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1
Trofmovich, M. A., A. L. Yurkov, A. A. Galiguzov, L. V. Malakho, L. V. Oktyabr'skaya e S. V. Minchuk. "High-temperature transformations in the fibrous-polymer composites at ablation testing". NOVYE OGNEUPORY (NEW REFRACTORIES), n. 8 (27 dicembre 2018): 43–48. http://dx.doi.org/10.17073/1683-4518-2018-8-43-48.
Testo completoAbstract (sommario):
The comparative investigation on the ablation transformations were carried out for the phenolformaldehyde resin composites on base of silica fabric and hollow corundum micro spheres. It was establish that the corundum micro spheres addition lead to the composite's heat conductivity reduction. As a result the temperature increased at the exposed spot, the linear erosion rate increased by the factor of 2,7 and the coking front line decreased by a factor of 2,3. In the issue the ablation gave rise to the high-temperature mechanical and chemical erosion and these last in turn triggered the number of the serial-parallel chemical reactions with both the composite material porosity increasing and the creation of the hightemperature reaction products mainly the silicon carbide.Ill.9. Ref. 9. Tab. 4.
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Trofimovich, M. A., A. L. Yurkov, A. A. Galiguzov, A. P. Malakho, L. V. Oktyabr’skaya e S. V. Minchuk. "High-Temperature Transformations in Fibrous-Polymer Composites During Ablation Testing". Refractories and Industrial Ceramics 59, n. 4 (novembre 2018): 410–15. http://dx.doi.org/10.1007/s11148-018-0245-x.
Testo completo
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Sztuk - Sikorska, Ewa, e Leon Gradon. "Biofouling reduction for improvement of depth water filtration. Filter production and testing". Chemical and Process Engineering 37, n. 3 (1 settembre 2016): 319–30. http://dx.doi.org/10.1515/cpe-2016-0026.
Testo completoAbstract (sommario):
AbstractWater is a strategic material. Recycling is an important component of balancing its use. Deep-bed filtration is an inexpensive purification method and seems to be very effective in spreading water recovery. Good filter designs, such as the fibrous filter, have high separation efficiency, low resistance for the up-flowing fluid and high retention capacity. However, one of the substantial problems of this process is the biofouling of the filter. Biofouling causes clogging and greatly reduces the life of the filter. Therefore, the melt-blown technique was used for the formation of novel antibacterial fibrous filters. Such filters are made of polypropylene composites with zinc oxide and silver nanoparticles on the fiber surface. These components act as inhibitors of bacterial growth in the filter and were tested in laboratory and full scale experiments. Antibacterial/bacteriostatic tests were performed on Petri dishes with E. coli and B. subtilis. Full scale experiments were performed on natural river water, which contained abiotic particles and mutualistic bacteria. The filter performance at industrial scale conditions was measured using a particle counter, a flow cytometer and a confocal microscope. The results of the experiments indicate a significant improvement of the composite filter performance compared to the regular fibrous filter. The differences were mostly due to a reduction in the biofouling effect.
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Zhang, Wenfu, Cuicui Wang, Shaohua Gu, Haixia Yu, Haitao Cheng e Ge Wang. "Physical-Mechanical Properties of Bamboo Fiber Composites Using Filament Winding". Polymers 13, n. 17 (29 agosto 2021): 2913. http://dx.doi.org/10.3390/polym13172913.
Testo completoAbstract (sommario):
In order to study the performance of the bamboo fiber composites prepared by filament winding, composites reinforced with jute fiber and glass fiber were used as control samples. The structure and mechanical properties of the composites were investigated by scanning electric microscope (SEM), tensile testing, bending testing, and dynamic mechanical analysis. The results demonstrated that the bamboo fiber composites exhibited lower density (0.974 g/cm3) and mechanical properties in comparison of to fiber composite and glass fiber composite, because the inner tissue structure of bamboo fiber was preserved without resin adsorbed into the cell cavity of fibrous parenchyma. The bamboo fibers in composites were pulled out, while the fibers in the surface of composites were torn, resulting in the lowest mechanical performance of bamboo fiber composites. The glass transition temperature of twisting bamboo fiber Naval Ordnance Laboratory (TBF-NOL) composite (165.89 °C) was the highest in general, which indicated that the TBF circumferential composite had the best plasticizing properties and better elasticity, the reason being that the fiber-reinforced epoxy circumferential composite interface joint is a physical connection, which restricts the movement of the molecular chain of the epoxy matrix, making the composite have a higher storage modulus (6000 MPa). In addition, The TBF-NOL had the least frequency dependence, and the circumferential composite prepared by TBF had the least performance variability. Therefore, the surface and internal structures of the bamboo fiber should be further processed and improved by decreasing the twisting bamboo fiber (TBF) diameter and increasing the specific surface area of the TBF and joint surface between fibers and resin, to improve the comprehensive properties of bamboo fiber composites.
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Lausch, J., M. Takla e H. G. Schweiger. "Crush testing approach for flat-plate fibrous materials". Composites Part B: Engineering 200 (novembre 2020): 108333. http://dx.doi.org/10.1016/j.compositesb.2020.108333.
Testo completo
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Alireza, Amiri Asfarjani, Adibnazari Sayid e Reza Kashyzadeh Kazem. "Experimental and Finite Element Analysis Approach for Fatigue of Unidirectional Fibrous Composites". Applied Mechanics and Materials 87 (agosto 2011): 106–12. http://dx.doi.org/10.4028/www.scientific.net/amm.87.106.
Testo completoAbstract (sommario):
Fibrous composites are finding more and more applications in aerospace, automotive, and naval industries. They have high stiffness and strength to weight ratio and good rating in regards to life time fatigue. Investigating mechanical behavior under dynamic loads to replace this material is very important. In the present article, investigate Fatigue of Unidirectional Fibrous Composites by using finite element analysis. So, to achieve this purpose Firstly, modeling fiber and matrix in separate case and simulated semi actual conditions, attained S-N curve of fiber and matrix and after that by using micromechanical model of combination fiber and matrix can approach S-N curve of Unidirectional Fibrous Composites. Finally, Comparisons of the finite element analysis of Ansys and the experimental predictions indicate based on three point bending fatigue testing that the results are satisfactorily in good agreement with each other which approves the power law assumption in the model.
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Zolkiewski, Sławomir. "Mechanical Properties of Fibre-Metal Composites Connected by Means of Bolt Joints". Advanced Materials Research 837 (novembre 2013): 296–301. http://dx.doi.org/10.4028/www.scientific.net/amr.837.296.
Testo completoAbstract (sommario):
The fibre-metal laminates made of a steel plate and fibreglass laminate plate were tested in the special laboratory stands. Epoxy resin and polyester resin were used as matrix to fabricate the composites. The fibre-metal laminates combine advantages of metals and laminates. These materials have very good force versus displacement characteristics and overall mechanical properties. They are very popular and widely applied in technical systems. They can be put to use in connecting materials made of various fabrics, connecting high number layer laminates and most of all connecting metals and laminates. In this paper there are the results of testing fibrous composite materials connected in bolt joints presented. Composite materials reinforced with fiberglass, carbon and aramid fibers are considered. The impact of number of applied bolts in a joint on strength properties was investigated. The connections by means of eight or sixteen bolts were compared. A major problem of modelling the composites is assuming physical and material parameters of the analyzed elements.
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Md Ali, Afifah, Mohd Zaidi Omar, Mohd Shukor Salleh, Hanizam Hashim, Intan Fadhlina Mohamed e Nur Farah Bazilah Wakhi Anuar. "Mechanical Behaviour and Morphology of Thixoformed Aluminium Alloy Reinforced by Graphene". Materials 15, n. 19 (30 settembre 2022): 6791. http://dx.doi.org/10.3390/ma15196791.
Testo completoAbstract (sommario):
Thixoforming is a promising method that offers several advantages over both liquid and solid processing. This process utilizes semi-solid behaviour and reduces macrosegregation, porosity and forming forces during the shaping process. Microstructural and mechanical characterization of 0.3, 0.5 and 1.0 wt% graphene nanoplatelet (GNP) reinforced A356 aluminium alloy composite fabricated by thixoforming was investigated. Stir casting was employed to fabricate feedstocks before they were thixoformed at 50% liquid. The microstructure was characterized and evaluated by field emission scanning electron microscopy with an energy dispersive X-ray detector and X-ray diffraction. Mechanical testing, such as microhardness and tensile testing, was also performed to estimate the mechanical properties of the composites. The incorporation of 0.3 wt.% GNPs in Al alloy increased by about 27% in ultimate tensile strength and 29% in hardness. The enhancement in tensile strength is primarily attributed to load transfer strengthening due to the uniform dispersion of these GNPs within the Al matrix, which promotes effective load transfer during tensile deformation, and GNPs’ wrinkled surface structure. Simultaneously, the addition of GNPs enhances the grain refinement effect of the Al alloy matrix, resulting in a grain size strengthening mechanism of the GNPs/Al composites. The results reveal that thixoformed composite microstructure consists of uniformly distributed GNPs, α-Al globules and fine fibrous Si particles. The composites’ grains were refined and equiaxed, and the mechanical properties were improved significantly. This study creates a new method for incorporating GNPs into Al alloy for high-performance composites.
