Search

To effectively manage turbine blade weight and blade deflection under severe weather conditions, longer and stiffer blades are required, fiber glass producers have devoted significant efforts to developing and commercializing high‐modulus (HM) glass fiber products of the first generation. The current focuses aim at the commercialization of the second generation and the development of the third‐generation products. This article briefly reviews four key areas: (a) the benefit of longer blades on wind energy generation, (b) characteristics of HM glass fibers of various generations, (c) fundamental science and understanding behind HM glass fiber development, and (d) finally statistically based composition (C)–property (P) and structure (S)–property (P) modeling approaches in new glass design. [ABSTRACT FROM AUTHOR]

Abstract The aim is to develop new fiber-reinforced polymer (FRP) water pipe by activating fiber glass (FG) by vinyltriethoxysilane (VS) getting vinylsilane-activated FG (AFG) for filling vinylester (VE) via continuous winding to make a novel VE-AFG composite. The novelty of this work is the activation of fiber glass by vinylsilane as a single filler in vinylester and compounding them via a two-dimensional continuous winding process for the first time. The crosslinking occurred in the AFG/VE/curing agent system after activation. The activated composites increased thermal stability; 25% VE-AGF increased the degradation temperatures at 10%, 25%, and 50% weight loss by 73.3%, 10%, and 7.2%. With the activated 20% composite, values of axial strength, hoop strength, and hardness were developed by 6.3%, 2%, and 8.7%, respectively. The decay resistance to different microorganisms was increased with VE-AFG composites as a result of a sharp decrease in biodegradability percentages. The activated composites are stable toward water absorption; the least percentage was recorded by 25% VE-AFG, which minimized the water absorptivity by more than 62%. The reported characterization sentence approves enhancement of thermal, physical, and mechanical stability of sustainable vinylester-fiber glass composites manufactured by continuous winding; this is recommended for application in water pipe systems.

Textile Composites is a resin system containing a textile fiber, yarn, or fabric system for special properties. Cord knit is a simple and economic and fast technique for producing tubular textile fabrics. This article studied the effect of some variables such as outer layer yarn count and core material of poly-amide cord knitted fabrics on its properties and applying it as a cord-knitted composite bar for reinforcing concrete. six samples with two different outer layer yarn counts (1200 and 2400 denier) and three different core materials (polyamide, fiberglass, and polyethylene 50%, and polypropylene 50%) were produced and tested, then inserted in epoxy to convert to a composite cord. The properties of composite cord knitted fabrics were tested. Then different numbers of bars were used (one bar, two bars, and three bars) from the highest properties cord knitted poly-amide composite fabrics for reinforcing concrete beams (50 cm*10cm*10cm), flexure of those beams were tested and it was found that using two bars from poly-amide composite has the highest effect on reinforcing concrete beams. [ABSTRACT FROM AUTHOR]

The oil and gas industry has long dominated Nigeria’s blue economic growth. However, a new frontier that can play sustainable economic growth in the maritime industry and therefore national economic leverage is offshore aquaculture. Hence, this paper aims to provide relevant information on the economic analysis of the potential offshore aquaculture practice to enhance the diversification of the blue economy in Nigeria using secondary data. Sensitivity analysis considering input variations of up to 45% is also performed to take care of the unforeseen. Offshore aquaculture in this paper refers to fish production in the Open Ocean using large cages/nets. Ten (10) fish cages of 37500-fish capacity per cage were hypothetically designed with fiberglass materials and installed in Escravos offshore. A mortality of 30% was used with the current prices of other required investments. The analysis recorded a breakeven period of 2 years and NPV value of over one trillion Naira in 9 years indicating massive profitability comparable to the oil and gas industry! Sensitivity analysis identified mortality/loss of fish and falling prices of fish as events that could adversely affect the investment. It is suggested that the investment should be done with experienced professionals in fishery, offshore engineering, and cost control. [ABSTRACT FROM AUTHOR]

