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1

Porównanie ugięcia betonowych belek zbrojonych prętami GFRP, BFRP i ze stali B500

Pytlowany Tomasz, Leń Dariusz, Piszczek Kazimierz, Zimka Roman

Przegląd Budowlany

|

2024

|

R. 95, nr 1-2

77--80

PL

Głównym celem badań było uzyskanie danych związanych z jakościową oceną sztywności belek betonowych zbrojonych prętami stalowymi EPSTAL B500SP oraz kompozytowymi prętami zbrojeniowymi GFRP i BFRP przy zachowaniu tego samego stopnia zbrojenia belek. Przyjęto schemat statyczny badanych elementów w postaci belki swobodnie podpartej o rozpiętości 1,5 m. Podstawowym opisem zachowania badanych elementów, zarejestrowanym podczas badań, była ścieżka równowagi statycznej opisana w układzie współrzędnych: siła obciążająca P i ugięcie belki u, rejestrowane za pomocą czujników, zarejestrowane zależności P-u. Podane na wykresach wartości ugięcia belek u są średnią arytmetyczną pomiarów z czujników przemieszczenia. W trakcie badań wykonano również pomiary odkształceń prętów zbrojeniowych w zależności od wartości przyłożonego obciążenia P. Wyniki tych pomiarów przedstawiono graficznie.

EN

The main purpose of the research was to obtain data related to the qualitative assessment of the stiffness of concrete beams reinforced with B500SP EPSTAL steel reinforcement bars and GFRP and BFRP composite reinforcing bars while maintaining the same degree of reinforcement of the beams. A static scheme of the tested elements was adopted in the form of a simply supported beam with a span of 1,5 m. The basic description of the behavior of the tested elements, recorded during the tests, was the static equilibrium path described in the coordinate system: loading force P and beam deflection u, recorded using sensors, the recorded P-u dependencies. The deflection values of the beams u given in the graphs are the arithmetic mean of the measurements from the displacement sensors. During the tests, measurements of reinforcing bars deformation were also carried out depending on the value of the applied load P. The results of these measurements are presented graphically.

2

Odporność systemów ociepleń ETICS na uszkodzenia mechaniczne

Pogorzelec Paweł

Izolacje

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2023

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T. 28, nr 9

126, 128--137

PL

Przedmiotem artykułu jest odporność systemów ociepleń ETICS na uszkodzenia mechaniczne. Autor przedstawia sposób wytwarzania i właściwości siatek zbrojących z włókna szklanego do systemów ETICS, a także omawia formalne warunki dopuszczenia siatek zbrojących do zastosowania w systemach ETICS, sposoby zwiększania odporności systemów ociepleń na uderzenia oraz miejsca zastosowania podwójnego zbrojenia w systemach ETICS.

EN

The subject of the article is the resistance of ETICS thermal insulation systems to mechanical damage. The author presents the method of manufacturing and properties of fibreglass mesh for ETICS systems, and he also discusses the formal conditions for admitting reinforcing mesh to be used in ETICS systems, methods of increasing the impact resistance of thermal insulation systems and places to use double reinforcement in ETICS systems.

3

Comparative study on the impact transition behaviour of PPS reinforces with 40% VF Glass

Kadhim Rand Fadhil, Jassim Noor Alhuda Sabah, Abdulhasan Maryam Jawad

Diagnostyka

|

2023

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Vol. 24, No. 3

art. no. 2023314

EN

Composite materials, in most cases polymers reinforced with fibers, are these days utilized in numerous applications such as aerospace applications in which lightweight, high strength, high specific modulus and low temperature resistance are critical issues. As these materials have possible applications in different designing areas, a lot of work has been put into enhancing their performance. This study's aim was to study the impact transition behavior of PPS and its composite under different ranges of temperatures by investigating their thermal, mechanical and structural characteristics. PPS and its composite reinforced with 40% vf (volume fraction) glass fibers are employed in this study. The impact transition behavior of PPS and 40%Vf glass fibers composite were investigated by analyzing the mechanical properties: impact, tensile, bending and, hardness at the following temperature ranges: 23°C, -26°C, and -78°C. A particular refrigerator and dry ice were used to achieve the extremely low temperatures (-26 C and -78 C, respectively). The results showed that the addition of 40% glass fibers improved the impact transition behavior of 40%GF PPS composite with temperature decreasing. Which with decreasing in temperature from 23˚C to -78˚C, the impact strength of PPS decreased by fifty five percent while it increased by twenty three percent for 40%GF PPS composite.