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Mermerdaş, Kasım, Süleyman İpek e Zana Mahmood. "Visual inspection and mechanical testing of fly ash-based fibrous geopolymer composites under freeze-thaw cycles". Construction and Building Materials 283 (maggio 2021): 122756. http://dx.doi.org/10.1016/j.conbuildmat.2021.122756.
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Qu, Yingying, Ping Xu, Hu Liu, Qianming Li, Ning Wang, Shuaiguo Zhao, Guoqiang Zheng, Kun Dai, Chuntai Liu e Changyu Shen. "Tunable temperature-resistivity behaviors of carbon black/polyamide 6 /high-density polyethylene composites with conductive electrospun PA6 fibrous network". Journal of Composite Materials 53, n. 14 (6 dicembre 2018): 1897–906. http://dx.doi.org/10.1177/0021998318815731.
Testo completoAbstract (sommario):
Temperature-resistivity behaviors of carbon black/polyamide 6/high-density polyethylene conductive polymer composites containing electrospun polyamide 6 fibrous network were studied systematically. The positive temperature coefficient intensity of the conductive polymer composites increased firstly and then reduced gradually with increasing heating rate, showing a heating rate-dependent positive temperature coefficient intensity. The fascinating phenomenon was ascribed to the microstructure change of conductive network induced by the volume expansion and the thermal residual stress generated in the composites. During the heating-cooling runs at different top testing temperature of 140, 150 and 180℃, the room-temperature resistivity of sample was observed to be 30, 2.3 and 1.6 orders of magnitude higher than the initial value after one heating-cooling run, respectively. The thermal treatment time above the melting temperature of high-density polyethylene and the viscosity variation of the conductive polymer composites were responsible for the increased resistivity. This study provides a guideline for fabricating conductive polymer composites with tuning positive temperature coefficient property.
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Mikołajczyk, Zbigniew, Katarzyna Pieklak e Aleksandra Roszak. "Knitted Meshes for Reinforcing Building Composites". Fibres and Textiles in Eastern Europe 27, n. 4(136) (31 agosto 2019): 102–11. http://dx.doi.org/10.5604/01.3001.0013.1826.
Testo completoAbstract (sommario):
Modern technical textiles, including knitted fabrics, are widely used in the construction industry. Regarding textiles in concrete reinforcement, methods based on shredded fibres, meshes, reinforcing mats, woven textiles and knitted DOStapes are frequently used as underlays of concrete constructions. Textiles are also used in the reinforcement of fibrous FRP composites. The research presented focused on producing composites made of MapeiMapefill concrete mass with reinforcement in the form of three variants of knitted meshes made of 228 tex polyamide threads, polypropylene threads of 6.3 tex and 203 tex glass threads, as well as identification of their mechanical properties. The mesh variant made of glass fibre is especially noteworthy, as its strength is more than three times higher than that of polyamide meshes. At the same time, a very small relative elongation of 3% is observed for this variant of knitted fabric, which is a desired property regarding the comparatively low stretching extension of concrete. In the process of making the composites, the adhesion of the concrete mass to the surface of the threads was analyzed. For this purpose, a "Sopro HE449" type agent was used. Composite beams were subjected to a three-point bending strength analysis on a testing machine. The results of strength measurements of the composites obtained prove that those with glass fibres demonstrate a threefold increase in strength compared to the original concrete beam.
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Querido, Victor A., José Roberto M. d’Almeida e Flávio A. Silva. "Development and analysis of sponge gourd (Luffa cylindrica L.) fiber-reinforced cement composites". BioResources 14, n. 4 (31 ottobre 2019): 9981–93. http://dx.doi.org/10.15376/biores.14.4.9981-9993.
Testo completoAbstract (sommario):
Sponge gourd (Luffa cylindrica L.) fiber-reinforced cement composites were developed and analyzed. Dried sponge gourd fruit’s fibrous vascular system forms a natural 3D network that can reinforce matrices in composite materials, diverting cracks along the complex array of 3D interfaces between the fibers and the cementitious matrix. To avoid fiber deterioration, the cement paste was modified by incorporating pozzolanic materials. The fibers were mechanically characterized by tensile testing of strips of the 3D natural fiber array and of single fibers extracted from the array. The fibers had an average tensile strength of 140 MPa and an average Young’s modulus up to 28 GPa. Image analysis showed that the fiber spatial distribution inside the 3D network was random. The modified cement paste was characterized by its workability (flow table test) and mechanical behavior (compression and three-point bending tests), with average results of 430 mm, 62.7 MPa, and 6.2 MPa, respectively. Under bending, the cement matrix collapsed after the first crack. The sponge gourd-cement composite manufactured with 1 wt% of fibers showed an average flexural strength of 9.2 MPa (approximately 50% greater than the unreinforced matrix). Importantly, the composite also presented a limited deflection-hardening behavior. These results support sponge gourd’s possible use as reinforcement in cement matrix composites.
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Jinga, Zamfirescu, Voicu, Enculescu, Evanghelidis e Busuioc. "PCL-ZnO/TiO2/HAp Electrospun Composite Fibers with Applications in Tissue Engineering". Polymers 11, n. 11 (1 novembre 2019): 1793. http://dx.doi.org/10.3390/polym11111793.
Testo completoAbstract (sommario):
The main objective of the tissue engineering field is to regenerate the damaged parts of the body by developing biological substitutes that maintain, restore, or improve original tissue function. In this context, by using the electrospinning technique, composite scaffolds based on polycaprolactone (PCL) and inorganic powders were successfully obtained, namely: zinc oxide (ZnO), titanium dioxide (TiO2) and hydroxyapatite (HAp). The novelty of this approach consists in the production of fibrous membranes based on a biodegradable polymer and loaded with different types of mineral powders, each of them having a particular function in the resulting composite. Subsequently, the precursor powders and the resulting composite materials were characterized by the structural and morphological point of view in order to determine their applicability in the field of bone regeneration. The biological assays demonstrated that the obtained scaffolds represent support that is accepted by the cell cultures. Through simulated body fluid immersion, the biodegradability of the composites was highlighted, with fiber fragmentation and surface degradation within the testing period.
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Pérez-Salinas, Cristian, Christian Castro e Roberto Valencia. "The cubic regression model of thermal estimation in the flammability test of the fibrous compound used in bus bodies". MATEC Web of Conferences 264 (2019): 02004. http://dx.doi.org/10.1051/matecconf/201926402004.
Testo completoAbstract (sommario):
The fire behavior of fiber compounds is a serious concern in automotive applications. The objective of the proposed work is to predict thermal behavior during flammability testing of the composite material of polymer matrix reinforced with fiberglass used in the interior lining of bodies. Different regression models were performed to determine the best fit. This regression analysis determines the existing correlation between the acquired parameters of burn time and temperature versus two types of fibers used for the interior decorative lining. Different regression coefficients were determined and used for the prediction. Through the best fit regression model, thermal behavior of burning during the flammability test is predicted under ISO standard 3795: 1989 and FMVSS 302. The prediction was made for two types of composites, Roof Fiber, FT, and Fiber for laterals, FL. The cubic regression model showed the best prediction fit with a Rq of 0.79 for FT and 0.81 for FL.
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Esfandiari, Puria, João Francisco Silva, Paulo Jorge Novo, João Pedro Nunes e Antonió Torres Marques. "Production and processing of pre-impregnated thermoplastic tapes by pultrusion and compression moulding". Journal of Composite Materials 56, n. 11 (25 marzo 2022): 1667–76. http://dx.doi.org/10.1177/00219983221083841.
Testo completoAbstract (sommario):
Although there is no doubt that composite materials are the future of lightweight structures and components, most of composites currently produced are made from thermoset polymers, which are not able to be recycled or reprocessed. In contrast, thermoplastic polymers offer the possibility to recycle and reprocess and when combined with a fibrous reinforcement, provide interesting mechanical properties. This work reviews the production of two thermoplastic pre-impregnated materials in a tape form, one of which is produced on new prototype equipment developed in our laboratories. The method for the production of tape is described, and the prepregs presented here were subjected to two processing techniques. The first processing method, pultrusion, is an efficient and autonomous method to produce composite profiles, marking itself as a continuous and cost-effective way to produce these materials. Pultrusion bars were then subjected to heated compression moulding, a process that allows to obtain more complex-shaped parts. The second method, heated compression moulding, is a relatively simple process which was used to obtain composite laminates. The pultrusion bars and composite laminates were then subjected to mechanical testing to evaluate the levels of consolidation of the final material. A microscope testing was also carried out to analyse the dispersion of fibres and polymer, as well as the amount of voids present in the composite.