Filament winding method is the most commonly used method to produce profiles with different cross sections as composite product manufacturing. In this method, fiber material is wound with resin at different angles on a mold that has a suitable cross section shape. As a winding strategy, angled and helical winding can be done. Motion planning for this process is done with geodesic and nongeodesic theories. Requirement to use mold in the filament winding method increases the cost. Also, there is an obligation to helical windings. In winding of different layers, 90° angle cannot be given between the layers. To overcome all these constraints, UV curing can be achieved using photopolymer resin and continuous fiber glass fiber with the help of robotic additive manufacturing technology. Toolpath strategies for production has a key role in this work. As a tool path strategy, nonplanar slicing can be done and manufactured composite elbow in angular layers without mold. Then, under favour of 6-axis mobility of the industrial robot arm, layers can be obtained at exactly 90° angle. In addition, in this method, unlike other winding methods, internal voids, i.e. a filling rate, can be given within the cylindrical encircled layers. In order to verify whether the elbows produced with this method meet the requirements of the desired applications in the industry in terms of mechanical properties, at different filling rates (50%, 75%, 100%), winding turns (0 and 1/8), and different fiber densities (45%, 55% and 65%) 90° curved composite elbows were produced and their internal pressure strength tests were tested. Afterwards, an optimization study was carried out with the Taguchi method for the production parameters that will maximize the internal pressure strength. According to the results of the optimization study, it is seen that it is appropriate to choose the printing parameters that will obtain the highest internal pressure strength values for production with this method, 100% fill rate, 65% fiber density and 0° winding angle. The products made of this process have the advantage of easy-shaping, reasonable ratio of axial strength and encircled strength, specification easy-unifying, stable product quality. [ABSTRACT FROM AUTHOR]

The oil and gas industry has long dominated Nigeria’s blue economic growth. However, a new frontier that can play sustainable economic growth in the maritime industry and therefore national economic leverage is offshore aquaculture. Hence, this paper aims to provide relevant information on the economic analysis of the potential offshore aquaculture practice to enhance the diversification of the blue economy in Nigeria using secondary data. Sensitivity analysis considering input variations of up to 45% is also performed to take care of the unforeseen. Offshore aquaculture in this paper refers to fish production in the Open Ocean using large cages/nets. Ten (10) fish cages of 37500-fish capacity per cage were hypothetically designed with fiberglass materials and installed in Escravos offshore. A mortality of 30% was used with the current prices of other required investments. The analysis recorded a breakeven period of 2 years and NPV value of over one trillion Naira in 9 years indicating massive profitability comparable to the oil and gas industry! Sensitivity analysis identified mortality/loss of fish and falling prices of fish as events that could adversely affect the investment. It is suggested that the investment should be done with experienced professionals in fishery, offshore engineering, and cost control.

Copyright of Al-Nahrain Journal for Engineering Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, the mechanical properties of an epoxy, unidirectional woven carbon and fiberglass composite were investigated experimentally. ASTM used for preparing the composite specimen. Different ranges of mixing ratios of woven carbon and fiberglass with epoxy are studied. Tensile, impact and bending test are carried out to investigate the mechanical properties for produced new composites. After testing the mechanical properties of the specimens, it is noted that adding of unidirectional woven carbon layers will leads to strengthens the samples. The mechanical properties of woven carbon composite are far superior to those of woven carbon composite with fiberglass.

Concrete is a brittle material which has a higher compressive strength compared to its tensile strength. Steel, glass or polymer fibers are usually added to concrete in order to improve the ductility under mechanical loads. One of the most important factors taken into consideration in producing a durable concrete is by imperviousness concrete. In this study, the mechanical and permeability properties of fiber reinforced mortars were investigated. For this purpose, in addition to the reference, 0.1%, 0.2% by volume, glass fiber reinforced and 1.15% and 2% impermeability admix incorporated series were prepared. The effective water/cement ratio of all produced mortar samples was determined to be 0.5. The workability, ultrasonic pulse velocity (UPV), flexural strength, compressive strength, splitting tensile strength, determination of water penetration depth under pressure were determined in all series. According to the test results, as the glass fiber ratio increased, the water penetration depth decreased by 15% compared to the reference. In the series where 0.2% glass fiber was used, there was a 20% increase compared to the reference in terms of splitting tensile strength. In addition, there is an increase in splitting tensile strength in series produced using glass fiber and impermeability additive.