4

Effect of alkaline treatment on mechanical properties of palmyra and S-glass fiber reinforced epoxy nanocomposites

Sravya Navuluri Padma, Sivaganesan S., Venkatesh R., Manikandan R.

Archives of Civil and Mechanical Engineering

|

2023

|

Vol. 23, no. 2

art. no. e116, 2023

EN

Although epoxy resins have many advantages, their use needs to be expanded by improving their mechanical properties, including a wide variety of material quality, easy processing, negligible shrinkage due to curing, and good adhesiveness to many forms of fiber materials. The research focuses cost-effective utilization of palmyra fiber treated with 5% alkali solution and different volume percentages of S-glass fiberglass incorporated by epoxy resin developed by hand layup technique. The final epoxy hybrid composite consists of different weight ratios of palmyra/S-glass fiberglass as 25:75, 50:50, and 75:25. Influences of palmyra (treated) fiber dispersion quality on density, voids, mechanical and moisture absorption performance of the epoxy hybrid composite is studied by ASTM rule. The elevated output characteristics performance is compared with untreated fiber composite. Based on the rule of mixture, composite density is varied and Archimedes’ principle measures voids. The alkali treated composite samples showed good tensile stress, flexural and impact strength. While compared to untreated fiber composite, the tensile, flexural, and compressive strength of TPF/GF(25:75) composite was improved by 19.58%, 29%, and 14.3%, respectively. The reduced water absorption behaviour was observed on the treated composites. The effect of fiber dispersion on the mechanical failure of hybrid composite is studied by SEM analysis.

5

Zastosowanie betonu zbrojonego włóknami szklanymi do tworzenia elementów konstrukcyjnych oraz form architektonicznych

Blazy Julia, Drobiec Łukasz, Blazy Rafał

Przegląd Budowlany

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2022

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R. 93, nr 5-6

27--33

PL

W artykule opisano obszary zastosowań fibrobetonów z włóknami szklanymi oraz podkreślono możliwość tworzenia nie tylko elementów konstrukcyjnych przeznaczonych głównie do przenoszenia obciążeń, ale także struktur towarzyszących procesom budowlanym oraz form małej architektury, które uatrakcyjniają i urozmaicają przestrzenie publiczne. Dzięki ulepszonym właściwościom mechanicznym, zmniejszonym ciężarze i większej swobodzie projektowej elementów z włóknami szklanymi możliwe jest tworzenie wytrzymalszych, bezpieczniejszych, trwalszych oraz nowocześniejszych konstrukcji.

EN

The article describes the areas of application of glass fiber reinforced concrete and emphasizes the possibility of creating not only structural elements intended mainly for carrying loads but also structures accompanying construction processes and forms of small architecture that make public spaces more attractive and diversified. Thanks to improved mechanical properties, reduced weight, and greater design freedom of elements with glass fibers, it is possible to create stronger, safer, more durable, and modern structures.

6

Mechanical and thermal properties of cotton-bamboo fabric/glass fiber epoxy composites

Chandrasekaran Kailasam, Shanmugam Periyasamy, Senthilkumar Palanisamy

Polimery

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2022

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Vol. 67, nr 11-12

567--574

EN

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.

PL

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.

