Mathematical characterization of values of rheological variables during the networking reaction of rubber mixtures based on SBR

The article presents an analysis of cross-linking reaction using measurements of time dependencies of torque at constant temperature from the range 100 up to 200 degrees C. The measured results obtained on sample based on styrene - butadiene (SBS) prepared in the laboratory show the behaviour which can be well described by equations of chemical reactions of first-order kinetics. It is possible mathematically describe significant constants of the kinetics of networking reaction (induction period, reaction rate coefficient) by the solution of differential equations and by mathematical approximation. Constants are exponentially dependent on the temperature of vulcanization, while dependencies are Arrhenius like. Math description allows describe the progress of the vulcanization reaction also in the temperature range outside of the monitoring interval, i.e. in the area of extremely long times required for the realization of the cross-linking reaction

Investigation of physical properties of polymer composites filled with sheep wool

Sheep farmers are currently facing an oversupply of wool and a lack of willing buyers. Due to low prices, sheep wool is often either dumped, burned, or sent to landfills, which are unsustainable and environmentally unfriendly practices. One potential solution is the utilization of sheep wool fibers in polymer composites. This paper focuses on the study of mechanical vibration damping properties, sound absorption, light transmission, electrical conductivity of epoxy (EP), polyurethane (PU), and polyester (PES) resins, each filled with three different concentrations of sheep wool (i.e., 0%, 3%, and 5% by weight). It can be concluded that the sheep wool content in the polymer composites significantly influenced their physical properties. The impact of light transmission through the tested sheep wool fiber-filled polymer composites on the quality of daylight in a reference room was also mathematically simulated using Wdls 5.0 software.Internal Grant of Tomas Bata University in Zlin [IGA/FT/2024/002]; European Union [CZ.10.03.01/00/22_003/0000048

Monitoring of vulcanization process using measurement of electrical properties during linear increasing temperature

The article presents the possibilities of diagnostics of irreversible chemical reaction vulcanization in case of laboratory prepared rubber mixture based on styrene - butadiene (SBR) using measurements of selected physical parameters. Our work is focused on the measurement of current rheologic parameters (torque at defined shear deformation) and selected electrical parameters (DC conductivity) during linear increasing temperature. The individual steps of vulcanization are well identified by means of measurements of rheologic parameters, while significantly affecting the value of the electrical conductivity. The value of the electrical conductivity increases with the increasing of rate of the crossbridging reactions during vulcanization. The rate of the heating affects both types of measurements. When the rate of the heating is increasing the temperature of the beginning of networking step of reactions and also the rate of vulcanization grow. The sensitivity of the both types of measurements allows a good mathematical description of the temperature dependence of the torque and the electric conductivity during the vulcanization of rubber mixtures based on SBR

The Relationship Between Mechanical and Electrical Properties During Vulcanisation of SBR Based Rubber

The aim of this paper is description of vulcanization process by monitoring of selected electrical and mechanical parameters. The experiments have shown that the vulcanization process can be qualitatively and quantitatively evaluated on the basis of measurements of mechanical (standard procedure in rubber industry) and also electrical parameters. The results obtained for model system SBR rubber mixture under conditions of linear heating are presented also

The technological properties of polymer composites containing waste sheep wool filler

New technologies are using natural fibres in composites materials in the industry. It is still often natural fibres in modern buildings, chemists, airports, sport and automotive. Using for construction pieces and their better properties than steel or traditional materials. New forward science and technic are recycled or decrease waste. The problem for central Europe is a waste of agricultural, invention relates to an epoxy resin filled with an organo-inorganic filler of natural origin, production especially plants and sheep wool as well as other usable wastes such as old textiles. New applications are in new construction types and industries finding cheaper materials. There is available modern technology for injection moulding granulate polypropylene with filler from sheep wool and plant fibres. For example, to make furniture or building cladding. This could reduce waste production, pollution of nature and emissions in the production of these products from new raw materials. The work presents the possibilities of using new polymer-based materials contain sheep wool as filler. The paper deals with the evaluation of the mechanical properties of the effect of the addition of sheep wool in a concentration of 3% to selected types of thermosetting matrices. In the experiments, the modulus of elasticity, tensile strength, ductility and deformation work were built on the sample set. The results are statistically processed and document the possibilities of adjusting the mechanical properties of composites with sheep wool. © 2020 Trans Tech Publications Ltd, Switzerland

New Dynamic Method for Examination of Elastic Properties of Thin Wire Samples

Classical reverse pendulums are currently used for measuring the gravity acceleration g, or – when pendulums bodies are connected by the spring – for demonstration of composition of parallel vibrations. In this paper we present the reversed pendulums in „non-traditional” position – as a device for measuring of elastic modulus of wire samples. The connection is realized by the measured wire sample with the circle shape

Properties of Sn-Ag-Cu Solder Joints Prepared by Induction Heating

In the present work, one near-eutectic and three hypoeutectic Sn-Ag-Cu alloys have been employed for soldering by induction heating. The alloys were produced by induction melting of high purity Ag, Cu, and Sn lumps. The melting behavior of the alloys was investigated by differential scanning calorimetry. The solder alloys were subsequently applied for soldering by conventional hot-plate heating as well as induction heating and both soldering times and peak temperatures were recorded during soldering. Solder joints of two copper sheets were produced. The electrical resistance, tensile strength, and microstructure were analyzed on each soldered joint. The results indicate that the physical and mechanical properties of solder joints are determined by their chemical composition and soldering technology. Induction soldered joints not only have a slightly higher electrical resistivity but also higher mechanical strength, except of the 0.3 wt.% Ag hypoeutectic solder. The highest increase in ultimate tensile strength (28%) was observed for induction soldered joints with 1 wt.% Ag hypoeutectic solder. This effect is ascribed to the homogenous distribution of the intermetallic compounds within the eutectic in the alloy microstructure. The homogenous distribution is aided by rotation of liquid solder due to eddy currents and high-frequency magnetic field generated during induction heating

Preparation and luminescence properties of Pr-doped heavy metal oxide glasses by ion implantation

International audienceThe paper presents the procedure of Praseodymium (Pr) doping at 1000 and 2000 wt. ppm by ion implantation into 65 Sb2O3 − 25 PbCl2 − 10 LiCl and 60 PbO – 40 GaO3/2 glasses prepared by the melting-quenching method. The implanted layer thickness was 250 nm. The luminescence properties have been determined across the spectral range of 400-800 nm and the impact of Praseodymium (Pr) implantation on the optical and electrical properties of the glasses was investigated. The observed luminescence signal was relatively weak. The characteristic Pr3+ emission bands were observed at ∼488, 608, and 650 nm. The electric conductivity of modified layers was characterized using the Van der Pawn method and the obtained results are discussed. It was found that the DC conductivity of the prepared annealed layers increases with applied fluences of Pr used during ion implantation