For analyzing arbitrary static 3D stress states in solid rubber compounds, three different material tests are performed. These tests represent uniaxial tension, equibiaxial tension and planar shear. Tests on three different rubber compounds are examined at room temperature and at 60 degrees C. Subsequently, the retrieved stress-strain data are fitted to suitable hyperelastic material models, using computer software. To overcome stress inhomogeneities in a simple but time efficient equibiaxial test setup, the initially calibrated material parameters are gradually optimized in order to represent homogeneous stress states in all material test setups.
Rubbers are generally filled with rigid particles to improve their mechanical properties, especially their stiffness. The increase in stiffness can be described by the so-called hydrodynamic amplification factors. For the non-linear regime of deformation the strain amplification approach according to Mullins and Tobin is often used. In this work the origin of the hydrodynamic amplification factors are discussed and the question of the validity of the Guth-Gold equation for filled rubbers is raised. Also the strain amplification approach of Mullins and Tobin is discussed critically.
Zinc oxide (ZnO) plays a major role in the accelerated sulphur vulcanization process. Nano ZnO at different levels were incorporated into natural rubber latex (NR) and the properties of the resulting vulcanizates were compared with conventional micro ZnO incorporated into films. The latex compounds (containing micro and nano ZnO) were cast into sheets and cured. The antifungal activities of nano ZnO incorporated into dry films were evaluated. Mechanical properties such as tensile strength, elongation at break, modulus and tear strength were measured and compared with dry vulcanizates containing micro ZnO. Effect of ageing and leaching on the properties of the dry films were also evaluated. The reinforcing effect of nano ZnO was observed from the mechanical property measurements.
As magneto-active elastomers rubber composites based on highly elastic polymer matrix filled with magnetic barium ferrite (BaFe12O19) particles were investigated. Due to the high ratio of surface to volume and magnetization are magnetic particles prone to aggregate. To enhance the dispersion and the compatibility between the particle and the rubber matrix a functionalization of the ferrite should be used. A better dispersion of the ferrite particles contributes to better switching ability of the magneto -active elastomers actuated by a magnetic field. In this work the barium ferrite surface were modified using triethoxy(octylsilane) as a coupling agent. Especially the effects on the viscoelastic performance of the magneto active elastomers based on butadiene and silicon rubbers were investigated.
An improved understanding of nonlinear elastic effects of rubber polymers involving very high relaxation times is of intensified interest, while the description and simulation of such flows is still a challenging problem. The present work "Evaluation of nonlinear differential models for the simulation of polymer melts" evaluates the capability of certain differential viscoelastic models in describing the nonlinear behavior at standard rheological flow states. It turns out that the numerical results using the differential model approach are not able to represent basic flow effects sufficiently. The inadequacies will be analyzed further and traced back to principal limits of the differential modeling approach used.
The present work investigates the effect of hardness and thickness on the electrostatic charge generated from the sliding of the rubber sole against recycled rubber tiles. Based on the experimental observations, it was found that at dry, water wet, detergent wet, oil lubricated and sand contaminated sliding, voltage decreased with increasing the hardness. Voltage generated at water wet floor tiles showed relatively lower values than that observed for dry sliding. At sand contaminated sliding, soft tiles showed very high voltage values. Voltage generated significantly increased with increasing the thickness of the tested tiles. Water wet sliding showed voltage lower values than that observed for dry sliding, while detergent wet sliding showed relatively higher values than that observed for water wet sliding.
The influence of spherical beech cellulose (BuRe), a fibrous regenerated cellulose (FCP) and a nanoscale bacterial cellulose (BNC) was examined on the elastomeric properties in a S-SBR model mixture. All types of cellulose are suitable as elastomeric fillers. However, they should be used always modified to increase the compatibility between the hydrophilic cellulose and the hydrophobic elastomer matrix. The rein-forcing effect differs for each filler type in the order FCP>BuRe>BNC. The ad-vantages of the nanoscale of the BNC cannot be realized because of the essential grinding process that makes particle sizes macroscopic.