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Mohsan, Ali Hasan, e Nadia A. Ali. "Electro spinning of Polycaprolactone / Hydroxyapatite Composites in Wound Dressing Application". Iraqi Journal of Physics (IJP) 20, n. 1 (1 marzo 2022): 14–25. http://dx.doi.org/10.30723/ijp.v20i1.703.
Testo completoAbstract (sommario):
Polycaprolactone polymer is widely used in medical applications due to its biocompatibility. Electro spinning was used to create poly (ε- caprolactone) (PCL) nanocomposite fiber mats containing hydroxyapatite (HA) at concentrations ranging from 0.05 to 0.4% wt. The chemical properties of the fabricated bio composite fibers were evaluated using FTIR and morphologically using field-emission scanning-electron microscopy (FESEM), Porosity, contact angle, as well as mechanical testing(Young Modulus and Tensile strength) of the nanofibers were also studied. The FTIR results showed that all the bonds appeared for the pure PCL fiber and the PCL/HA nano fibers. The FESEM nano fiber showed that the fiber diameter increased from 54.13 to 155.79 (nm) at the HA values from (0.05 % and 1%wt.). Porosity, wettability of (PCL/HA) composites has improved, and the contact angle has decreased from 103.59o to 85.57o for fibrous scaffolds. The inclusion of hydroxyapatite increased the tensile strength of nano fiber scaffolds, and the maximum tensile strength of 0.4% percent was about 0.127 MPa, with a lowering in elongation to 40%.
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Murali, Gunasekaran, Nandhu Prasad, Sergey Klyuev, Roman Fediuk, Sallal R. Abid, Mugahed Amran e Nikolai Vatin. "Impact Resistance of Functionally Layered Two-Stage Fibrous Concrete". Fibers 9, n. 12 (20 dicembre 2021): 88. http://dx.doi.org/10.3390/fib9120088.
Testo completoAbstract (sommario):
The impact resistance of functionally layered two-stage fibrous concrete (FLTSFC) prepared using the cement grout injection technique was examined in this study. The impact resistance of turtle shells served as the inspiration for the development of FLTSFC. Steel and polypropylene fibres are used in more significant quantities than usual in the outer layers of FLTSFC, resulting in significantly improved impact resistance. An experiment was carried out simultaneously to assess the efficacy of one-layered and two-layered concrete to assess the effectiveness of three-layered FLTSFC. When performing the drop-mass test ACI 544, a modified version of the impact test was suggested to reduce the scattered results. Instead of a solid cylindrical specimen with no notch, a line-notched specimen was used instead. This improvement allows for the pre-definition of a fracture route and the reduction of the scattering of results. The testing criteria used in the experiments were impact numbers associated to first crack and failure, mode of failure, and ductility index. The coefficient of variation of the ACI impact test was lowered due to the proposed change, indicating that the scattering of results was substantially reduced. This research contributes to the idea of developing enhanced, more impact-resistant fibre composites for use in possible protective structures in the future.
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Fonteles, Carlos Alberto Lopes, Gustavo Figueiredo Brito, Laura Hecker Carvalho, Tatianny Soares Alves e Renata Barbosa. "Composites Based on Thermoset Resin and Orbignya phalerata (Babassu Coconut): Evaluation of Mechanical Properties, Morphology and Water Sorption". Materials Science Forum 869 (agosto 2016): 237–42. http://dx.doi.org/10.4028/www.scientific.net/msf.869.237.
Testo completoAbstract (sommario):
Researches in plant fiber composites have been developed with greater frequency during the last years, especially on environmental issues. The opening of the market, especially in the automotive sector, points to the replacement of synthetic additives by natural reinforcements. Characteristics such as low density and abrasiveness, superior mechanical properties and low cost are the most sought in these composites. The aim of this study was to evaluate the behavior of composites based polyester matrix and fiber of the babassu coconut epicarp, at levels of 5, 7.5 and 10% under testing of tensile strength and impact, as well as the morphology by microscopy scanning electron and water absorption. All composites were prepared raw fibers and fiber with treated with alkaline solution of 5% NaOH. As regards the mechanical properties, an increasing of the rigidity of the system was observed, and the kinetics of water absorption increased levels indicated for compounds with high content of fibrous reinforcement. By SEM there was greater interaction between fiber and matrix.
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Prasad, Nandhu, Gunasekaran Murali e Nikolai Vatin. "Modified Falling Mass Impact Test Performance on Functionally Graded Two Stage Aggregate Fibrous Concrete". Materials 14, n. 19 (6 ottobre 2021): 5833. http://dx.doi.org/10.3390/ma14195833.
Testo completoAbstract (sommario):
This research examined the performance of functionally graded two-stage fibrous concrete (FTSFC) against modified repeated falling-mass impacts. This study led to the concept of creating improved multiphysics model of fibre composites with better impact resistance for potential protective constructions. FTSFC was developed based on the bio-inspiring strength of turtle shells. The excellent impact resistance of FTSFC was accomplished by including a larger quantity of steel and polypropylene fibres in the outer layers. At the same time, one- and two-layered concrete were cast and compared to evaluate the efficiency of three-layered FTSFC. To minimize the dispersed test results, a modified form of the 544 drop-mass impact test was recommended by the American Concrete Institute (ACI). The modification was a knife-edge notched specimen instead of a solid cylindrical specimen without a notch. This modification predefined a crack path and reduced the dispersion of results. Cracking and failure impact numbers, ductility index, and failure mode were the testing criteria. The suggested modification to the ACI impact test decreased the coefficient of variance, showing that the dispersion of test results was reduced significantly. This study led to the concept of creating improved, fibre composites with better impact resistance for potential protective constructions.
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El-Sabbagh, A., I. Taha e R. Taha. "Prediction of the Modulus of Elasticity of Short Fibre Reinforced Polymer Composites by Finite Element Modelling". Polymers and Polymer Composites 19, n. 9 (novembre 2011): 733–42. http://dx.doi.org/10.1177/096739111101900903.
Testo completoAbstract (sommario):
Recently, there has been increased interest in fibre-reinforced polymer composites, due to their distinctive specific strength, corrosion resistance and fatigue resistance, as well as high damping characteristics. In this paper, finite-element models for the prediction of the modulus of elasticity of short-fibre reinforced composites (SFRC) are introduced. The stiffness of a structure is of principal importance in many engineering applications and the modulus of elasticity is often one of the primary properties considered when selecting a material. In the developed models, different factors affecting the overall performance of such composites are considered. These factors include the respective volume fractions of the polymer matrix and fibrous reinforcement, fibre orientation and agglomeration. Three finite-element models with different sophistication levels are proposed. The models are validated by comparing the effective modulus of elasticity predicted by the different models to experimental results obtained by tensile testing SFRC samples consisting of glass fibres in a polypropylene matrix at different volume fractions.
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Muangma, Rakdiaw, Supattra Wongsaenmai e Tawat Soitong. "Numerical-Experimental Model and Polynomial Regression Method for Interpretation of G-BHN Relation of Kraft-Based Fibrous Composites Evaluated by Using Brinell Analysis". Key Engineering Materials 798 (aprile 2019): 370–75. http://dx.doi.org/10.4028/www.scientific.net/kem.798.370.
Testo completoAbstract (sommario):
This research focused on the mathematical model that could be simplified as the series function. This function used for macroscopic explanation of the relationship between shear modulus and Brinell hardness of fibrous composites. Kraft paper was used as the sample for this testing. The paper-grammage was varied as following:150, 230, and 420, whereas, the dwell time of indentation was ranging as: 10, 20, and 30 seconds, respectively. And then, the correlation between shear modulus (G) and Brinell Hardness Number (BHN) was obtained by using the simulation of experimental results. These were collected by the Brinell hardness testing machine. After that, the refitting process was analyzed using the polynomial based on linear and quadratic model, respectively. It was found that the interpretation of G-BHN relation using the quadratic be better than the linear one. Because of the coefficient of determination (R2) that analyzed by quadratic function present in higher value than another one.
