Papers by Author: Tibor Czigány

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Authors: Sándor Kling, Tibor Czigány
Abstract: The geometry and mechanical properties of solid and hollow carbon fibres were investigated by light-and scanning electron microscopy, and by single fibre tensile tests. The hollowness factor of fibres was determined by their external and internal diameter. The tensile strength was determined by single fibre tensile break tests. It was shown that the bigger the diameter of the fibres the lower the mechanical properties is. It was found that the hollow carbon fibres are suitable for preparation of a self-repairing composite with the advantage over other solutions because of their geometrical and mechanical properties.
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Authors: Tibor Czigány
Abstract: Short fiber (basalt, carbon, ceramic, and glass) reinforced polypropylene hybrid composites were investigated to determine their mechanical properties in case of different reinforcing fiber types. The composites were reinforced with fibers and were produced by hot pressing after hot mixing techniques. Composite properties such as flexural strength, stiffness, static and dynamic fracture toughness were measured. It was realized that the main damage modes of the composites are fiber pullout and debonding. It was also found that basalt fibers are the most sensitive to the lack of the treatment with additives. These results were supported by scanning electron micrographs taken of the fracture surfaces.
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Authors: Brúnó Vermes, Tibor Czigány
Abstract: Melamine-formaldehyde (PMF) coated microcapsules were produced with liquid pentaerythritol-tetrakis (3-merkaptopropionate) (PETMP) and UV-sensitive indicator colored PETMP cores. Capsules with an average diameter of 43 μm formed due to the adjustments on magnetic stirring, compound ratios, acidity and reaction time. Reproducible recipe was found to produce colored PETMP filled capsules with yields of 1-10%. Optical microscopic investigations were conducted to follow the formation of the particles, and scanning electron-microscope (SEM) was used to verify that the capsules did not break up as an effect of the brittle failure of the epoxy matrix specimens. Improvement of the shell-matrix adhesion was attempted with silane compounds and investigated with X-ray photoelectron spectroscopy (XPS) and SEM.
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Authors: Mátyás Andó, Gábor Kalácska, Tibor Czigány
Abstract: Due to the effect of graphite and montmorrilonit additives, the impact strenght slightly decreases, but by the influence of softening material, the value of impact strength can be three times more than the pure PA6. It is determined that graphite can be added until 3%, montmorrilonit can be added until 6% and softening material can be added until 15% to the base matrix. These samples give basis for special characteristics examinations.
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Authors: Min Zhi Rong, Ming Qiu Zhang, Su Ping Wu, Hong Juan Wang, Tibor Czigány
Abstract: In this work, plastic foams were prepared from plant oil resins based on soybean oil and castor oil. Firstly, epoxidized soybean oil (ESO) reacted with acrylic acid using N, N-dimethyl benzyl amine as the catalyst, and castor oil was modified with maleic anhydride, respectively. Acid number was used to monitor the reaction process, and structures of the resultant acrylated epoxidized soybean oil (AESO) and maleate castor oil (MACO) were proved by Fourier Transform Infrared (FTIR) measurements. It was found that the catalyst is quite effective in synthesizing AESO. Then, plastic foams based on AESO and MACO were synthesized through free radical initiated copolymerization with diluent monomers including styrene and methyl methacrylate. Mechanical properties, reinforcing effect of sisal fiber and biodegradable feature of the foams were characterized, showing the suitability of the bio-foams for acting as packaging materials.
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Authors: Gabor Balogh, Tibor Czigány
Abstract: Composite sheets were made of cyclic butylene terephthalate as matrix and carbon fibers as reinforcing material.Hot press method was used at different temperatures for composite processing. The mechanical properties of these materials and the effect of processing temperature were tested. The samples were kept in a climate chamber, and the effect of air humidity was examined through the change of the mechanical properties. Pictures were taken by a scanning electron microscope of the broken surfaces of the specimens. The results give conclusions about the outdoor application of these composites.
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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: Tamás Deák, Tibor Czigány
Abstract: Basalt fiber reinforced polyamide composites were investigated to determine their static and dynamic mechanical properties. The composites were compounded in an extruder and were injection molded. A glass fiber reinforced composite also was investigated. Two different basalt fibers were used with silane sizing and one of them was used also without sizing. The results show that composites with silane sized basalt fibers have properties similar to glass fiber reinforced composites, while unsized basalt fibers eventuate smaller strength and higher brittleness.
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Authors: Z. Kocsis, Tibor Czigány
Abstract: Wood fiber reinforced polypropylene composites of different fiber contents without any treatment were prepared, and tensile tests were carried out on injection molded specimens. With increasing fiber content a decrease of the tensile strength was experienced. The weak adhesion at the fiber-matrix interface and the typical composite failures can be seen on SEM pictures. During the tests acoustic emission was monitored to get more information about the damage mechanism. From the AE counts distribution it can be concluded that the maximum number of AE counts decreases simultaneously with the tensile strength in case of the different composites.
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Authors: Bálint Morlin, Tibor Czigány
Abstract: The possibilities of the application of microbond test and cylinder tests for determining the interfacial shear strength at the fiber-matrix interface in thermoplastic matrix polymer composites were investigated. Possibilities of test specimen preparation were also investigated. Finally the applicability of the method to make high precision measurement of interfacial shear strength was evaluated.
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