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Wunde M.,German Institute for Rubber Technology | Kluppel M.,German Institute for Rubber Technology
Continuum Mechanics and Thermodynamics | Year: 2017

Based on a viscoelastic model, the filler distribution and the amount of interphase of carbon black-filled blends of natural rubber (NR) with styrene-butadiene rubber (SBR) are evaluated. Hereby, the total dissipated energy (Formula presented.) during dynamical straining is decomposed into the contributions of the different polymer phases and the interphase. For the NR/SBR blends, we find a higher filling of the SBR phase and the interphase and a lower filling of the NR phase. The filler distribution itself depends not only on the affinity of the polymer to the filler but also on the mixing procedure. This is investigated by studying NR/SBR blends prepared by two different mixing procedures. In the standard mixing procedure, the polymers are mixed first, and then, the filler is added. In the batch mixing procedure, the filler is previously mixed in the NR only and then blended with SBR. Batch mixing is resulting in an increase in the filling of the interphase due to filler transfer from NR to SBR. The results for the filler distribution are compared to fatigue crack propagation rates under pulsed excitation. The crack propagation is accelerated when substituting NR with SBR. The batched samples show higher crack propagation rates at higher tearing energies due to a worse dispersion of the carbon black and/or higher filler loading of the interphase. © 2017 Springer-Verlag Berlin Heidelberg

Wunde M.,German Institute for Rubber Technology | Kluppel M.,German Institute for Rubber Technology
Rubber Chemistry and Technology | Year: 2016

The filler distribution and the amount of interphase are determined for carbon black (CB) filled blends of natural rubber (NR) with butadiene rubber (BR) and styrene-butadiene rubber (SBR) and compared with fatigue crack propagation rates under pulsed excitation. A viscoelastic model is used to separate the contributions of the different polymer phases and the interphase to the total dissipated energy G'' during dynamic straining. The filler amount in any phase can be calculated from the increase of the energy dissipation. For NR/SBRblends a higher filler load of theSBRphase and the interphase and a lower filling of the NR phase are identified. In contrast NR/BR blends show a very low filled BR phase and higher filling of the NR phase and the interphase. The carbon black distribution also depends on mixing procedures. Through a batch mixing procedure, in which the filler is previously mixed in the NR only and then blended with BR, the filler transfer from NR to BR increases the filling of theBR phase. The phase morphological results deliver information for a better understanding of crack propagation in CB filled NR/BR and NR/SBR blends. The fracture behavior differs significantly if NR is successively replaced by BR or SBR, respectively. A less pronounced effect is found for the variation of mixing procedure, although it seems that the more heterogeneous filler distribution with a high amount ofCBinNRof the batched samples delivers slightly reduced crack propagation rates.

The aim of the LORRY project is to reduce trucks carbon footprint by developing an innovative low rolling resistance tyre concept combined with a comprehensive tool box for fleet fuel saving management. This proposed concept will go beyond current state of art and stakeholder or market expectations regarding tyre rolling resistance, mileage, driving safety, driving performance and material and manufacturing sustainability. Steer and trailer tyres developed in the framework of the project will demonstrate a minimum 20% gain in truck tyre rolling resistance. Truck tyre wear and wet safety performance levels will be improved additionally. To reach this objective, a multidisciplinary consortium (7 public / 4 private partners) has been created covering the fields of tyre technology, rubber and filler technology, nanotechnologies, composite physics, sensory, transport and road infrastructure. A complete set of complementary scientific evaluation methods will enable the understanding of interactions between new tread pattern design and new material composites as well as the tyre performance dependency on tyre-vehicle operation and road conditions. LORRY consists in a holistic approach for an intelligent surface transport system. New tyre and truck fleet operating concepts resulting from the programmed will go beyond European Green Car Initiative roadmap expectations for 2015 and smoothly bridge and feed next coming tailored trucks and sustainable trucks initiatives, forecasted respectively for 2020 and 2025.

Schlaad H.,Max Planck Institute of Colloids and Interfaces | Diehl C.,Max Planck Institute of Colloids and Interfaces | Gress A.,BASF | Meyer M.,German Institute for Rubber Technology | And 3 more authors.
Macromolecular Rapid Communications | Year: 2010

Poly(2-alkyl-2-cocazoline)s can be regarded as pseudo-peptides or bioinspired polymers, which are available through living/controlled cationic polymerization and polymer ("click") modification procedures. Materials and solution properties may be adjusted via the nature of the side chain (hydrophilic-hydrophobic, chiral, bio-functional, etc.), opening the way to stimulus-responsive materials and complex colloidal structures in aqueous environments. Herein, we give an overview over the macromolecular engineering of polyoxazolines, including the synthesis of biohybrids, and the "smart"/bioinspired aggregation behavior in solution Chemical Equation Presentation © 2010 WILEY-VCH Verlag GmbH & Co. KGaA.

Freund M.,TU Chemnitz | Lorenz H.,German Institute for Rubber Technology | Juhre D.,German Institute for Rubber Technology | Ihlemann J.,TU Chemnitz | Kluppel M.,German Institute for Rubber Technology
International Journal of Plasticity | Year: 2011

To describe the inelastic mechanical behavior of filled elastomers a microstructure-based material model for uniaxial loadings has been developed. The generalization of this one-dimensional material description to a fully three-dimensional constitutive model has been accomplished by using the concept of representative directions. The generalized model shows a very good agreement with cyclic uniaxial tension and compression tests as well as simple shear measurements for several rubber compounds. The FE-implementation enables finite element simulations of technical components though the original input model predicts the material behavior for uniaxial loadings only. © 2010 Elsevier Ltd. All rights reserved.