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Alyousef, Rayed, Hossein Mohammadhosseini, Ahmed Abdel Khalek Ebid e Hisham Alabduljabbar. "An Integrated Approach to Using Sheep Wool as a Fibrous Material for Enhancing Strength and Transport Properties of Concrete Composites". Materials 15, n. 5 (22 febbraio 2022): 1638. http://dx.doi.org/10.3390/ma15051638.
Testo completoAbstract (sommario):
An important goal to achieve sustainable development is to use raw materials that are easily recyclable and renewable, locally available, and eco-friendly. Sheep wool, composed of 60% animal protein fibers, 10% fat, 15% moisture, 10% sheep sweat, and 5% contaminants on average, is an easily recyclable, easily renewable, and environmentally friendly source of raw material. In this study, slump testing, compressive and flexural strengths, ultrasonic pulse velocity, sorptivity, and chloride penetration tests were investigated to assess the influence of wool fibers on the strength and transport properties of concrete composites. Ordinary Portland cement was used to make five concrete mixes incorporating conventional wool fibers (WFs) ranging from 0.5 to 2.5% and a length of 70 mm. The wool fibers were modified (MWFs) via a pre-treatment technique, resulting in five different concrete compositions with the same fiber content. The addition of WF and MWF to fresh concrete mixes resulted in a decrease in slump values. The compressive strength of concrete was reduced when wool fibers were added to the mix. The MWF mixes, however, achieved compressive strength values of more than 30 MPa after a 90-day curing period. Furthermore, by including both WF and MWF, the flexural strength was higher than that of plain concrete. In addition, adding fibers with volume fractions of up to 2% reduced the concrete composite’s sorptivity rate and chloride penetration depths for both WF and MWF content mixes. Consequently, biomass waste like sheep wool could be recycled and returned to the field following the circular economy and waste valorization principles.
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Pierdzig, Stefan. "Regulations Concerning Naturally Occurring Asbestos (NOA) in Germany—Testing Procedures for Asbestos". Environmental and Engineering Geoscience 26, n. 1 (20 febbraio 2020): 67–71. http://dx.doi.org/10.2113/eeg-2278.
Testo completoAbstract (sommario):
ABSTRACT In Germany, potential asbestos-containing rocks are used as raw materials for a number of engineering applications. These rocks are ultrabasites (dunite, harzburgite), igneous rocks (basalt, gabbro, norite), and metasomatic or metamorphic rocks like talcum, greenschist and amphibolite. Based on the German Gefahrstoffverordung (Hazardous Substances Ordinance), regulatory statutes exist for operations using these rocks and resultant composites and products. The authorities state that in Germany no natural rocks exist with more than 0.1 mass-% of one of the six regulated asbestos minerals. But it is well known that there are rocks with a high modal concentration of these minerals with a non-asbestiform, columnar to prismatic habitus. Under mechanical stress during handling, they can lead to fibrous cleavage fragments, which conform to the World Health Organization (WHO) “respirable asbestos fiber” definition. In view of this fact, the regulations changed in 2009, with revision of the Technical Rules for Hazardous Substances (TRGS) 517: any fibrous asbestos particles, regardless of whether or not they represent naturally occurring asbestos or are of cleavage origin, are evaluated for potential hazards associated with handling of these rocks. If the WHO fiber concentration is <0.1 mass-%, rocks and products can be used and re-used under protective measures. At concentrations >0.1 mass-%, the material is considered hazardous waste. These regulations apply to many industrial sectors that exploit and process rocks, using them in road building and track construction and when they are recycled. Analysis (by scanning electron microscopy, SEM/energy dispersive x-ray spectroscopy, EDS) to determine the asbestos concentration of rocks, gravels, or dusts is carried out in the <100-µm, grain-size fraction produced by sieving or grinding. The results provide a representation of a worst-case examination of the air quality during mechanical treatment of these materials. Workplace monitoring is done by air sampling to survey an exposure limit of 10,000 fibers/m3 of air (0.01 f/cc).
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Laurent, Christian M., Colin Palmer, Richard P. Boardman, Gareth Dyke e Richard B. Cook. "Nanomechanical properties of bird feather rachises: exploring naturally occurring fibre reinforced laminar composites". Journal of The Royal Society Interface 11, n. 101 (6 dicembre 2014): 20140961. http://dx.doi.org/10.1098/rsif.2014.0961.
Testo completoAbstract (sommario):
Flight feathers have evolved under selective pressures to be sufficiently light and strong enough to cope with the stresses of flight. The feather shaft (rachis) must resist these stresses and is fundamental to this mode of locomotion. Relatively little work has been done on rachis morphology, especially from a mechanical perspective and never at the nanoscale. Nano-indentation is a cornerstone technique in materials testing. Here we use this technique to make use of differentially oriented fibres and their resulting mechanical anisotropy. The rachis is established as a multi-layered fibrous composite material with varying laminar properties in three feathers of birds with markedly different flight styles; the Mute Swan ( Cygnus olor ), the Bald Eagle ( Haliaeetus leucocephalus ) and the partridge ( Perdix perdix ) . These birds were chosen not just because they are from different clades and have different flight styles, but because they have feathers large enough to gain meaningful results from nano-indentation. Results from our initial datasets indicate that the proportions and orientation of the laminae are not fixed and may vary either in order to cope with the stresses of flight particular to the bird or with phylogenetic lineage.
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Prabhakaran, S., V. Krishnaraj, Hemashree Golla e M. Senthilkumar. "Biodegradation behaviour of green composite sandwich made of flax and agglomerated cork". Polymers and Polymer Composites 30 (gennaio 2022): 096739112211036. http://dx.doi.org/10.1177/09673911221103602.
Testo completoAbstract (sommario):
Material experts are striving to use natural resources as skin and core in composite sandwiches to achieve light weight, biodegradability, and cost benefits. This paper reports one such newly developed green composite sandwich and its biodegradable behavior. The skin and core of newly developed sandwich are flax fiber and agglomerated cork respectively. This composite sandwich is manufactured by vacuum bagging technique in order to get higher volume fraction of fiber. The biodegradability testing of the composite sandwich has been executed by soil burial test. The verification of the same has been done using Scanning Electron Microscope (SEM) images, Fourier Transform Infrared Spectroscopy (FTIR) analysis and Thermoanalytical test. The test results portray the percentage of weight loss in the specimens and that, it increases with burial time. It also depicts that the newly developed Green Composite Sandwich (GCS) has 82% higher degradation than the Synthetic Composite Sandwich (SCS) taken for the comparison. SEM images show that the green composite sandwiches have lost their fibrous structure and cell wall surface due to the degradation. FTIR and Thermoanalytical tests also confirm the biodegradability of the developed green composite sandwich.
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Krampikowska, Aleksandra, e Anna Adamczak – Bugno. "Evaluation of destructive processes in FRC composites using time-frequency analysis of AE signals". MATEC Web of Conferences 262 (2019): 06006. http://dx.doi.org/10.1051/matecconf/201926206006.
Testo completoAbstract (sommario):
Modern fiber-cement boards currently used in construction are made of natural raw materials such as cement, cellulose fibers and of polyvinyl alcohol (PVA) and water. They replaced the eternitic plates, which were harmful to health, originated by Ludwig Hatschek. Materials made of fiber-cement are used in construction industry as a building and finishing material for facades, internal walls and roofs. Therefore, they are exposed to environmental conditions including rainfall and temperature changes, and in particular to frequent temperature transition through 0°C in a 24-hour cycle (cyclic freezing-thawing). In addition, fibrous cement materials, primarily used as cladding elements, are exposed to exceptional conditions, which include the high temperature caused by fire. The article presents the results of experimental tests of flexural strength of cement fiber boards subjected to exceptional conditions, to which the operation of fire belongs. The paper also presents a proposal to use a non-destructive method of acoustic emission based on time-frequency analysis for testing fiber-cement boards. Interesting research results were obtained that allowed to trace the differences in the mechanisms of material destruction under the influence of the changing time of external factors.
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Mani, Mohan Prasath, e Saravana Kumar Jaganathan. "Fabrication and characterization of electrospun polyurethane blended with dietary grapes for skin tissue engineering". Journal of Industrial Textiles 50, n. 5 (3 aprile 2019): 655–74. http://dx.doi.org/10.1177/1528083719840628.
