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Die Untersuchung beschäftigt sich mit einer neuen Spritzgießtechnologie zur Herstellung von Bauteilen aus Elastomeren. Mit dieser Technologie sind kürzere Zykluszeiten bei gleichbleibenden Bauteileigenschaften möglich. Die Höhe der Heizzeitreduzierung hängt von der Art der Bestimmung derselben ab und wird in der vorliegenden Arbeit auf unterschiedliche Weise quantitativ bestimmt. Je nach Verfahrensparameter und Bestimmungsmethode treten
Heizzeitreduzierungen von maximal etwa 40 % auf. Weiterhin werden Untersuchungen an den hergestellten Bauteilen durchgeführt, welche die Interpretation des Ausmaßes und der Qualität der Vernetzungsdichte über dem Probenquerschnitt erlauben. Es können deutliche Heizzeiteinsparungen bei mindestens gleichbleibenden und teilweise homogeneren Vernetzungsdichten über dem Querschnitt eines dickwandigen Elastomerbauteils attestiert werden.
Moderne Elastomere
(2009)
Semi-quantitative mechanical characterisation of fibre composites in the sub-micron-range by SFM
(2001)
Erratum: Homogeneity of Fillers Loaded Rubbers Investigated by the Dynamic Indentation Method
(2002)
The ongoing miniaturization, multi-layer structure parts and hybrid parts require methods to determine mechanical properties on a micro-scale. However, there is a gap in measuring techniques. On one hand there are the classical methods to measure hardness e.g. VICKERS, ROCKWELL, UNIVERSAL, IRHD etc having resolutions typically above 100μm. On the other hand there are well-developed AFM methods that allow for the determination of mechanical properties in the nanometer range. This paper describes an indentation technique that yields data of mechanical properties in the micrometer range between typically 5 to 50 μm. The measuring device and the data evaluation is presented. Results of micro-mechanical mapping are shown for NR-SBR rubber interfaces, a fuel tank and a part manufactured by two component injection moulding. Finally, the measured micro-mechanical stiffness is compared to the YOUNG’s modulus of the corresponding materials.
The ongoing use of miniaturization, multi layer structure parts, and hybrid parts requires methods to determine mechanical properties on a micro scale. However, there is a gap in measuring techniques. On one hand there are the classical methods to measure hardness, e.g., Vickers, Rockwell, Universal, and IRHD, having resolutions typically above 100 µm. On the other hand, there are well-developed AFM methods that allow for the determination of mechanical properties in the nanometer range. This article describes an indentation technique that yields data of mechanical properties in the micrometer range between typically 5 and 50 µm. The measuring device and the data evaluation are presented. Results of micro-mechanical mapping are shown for NR-SBR rubber interfaces, a fuel tank, and a part manufactured by two-component injection molding. Finally, the measured micro-mechanical stiffness is compared to the Young's modulus of the corresponding materials.
The heterogeneous effects due to filler interactions and chain dynamics of reinforcing nano-filler particles were characterized on a series of filled EPDM elastomers using the Payne effect and low field NMR, 1H transverse (T2), longitudinal (T1) and longitudinal in rotating frame (T1ρ) relaxation time measurements. Measurement of the Payne effect and NMR relaxation curves were used to obtain the distribution of filler/filler interactions and chain dynamics by one-dimensional Laplace inversion. Distributions of shear-strain constants in the Payne effect reveal the existence of weak, medium and strong filler/filler interactions which were correlated to filler properties and content. The analysis of relaxation-time distributions leads to the identification of multimodal polymer network dynamics.
Quantification of sulfur distribution on rubber surfaces by means of μ-X-ray fluorescence analysis
(2023)
A homogeneous distribution of sulfur in a rubber compound is often desired. Spatially resolved imaging techniques are useful for evaluating the distribution of this crosslinking chemical. Typical measurement methods such as SEM (scanning electron microscopy) or TEM (transmission electron microscopy) have very high resolutions. However, the sample size or the maximum area to be investigated is limited, which makes it difficult to obtain a statistically reliable determination of sulfur homogeneity across the component or sample.
In this work, an alternative measurement technique is therefore presented: the μ-XRF (μ-X-ray fluorescence analysis). With the help of this method, it is possible to scan surfaces of several cm2 and to show the distribution of different chemical elements. Its measuring principle has been known for decades but has hardly been used in the rubber industry so far.
The main reason for this is that its quantification process for polymeric samples is more complex than for geologic or metallic samples, which are typically been investigated with μ-XRF to date. In this paper, this issue is addressed and a solution is presented: With the help of the fundamental parameter method, the determination of sulfur homogeneity and distribution on rubber surfaces becomes possible. This opens up a variety of further possibilities for the use of μ-XRF in the rubber industry: For example, it could be used in areas of tire production, recycling of end-of-life rubber, and beyond.
Commercially available ground tyre rubber (GTR) made exclusively from post-consumer truck tyres was mixed into a typical truck tyre tread compound. As already shown in a previous study, this leads to a distinct deterioration in properties. The goal of the present investigation was to minimise these property losses through modification of the GTR in terms of processing methods. Modification methods already documented in the literature were used, e.g. application of sulphur and crosslinking agents to the GTR and the use of trans-polyoctenamer as well as liquid polymers, which in principle provide the potential for crosslinking of the GTR and polymer matrix through the availability of double bonds. For some methods of modification, small improvements are observed in comparison with the unmodified GTR. However, none of the GTR modifications reaches the level of the reference compound without GTR. An economic estimate for the modification with the highest potential for technical success shows that, in practice, considerable costs must be expected.
Der Einfluss von Lkw-Reifenmehl als Additiv auf die Eigenschaften einer Lkw-Laufflächenmischung
(2016)
Commercially available ground tire rubber (GRT) was mixed into a typical truck tire tread compound. The GRT originated from postconsumer truck tires and differed in the manufacturing process (cryogenic and warm grinding, resp.) as well as the ageing state. Regardless of the grinding process type, the vulcanizates containing GRT became softer, mechanical properties and the abrasion resistance worse and the Payne effect decreased. Additional artificial ageing of the GRT showed no further effects regarding property changes when adding GRT. Based on the vulcameter curves it could be seen, that the curing behaviour of the compounds changed and the crosslink density of the matrix obviously decreased by adding GRT. Additional ¡jXRF images and measurements for dynamic local indentation indicated increased sulphur content inside the GRT particles.