Model for the Simulation of dynamic Properties of filled Elastomers
We describe a modelling approach to the calculation of dynamic moduli of filled elastomers based on filler morphologies derived from the experimental interface tensions of the material‘s components. The proposed approach consists of two main parts. The first one is a Monte Carlo-based morphology generator, which is used to build model compounds on the µm-scale. In the second part, the Monte Carlo morphologies are mapped onto a topologically identical model, allowing to obtain the dynamic moduli. This combination of models ties the experimental surface tensions, characterizing the individual components, to the dynamic behavior of the macroscopic material.Weiterlesen...
Optimisation of the Simulation of Rubber Extrusion dies by means of the Integration of empirically determined charac-teristic Maps
By determining characteristic maps that describe the wall slip as a function of the compound composition and the extrusion temperature, boundary conditions in flow simulations can be determined in such a way that the effects on pressure and temperature distribu-tion in the extrusion process are considered. This enables an improved die design with fewer iteration steps. In addition, by means of a 2D simulation of the exit geometry, which only requires the pressure loss in the die as an input variable, the die geometry can be determined with minimal computing times in such a way that the extrudate geometry after swelling corresponds to the desired profile geometry.Weiterlesen...
Dynamic mechanical Analysis of Standard Indonesian Rubber
An essential component in an earthquake-resistant building is a seismic base isolator. Nowadays, seismic base isolators are usually produced from synthetic rubber such as Chloroprene Rubber (CR). This research investigated the possibility of combining CR and natural rubber. Specimens were prepared with different ratio compositions of CR and NR (SIR20). Surprisingly, the mechanical properties of 100 phr SIR20 fulfill the specification of the seismic base isolator. Dynamic Mechanical Analysis was also performed in the predominant earthquake frequencies. The mechanical and dynamic properties change slightly with temperature and frequency variations, which means the material is stable and predictable as seismic base isolators. The high loss factor indicates high damping properties, which is crucial in selecting seismic bearings.Weiterlesen...
Properties of ultrasonically devulcanized and revulcanized used Tire Rubber and their Blends with virgin natural Rubber
The continuous ultrasonic devulcanization of 40 mesh ground tire rubber (GTR) powder was carried out using an ultrasonically assisted twin-screw extruder. The die pressure and ultrasonic power consumption were recorded during the process. The gel fraction, crosslink density and revulcanization behavior were studied to investigate the degree of devulcanization. Untreated tire rubber (UTR) powder and ground tire rubbers after devulcanization were blended with natural rubber (NR) at different ratios Rheological properties, curing behavior, mechanical properties and abrasion loss of revulcanized rubbers were measured.Weiterlesen...
Tribological and mechanical Performance of HDPE/SWCNT Nanocomposites as Bearing Material
The nano-composite samples were prepared to the cylindrical shape and subjected to friction and wear tests using pin on disc tribometer. The samples were evaluated via examining the hardness, modulus of elasticity, and compressive yield stress. The results revealed that adding 0.4% by weight of SWCNT leads to improving the tribological and mechanical performance of HDPE matrix. It can be evident that the friction coefficient and weight loss were reduced with 20% and 24%, respectively, compared with pure sample. It can be noticed from the experiments that the modulus of elasticity and compressive yield stress increase about 25.6% and 57%, respectively.Weiterlesen...