Copyright of Dokuz Eylul University Muhendislik Faculty of Engineering Journal of Science & Engineering / Dokuz Eylül Üniversitesi Mühendislik Fakültesi Fen ve Mühendislik Dergisi is the property of Dokuz Eylul Universitesi Muhendislik Fakultesi Fen ve Muhendislik Dergisi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Weight is of great importance in the aircraft industry. Aircraft are made of aluminum alloys that are susceptible to heat treatment, because they are light in weight and are metal strong enough for the dynamic designed loads they can face, but there are other reasons for obtaining alternative materials, and these materials are composite materials that it is lighter in weight than aircraft made of aluminum, firstly, and secondly, it can be formed into attractive shapes, eliminating welding and rivets, and thirdly, it can be formed into aerodynamic shapes. This work is based on designing a three-dimensional model consisting of aluminum alloy (AA-6061-T6) of the structure helicopter and then comparing it with five other models of different metal and composite materials to obtain a structure that has the least weight among these models. The results indicate that the best model with the lowest weight is the fourth model consisting of carbon fiber, proportions and weight of a square meter and a thickness of (28 mm) than the weight of the first model consisting of aluminum and weighing (81 kg), it was less than (22.7%). Then the fifth model, which consisted of an outer layer of aluminum with a thickness of five millimeters and another inner layer of aluminum of the same thickness, and between the inner and outer layer eighteen layers of carbon fiber, where the percentage of decrease in it compared to the first model by up to (19.2%), and worse a model in terms of weight is the second model was made of steel, which has a weight that is almost twice the weight of the first model. [ABSTRACT FROM AUTHOR]

In this research, three mathematical models were designed, the first consisting of concrete, the second from carbon fiber, and the third from s-glass fiber, in order to compare the strength of composite materials to different stresses and deformations, because composite materials are better than concrete in terms of weight and shape and do not need to be applied to painting operations in addition to the fact that their thermal insulation is higher than Concrete in high proportions. From the results of the comparison, it was found that the second model was the best model in terms of bearing deformations, as the deformation percentage in it did not exceed the deformation of concrete a lot, reaching (17%), which is a very small percentage, and the stresses towards pregnancy for the second and third models were much better than the bearing of the first model, but the results indicate that the Von Mises Stress in the second model is higher than the first model by a percentage (57%), while the comparison of the third model with the first was the rate of increase percentage (47%). [ABSTRACT FROM AUTHOR]

3D printing technology has gradually taken its place in many sectors. However, expected performance cannot be obtained from the structural parts with this method due to the raw material properties and constraints of Cartesian motion systems. This technology cannot replace structural parts produced by traditional manufacturing methods. In order to avoid these constraints, it is preferred to use continuous fiber reinforced polymer composites in many areas such as automotive and aerospace industries due to their low weight and high specific strength properties. These automated composite manufacturing methods currently have limited production of geometric shapes due to the need for additional molds and production as flat surfaces. To overcome all these constraints, fiberglass reinforced ultraviolet ray-curing polymer matrix composite material are selected for robotic 3 D printing process and various parameters are examined. Fiber-polymer combination and layer structure formation was examined. Scanning Electron Microscopy (SEM) images of sections of 3 D printed test samples were taken and fiber resin curing was examined. The nozzle diameter, printing speed, fiber density and Ultra Violet (UV) light intensity parameters, which will provide effective 3 D printing process, are optimized with the Taguchi method. Tensile strength, flexural strength and izod impact values are considered as result parameters for optimization. It was found that it would be appropriate for 3D printing with a 1.0 mm nozzle diameter, 600 tex fiber density, 4 UV light, 600 mm/min printing speed. With these 3D printing process parameters, approximately 125 MPa tensile strength and 450 MPa flexural strength can be obtained. With this study, support and contribution was provided to researchers, composite producers, tool manufacturer and literature who want to use and develop this 3D printing process. [ABSTRACT FROM AUTHOR]

