Papers by Author: Tamás Bárány

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Authors: Tamás Bárány, András Izer, Tibor Czigány
Abstract: Highly oriented polypropylene fiber reinforced random PP copolymer composites were produced by film-stacking method. The reinforcing fibers were carded and needle punched and the film-stacked packages were compression molded at different processing temperatures (T=150…170°C) and holding times (t=90…600 s). For characterization of the consolidation of the composite sheets interlaminar strength was determined and further the polished sections were studied by light microscopy. Static tensile and dynamic impact (instrumented falling weight impact - IFWI) tests were performed on the specimens cut from the sheets. It was established that the best properties can be achieved when the processing conditions are 165°C and 90s. Increasing temperature and improving consolidation reduced perforation impact energy owning to better fiber/matrix adhesion and the smaller extent of delamination between the film-stacked layers.
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Authors: Zoltán Kiss, Ákos Kmetty, Tamás Bárány
Abstract: In the present work the weldability of self-reinforced composite was investigated. As reinforcement a fabric, woven from highly stretched split PP yarns, whereas as matrix materials of two kinds of random polypropylene copolymer (with ethylene) were used. The composite sheets were produced by film-stacking method and compression molded with different thickness (1 mm, 2 mm) with different contents at different processing temperatures keeping the holding time and pressure constant. The SRPPC sheets were welded by ultrasonic welding machine with different welding parameters. The welds were qualified by mechanical and microscopic tests. The results showed that the thermoplastic reinforcement has not got melted; therefore the reinforcement was kept the strength-increasing effect.
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Authors: Wen Hong Ruan, Ming Qiu Zhang, Ming Hui Wang, Min Zhi Rong, Tamás Bárány, Tibor Czigány
Abstract: To improve the properties of polypropylene (PP), a new route that combines nanoparticles filling with self-reinforced technique was applied in this work. That is, nano-silica particles were firstly modified by graft polymerization to increase interfacial interaction between nanoparticles and matrix. Then the grafted nanoparticles were melt-compounded with PP producing composites sheets, and the sheets were stretched under a temperature slight lower than the melt point of PP at a constant velocity. Finally, the stretched sheets were film-stacked with random PP copolymer by a special designed mold and were hot pressd at different processing temperature (T=150-175°C) and holding pressure (2.0-5.0MPa) under constant holding time of 5min. The resultant self-reinforced nanocomposite are much stronger and stiffer than the unfilled polymer as characterized by mechanical test. The results show that the optimum processing conditions for hot consolidation are 160°C and 2.5MPa. Addition of nanoparticles increases crystallinity of PP, and induces the formation of craze and cause much more surrounding matrix polymer to involve in large-scale plastic deformation, which might ensure an overall improvement of mechanical properties.
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