7

Influence of chemical foaming on the structure and selected properties of glass fiber reinforced PA6

Konczal Natalia, Nowinka Bartosz, Bieliński Marek

Polimery

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2022

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Vol. 67, nr 10

475--482

EN

The effect of the chemical foaming on the structure (SEM) and selected properties of glass fi ber (30, 60 wt%) reinforced polyamide 6 (PA 6) was investigated. Density, tensile properties and Charpy impact strength were determined. Hydrocerol ITP 825 was used as a blowing agent in the amount of 2 wt%. The size of the pores and the foaming degree depended on the distance from the injection point. The smallest pore size (64 μm) was observed for 60 wt% glass fiber reinforced PA6.

PL

Zbadano wpływ procesu spieniania chemicznego na strukturę (SEM) oraz wybrane właściwości poliamidu 6 wzmocnionego włóknem szklanym (30, 60 % mas.). Oznaczono gęstość, właściwości mechaniczne przy rozciąganiu i udarność Charpy’ego. Jako porofor stosowano Hydrocerol ITP 825 w ilości 2% mas. Wielkość porów i stopień spieniania zależały od odległości od punku wtryskiwania. Najmniejszą wielkość porów (64 μm) stwierdzono w przypadku poliamidu zawierającego 60% mas. włókna szklanego.

8

Zbrojenie kompozytowe z włókien szklanych - potencjalne źródło problemów inżynierskich

Błyszko Jarosław

Inżynieria i Budownictwo

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2022

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R. 78, nr 3-4

128--131

PL

W artykule omówiono zastosowanie prętów kompozytowych z włókna szklanego jako alternatywnego sposobu zbrojenia elementów zginanych. Przedstawiono koncepcję zbrojenia minimalnego wyliczanego na podstawie układu sił w przekroju zginanym, a następnie porównano z wynikami badań. Wykazano, że w przypadku zbrojenia GFRP opieranie się jedynie na zależnościach statycznych może prowadzić do zaniżenia nośności.

EN

This paper presents the use of fiberglass composite bars as an alternative reinforcement method for flexural elements. The concept of the minimal reinforcement calculated from the balance of forces in the element is presented and then compared with test results. It is shown that when calculating the minimum degree of GFRP reinforcement, basing only on static relationships can result in too low a load capacity.

9

Investigation of glass fiber influence on mechanical characteristics of natural fiber reinforced poliester composites : an experimental and numerical approach

Mohapatra Deepak Kumar, Deo Chitta Ranjan, Mishra Punyapriya

Composites Theory and Practice

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2022

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R. 22, nr 3

123--129

EN

In the past few decades, natural fiber reinforced polymeric composites have gained significant importance for various structural applications in different sectors like the automotive, aerospace, sports and building construction industries. However, hybridizations make the composite more versatile in term of strength, weight and its processing for many engineering applications. In the current study, a polyester resin matrix was reinforced with two different natural fibers, namely kenaf and palmyra palm leaf stalk (PPLS) and hybridized with glass fiber. Four layers of two different fiber mats, kenaf/glass and PPLS/glass with different stacking sequences were employed to fabricated laminates by the hand lay-up technique. In this case, an attempt was made using the numerical approach to investigate the influence of glass fiber on the mechanical characteristics of the laminates. To substantiate the results of the numerical approach, experiments were conducted. Enhancement of both the tensile and flexural strength was observed due to hybridization of both the kenaf and PPLS fiber with glass fiber. The tensile and flexural strength improved by 68.91 and 37.63% respectively when the kenaf fiber was hybridized with glass fiber. Similarly, enhancement of 54.42% of the tensile strength and 15.92% of the flexural strength were noticed when the PPLS fiber was hybridized with glass fiber. Through the use of ANSYS software, finite element analysis (FEA) was employed as a simulation method to examine the tensile and flexural strength. The numerical findings were found to be quite close to the experimental results, with a variation of less than 3%.

