Composite materials are a constantly evolving group of engineering materials, which has significantly changed their current, and potential role as structural materials over the past decades. Composites offer greater strength, stiffness, and less deformation to structural designers than previously available engineering materials. Resin matrix composites are widely used in the transportation, marine, aerospace, energy, and even sports industries. The manufacturing stage has a profound influence on the quality of the final product. This paper presents the production of composite materials by gravity casting in silicone moulds, using an epoxy/polyester resin matrix reinforced with wood chips and shredded glass fiber reinforced composite from recycled wind turbine blades. Some of the fabricated samples were degassed in a reduced-pressure chamber. The mechanical properties of the produced material were then examined. It was noted that the silicone moulds did not affect the resin self-degassing due to the large surface area to weight ratio, and the remaining small air bubbles had a limited effect on the mechanical properties of the samples. The filler used also played a significant role. Composites filled with crushed GFRC showed better strength properties than composites filled with wood chips. The conducted research is aimed at selecting materials for further testing with a view to their use in the manufacture of next-generation wood-based composite structural materials.
Artykuł omawia problematykę rozpoznania defektów izolacji odlewanej w transformatorach suchych typu cast-coil. W badaniach użyto metody rejestracji obrazów defektów w podczerwieni.
EN
The article discusses the issue of identifying defects in cast insulation in dry cast-coil transformers. The in the research method was used recording images of defects in infrared.
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Nowe nanomateriały dla sprzętu sportowego zostały przygotowane poprzez wzmocnienie żywicy epoksydowej (EP) włóknami węglowymi (CF) i/lub nanorurkami węglowymi (CNT) w celu poprawy jakości, twardości, plastyczności i odporności na starzenie materiałów kompozytowych. CNT zostały równomiernie rozmieszczone poprzez filtrację próżniową i fizyczne osadzanie na powierzchni włókien CF. Wytrzymałość na zginanie kompozytów CF/EP-CNT była o 28,08% większa niż niemodyfikowanego kompozytu CF/EP. Po starzeniu w temp. 120°C naprężenia w kompozycie zostały rozproszone ze względu na doskonałą dyspergowalność CNT, a tłumienie długich pęknięć spowodowało zmniejszenie obszaru uszkodzenia.
EN
New nanomaterials for sport equipment were prepd. by reinforcing an epoxy resin (EP) with C fibers (CF) and/or C nanotubes (CNT) to improve quality, hardness, plasticity and aging resistance of the composite materials. The CNT were uniformly dispersed by vacuum filtration and phys. deposition on CF fiber surface. The bending strength of CF/EP-CNT composites was by 28.08% higher than that of an unmodified CF/EP composite. After aging at 120°C, the stress in the composite was dispersed due to the excellent dispersibility of CNT, and the suppression of long cracks resulted in a redn. of damage area.
This paper deals with changes in selected properties of composite material and surface degradation after exposure to an acidic environment. A carbon fiber-reinforced composite (CFRP) produced from prepregs was tested. The weight change, micro-hardness, and surface degradation of the CFRP composite made of cured pre-impregnated laminates were evaluated in this study. Material consisting of a DT121R epoxy resin matrix with high reactivity and high viscosity, with two reinforcing carbon fabrics layers, is characterized by a low value of tensile strength. Evaluation of changes in the material properties was performed before and after exposure to specific environmental conditions, which are achieved by using a chemical solution of 15% H2SO4 at various temperatures. Subsequently, the effect of 15% H2SO4 at various temperatures on the material properties was monitored. The specimens were immersed in the solution for up to 3 and 6 weeks at the temperatures of 23°C, 40°C, and 60°C. It was found out, that the degradation of the composite material is conditioned by the aging of the epoxy resin (matrix). Carbon fibers (reinforcement) are relatively stable. The weight change, micro-hardness, and surface quality depend on the time of exposure to acidic solution and temperature. The micro-hardness tests show a significant influence on exposure time. The biggest changes in weight change and surface quality of the CFRP composite were observed after exposure at the temperature of 60°C.
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The demand for environment-friendly ceramic reinforced polymer matrix composite (CRPMC) fabrication leads to the development of lead-free CRPMC. Calcium copper titanate (CCTO) and barium titanate (BT) are two of the most widely used lead-free ceramics for embedded capacitor applications. In the present study, the mechanical and morphological properties of both single and hybrid ceramic (CCTO and BT) filled epoxy composites were evaluated and compared with the unfilled pure epoxy resin. Hand lay-up followed by the compression molding technique were used to synthesize the CRPMC samples. Among the single filler CRPMCs, the BT/epoxy composite exhibited better mechanical properties and density values than the CCTO/epoxy composite. The 60:40 ratio hybrid CCTO-BT/epoxy composite possessed the highest mechanical properties and density values in contrast to the other composite specimens. The SEM micrographs of the fractured surfaces of the BT and CCTO CRPMC specimens were found to have a rougher and wavier appearance than the unfilled epoxy.