Testo completoAbstract (sommario):
The tissue-engineered skin has emerged as a plausible alternative approach to the traditional wound dressing owing to its inherent advantages. Further, in tissue engineering applications, fibrous scaffold obtained through textile technologies is widely attractive. The present study focused on the fabrication of electrospun textile polyurethane wound dressing scaffold incorporated with grape extract. The fabricated composites showed smooth as well as reduced fiber (730 ± 127 nm) and pore (873 ± 51 nm) diameter than the control polyurethane (fiber diameter –890 ± 117 and pore diameter –1064 ± 74 nm) as revealed in the scanning electron microscopy. The formation of hydrogen bond in Fourier transform infrared spectroscopy revealed the interaction between the polyurethane and grape. The addition of grape enhanced the wettability behavior (86° ± 2) and the surface roughness (469 nm) of the polyurethane membrane. Thermal gravimetric analysis and mechanical testing revealed the enhancement of thermal and tensile strength with the incorporation of the grape into the polyurethane matrix. The in vitro blood compatibility and cytocompatibility studies revealed enhanced antithrombogenicity behavior and the non-toxic nature to human dermal fibroblast cells for the fabricated composites than the pristine polyurethane. Hence, the addition of grape into the polyurethane matrix had enhanced the physicochemical characteristics and biocompatibility parameters which could promote this candidate as a valid alternative for skin tissue engineering regeneration.
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Kapsalis, Panagiotis, Tine Tysmans, Danny Van Hemelrijck e Thanasis Triantafillou. "State-of-the-Art Review on Experimental Investigations of Textile-Reinforced Concrete Exposed to High Temperatures". Journal of Composites Science 5, n. 11 (5 novembre 2021): 290. http://dx.doi.org/10.3390/jcs5110290.
Testo completoAbstract (sommario):
Textile-reinforced concrete (TRC) is a promising composite material with enormous potential in structural applications because it offers the possibility to construct slender, lightweight, and robust elements. However, despite the good heat resistance of the inorganic matrices and the well-established knowledge on the high-temperature performance of the commonly used fibrous reinforcements, their application in TRC elements with very small thicknesses makes their effectiveness against thermal loads questionable. This paper presents a state-of-the-art review on the thermomechanical behavior of TRC, focusing on its mechanical performance both during and after exposure to high temperatures. The available knowledge from experimental investigations where TRC has been tested in thermomechanical conditions as a standalone material is compiled, and the results are compared. This comparative study identifies the key parameters that determine the mechanical response of TRC to increased temperatures, being the surface treatment of the textiles and the combination of thermal and mechanical loads. It is concluded that the uncoated carbon fibers are the most promising solution for a fire-safe TRC application. However, the knowledge gaps are still large, mainly due to the inconsistency of the testing methods and the stochastic behavior of phenomena related to heat treatment (such as spalling).
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Tan, Qiaoyin, Cuicui Wu, Lei Li, Weide Shao e Min Luo. "Nanomaterial-Based Prosthetic Limbs for Disability Mobility Assistance: A Review of Recent Advances". Journal of Nanomaterials 2022 (31 marzo 2022): 1–10. http://dx.doi.org/10.1155/2022/3425297.
Testo completoAbstract (sommario):
The emergence of new hybrid nanomaterial has enabled prosthetic devices to have more performance and significantly improved the quality of life of the disabled. Due to the biosensing properties of prosthetic limbs made of nanomaterials, a large number of nanocomposites have been designed, developed, and evaluated for various prosthetic limbs, such as e-skin, e-skin’s neurotactility sensing, human prosthetic interface tissue engineering, bones, and biosensors. Nano-based materials are also considered to be the new generation of scientific and technological materials for the preparation of various prosthetic devices for the disabled, which can effectively improve the sense of use of the disabled and achieve functional diversity. The study described various nanomaterials for prosthetic devices, and introduced some basic components of nanocomposites; their applications are in three areas, such as bone, skin, and nerve, and evaluated and summarized the advantages of these applications. The results show that (1) carbon-based nanomaterials as neural materials have been studied most deeply. Due to that strong stability of the carbon-based material and the simple transmission mechanism, the cost can be controlled in manufacturing the artificial limb. Materials with human-computer interaction function are the research focus in the future. (2) Skin nanomaterials are mainly composite materials, generally containing metal- and carbon-based materials. Ionic gels, ionic liquids, hydrogels, and elastomers have become the focus of attention due to the sensitivity, multimodal, and memory properties of their materials. (3) Outstanding nanomaterials for bone are fibrous materials, metallic synthetic materials, and composite materials, with extremely high hardness, weight, and toughness. Of the skeletal materials, the choice of prosthetic socket material is the most important and is typically based on fiber laminate composites. Some of these materials make sensors for durability and performance that can be used for large-scale clinical testing.
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Łandwijt, Marcin, Marcin H. Struszczyk, Wiesława Urbaniak-Domagała, Adam K. Puszkarz, Bożena Wilbik-Hałgas, Magdalena Cichecka e Izabella Krucinska. "Ballistic Behaviour of PACVD-Modified Textiles". Fibres and Textiles in Eastern Europe 27, n. 1(133) (28 febbraio 2019): 85–90. http://dx.doi.org/10.5604/01.3001.0012.7512.
Testo completoAbstract (sommario):
A comprehensive study was performed using the Plasma Assisted Chemical Vapour Deposition (PACVD) modification of ultrahigh molecular weight polyethylene (UHMWPE) fibrous composites and paramid fabrics with the deposition of fluoro-or silane-like-polymer onto their surface. Research on the resistance to fragments was performed on the basis of our own testing procedure elaborated on the basis of the STANAG 2920 Ballistic Test Method For Personal Armour Materials And Combat Clothing, revision 2. The model insert systems made of the modified or unmodified unwoven sheets of UHMWPE fibres exhibited significantly different trends of changes in fragment-proofness when the temperature together with humidity were applied as the ageing factors. In the inserts made of modified unwoven sheets, an increase in the V50 value was observed, while the V50 of the inserts made of unmodified sheets decreased along with the extension of the accelerated ageing process. Modification with low-temperature plasma in the presence of vapours of low-molecular fluorine- or silane-genic substrates altered the properties of the fabrics and unwoven sheets. PACVD modification allows to prevent the destructive influence of humidity during the aging process.
31
Santulli, Carlo, Marco Rallini, Debora Puglia, Serena Gabrielli, Luigi Torre e Enrico Marcantoni. "Characterization of Licorice Root Waste for Prospective Use as Filler in more Eco-Friendly Composite Materials". Processes 8, n. 6 (24 giugno 2020): 733. http://dx.doi.org/10.3390/pr8060733.
Testo completoAbstract (sommario):
The extraction of glycyrrhizin from licorice root and stolon with ethanol/water solutions leaves a lignocellulosic residue, which could be potentially applied in biocomposites. This process proved difficult in principle, given the considerable hardness of this material as received, which impedes its use in polymer resins in large amounts. After ball milling, up to 10% of this fibrous residue, which shows very variable aspect ratio, was introduced into an epoxy matrix, to investigate its possible future application in sustainable polymers. Of the three composites investigated, containing 1, 5 and 10 wt% of licorice waste, respectively, by performing flexural testing, it was found that the introduction of an intermediate amount of filler proved the most suitable for possible development. Thermal characterization by thermogravimetry (TGA) did not indicate large variation of degradation properties due to the introduction of the filler. Despite the preliminary characteristics of this study, an acceptable resin-filler interface has been obtained for all filler contents. Issues to be solved in future study would be the possibility to include a larger amount of filler by better compatibilization and a more uniform distribution of the filler, considering their orientation, since most of it maintains an elongated geometry after ball milling.
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Wang, Biao, Rui Juan Xie e Yang Yang Huang. "Preparation and Characterization of Silk Fibroin/Calcium Phosphate Composite". Advanced Materials Research 332-334 (settembre 2011): 1655–58. http://dx.doi.org/10.4028/www.scientific.net/amr.332-334.1655.
Testo completoAbstract (sommario):
In this paper, calcium phosphate cement (CPC) was prepared with tetracalcium phosphate (TTCP)/dicalcium phosphate anhydrous (DCPA) system as solid phase and phosphate buffered solution (PBS) as liquid phase, then silk fibroin (SF) was added into CPC to form silk fibroin/calcium phosphate composite. To study the effect of SF on the properties of composite, different mass fraction of SF was added into the composite. The surface morphology was observed by Scanning Electron Microscope. The setting time was investigated by ISO Cement Standard Consistency Instrument. The structure of the composite was studied by X-ray diffraction and infrared spectroscopy. Mechanical properties of samples were tested by Instron Universal Testing Machine. The results showed that the particles of SF could be seen obviously in the surface of all composite, and acicular crystal of hydroxyapatite (HA) was formed in the hardening body of both the composite and the pure CPC. The acicular crystal of HA derived from composite with SF appeared to be thinner. The setting times of the composites were all between 9 to 15min. Compared to pure CPC, the compressive strength and work-of-compressive of composites were all improved. The compressive strength of the composite with 1% SF increased obviously.