Freund M.,German Institute for Rubber Technology | Ihlemann J.,TU Chemnitz
ZAMM Zeitschrift fur Angewandte Mathematik und Mechanik | Year: 2010

The concept of representative directions is intended to generalize one-dimensional material models for uniaxial tension to complete three-dimensional constitutive models for the finite element method. The concept is applicable to any model which is able to describe uniaxial loadings, even to those for inelastic material behavior without knowing the free energy. The typical characteristics of the respected material class are generalized in a remarkable similarity to the input model. The algorithm has already been implemented into the finite element systems ABAQUS and MSC.MARC considering several methods to increase the numerical efficiency. The implementation enables finite element simulations of inhomogeneous stress conditions within technical components, though the input model predicts uniaxial material behavior only. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Alshuth T.,German Institute for Rubber Technology
KGK Kautschuk Gummi Kunststoffe | Year: 2014

Magnetisch Aktive Elastomere (MAE) sind Kompositmaterialien die auf Basis von Silikonkautschuk und weichmagnetischen Manganferriten (MnFe2O4) hergestellt wurden. Die Oberfläche Mn-Fe2O4 wurde mit ölsäuren modifiziert. Die Kristallstruktur wurde mit Hilfe von Röntgen Pulver Diffraktometrie (XRD) analysiert. So hergestelltes Manganferrit kristalisiert in cubischer inverser Spinellstruktur mit der Raumgruppe Fd-3m (227). Die magnetischen Eigenschaften und der exakte Verlauf der magnetischen Hysteresekurven wurden mit einem Superconducting Quantum Interference Device (SQUID) und Mössbauer Spektroskopie bestimmt. Die maximale Sättigungsmagnetisierung lag bei 37 emu/g. Die Struktur der Partikel wurde mit einem Rasterelektronenmikroskopie (SEM) untersucht.

Aloui S.,German Institute for Rubber Technology | Kluppel M.,German Institute for Rubber Technology
Smart Materials and Structures | Year: 2015

We study the magneto-rheological response of hybrid-magnetic elastomer composites consisting of two different magnetic filler particles at fixed overall concentration. Thereby, we focus on an optimization of mechanical and magnetic properties by combining highly reinforcing magnetic nano-particles (MagSilica) with micro-sized carbonyl-iron particles (CIP), which exhibit high switch ability in a magnetic field. We observe a symbiotic interaction of both filler types, especially in the case when an orientation of the magnetic filler particles is achieved due to curing in an external magnetic field. The orientation effect is significant only for the micro-sized CIP particles with high saturation magnetization, indicating that the induced magnetic moment for the nano-sized particles is too small for delivering sufficient attraction between the particles in an external magnetic field. A pronounced switching behavior is observed for the non-cross-linked melts with 15 and 20 vol.% CIP, whereby the small strain modulus increases by more than 50%. For the sample without the coupling agent silane, one even observes a relative modulus increase of about 140%, which can be related to the combined effect of a higher mobility of the particles without a silane layer and the ability of the particles to come in close contact when they are arranged in strings along the field lines. For the cross-linked samples, a maximum switching effect of about 30% is achieved for the system with pure CIP. This magneto-sensitivity decreases successively if CIP is replaced by MagSilica, while the tensile strength of the systems increases significantly. The use of silane reduces the switching effect, but it is necessary for a good mechanical performance by delivering strong chemical bonding of the magnetic filler particles to the polymer matrix. © 2015 IOP Publishing Ltd.

Fritzsche J.,German Institute for Rubber Technology | Kluppel M.,German Institute for Rubber Technology
Journal of Physics Condensed Matter | Year: 2011

The combined effect of filler networking and reduced chain mobility close to the filler interface is analyzed based on investigations of the relaxation dynamics of a solution of styrene butadiene rubber filled with different loadings and types of nanostructured carbon blacks. Dynamic-mechanical and dielectric spectra are studied in a wide frequency and temperature range. By referring to a tunneling process of charge carriers over nanoscopic gaps between adjacent carbon black particles the gap distance is evaluated from the dielectric spectra. This distance corresponds to the length of glassy-like polymer bridges forming flexible bonds between adjacent filler particles of the filler network. It is found that the gap distance decreases with increasing filler loading and specific surface area which correlates with an increase of the apparent activation energy of the filler network evaluated from dynamic-mechanical data. Due to the thermal activation of glassy-like polymer bridges the time-temperature superposition principle is not fulfilled for filled elastomers and the introduction of vertical shift factors is necessary to obtain viscoelastic master curves. The change in the low frequency viscoelastic properties by the incorporation of fillers is shown to be related to the superimposed dynamics of the filler network governed by the viscoelastic response of the glassy-like polymer bridges. This effect is distinguished from the reduced chain mobility close to the filler surface which results in a broadening of the glass transition on the high temperature or low frequency side. The microstructure-based interpretation of viscoelastic data is supported by an analysis of the relaxation time spectra. © 2011 IOP Publishing Ltd.

Geberth E.,German Institute for Rubber Technology | Kluppel M.,German Institute for Rubber Technology
Macromolecular Materials and Engineering | Year: 2012

The role of polymer/filler interactions on the mechanical and electrical properties of elastomer nanocomposites is analyzed using dielectric spectroscopy, cyclic stress/strain tests, and online dc-conductivity measurements. Pristine and deactivated (graphitized) CBs are studied in different rubber matrices. Due to confinement effects, an interphase of strongly immobilized polymer is present between adjacent filler particles, representing stiff but flexible mechanical bonds of the filler network. Under deformation of the sample, these bonds bend and finally break. Cyclic stress/strain measurements are analyzed by fitting the data to a microstructure-based material model that allows for the evaluation of microscopic parameters of the polymer and filler network. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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