In this study, thermal conductivity, mechanical properties, and thermal degradation of pumice-added epoxy materials were investigated. 2%, 4%, 6%, 8%, and 10% of pumice was added to the epoxy resin (EP) % by weight. Various types of analyses and tests were conducted to determine the thermal conductivity, mechanical properties, and thermal degradation of these epoxy materials. The tests and analyses proved that the addition of pumice leads to a decrease in the thermal conductivity coefficient and density of the pure EP material. It also increases the degree of hardness. The addition of pumice had a positive effect on mechanical properties. Compared to pure EP, it increased the tensile strength, Young’s modulus, bending strength, and flexural modulus. As a result of TGA analysis it was determined that with the incorporation of pumice into the EP, its decomposition rate progressed more slowly. At 800_C, the carbon residue improved as a result of the addition of pumice.
Ornamental stones have been used quite a lot from past to present, and they are produced both naturally and synthetically in terms of visuality, durability and rarity. Naturally used ornamental stones are divided into two different classes as precious and semi-precious, and obsidian with two different colors belonging to the Nemrut volcanics used in the study is classified as semi-precious stones. Obsidian is a volcanic glass, showing a special fracture (conchoidal) and fracture surfaces give the rock a distinctive shine. In this study, obsidian was classified by breaking in different sizes (8-4.75 mm, 4.75-2 mm and 2-0.6 mm) in order to achieve this brightness. While black obsidian shards were obtained from 4.75-2 mm in size, brown obsidian shards were obtained from 2-0.6 mm shards and chose with the help of tweezers. Obsidian fragments with both colors were bonded with epoxy resin mixed at a ratio of 2:1 (epoxy and hardener) and placed in jewelry apparatus. The known durability properties and gloss of epoxy and the gloss on the broken surfaces of obsidian have been highlighted, and it has been observed that obsidian which has been used with different cutting and polishing techniques until now, can be obtained as a new product by using binder material. It is suitable to be used as an ornamental stone in jewelry making as a result of binding the obsidian fragments with epoxy by making use of the shines that occur on the fractured surfaces of the obsidian. In addition, it has been revealed that new products can be obtained as a result of bonding many natural rocks and minerals by using different binding materials.
Five-layer epoxy composites consisting of two outer layers made of glass fiber and three inner layers of cotton-bamboo fabric were obtained by compression molding. The influence of cotton-bamboo fabric/glass fiber content (35, 40, 45 and 50 wt%) and the order of stacking laminate layers on the mechanical properties (tensile, flexural, compressive, impact strength), thermal properties (TGA) and structure (FTIR, SEM) of the composites was investigated. The best mechanical and thermal properties were obtained with the content of 45 wt% cotton-bamboo fabric/glass fiber.
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Metodą prasowania tłocznego otrzymano pięciowarstwowe kompozyty epoksydowe składające się z dwóch warstw zewnętrznych wykonanych z włókna szklanego oraz trzech wewnętrznych z tkaniny bawełniano-bambusowej. Zbadano wpływ zawartości włókna szklanego (35, 40, 45 i 50% mas) oraz kolejności układania warstw laminatu na właściwości mechaniczne (wytrzymałość na rozciąganie, zginanie i ściskanie oraz udarność), termiczne (TGA) oraz strukturę (FTIR, SEM) kompozytów. Najlepsze właściwości mechaniczne i termiczne uzyskano przy zawartości 45% mas. włókna szklanego.
The influence of anatural filler (lignin, chitosan, starch) used in the amount of 1, 5 and 10 wt% on thermal and mechanical properties of composites based on epoxy resin (Epidian®5) was investigated. Cross-linking of the resin with polyamine (IDA) was confirmed by the ATR/FT-IR method. The differential scanning calorimetry (DSC) was used to evaluate the thermal properties. Tensile and flexural mechanical properties as well as Shore hardness were also determined.