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Almudaihesh, Faisel, Stephen Grigg, Karen Holford, Rhys Pullin e Mark Eaton. "An Assessment of the Effect of Progressive Water Absorption on the Interlaminar Strength of Unidirectional Carbon/Epoxy Composites Using Acoustic Emission". Sensors 21, n. 13 (25 giugno 2021): 4351. http://dx.doi.org/10.3390/s21134351.
Testo completoAbstract (sommario):
Carbon Fibre-Reinforced Polymers (CFRPs) in aerospace applications are expected to operate in moist environments where carbon fibres have high resistance to water absorption; however, polymers do not. To develop a truly optimised structure, it is important to understand this degradation process. This study aims to expand the understanding of the role of water absorption on fibrous/polymeric structures, particularly in a matrix-dominant property, namely interlaminar strength. This work used Acoustic Emission (AE), which could be integrated into any Structural Health Monitoring System for aerospace applications, optical strain measurements, and microscopy to provide an assessment of the gradual change in failure mechanisms due to the degradation of a polymer’s structure with increasing water absorption. CFRP specimens were immersed in purified water and kept at a constant temperature of 90 °C for 3, 9, 24 and 43 days. The resulting interlaminar strength was investigated through short-beam strength (SBS) testing. The SBS values decreased as immersion times were increased; the decrease was significant at longer immersion times (up to 24.47%). Failures evolved with increased immersion times, leading to a greater number of delaminations and more intralaminar cracking. Failure modes, such as crushing and multiple delaminations, were observed at longer immersion times, particularly after 24 and 43 days, where a pure interlaminar shear failure did not occur. The observed transition in failure mechanism showed that failure of aged specimens was triggered by a crushing of the upper surface plies leading to progressive delamination at multiple ply interfaces in the upper half of the specimen. The crushing occurred at a load below that required to initiate a pure shear failure and hence represents an under prediction of the true SBS of the sample. This is a common test used to assess environmental degradation of composites and these results show that conservative knockdown factors may be used in design. AE was able to distinguish different material behaviours prior to final fracture for unaged and aged specimens suggesting that it can be integrated into an aerospace asset management system. AE results were validated using optical measurements and microscopy.
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Abbass, Ahmmad A., Sallal R. Abid, Ali I. Abed e Sajjad H. Ali. "Experimental and Statistical Study of the Effect of Steel Fibers and Design Strength on the Variability in Repeated Impact Test Results". Fibers 11, n. 1 (30 dicembre 2022): 4. http://dx.doi.org/10.3390/fib11010004.
Testo completoAbstract (sommario):
The ACI 544-2R repeated impact test is known as a low-cost and simple qualitative test to evaluate the impact strength of concrete. However, the test’s main deficiency is the high variability in its results. The effect of steel fibers and the compressive strength of concrete on the variability in repeated impact test results was investigated experimentally and statically in this study. Two batches from four mixtures were prepared and tested for this purpose. Hooked-end steel fibers were utilized in the fibrous mixtures. The mixtures NC, NC-SF0.5 and NC-SF1.0 were normal strength mixtures with 0, 0.5 and 1.0% of steel fibers, respectively, while HC was a plain high-strength mixture. The impact tests were conducted using an automatic testing machine following the setup of the ACI 544-2R repeated impact test. The impact numbers at cracking (N1) and at failure (N2) were recorded for both batches of the four mixtures. The results were also analyzed using the normal probability and Weibull distribution tests. The test results showed that the fibers increased the impact results at the cracking stage and significantly increased the failure impact resistance. Adding 0.5 and 1.0% of steel fibers increased the N1 by up to 66 and 111%, respectively, and increased the N2 by 114 and 374%, respectively. The test results also showed that duplicating the design compressive strength from 40 to 80 MPa increased the impact resistance by up to approximately 190%. The test results revealed no clear trend of an effect of steel fibers and compressive strength on the variability in the test results.
35
Dhandayuthapani, Brahatheeswaran, Saino Hanna Varghese, Ravindran Girija Aswathy, Yasuhiko Yoshida, Toru Maekawa e D. Sakthikumar. "Evaluation of Antithrombogenicity and Hydrophilicity on Zein-SWCNT Electrospun Fibrous Nanocomposite Scaffolds". International Journal of Biomaterials 2012 (2012): 1–10. http://dx.doi.org/10.1155/2012/345029.
Testo completoAbstract (sommario):
Design of blood compatible surfaces is required to minimize platelet surface interactions and increase the thromboresistance of foreign surfaces when they are used as biomaterials especially for artificial blood prostheses. In this study, single wall carbon nanotubes (SWCNTs) and Zein fibrous nanocomposite scaffolds were fabricated by electrospinning and evaluated its antithrombogenicity and hydrophilicity. The uniform and highly smooth nanofibers of Zein composited with different SWCNTs content (ranging from 0.2 wt% to 1 wt%) were successfully prepared by electrospinning method without the occurrence of bead defects. The resulting fiber diameters were in the range of 100–300 nm without any beads. Composite nanofibers with and without SWCNT were characterized through a variety of methods including scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and tensile mechanical testing. The water uptake and retention ability of composite scaffolds decreased whereas thermal stability increased with an addition of SWCNTs. Hemolytic property and platelet adhesion ability of the nanocomposite (Zein-SWCNTs) were explored. These observations suggest that the novel Zein-SWCNTs composite scaffolds may possibly hold great promises as useful antithrombotic material and promising biomaterials for tissue engineering application.
36
Sarkar, Lisa, Mudigunda V. Sushma, Bhavani Prasad Yalagala, Aravind Kumar Rengan, Shiv Govind Singh e Siva Rama Krishna Vanjari. "ZnO nanoparticles embedded silk fibroin—a piezoelectric composite for nanogenerator applications". Nanotechnology 33, n. 26 (8 aprile 2022): 265403. http://dx.doi.org/10.1088/1361-6528/ac5d9f.
Testo completoAbstract (sommario):
Abstract This paper demonstrates a flexible nanogenerator (NG) using Silk-Zinc Oxide (ZnO) composite by exploiting the inherent piezoelectric properties of silk and ZnO. A direct precipitation method was employed to synthesize Zinc Oxide nanoparticles (NPs). Silk-ZnO composite film was then prepared by spin-coating the homogenous silk-ZnO solution. The composition and morphology of silk-ZnO composite were analyzed using various standard characterization procedures. The biocompatibility study of the composite film was also performed through cell viability testing. The utility of as prepared composites was demonstrated through the fabrication of piezoelectric nanogenerator. This hybrid nanogenerator was capable to generate a maximum open circuit voltage of 25 V (peak to peak value) in the bending state for a specific ZnO concentration. The output response of the nanogenerator exhibited a good correlation with the bending angle of the device. A peak outputpower density of 6.67 mW cm−3 was achieved from the nanogenerator. The fabricated prototype is efficient to light-up commercial red LEDs and to harvest energy from human body movement. The piezoelectric coefficient (d 33) of silk-ZnO composite film was also experimentally figured out.
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Kamal, Tahseen, Mazhar Ul-Islam, Sher Bahadar Khan, Esraa M. Bakhsh e Muhammad Tariq Saeed Chani. "Preparation, Characterization, and Biological Features of Cactus Coated Bacterial Cellulose Hydrogels". Gels 8, n. 2 (30 gennaio 2022): 88. http://dx.doi.org/10.3390/gels8020088.
Testo completoAbstract (sommario):
The current study was aimed at developing BC-Cactus (BCC) composite hydrogels with impressive mechanical features for their potential applications in medical and environmental sectors. BCC composites hydrogels were developed through cactus gel coating on a never dried BC matrix. The FE-SEM micrographs confirmed the saturation of BC fibrils with cactus gel. Additionally, the presence of various functional groups and alteration in crystalline behavior was confirmed through FTIR and XRD analysis. Mechanical testing illustrated a three-times increase in the strain failure and an increase of 1.6 times in the tensile strength of BCC composite. Absorption capabilities of BCC were much higher than pure BC and it retained water for a longer period of time. Additionally, the rewetting and absorption potentials of composites were also higher than pure BC. The composite efficiently adsorbed Pb, Zn, Cu, and Co metals. Biocompatibility studies against human HaCat cell line indicated much better cell adhesion and proliferation of BCC compared to BC. These findings advocate that the BCC composite could find applications in medical, pharmaceutical and environmental fields.
38
Xiong, Jie, Pengfei Huo e Frank K. Ko. "Fabrication of ultrafine fibrous polytetrafluoroethylene porous membranes by electrospinning". Journal of Materials Research 24, n. 9 (settembre 2009): 2755–61. http://dx.doi.org/10.1557/jmr.2009.0347.
