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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. Source

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. Source

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.

Lorenz H.,German Institute for Rubber Technology | Kluppel M.,German Institute for Rubber Technology | Heinrich G.,Leibniz Institute fur Polymerforschung Dresden e.V.
ZAMM Zeitschrift fur Angewandte Mathematik und Mechanik | Year: 2012

Reinforcement of rubber by nanoscopic fillers induces strong nonlinear mechanical effects such as stress softening and hysteresis. The proposed model aims to describe these effects on a micromechanical level in order to predict the stress-strain behaviour of a rubber compound. The material parameters can be obtained by fitting stress-strain tests. These quantities have a clear defined physical meaning. The previously introduced "dynamic flocculation model" was extended for general deformation histories. Stress softening is modelled by hydrodynamic reinforcement of rubber elasticity due to strain amplification by stiff filler clusters. Under stress these clusters can break and become softer, leading to a decreasing strain amplification factor. Hysteresis is attributed to cyclic breakdown and re-aggregation of damaged clusters. When stress-strain cycles are not closed, not all of these clusters are broken at the turning points. For the resulting "inner cycles" additional elastic stress contributions of clusters are taken into account. The uniaxial model has been generalized for three-dimensional stress states using the concept of representative directions. The resulting 3D-model was implemented into a Finite Element code, and an example simulation is shown. Good agreement between measurement and simulation is obtained for uniaxial inner cycles, while the 3D-generalization simulates the behaviour closer to the experiment than the original model. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Lorenz H.,German Institute for Rubber Technology | Kluppel M.,German Institute for Rubber Technology
Journal of the Mechanics and Physics of Solids | Year: 2012

A physically motivated theory of rubber reinforcement based on filler cluster mechanics is presented considering the mechanical behaviour of quasi-statically loaded elastomeric materials subjected to arbitrary deformation histories. This represents an extension of a previously introduced model describing filler induced stress softening and hysteresis of highly strained elastomers. These effects are referred to the hydrodynamic reinforcement of rubber elasticity due to strain amplification by stiff filler clusters and cyclic breakdown and re-aggregation (healing) of softer, already damaged filler clusters. The theory is first developed for the special case of outer stressstrain cycles with successively increasing maximum strain. In this more simple case, all soft clusters are broken at the turning points of the cycle and the mechanical energy stored in the strained clusters is completely dissipated, i.e. only irreversible stress contributions result. Nevertheless, the description of outer cycles involves already all material parameters of the theory and hence they can be used for a fitting procedure. In the general case of an arbitrary deformation history, the cluster mechanics of the material is complicated due to the fact that not all soft clusters are broken at the turning points of a cycle. For that reason additional reversible stress contributions considering the relaxation of clusters upon retraction have to be taken into account for the description of inner cycles. A special recursive algorithm is developed constituting a frame of the mechanical response of encapsulated inner cycles. Simulation and measurement are found to be in fair agreement for CB and silica filled SBR/BR and EPDM samples, loaded in compression and tension along various deformation histories. © 2012 Elsevier Ltd. Source

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