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W pracy zbadano wpływ napełniacza naturalnego (lignina, chitozan, skrobia) stosowanego w ilości 1, 5 i 10% mas. na właściwości termiczne i mechaniczne kompozytów otrzymanych na bazie żywicy epoksydowej (Epidian®5). Sieciowanie żywicy poliaminą (IDA) potwierdzono metodą ATR/FT-IR. Do oceny właściwości termicznych zastosowano różnicową kalorymetrię skaningową (DSC). Oznaczono również właściwości mechaniczne przy rozciąganiu i zginaniu oraz twardość metodą Shore’a.
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W artykule zaprezentowano wpływ Mg(OH)2, Al(OH)3 oraz Roflamu F5 i Roflamu B7 na właściwości palne utwardzonej żywicy epoksydowej Epidian 5. Po analizie szybkości wydzielania ciepła w kalorymetrze stożkowym oraz analizie termograwimetrycznej stwierdzono, że wprowadzone dodatki są skutecznymi antypirenami testowanych materiałów epoksydowych. Najmniejszą wartość maksymalnej szybkości wydzielania ciepła zanotowano dla próbki składającej się z Epidianu 5 oraz 10% wag. Roflamu F5 oraz 5% wag. Al(OH)3.
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The article presents the effect of Mg(OH)2, Al(OH)3, Roflam F5 and Roflam B7 on the flammability properties of the hardened epoxy resin Epidian 5. After analyzing the heat release rate in the cone calorimeter and thermogravimetric analysis, it was found that the introduced additives are effective antirenes of the tested epoxy materials. The lowest value of the maximum heat release rate was recorded for the sample consisting of Epidian 5 and 10 wt.% of Roflam F5 and 5 wt. Al(OH)3.
In today's fast-developing world, the use of composite materials is closely related to environmental pollution, renewable and biodegradable resources. A researcher is looking for environmentally friendly materials. Natural and synthetic fibres come in a wide range of shapes and sizes. Natural fibres include jute, straw wheat, rice husk banana fibre, pineapple leaf fibre, cotton, Sisal, Coir, Oats, and Bagasse. Every year, 13.5 tonnes of banana fibre are produced in India. Teabags, paper, and polymer composite reinforcement are just a few of the applications for banana fibre. This article focuses on the manufacture of banana fibre with epoxy and a variety of other natural fibres. By combining banana fibre with some current technology, waste will be reduced, and energy efficiency will be increased, all while supporting sustainability. Banana fibres are covered in this work, along with their uses, applications, and mechanical qualities, as well as how banana fibre might improve mechanical properties.
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Due to the modern requirements regarding the reliability of electrical devices operation, research on improving the parameters of materials and insulation systems, in particular high-voltage ones, used in the production, transmission and distribution of electricity is still valid. One of the research directions is the development and application of insulating materials modified with nanofillers. The paper presents the results of stability studies of selected dielectric properties of samples of insulation materials based on epoxy resin modified with titanium dioxide TiO2 nanopowders. Changes in parameters caused by different wt% nanofiller content and their long-term stability after 10,000 hours from manufacturing are compared and analyzed.
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Współczesne wymagania dotyczące niezawodności pracy urządzeń elektrycznych powodują, że wciąż aktualnymi są badania dotyczące poprawy parametrów materiałów i układów izolacyjnych, w szczególności wysokonapięciowych, stosowanych w wytwarzaniu, przesyle i rozdziale energii elektrycznej. Jednym z kierunków badań jest opracowanie i zastosowanie materiałów izolacyjnych modyfikowanych nanowypełniaczami. Referat przedstawia wyniki badań stabilności wybranych właściwości dielektrycznych próbek materiałów izolacyjnych na bazie żywicy epoksydowej modyfikowanej nanoproszkami tlenku tytanu TiO2. Porównane są i analizowane zmiany parametrów powodowane różną zawartością wt% nanowypełniacza oraz ich stabilność długoczasowa po 10.000 godzin od wytworzenia.
This study aims to investigate the effect of fiber hybridization of sugar palm yarn fiber with carbon fiber reinforced epoxy composites. In this work, sugar palm yarn composites were reinforced with epoxy at varying fiber loads of 5, 10, 15, and 20 wt % using the hand lay-up process. The hybrid composites were fabricated from two types of fabric: sugar palm yarn of 250 tex and carbon fiber as the reinforcements, and epoxy resin as the matrix. The ratios of 85 : 15 and 80 : 20 were selected for the ratio between the matrix and reinforcement in the hybrid composite. The ratios of 50 : 50 and 60 : 40 were selected for the ratio between sugar palm yarn and carbon fiber. The mechanical properties of the composites were characterized according to the flexural test (ASTM D790) and torsion test (ASTM D5279). It was found that the increasing flexural and torsion properties of the non-hybrid composite at fiber loading of 15 wt % were 7.40% and 75.61%, respectively, compared to other fiber loading composites. For hybrid composites, the experimental results reveal that the highest flexural and torsion properties were achieved at the ratio of 85/15 reinforcement and 60/40 for the fiber ratio of hybrid sugar palm yarn/carbon fiber-reinforced composites. The results from this study suggest that the hybrid composite has a better performance regarding both flexural and torsion properties. The different ratio between matrix and reinforcement has a significant effect on the performance of sugar palm composites. It can be concluded that this type of composite can be utilized for beam, construction applications, and automotive components that demand high flexural strength and high torsional forces.