Testo completoAbstract (sommario):
Poly(vinyl alcohol) (PVA) and poly(tetrafluoroethylene) (PTFE) emulsion were blended with different mass concentrations and the blended spinning solutions were electrospun into composite nanofibers. The influence of the blend ratio of PVA to PTFE and electrospinning technical parameters on the morphology and diameter of the composite nanofibers were investigated. According to the result of thermogravimetric analyzer analysis, the composite membrane was sintered at 390 °C. The membranes were then characterized by differential scanning calorimetry, attenuated total reflection-Fourier transform infrared (ATR-FTIR), and scanning electron microscopy, respectively. The mechanical properties of the membranes before and after sintering were analyzed through tensile testing. The results show that the PTFE porous membranes could be electrospun effectively, thus demonstrating their potential application as filter media.
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Syafri, Rahmadini, Chairil Chairil, Muhammad Rizqi Pratama, Muhammad Alfayed, Kardina Febriani e Hardi Rahayu Saputra. "Utilization of Rubber seed shell and Palm Oil Fronds as Composite Materials for Automotive Industry". Jurnal Kimia Sains dan Aplikasi 23, n. 4 (20 marzo 2020): 102–8. http://dx.doi.org/10.14710/jksa.23.4.102-108.
Testo completoAbstract (sommario):
Rubber seed shell (RSS) and Palm Oil Fronds (POF) are types of solid waste produced from rubber and palm oil plantation that has not been fully utilized. Meanwhile, in the automotive industry, composites have been the material of choice in some of its components. For example, composite body panels have been widely used in sports cars and passenger cars. This study aimed to utilize RSS powder and POF fiber waste as reinforcing fillers for the composite matrix. The matrix used was liquid polyester resin with the addition of catalyst as a hardener. RSS, which has been carbonized, was then activated using H2SO4 while POF fiber was pre-treated with 5% NaOH, then characterized both fillers by FTIR and SEM. Composites filled by RSS and POF in 4 variations were tested for mechanical properties with matrix composites without fillers as controls. FTIR testing of RSS carbonized powder found that carbonyl group consisting of tar compounds and remnants of carbon dioxide compounds that lost after activation with the H2SO4 solution. Meanwhile in POF fibers found that carbonyl group consisted of lignin and hemicellulose disappear after pre-treatment by 5% NaOH. SEM testing of RSS and POF fillers showed changes in surface morphology. The RSS and POF surface became coarser and porous, and the fibrils of POF fiber more obvious. The mechanical properties showed that the optimum result obtained in the composition of Matrix/POF/RSS (92.5/2.5/5).
40
Gilat, Amos, e Jeremy D. Seidt. "Compression, Tension and Shear Testing of Fibrous Composite with the Split Hopkinson Bar Technique". EPJ Web of Conferences 183 (2018): 02006. http://dx.doi.org/10.1051/epjconf/201818302006.
Testo completoAbstract (sommario):
The Split Hopkinson Bar (SHB) technique is used for high strain rate testing of T800/F3900 composite in compression, tension and shear. Digital Image Correlation (DIC) is used for measuring the full-field deformation on the surface of the specimen by using Shimadzu HPV-X2 high-speed video camera. Compression tests have been done on specimens machined from a unidirectional laminate in the 0°and 90° directions. Tensile tests were done in the 90° direction. Shear tests were done by using a notched specimen in a compression SHB apparatus. To study the effect of strain rate, quasi-static testing was also done using DIC and specimens with the same geometry as in the SHB tests. The results show that the DIC technique provides accurate strain measurements even at strains that are smaller than 1%. No strain rate effect is observed in compression in the 0° direction and significant strain rate effects are observed in compression and tension in the 90° direction, and in shear.
41
Zhou, Zhiya. "Garment Digital Design Method Oriented to the Production Process of Graphene-Modified Nylon Knitted Fabric". Journal of Nanomaterials 2022 (18 marzo 2022): 1–13. http://dx.doi.org/10.1155/2022/6114483.
Testo completoAbstract (sommario):
Graphene is a single-atom-thick layer of carbon atoms, the thinnest material ever discovered. The special single atomic layer structure of graphene makes it have many unique physical and chemical properties, and these excellent properties make graphene have a bright application prospect in the field of composite materials. The use of modern digital production technology to coordinate the management of various production departments of an enterprise can greatly reduce the input of human resources and improve the utilization of materials and equipment resources. In the process of caprolactam monomer polymerization, adding filler is a common method to strengthen and toughen nylon. The main fillers are powder fillers and fibrous materials. In order to make the fillers denatured, the fillers are usually pretreated with a silane coupling agent before modification. This research mainly discusses the digital clothing design method oriented to the production process of graphene-modified nylon knitted fabric. The color of graphene-modified cotton fiber is gray and black. With the increase of graphene content, the color becomes darker. Graphene has become a hotspot in materials science due to its unique two-dimensional crystal structure and excellent mechanical, thermal, and electrical properties. In this paper, the preparation and organic modification of graphene oxide and its application in cast nylon are mainly studied. Therefore, when designing graphene-modified cotton fiber jacquard graphene knitted fabric, the color matching has certain restrictions. The shrinking is to reduce the friction between the fibers through the appropriate concentration of the shrinking agent and improve the stretching and shrinking ability of the wool fiber. The fabric feels plump after shrinking, forming fluff, and improving the warmth retention performance. Due to the different design of the veil material, ground yarn material, and organizational structure of the fabric sample, the basic parameters of the fabric are directly different. Therefore, first perform the width, density, areal density, thickness, and raw material content ratio of the blank sample of the fabric. And wait for testing. In order to realize the digitization of styles, this research has developed a drawing system, which provides a large number of drawing tools to enable designers to draw clothing styles more accurately. The system for digital realization consists of six parts, including desktop environment, drawing tools, linear settings, curve drawing, data storage, and user interface. There are a variety of curves to choose from in computer graphics. The B3 spline curve has become the first choice due to its smoothness, no Runge phenomenon, and few saved data. When the mass fraction of graphene-modified nylon was reduced to 18%, the inhibitory rate of Staphylococcus aureus and Escherichia coli was still greater than 80%. Nylon/modified graphene oxide nanocomposites with different filler contents were prepared by in situ polymerization with modified graphite oxide as modified filler. The effects of modified graphene oxide on the mechanical properties, wear resistance, and thermal properties of the composites were investigated. This research will promote the development of a customized platform for apparel collaborative management.
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Dessalegn, Yalew, Balkeshwar Singh, Aart W. van Vuure, Irfan Anjum Badruddin, Habtamu Beri, Mohamed Hussien, Gulam Mohammed Sayeed Ahmed e Nazia Hossain. "Investigation of Bamboo Fibrous Tensile Strength Using Modified Weibull Distribution". Materials 15, n. 14 (19 luglio 2022): 5016. http://dx.doi.org/10.3390/ma15145016.
Testo completoAbstract (sommario):
Ethiopia has a large coverage of bamboo plants that are used for furniture making and house building. So far, researchers have not studied the strength of Ethiopian bamboo fibers, which are utilized for composite applications. The current study measured the strength of bamboo fibers based on various testing lengths and calculated the predictive tensile strength using a modified Weibull distribution. Moreover, the quality of the extraction machine is evaluated based on shape and sensitivity parameters. This research paper incorporates the coefficient of variation of the fiber diameters, considering the defects distribution through the length for measuring the predictive strength of the fibers. The fiber diameters were calculated using the area weight methods, which had its density measured using a Pycnometer. It has been examined that as the testing gauge length and coefficient variation of fiber diameter simultaneously increased, the tensile strength of the bamboo fibers decreased. The shape parameter, sensitivity parameter, and characteristic strength of Injibara bamboo (Y. alpina) are 6.02–7.83, 0.63, and 459–642 MPa, whereas Kombolcha bamboo (B. oldhamii) are 5.87–10.21, 0.33, and 408–638 MPa, as well as Mekaneselam bamboo (Y. alpina) are 5.86–9.63, 0.33 and 488–597 MPa, respectively.
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Anoshkin, A. N., V. Yu Zuiko, A. V. Tchugaynova e E. N. Shustova. "Experimental-Theoretical Research of Mechanical Properties of Perforated Composite Sandwich Panels". Solid State Phenomena 243 (ottobre 2015): 1–10. http://dx.doi.org/10.4028/www.scientific.net/ssp.243.1.
Testo completoAbstract (sommario):
This work is devoted to experimental-theoretical analysis of mechanical properties of sandwich panels made of fibrous polymer composite materials. The structures with tubular core were considered. Numerical simulations of the mechanical behaviour and tensile testing of full-scale samples of sandwich panels were done. The analysis of influence of perforation on mechanical properties of fiberglass laminates and sandwich panels was alsoperformed.
