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Short-fiber reinforcement is a potent approach to improving the material properties of injection-molded parts. The main consideration in such reinforced materials is to preserve the fiber length, as this is the major influence on the properties of a given composite. The aim of this work was to investigate the different influencing parameters in injection molding processing on the properties of short carbon and glass fiber-reinforced polypropylene. We investigated parameters like melt temperature and back pressure, but also machine size and pre-heating regarding their influence on the tensile properties. We found that adjustments of melt temperature and back pressure only yield small improvements in the fiber length and the tensile properties, also depending on machine size, but a pre-heating step of the granules can significantly improve the properties. [ABSTRACT FROM AUTHOR]

Aiming at the new control method of filling unbalance in the flow channel by using convection mixing， the influence of micro-scale polymer melt flow factors on the control characteristics of melt temperature distribution in the flow channel was studied by numerical simulation. Taking the "H" flow channel as the research object， the convection mixing device was arranged in the flow channel. The effects of melt temperature， convective heat transfer coefficient and flow channel size on melt filling unbalance were studied by single factor experiment. The numerical simulation results show that， the increase in melt temperature is accompanied by the decrease of melt self-viscosity under adiabatic boundary conditions. The temperature difference between symmetric points decreases， which improves the filling imbalance. Under the convective heat transfer boundary， the increase of melt temperature increases the heat loss of melt through the wall， and the increase of temperature difference between symmetric points leads to the more obvious filling imbalance. The lower the convective heat transfer coefficient， the lower the thermal conductivity efficiency between melt and wall， and the higher the average melt temperature， which increases the temperature difference between symmetric points and intensifies the filling imbalance. With the decrease in the size of the flow path， the micro-scale effect is weakened， the temperature difference between symmetric points can be reduced， and the phenomenon of filling imbalance is better improved. The convective heat transfer coefficient has the greatest influence on the filling unbalance， followed by the flow channel size， and finally the melt temperature.

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Short-fiber reinforcement is a potent approach to improving the material properties of injection-molded parts. The main consideration in such reinforced materials is to preserve the fiber length, as this is the major influence on the properties of a given composite. The aim of this work was to investigate the different influencing parameters in injection molding processing on the properties of short carbon and glass fiber-reinforced polypropylene. We investigated parameters like melt temperature and back pressure, but also machine size and pre-heating regarding their influence on the tensile properties. We found that adjustments of melt temperature and back pressure only yield small improvements in the fiber length and the tensile properties, also depending on machine size, but a pre-heating step of the granules can significantly improve the properties.

This article devoted the mathematical model of the plasticization process for the injection molding processes in a cylindrical domain influenced from the main thermodynamic characteristics: particle velocity, pressure distribution, particle flow density, and melting temperature. Here is determined a thermodynamic relationship between the particle velocity vector and the scalar pressure function in which the particle velocity is defined by the three-dimensional Maxwell distribution satisfying the energy conservation law. The presented mathematical model has been described via the initial-boundary value problem for second-order parabolic equations in a cylindrical domain. Here the three-dimensional energy conservation law regulates the pressure instability effect according to the particle velocity vector in a turbulent flow. It is a new issue for defining the processing pressure distribution that is provided proofing the theorem of existence and uniqueness of their classical parameters. This result as Maxwell distribution of the particle velocity has great opportunity for studying the transient particle flows in multiscale modeling the thermodynamic diffusivity for the injection moldings processes. In the previous author's research was investigated a weak formulation of the Navier–Stokes problem. [ABSTRACT FROM AUTHOR]

During a severe accident in light water reactors, the molten reactor core (corium) falls into a water pool in the form of a jet. Complex interactions may occur between the melt and coolant known as molten fuel–coolant interactions (FCI), including energetic coolant evaporation and metallic melt (e.g., Zr and Fe) oxidation. This may further lead to steam and hydrogen explosions, which are both substantial safety risks for nuclear power plants. The heat of reaction and hydrogen production during oxidation can influence the progress and severity of the accidents. For example, the reaction heat may prolong the liquid state of corium, potentially leading to high-intensity explosions, whereas the generated hydrogen can create a combustible atmosphere, increasing the risk of hydrogen explosion. Therefore, this study evaluates the hydrogen production and oxidation degree of molten metallic droplets falling into a water pool to improve the FCI models for the risk evaluation of severe accident safety. The MISTEE-OX facility at KTH, which has been primarily built to study steam explosions is modified to investigate oxidation during FCI and provide experimental data on the oxidation behaviour of metallic droplets (Zr/Fe) quenched in a subcooled water pool. The dynamics of the falling droplets and generated bubbles are recorded using a high-speed camera, and the total volume of the bubbles is measured using a graduated cylinder. This study presents preliminary experimental results of the oxidation between Zr/Fe droplets and water, as well as recent improvements in measurement methods and facility upgrades. Our research findings are useful to enhance the knowledge of the oxidation process in FCI phenomena and validate the related mechanistic models in FCI codes. [ABSTRACT FROM AUTHOR]