PL
Zbadano wpływ dodatku przędzy z włókien palmy cukrowej o grubości 250 tex na wytrzymałość kompozytów epoksydowych wzmocnionych włóknem węglowym. Sumaryczna zawartość włókien w osnowie żywicy epoksydowej była równa 5, 10, 15 i 20% mas., a stosunek udziału przędzy palmy cukrowej do włókna węglowego wynosił 50 : 50 i 60 : 40. Właściwości mechaniczne kompozytów hybrydowych o stosunku osnowy do wzmocnienia 85 : 15 i 80 : 20 scharakteryzowano na podstawie testów na zginanie i skręcanie. Stwierdzono, że wytrzymałość na zginanie i skręcanie kompozytu epoksydowego z udziałem 15% mas. przędzy palmy cukrowej była większa niż pozostałych kompozytów niehybrydowych i wynosiła, odpowiednio, 7,40% i 75,61%. W wypadku kompozytów hybrydowych stwierdzono, że najlepszą wytrzymałość na zginanie i skręcanie wykazywały kompozyty z udziałem 15% mas. wzmocnienia w stosunku 60 : 40 włókien palmy cukrowej do włókien węglowych. Różna zawartość włókien wzmacniających w osnowie epoksydowej miała istotny wpływ na właściwości wytwarzanych kompozytów. Kompozyty tego rodzaju można wykorzystać do budowy elementów konstrukcyjnych i motoryzacyjnych, o dużej wytrzymałości na zginanie i działanie sił skręcających.
Artykuł poświęcony jest modyfikacji żywicy epoksydowej Epidian 5 przez wprowadzenie włókien naturalnych (konopi) oraz kauczuku butadienowo-akrylonitrylowego zakończonego grupami aminowymi (ATBN). Otrzymano kompozyty zawierające 5 - 15% wag. włókien naturalnych o różnej wielkości, 5 - 15% wag. ATBN, 5% wag. włókien naturalnych oraz jednocześnie 5 - 15% wag. ATBN. Przeprowadzono ocenę wpływu zastosowanych dodatków na wybrane właściwości mechaniczne otrzymanych kompozytów, tj. udarność, krytyczny współczynnik intensywności naprężeń oraz czas żelowania. Na podstawie badań stwierdzono, że dodatek włókien konopi lub ATBN zdecydowanie poprawia odporność na kruche pękanie. Jednak najwyższe wartości udarności osiągnęły kompozycje zawierające jednocześnie ATBN oraz 5% włókien naturalnych.
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The article describes the modification of the epoxy resin (Epidian 5) by the incorporation of natural fibers (hemp) and amino-terminated butadiene-acrylonitrile rubber (ATBN). Composites containing: 5 - 15 wt% natural fibers of various sizes, 5 - 15 wt% ATBN, 5 wt% natural fibers and at the same time 5 - 15 wt.%. ATBN. The effect of additives on selected properties of the obtained composites: impact strength, critical stress intensity factor and gelation time was evaluated. The results showed that the addition of hemp or ATBN fibers significantly improves fracture toughness. However, the highest impact value were achieved by compositions containing both ATBN and 5% hemp fibers.
W artykule przedstawiono sposób przygotowania kompozytów na bazie żywicy epoksydowej Epidian 5 poddanej modyfikacji włóknem pochodzenia naturalnego. Napełniacz (włókna konopi) był dodawany do żywicy w ilości 5, 10, 15 % wagowych. Do utwardzenia wykorzystano trietylenotetraminę – utwardzacz Z1. Następnie poddano je wybranym badaniom wytrzymałościowym. Badania miały na celu wskazanie wpływu włókien naturalnych na właściwości kompozycji: czas żelowania, lepkość udarność oraz odporność na zginanie. Zaobserwowano silną korelację między wielkością włókien a właściwościami otrzymanych kompozytów.