44
Wang, Biao, Rui Juan Xie, Qiong Wan, Yang Wang e Yang Yang Huang. "Effect of Silk Fibroin on the Properties of Calcium Phosphate Cement". Advanced Materials Research 175-176 (gennaio 2011): 100–104. http://dx.doi.org/10.4028/www.scientific.net/amr.175-176.100.
Testo completoAbstract (sommario):
To improve the physicochemical properties of calcium phosphate cement (CPC), silk fibroin (SF) in the different forms were added into CPC. The structure of the composites was studied by X-ray diffraction. The setting time was investigated by ISO Cement Standard Consistency Instrument. Scanning Electron Microscope was used to observe the surface morphology. Mechanical properties of samples were tested by Instron Universal Testing Machine. The results indicated that acicular crystal of hydroxyapatite (HA) was formed in the hardening body of both CPC with SF and the pure CPC. Addition of SF had no significant effect on the structure of SF/CPC composite. The setting time of CPC with SF was significantly shorter than that of the pure CPC (30.3 mins). The setting time of CPC by adding silk fibroin powder I (SFP) and silk fibroin fiber (SFF) was greatly shortened, which was only 11.7 minutes. The setting time of CPC with SFP decreased approximately by 1/3, while the setting time of the CPC with SFF decreased nearly by 1/2. With the adding of SF, the compressive strength of CPC increased significantly. There was a distinct increase in the work-of-compressive of CPC with the adding of SFF.
45
Hamad, Sameer F., Nicola Stehling, Simon A. Hayes, Joel P. Foreman e C. Rodenburg. "Exploiting Plasma Exposed, Natural Surface Nanostructures in Ramie Fibers for Polymer Composite Applications". Materials 12, n. 10 (18 maggio 2019): 1631. http://dx.doi.org/10.3390/ma12101631.
Testo completoAbstract (sommario):
Nanoscale surface morphology of plant fibers has important implications for the interfacial bonding in fiber-polymer composites. In this study, we investigated and quantified the effect of plasma-surface modification on ramie plant fibers as a potential tool for simple and efficient surface modification. The extensive investigation of the effects of plasma treatment of the fiber surface nano-morphology and its effect on the fiber-polymer interface was performed by Low-Voltages Scanning Electron Microscopy (LV-SEM), infrared spectroscopy (FT-IR) analysis, fiber-resin angle measurements and mechanical (tensile) testing. The LV-SEM imaging of uncoated plasma treated fibers reveals nanostructures such as microfibrils and elementary fibrils and their importance for fiber mechanical properties, fiber wettability, and fiber-polymer matrix interlocking which all peak at short plasma treatment times. Thus, such treatment can be an effective in modifying the fiber surface characteristics and fiber-polymer matrix interlocking favorably for composite applications.
46
Hu, Zhanao, Wasim Akram, Shixian Chen, Shuqin Yan e Qiang Zhang. "Facile Fabrication of Silk Fibroin/Konjac Glucomannan Composite Membranes". AATCC Journal of Research 8, n. 2_suppl (dicembre 2021): 23–27. http://dx.doi.org/10.14504/ajr.8.s2.5.
Testo completoAbstract (sommario):
Silk fibroin (SF)-based biocomposites have attracted considerable attention for several decades, due to excellent biocompatibility and mechanical toughness. However, insufficient hydrophilicity and mechanical brittleness limit its practical application, especially in tissue engineering. In this study, by blending konjac glucomannan (KGM) with SF, along with the water-insoluble treatment of ethanol and ammonia, SF/KGM composite membranes were generated with good flexibility and water adsorption capacity. Scanning electron microscopy (SEM) showed that KGM/SF membrane surfaces were uniform and dense. Fourier transform infrared spectroscopy (FTIR) showed that the silk II structure was dominant. Contact angle and mechanical testing showed that the use of KGM with SF in membranes helped to form more flexible and hydrophilic membranes for potential use in biomaterials and devices.
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Si, Yi, e D. S. Kevluzov. "Research on the Long-Lasting and Remelting Properties of Nd Modification Effect on Cast Al-Mg2Si Metal Matrix Composite". Materials Science Forum 1001 (luglio 2020): 196–201. http://dx.doi.org/10.4028/www.scientific.net/msf.1001.196.
Testo completoAbstract (sommario):
The cast Al-Mg2Si metal matrix composite was prepared by metal model casting process with rare earth element Nd as the modificator. The effects of modification duration and remelting times on microstructure and mechanical properties of the composite were investicated by optical microscope (OM) and electronic universal testing machine. The results show that, after introducing a proper amount of Nd, both primary and eutectic Mg2Si in the Al-18 wt.%Mg2Si composite were well modified. The morphology of primary Mg2Si is changed from irregular or dendritic to polyhedral shape and the morphology of the eutectic Mg2Si phase is altered from flake-like to very short fibrous or dot-like. Moreover, the effect is of long-lasting and remelting properties. After the composite is modified for 300 min and remelted by 6 times, its primary and eutectic Mg2Si structures are still in modification state of small block and slices, and the tensile properties of the composite are not significantly affected.
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Smirnov, Maksim M., e Andrey R. Korabelnikov. "OBTAINING COMPOSITE FIBROUS MATERIALS BY ELECTROSPINNING FROM SOLUTIONS OF POLYMETHYL METHACRYLATE WITH THE ADDITION OF CARBON NANOTUBES". Technologies & Quality 52, n. 2 (2 luglio 2021): 56–61. http://dx.doi.org/10.34216/2587-6147-2021-2-52-56-61.
Testo completoAbstract (sommario):
The article is devoted to the research and testing of a method for producing nonwoven material from nano- and microfibres saturated with carbon nanotubes by the method of electrospinning, the study of the effect of ultrasonic treatment of a polymer solution and the addition of carbon nanotubes on the properties of the solution and the morphology of the resulting material. As a result of the study, samples of materials were obtained from solutions of polymethylmethacrylate, treated and not treated with ultrasound, organoleptic and microscopic studies of the obtained samples were carried out. A decrease in the viscosity of a polymer solution treated with ultrasound and a significant decrease in the diameter of fibres obtained from such solutions were found.
49
Alifanov, O. M., S. A. Budnik, A. V. Nenarokomov e D. M. Titov. "Experimental testing of heat flux sensors based on the inverse problem technique". VESTNIK of Samara University. Aerospace and Mechanical Engineering 18, n. 4 (21 gennaio 2020): 7–17. http://dx.doi.org/10.18287/2541-7533-2019-18-4-7-17.
Testo completoAbstract (sommario):
In final adjustment of thermally-loaded elements of space structures information on thermal loads (heat fluxes and surface temperatures) for the whole period of flight in the atmosphere is of primary importance. The level of temperature and the processes taking place on the surface of the heat shield do not always allow using conventional methods of measuring thermal loads. In this case determining thermal loads by the results of measuring the temperature at several points of elements of the heat shield structure is an alternative to direct measurements. The aim of this work is to develop and test sensors for measuring heat loading of thermal-protective coating of modern descent vehicles, as well as to test the developed methods of carrying out thermo-physical tests. Heat flux sensors for indestructible composite fibrous materials with a high degree of non-uniformity are described in the paper.
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Doench, Ingo, Tuan Tran, Laurent David, Alexandra Montembault, Eric Viguier, Christian Gorzelanny, Guillaume Sudre et al. "Cellulose Nanofiber-Reinforced Chitosan Hydrogel Composites for Intervertebral Disc Tissue Repair". Biomimetics 4, n. 1 (20 febbraio 2019): 19. http://dx.doi.org/10.3390/biomimetics4010019.
Testo completoAbstract (sommario):
The development of non-cellularized composites of chitosan (CHI) hydrogels, filled with cellulose nanofibers (CNFs) of the type nanofibrillated cellulose, was proposed for the repair and regeneration of the intervertebral disc (IVD) annulus fibrosus (AF) tissue. With the achievement of CNF-filled CHI hydrogels, biomaterial-based implants were designed to restore damaged/degenerated discs. The structural, mechanical and biological properties of the developed hydrogel composites were investigated. The neutralization of weakly acidic aqueous CNF/CHI viscous suspensions in NaOH yielded composites of physical hydrogels in which the cellulose nanofibers reinforced the CHI matrix, as investigated by means of microtensile testing under controlled humidity. We assessed the suitability of the achieved biomaterials for intervertebral disc tissue engineering in ex vivo experiments using spine pig models. Cellulose nanofiber-filled chitosan hydrogels can be used as implants in AF tissue defects to restore IVD biomechanics and constitute contention patches against disc nucleus protrusion while serving as support for IVD regeneration.