The objective of this study is to investigate the mechanical properties of the polymeric composite hybrid type interply reinforced with glass fibers GF and carbon fibers CF with the structure of the material consisting of: a) three layers CF:GF with the sequence [CF/GF/CF]; b) five layers CF:GF with the sequence: 1) [CF/GF/CF/GF/CF] and 2) [CF/CF/GF/CF/CF]. The GF:CF hybrid biocomposite interply type is made using the working methodology based on the Liquid resin Infusion (LRI) and Vacuum infusion techniques. The general mechanical properties are evaluated experimentally using standard tensile and bending tests using five specimens made according to ASTM standards. Based on the experimental results and the diagrams obtained at the tensile and bending tests of the hybrid polymeric biocomposite type interply comparisons are made regarding the mechanical properties of the composite for each type of structure. The general results confirm, from a mechanical point of view, the usefulness of this type of composite for engineering and biomedical applications. [ABSTRACT FROM AUTHOR]

In the decade since the last published comprehensive report of occupational exposures in the glass wool insulation industry, many process and regulatory changes have occurred in the glass wool manufacturing sector. This paper assesses whether any significant changes in worker exposures to glass wool fibers have resulted from these process and regulatory changes. The analysis compares worker exposures to glass wool overall and across different product and job categories in the manufacturing sector prior to and after 2007, the data cutoff period for the last comprehensive update of occupational exposures in this industry. The exposure data were downloaded from the North American Insulation Manufacturers Association's synthetic vitreous fiber (SVF) exposure database, which has been continually updated with all new available SVF exposure data for the past two decades. This analysis finds no major changes in worker exposures in the glass wool manufacturing industry over the past decade, with exposures remaining well below the 1 f/cc voluntary permissible exposure limit. [ABSTRACT FROM AUTHOR]

In this paper were highlighted some aspects regarding the manufacturing process of the fiber glass reinforced polymer composites. Polymeric composites reinforced with glass fiber they are used mainly utilized in aircraft industries and is due to low specific weight, increase of corrosion resistance in the fasteners and reduction number of structural components. The paper essentially approaches the steps for the manufacture of a landmark such as ram air inlet. [ABSTRACT FROM AUTHOR]

Introduction. An immobilisation system is defined as a device made in order to stabilise mobile teeth. Aim. This study aims to perform a clinical assessment of the efficiency of applying dental immobilisation in the case of periodontal patients with pronounced dental mobility in the lower frontal group. Material and Methods. In order to carry out this study, we have selected a group of 30 patients aged 50 to 70, with an average age of 57, who have visited the “Grigore T. Popa” University of Medicine and Pharmacy, Iasi, Periodontology Clinic in the interval March 2016 - June 2017. The patients received splinting treatment through using three different composites. Results and Discussion. Overall, we have found a success rate of 55% of the 30 patients, individuals in which the immobilisation system was intact. For the remaining 45%, 20% had 2 disaggregated elements, 15% had one disaggregated element, 7 % had 3 disaggregated elements and 3% had a fractured immobilisation system. Conclusions. Highly viscous flowable composites have shown the best survival rate after 12 months, being therefore a good candidate for a first-choice material for performing direct immobilisations in periodontal treatment.

This paper deals with the construction of a rigid pavement road which uses concrete as a construction material. This paper deals with the partial replacement of fine aggregates in the concrete with fiber glass. The concrete with fiber glass and without fiber glass is analyzed in terms of compressive strength and rise in temperature due to sunlight. The concrete considered for this research work is M20 mix. The fine aggregate replacements for the concrete ratio are 5%, 10% and 20%. The characteristic compressive strength of conventional M20 concrete and developed M20 concrete is nearly equal with a visible difference in temperatures after sunlight exposure. The outcome of this research work is that fiber glass is effectively efficient to be used for cool pavement & cool Roofing and can be adopted easily as it consumes waste. [ABSTRACT FROM AUTHOR]