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The article describes the preparation of composites based on epoxy resin modified with natural fibers. As a filler was added cannabis fibers in an amount of 5, 10 and 15 %w/w. Triethylenetetramine was used to cure. Compo- sites were tested for processing and mechanical properties determination.The results showed that there is a strong correlation between the fibers size and the strength properties of prepared composites
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W artykule omówiono wpływ modyfikacji płynnej żywicy epoksydowej odpadową mączką wapienną na jej lepkość kinematyczną. Badania przeprowadzono na dwóch seriach próbek żywicy epoksydowej zawierającej oraz pozbawionej utwardzacza. Jako dodatek zastosowano odpadową mączkę wapienną w trzech frakcjach. Do badań przygotowano dwie mieszaniny referencyjne. W przypadku każdego dodatku wykonano po pięć mieszanin o rożnej zawartości odpadowej mączki wapiennej. Badano lepkość kinematyczną za pomocą kubka wypływowego. Wykazano, że wraz ze wzrostem ilości odpadowej mączki wapiennej zwiększa się lepkość kinematyczna płynnej żywicy epoksydowej zarówno bez, jak i z utwardzaczem. Dodatkowo udowodniono, że lepkość kinematyczna żywicy epoksydowej z dodatkiem odpadowej mączki wapiennej zależy głownie od ilości tego dodatku, a w pomijalnie małym stopniu od wielkości jego ziaren i składu.
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The main aim of the article is to describe the influence of modification of liquid epoxy resin with waste limestone powders on its kinematic viscosity. The tests were carried out for two series of samples: epoxy resin with and without a hardener. As an additive, waste limestone powders were used in three fractions. Two reference mixtures were prepared for the tests, one for each series. For each additive, five mixtures were made with different contents of the waste limestone powder. The kinematic viscosity of the prepared mixtures was tested using a flow cup. On the basis of the research, it was shown that with the increase in the amount of waste limestone powder, the kinematic viscosity of the liquid epoxy resin increases, both with and without the hardener. Additionally, it has been proved that the kinematic viscosity of epoxy resin with the addition of waste lime powder mainly depends on the amount of this additive, and to a negligible extent on the grain size and composition of this additive.
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Today, using Fiber Reinforced Polymer (FRP) sheets is one of the conventional methods in retrofitting concrete structures. Some factors affecting FRP sheets proper performance include mechanical properties, surface specifications, connector’s material and connecting approach in concrete elements. Previous studies showed that FRP epoxy resin and its basic surface have a significant impact on the ultimate bearing capacity. In line with the development of nanotechnology in recent years, this paper presents an experimental study to show the effects of adding the best percentage of nano-carbons to adhesive resin and evaluate the ultimate axial, shear and bending strengths in concrete samples. The results show that using FRP with carbon nanotube reinforced resins will significantly increase stiffness and ductility by 100%; moreover, it shows an effective increase of almost 13% in axial and flexural strengths of specimens.
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Natural fiber-reinforced composites are getting more attention from researchers and manufacturing companies to replace metals and synthetic materials that have dominated the manufacturing industries. In this study, the mechanical properties of unidirectional (UD) flax roving-reinforced composites and woven fabric-reinforced composites were investigated. Three different composites were prepared from flax rovings, which have the same linear density and epoxy resin matrix, with different reinforcement and composite preparation methods. The samples were subjected to experimental tests of flexural rigidity and tensile strength in a parallel and perpendicular direction to fiber orientation. The test results showed that flexural rigidity and tensile strength of flax fiber-reinforced composites are highly dependent on the direction of fiber orientation. The results also reveal that in a parallel direction to fiber orientation, UD composites have higher flexural rigidity and tensile strength than woven fabric-reinforced composite.
Purpose: The article presents the possibilities of using anchoring systems in the walls of three-layer large slab panel buildings. The use of diagonal anchors allows to increase the effective anchorage depth, which significantly increases the durability of the façade textured layer. Design/methodology/approach: Pilot tests have confirmed the necessity to use an anchor system in various configurations. Findings: The documents used included the conclusions of the pilot tests on the real object and the main experimental tests carried out on concrete samples. Research limitations/implications: The design of new anchorage systems and the proposed theoretical models for estimating their theoretical load capacity are based on the Guidelines contained in the European Technical Approvals. Practical implications: Single bonded anchorages used in engineering practice require evaluation in order to increase the durability of larger areas of the façade textured layer. Originality/value: The possibility of differentiating system anchors makes it possible to use them in very thin structural layers (diagonal anchors).
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