10

Polimerobeton zbrojony krótkimi włóknami szklanymi, z dodatkiem odpadowego szkła kineskopowego

Smoleń Jakub, Tomaszewska Klaudia, Junak Grzegorz, Kozioł Mateusz

Cement Wapno Beton

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2022

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R. 27, nr 2

102--114

PL

W pracy omówiono wykorzystanie odpadowego szkła kineskopowego, do wytwarzania polimerobetonów. Szkło kineskopowe poddano kilkakrotnemu rozdrabnianiu, w celu otrzymania ziaren mniejszych od 2 mm. Utworzono szereg polimerobetonów wzmocnionych hybrydowo: zmielonym szkłem kineskopowym, piaskiem oraz pociętym włóknem szklanym, o długości 4,5 mm i 12 mm. Zbadano wpływ dodatku włókien szklanych i ich długości na właściwości polimerobetonów, z 30% dodatkiem objętościowym żywicy epoksydowej, pełniącej rolę lepiszcza. Przeprowadzono badania szkła kineskopowego, oznaczając jego skład chemiczny, rozkład wielkości cząstek i budowę ziaren. Oznaczono wytrzymałość na zginanie i na ściskanie oraz porowatość otwartą, gęstość pozorną i nasiąkliwość wodą. Wyniki badań wykazały, że polimerobetony z dodatkiem zmielonego szkła kineskopowego, są dobrą metodą na zagospodarowanie, tego nietypowego odpadu. Uzyskane polimerobetony mają kilkukrotnie lepsze właściwości mechaniczne niż tradycyjne betony oraz znacznie mniejszą porowatość i nasiąkliwość wodą, co czyni ten materiał korzystny do produkcji wyrobów cienkościennych oraz narażonych na działanie wody i odczynników chemicznych. Dodatek ciętych włókien szklanych powoduje poprawę właściwości mechanicznych polimerobetonów, a także chroni ten materiał, przed gwałtowną dezintegracją, po przekroczeniu maksymalnych naprężeń. Jest to niezwykle ważne dla bezpieczeństwa użytkowania konstrukcji, w przypadku awarii.

EN

This paper describes the use of CRT glass waste for the production of polymer concrete. The CRT glass was subjected to a multistage mechanical disintegration process, in a way that allowed obtaining grains smaller than 2 mm. A set of hybrid reinforced polymer concrete was produced by using: ground CRT glass, sand and cut glass fibers 4.5 mm and 12 mm long. The influence of the volume of fibers and the length of glass fibers on the properties of polymer concrete with 30% by volume of epoxy resin, acting as a binder was described. Tests of CRT glass were carried out, among others study of chemical composition, particle size distribution and analysis of grain morphology. For polymer concrete, the flexural strength and compressive strength were determined, and the open porosity, apparent density, and water absorption were examined. The test results showed that polymer concrete with the use of milled CRT glass is a good way to manage this problematic waste. The polymer concrete has several times better than traditional concretes and significantly lower porosity and water absorption, which makes this material advantageous in applications such as the production of thin-walled products and products exposed to water and chemical attack. The addition of chopped glass fibers leads to an increase in mechanical properties and also protects the material against rapid disintegration after exceeding the maximum stresses, which is extremely important for the safety of use of the structure in the event of a failure.

11

Bending Failure Behavior of the Glass Fiber Reinforced Composite I-Beams Formed by a Novel Bending Pultrusion Processing Technique

Zhu Lvtao, Cao Shengbin, Zhang Xiaofeng, Li Lei

Autex Research Journal

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2022

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Vol. 22, no. 2

172--176

EN

The glass fiber reinforced resin matrix composite I-beams were designed and formed via a type of novel bending pultrusion processing technique, and the three-point bending tests were carried out to analyze the mechanical bending performances. The obtained results show that the main failure mode of the composite I-beam under the bending load is the upper structure (top flange) cracks along the length direction of the fibers, and the cracks simultaneously propagate downwards in the vertical direction. The bifurcated cracks can be found at the junction area between the top flange and web. In addition, the main bending failure mechanism of the composite I-beam includes the matrix cracking, propagation of cracks, and final fracture failure. In particular, noting that when the crack reaches the I-shaped neck position, the lateral bifurcation occurs, and the resulting secondary cracks further extend in two directions, which leads to the serious damage between the top flange and web, and the ultimate fracture failure occurs.

