Dem Fraunhofer IPA ist es zusammen mit der Uni Paderborn und Siegwerk gelungen, biogene Pigmente aus Chitin und biobasierte Farbstoffe herzustellen.Weiterlesen...

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...

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...

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...

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...

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...

In rubber extrusion, stable pressure and throughput over time is of central importance for the quality of the extrudate. One challenge is the non-uniform material intake of feed strips. Variable feed behaviour causes pressure and throughput fluctuations in the feed zone, which propagate to the die and may lead to dimensional deviations of the extrudate. The feed roller speed can influence the intake of the feed strip and therefore help to keep steady the pressure in the feed zone. Thanks to a measurement of the drive torques from the screw and the feed roller, deviations in the feeding can quickly be identified.Weiterlesen...

The model for strain-induced crystallization (SIC) in elastomer networks proposed by Plagge and Hentschke [1] is extended for the simulation of rupture. A critical force for rupture of links, i.e. the polymer chains in the model network, is defined. The variation of parameters which affect the structure of the networks or the free energy of the links has not improved the tensile strength of strain-crystallizing networks compared to non-crystallizing networks in both the 2D- and the 3D-case. Thus, a critical crystallinity is introduced. If the crystallinity of a link exceeds this threshold, the link becomes unbreakable. The tensile strength of crystallizing 2D- and 3D-networks has improved significantly.Weiterlesen...

This paper presents of sophisticated aspects of the N-(1,3-benzothiazol-2-ylsulfanyl)cyclohexanamine-accelerated vulcanization of isoprene rubber (IR) as a mini-reviewed, where zinc oxide (ZnO), stearic acid (StH) and/or zinc stearate are used as activators. The combination of these activators enables the control of the mesh size in the network, where new complexes are generated by a reaction of ZnO with StH, or by zinc stearate near the vulcanization temperature. The complexes accelerate the sulfur cross-linking of IR like an enzyme. An electron-transfer and a dispersion effects of IR for the complexes play roles of the acceleration of cross-linking and the formation of homogeneous network structure, respectively. In addition, the complexes predominantly generate the disulfidic linkages in the sulfur cross-linking.Weiterlesen...

Tire wear significantly contributes to the growing amount of microplastic in the environment. It is found in the waters and in the soils, meanwhile also in living beings.Weiterlesen...