Reinforced concrete was invented and developed simultaneously by several people in the mid-nineteenth century. Besides versions "classical" fiber reinforced concrete (by using steel bars, whatever "style" of them), there are new ways to further concrete strength. Transparent concretes (translucent) is gaining much ground in the construction of the West Europe. "Light Transmitting Concrete" is a concrete-like product, which is translucent due to the mixture of fiber glass, plus a combination of finely divided crushed stone, cement and water. After the strengthening of composition, blocks of various shapes are obtained, with features of concrete and glass. Transparent concrete is a translucent material created by the combination of concrete and thousands of optical fiber wires acting as a filler. [ABSTRACT FROM AUTHOR]

Lightweight, glass fiber reinforced plastic composites (GFRP) have gained a broad, global acceptance in commercial markets, among which wind turbine blade for the renewable energy sector is one of the fastest growing areas. The usfsupplee of longer wind turbine blades can effectively reduce the cost of energy generation. However, it requires a fiberglass product with a higher tensile modulus to make the blades stiffer to meet the blade deflection requirement under severe weather conditions. Traditional wind turbine blades are made from conventional E-Glass fibers with and without boron. E-Glass is primarily composed of CaO-Al 2 O 3 -SiO 2 (CAS) with and without minor components of MgO (less than 4 %) and/or B 2 O 3 (less than 1 %). Glass with higher modulus belongs to MgO (>7 %) -CaO-Al 2 O 3 -SiO 2 (MCAS) system or R-Glass. Our study focuses on the effects of selective key oxides on the glass network structure by using Raman spectroscopic technique. The Raman derived plausible structure groups are then used to build statistical structure (S) – property (P) models. The S-P models are then compared with the conventional statistical C-P models. A good agreement between S-P and C-P models led to the final construction of C-S-P model platform for future glass design. [ABSTRACT FROM AUTHOR]

In this research a polymeric composites have been prepared using epoxy resin reinforced with fiber glass and two nano fillers silicon oxide SiO2 particle size around 35 nm and titanium dioxide TiO2 particle size around (100-150 nm). These composites have been prepared in square slices (25x25) cm and 8mm thickness, by saturating fiber glass mattresses in the liquid epoxy resin with nano fillers and then cutting the product in suitable shapes to conduct the mechanical tests highest properties (tensile strength, elongation, Flexural strength, hardness strength, and impact strength. were (116.1 N/mm2, 9.98%, 396 N/mm2, 83.8 shore-D and 5.8 J). The aim of this research is to prepare polymeric materials with high mechanical properties that can be used in many industrial applications especially in the manufacture of oil and gas pipe systems and crude oil pipelines.

Flexural properties were evaluated of blockboard with spruce (Picea abies Mill) core and faces made of 2.5-mm fromager (Ceiba pentandra) veneer and 3-mm high-density fiberboard (HDF). For these two types of structures, fiber glass, jute, gauze, and cotton fabrics, were separately bonded under the face layers to improve the strength performance. Flexural properties, modulus of rupture (MOR), and modulus of elasticity (MOE) were determined under laboratory conditions. Improved values were found for MOR and MOE tested in the parallel to core grain direction compared to those perpendicular-to-grain. They were 32% to 49% (MOR) and 39% to 95% (MOE) improvements in case of veneer faces and 142% to 161% (MOR) and 134% to 245% (MOE) improvements in case of HDF faces. The best results of MOR and MOE were obtained for glass fiber used as insertion material, the higher ones being reached for specimens tested in the parallel direction to grain, which were 56.1 N/mm² (MOR) and 6704 N/mm² (MOE) for HDF faces. Generally, the improvements were more evident on the blockboard structures with veneer faces oriented perpendicular-to-core grain (30% for MOR and 18% MOE) and for HDF faces with parallel core grain orientation (16% for MOR and 6% MOE). [ABSTRACT FROM AUTHOR]