12

Flexural response of FRP‑strengthened lightweight RC beams: hybrid bond efficiency of L-shape ribbed bars and NSM technique

Tahmouresi Behzad, Momeninejad Kasra, Mohseni Ehsan

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 2

art. no. e95, 1--16

EN

This paper presents the results of an experimental study on employing near surface mounted (NSM) fiber-reinforced polymer (FRP) reinforcement technique, and L-shape ribbed bars, for flexural strengthening of lightweight reinforced concrete (RC) beams. 18 RC beams including 14 lightweight RC beams and four normal-weight concrete beams were designed. The beams were strengthened with glass fiber-reinforced polymer (GFRP) bars and carbon fiber-reinforced polymer (CFRP) laminate in bending tests. Test parameters included: (1) different FRP materials (glass bars and carbon sheets), (2) longitudinal steel reinforcement ratio, and (3) type of strengthening technique used (NSM reinforcement or hybrid). The ultimate tensile strength, deflection, compressive and tensile strain of concrete, and failure mode of the beams were examined under four-point flexural test. Results showed that the ultimate strength of all RC beams increased between 33 and 105% compared to the control beam. The ultimate strength of beams reinforced with CFRP in the mid-span region was 10% higher than that of beams strengthened at both ends, although the former exhibited 28% lower ultimate deflection. The ultimate strength and deflection of RC beams strengthened with combined steel reinforcing bars and GFRP bars were 10% and 108% higher, respectively, compared to those of RC beams strengthened with GFRP bars only. Hybrid L-shape ribbed bars beams showed a considerably higher ductility (up to 170% increase in the ultimate deflection) compared to other beams. The comparison of the experimental results of the ultimate strength of the beams with ACI440-2R guidelines indicated a reasonable and conservative prediction of the code expression.

13

Measurement and evaluation of delamination factors and thrust force generation during drilling of multiwall carbon nanotube (MWCNT) modified polymer laminates

Kumar Kuldeep, Verma Rajesh Kumar

Archive of Mechanical Engineering

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2022

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LXIX, nr 2

269--300

EN

In recent years, manufacturing industries have demanded high-performance materials for structural components development due to their reduced weight, improved strength, corrosion, and moisture resistance. The outstanding performance of polymer nano-composites substitutes the use of conventional composites materials. This study is concerned with the machining of MWCNT and glass fiber-modified epoxy com posites prepared by a cost-effective hand layup procedure. The investigations were carried out to estimate the generation of the thrust force (Th) and delamination factors at entry (DFentry) and exit (DFexit) side during the drilling of fiber composites. The effect of varying constraints on the machining indices was explored for obtaining an adequate quality of hole created in the epoxy nano-composites. The outcome shows that the feed rate (F) is the most critical factor influencing delamination at both entry and exit side, and the second one is the thrust force followed by wt.% of MWCNT. The statistical study shows that optimal combination of S (1650 Level-2), F (165 Level-2), and 2 wt.% of MWCNT (Level-2) can be used to minimize DFentry, DFexit, and Th. The drilling-induced damages were studied by means of a high-resolution microscopy test. The results reveal that the supplement of MWCNT substantially increases the machining efficiency of the developed nano-composites.

14

Quality improvement of gear wheels obtained from polymer materials by shaving process

Markowska Olimpia, Bulanda Katarzyna, Zajdel Magdalena

Polimery

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2021

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T. 66, nr 5

298--301

EN

The geometric accuracy of gears obtained by injection molding before and after finishing by shaving process has been compared. Significant assumptions in the application of this method to the finishing of polymer gears are presented. There is a clear influence of the applied technology on the dimensional stability improvement of the tested gears rim made of composite PA66 matrix containing 35 wt % glass fibers. The tested gears made of the composite materials used in some drive systems can successfully replace this type of machine elements made of metals.

PL

W pracy porównano dokładność geometryczną kół zębatych otrzymanych metodą wtryskiwania przed i po obróbce wykańczającej metodą wiórkowania. Przedstawiono istotne założenia dotyczące zastosowania tej metody do obróbki wykańczającej polimerowych kół zębatych. Zaobserwowano wyraźny wpływ zastosowanej obróbki na poprawę stabilności wymiarowej wieńca badanych kół zębatych z kompozytu na osnowie PA66 zawierającego 35% mas. włókna szklanego. Koła zębate z badanych materiałów kompozytowych mogą z powodzeniem być zamiennikami tego typu elementów wykonanych z metali.

15

Study of the Dielectric Properties and Conductivity of Double Coated Glass Fibre Felt Composites

Liu Yuanjun, Wang Caixia, Ma Yiping, Liu Yanyan, Wu Haiying, Zhao Xiaoming

Fibres & Textiles in Eastern Europe

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2021

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Vol. 29, no. 4 (148)

75--80

EN

Graphite/talcum powder double-coated glass fibre felt composites were prepared using glass fibre felt as the base material, graphite as the surface absorbing agent, talcum powder as the underlying absorbing agent, epoxy resin E44 as the adhesive and low molecular 650 polyamide as the curing agent. The influences of the surface graphite content and underlying talcum powder content on the dielectric properties and conductivity of glass fibre felt composites were the main focus of the investigation. Results showed that when the frequency is less than 103 Hz, the values of the real and imaginary parts of the dielectric constant for double-coated glass fibre felt composites are largest when the surface graphite content is 50%. When the frequency is larger than 106 Hz, the value of the real part of the conductivity is largest when the graphite contents are 40% and 50%. When the frequency is less than 104Hz, the real part of the dielectric constant of the glass fiber mat composites is the largest when the talc content is 40%, and when talc content is 60%, the imaginary part of dielectric constant of glass fiber mat composites is the largest. The maximum loss tangent value for the composites occurs when the talcum powder content is 40%. When the frequency is larger, the value of the real part of the conductivity increases gradually.

PL

W pracy przygotowano podwójnie powlekane kompozyty filcu z włókna szklanego w postaci grafit/talk. Użyto filcu z włókna szklanego jako materiału bazowego, grafitu jako powierzchniowego środka pochłaniającego, talku jako podstawowego środka pochłaniającego, żywicy epoksydowej E44 jako kleju i poliamidu 650 o niskiej masie cząsteczkowej jako środek utwardzającego. Głównym przedmiotem badań było określenie wpływu zawartości grafitu powierzchniowego oraz zawartości proszku talku na właściwości dielektryczne i przewodność kompozytów z filcu z włókna szklanego. Wyniki wykazały, że gdy częstotliwość jest mniejsza niż 103 Hz, wartości części rzeczywistej i urojonej stałej dielektrycznej dla podwójnie powlekanych kompozytów z filcu z włókna szklanego są największe, gdy zawartość grafitu powierzchniowego wynosi 50%. Gdy częstotliwość jest większa niż 106 Hz, wartość rzeczywistej części przewodnictwa jest największa, gdy zawartość grafitu wynosi 40% i 50%. Maksymalna wartość tangensa strat dla kompozytów występuje, gdy zawartość talku wynosi 40%. Gdy częstotliwość jest większa, wartość rzeczywistej części przewodnictwa stopniowo wzrasta.

16

Thermal gravimetric analysis of glass fiber reinforced composite for understanding the impact of copper oxide in relation to titanium oxide filler particles

Alam Shahinoor, Chowdhury Mohammad Asaduzzaman

Composites Theory and Practice

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2021

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R. 21, nr 1-2

12--21

EN

In this work, the composite samples required to investigate their thermal properties were fabricated employing the conventional hand lay-up technique, followed by a light compression molding process. A fixed weight of plain woven glass fiber and epoxy with four different types of fillers as calcium carbonate (CaCO3), aluminum oxide (Al2O3), magnesium oxide (MgO) and titanium oxide (TiO2) or copper oxide (CuO) of different weights (5, 10 and 15 g) were studied. According to thermal gravimetric analysis (TGA), it was observed that the melting point (Tm) and glass-transition temperature (Tg) are affected by the presence of CuO and TiO2, which indicate the degree of composite crystallinity established by the stronger interfacial interaction by the CuO than that of the TiO2 particles and the amorphous region of the chain. These studies were supported by examination of the surface morphology of the composites by means of scanning electron microscopy (SEM).

17

Analysis of Basis Weight Uniformity Indexes for the Evaluation of Fiber Injection Molded Nonwoven Preforms

Moll Patrick, Wang Shaofan, Coutandin Sven, Fleischer Jürgen

Autex Research Journal

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2021

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Vol. 21, no. 3

341--351

EN

Fiber injection molding is an innovative approach for the manufacturing of nonwoven preforms but products currently lack a homogeneous fiber distribution. Based on a mold-integrated monitoring system, the uniformity of the manufactured preforms will be investigated. As no universally accepted definition or method for measuring uniformity is accepted yet, this article aims to find a suitable uniformity index for evaluating fiber injection molded nonwovens. Based on a literature review, different methods are implemented and used to analyze simulated images with given distribution properties, as well as images of real nonwovens. This study showed that quadrant-based methods are suitable for evaluating the basis weight uniformity. It has been found that the indexes are influenced by the number of quadrants. Changes in sample size do not affect the indexes when keeping the quadrant number constant. The quadrants-based calculation of the coefficient of variation showed the best suitability as it shows good robustness and steady index for varying degrees of fiber distribution.

18

Durability performance of fibrous high-performance cementitious composites under sulfuric acid attack

Mermerdaş Kasım, Ipek Süleyman, Anwer Ahmed Motesem, Ekmen Şevin, Özen Mustafa

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 4

203--222

EN

The high-strength concrete having a better compressive strength demeanor can be manufactured by the addition of the fibers which eliminates the inherent weakness, the brittle failure due to lack of tensile strength. In this study, an experimental study covering the enhancement of the mechanical characteristics and the investigation of the performance against the aggressive acid attack of high-performance cementitious composites (HPCC). For this, steel and glass types of fiber were employed in the manufacturing of HPCC, as either single or hybrid at various levels. The HPCC mixtures were designed at a constant water-to-cementitious ratio of 0.25. Portland cement and microsilica were employed in the manufacturing as cementitious material whereas the aggregate was the mix of river and quartz sands. 14 HPCC mixtures were designed and the flowability, unit weight, compressive and flexural strengths, sorptivity index, ultrasonic pulse velocity were tested at various ages. Besides, the loss in the strength, mass, and dimension of HPCC mixtures was also measured after exposure of the mixtures 1- and 2-month aggressive sulfuric acid (H2SO4). Additionally, the experimental results were statistically evaluated through general linear model ANOVA. Based on the results, the highest compressive strength values were observed in the HPCC mixture manufactured with steel fiber. The lowest losses in both flexural and compressive strengths were observed in the mixtures produced with microsilica. Steel fiber addition increased the compressive strength not only after applying the normal curing regime but also after exposing the sulfuric acid. Both flexural and compressive strength of HPCC mixtures were influenced by fiber type and volume fraction. The addition of glass fiber decreased compressive strength.

19

Phenol-formaldehyde resin composites filled with modified phlogopite reinforced with hybrid glass and basalt fiber meshes used as grinding wheels

Oleksy Mariusz, Oliwa Rafał, Bulanda Katarzyna, Szałajko Robert, Budzik Grzegorz, Skrzypczak Izabela

Polimery

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2020

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T. 65, nr 11-12

833--837

EN

The research on obtaining composites based on phenol-formaldehyde resin (PFR) with modified phlogopite quaternary ammonium salt (QAS) reinforced with hybrid glass and basalt fiber was carried out. The influence of the reinforcement structure (glass mesh weave) and the type of fiber on the performance properties of the obtained composites were assessed, especially in terms of their use a grinding wheels reinforced with modified hybrid glass and basalt fiber meshes. Based on the obtained research results, it was found that composites reinforced with a glass fiber layer mesh with a matrix of phenol-formaldehyde resin filled with modified phlogopite are characterized by higher mechanical strength, abrasion resistance and dynamic strength of the disk compared to unmodified composites.

PL

Przeprowadzono badania nad otrzymaniem kompozytów na osnowie żywicy fenolowo-formaldehydowej (PFR) z flogopitem zmodyfikowanym czwartorzędową solą amoniową (QAS) wzmacnianych hybrydowymi siatkami z włókna szklanego i bazaltowego. Oceniono wpływ struktury wzmocnienia (splotu siatki szklanej) oraz rodzaju włókna na właściwości użytkowe otrzymanych kompozytów, zwłaszcza w kontekście ich zastosowania w charakterze ściernic. Na podstawie uzyskanych wyników badań stwierdzono, że kompozyty wzmocnione siatką warstwową z włókna szklanego z osnową żywicy fenolowo-formaldehydowej napełnionej zmodyfikowanym flogopitem charakteryzują się większą wytrzymałością mechaniczną, odpornością na ścieranie oraz wytrzymałością dynamiczną tarczy niż kompozyty niemodyfikowane.

20

Influence of fiber reinforcement towards the physical characteristics of low density polyethylene laminated composites

Ravichandran S., Raj A. Daniel, Visvanath P. Balaji, Mohammad Faruq, Al-Lohedan Hamad A., Sagadevan Suresh

Polimery

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2020

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T. 65, nr 6

449--457

EN

In recent years, the increased interest in the design and fabrication of lightweight polymer composites with various combinations and stoichiometry is due to their enhancement of electrical, mechanical, thermal, and biological properties compared to the properties of conventional materials. With that view, the present study deals with the effects of low density polyethylene composites (LDPE) reinforced with epoxy resin, glass fiber, carbon fiber, and Kevlar towards the mechanical, thermal, and water absorption properties. The mechanical studies showed that the LDPE composite reinforced carbon fiber has the best tensile properties compared to other composites and this can be mostly due to the proper bonding and associated interaction between the polymeric matrix and the bidirectional layer of the fibers. Also, the carbon fiber reinforced composite has superior properties of impart energy compared to the other composites and the non-reinforced ones and this is attributed to the crystalline nature of carbon fiber. Further studies of the thermal properties indicated that the retention of thermal stability for all the fiber-reinforced polymer composites, while the water absorption revealed a considerable increase in the weight of Kevlar fiber-reinforced composite. From the overall analysis, the enhanced properties of LDPE matrix reinforced fibers are linked to the morphological changes that occurred and are directly affected by the nature of the fiber.

PL

Zwiększone w ostatnich latach zainteresowanie projektowaniem i wytwarzaniem lekkich kompozytów polimerowych wynika z ich lepszych właściwości elektrycznych, mechanicznych, termicznych i biologicznych w porównaniu z cechami materiałów konwencjonalnych. Zbadano wpływ rodzaju wzmocnienia (włókno szklane, włókno węglowe i włókno Kevlar) na właściwości mechaniczne, termiczne i absorpcję wody laminatowych kompozytów polietylenu małej gęstości (LDPE) z żywicą epoksydową. Stwierdzono, że kompozyt LDPE z włóknem węglowym, w porównaniu z innymi kompozytami, wykazuje najlepszą wytrzymałość na rozciąganie, co może wynikać głównie z interakcji polimerowej osnowy z dwukierunkową warstwą włókien. Ponadto kompozyt ten ma większą zdolność przenoszenia energii niż pozostałe badane kompozyty, co można przypisać krystalicznej budowie włókna węglowego. Badania właściwości termicznych wykazały stabilność termiczną wszystkich kompozytów polimerowych wzmocnionych włóknami oraz znaczną absorpcję wody kompozytu wzmocnionego włóknem Kevlar.