Copyright of Odontología Pediátrica is the property of Asociacion Sociedad Peruana de Odontopediatria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Produksi kapal fiber glass di berbagai galangan kapal di Indonesia proses laminasi masih dilakukan secara manual (hand lay-up) di areal terbuka, hal ini sangat rentang terjadi udara terperangkap (air trap) yang dapat menimbulkan lepuh (blistering). Perawatan pitting defect akibat blistering, oleh galangan kapal hanya di sekrap, dibersihkan, didempul, diratakan/ dihaluskan dan gelcoat painting. Tujuan penelitian adalah menyelidiki penyebab kerusakan/ keretakan pelat zona lambung berkaitan dengan blistering. Metode yang digunakan adalah mengamati proses produksi dan pemeliharaan zona lambung kapal fiber glass dan pengujian pelat blistering zona lambung yang dibandingkan dengan pelat asli menggunakan peralatan uji FTIR sesuai standar ASTM E1252-07 dengan metode ATR dan Morphology Analysis. Sesuai pengamatan lapangan, galangan kapal tidak melakukan pengukuran kandungan air diarea blistering yang terdapat pitting defect sehingga terjadi peristiwa osmosis sebagaimana ditunjukan pada spektrum FTIR yakni terjadi penurunan intensitas bilangan gelombang dari gugus puncak 1724 cm-1 ke 1722 cm-1 disamping terdapat puncak tambahan pada sampel pelat blister akibat reaksi hidrolisa pada serat penguat, juga terdapat kerusakan yang signifikan pada pelat blistering dan terdapat rongga sehingga menimbulkan kelembaban dalam serat penguat. Dalam waktu (2 s/d 3) tahun serat penguat akan menjadi rapuh/getas sehingga jika terjadi benturan dengan gelombang laut atau objek lain dapat menyebabkann kerusakan/keretakan.

In this paper, we have built some composite bars with the reinforcement made by fiber glass which is randomly disposed and the matrix made by ambresit. Then, in order to study the samples free vibrations, we have clamped the bars at one end and we left the other free. At about 5 mm from the free end, we have placed an accelerometer and an initial deformation to the bar. Then, by removing the initial deformation we left the bar to freely vibrate. From these vibrations we have determined the bars damping factor and eigenfrequency.

In this paper, I have built a composite sample made from glass fiber as reinforcement and Aropol as matrix. For this sample, I have used an experimental procedure to determine the damping properties and the frequency of the first eigenmode. The experimental process is characterized by clamping the bar at one end and leaving it free at the other. At the free end, I have placed an accelerometer to record the bar free vibrations. I have applied an initial force, then I have removed the force and left the sample to vibrate without any other restrictions. From these vibrations I have determined the damping factor and the eigenfrequency.

This paper is aimed to determine the wear properties of nanosilica filled epoxy polymers and FRP composites. Woven fiberglass has been deployed as the reinforcement material. The fibers were mixed with three different percentages of nanosilica-modified epoxy resin, i.e: 5wt%; 13wt%; 25wt%, in order to fabricate the desired samples of FRP composites. The effect of nanosilica on wear properties was evaluated using dry sliding wear and slurry tests. The results show that increasing the amount of nanosilica content has reduced the amount of accumulated mass loss. It was found that the FRP laminates with 25wt% of nanosilica have the highest wear resistance. The nanosilica filled fiber reinforced polymer composites have a high potential in tribological application such as ball bearing housing and snow sleds.

This study was aimed to increase the impact resistance of circular tubes reinforced by fiber reinforced plastic (FRP).The tube made of aluminum 6063-T5 with the D/t ratio of 25.40, 29.63, and 42.33. Outside surface of aluminum tube was reinforced by wrapping fiberglass/polyester. The fiber orientation angle were [0]3 , [45]3 , [90]3 , [0/902 ], [45/-452 ], and [90/02 ]. Then, they were tested under impact with cross head of 45 kg and speed of 6.26 m/s in axial direction. The result revealed that the impact resistance of the hybrid tube and aluminum tube trend to increase as the D/t ratio increases and The hybrid tube with wrapped angle of [0/902 ] was maximum mean load and higher than aluminum tube by 50.02, 45.14, and 52.03 % at D/t = 25.40, 29.63, and 42.33 receptively. Failure mode and crush behavior of hybrid tube were also presented and disused in this paper.

Glasses and/or glass fibers of a new glass system, RE 2 O 3 (RE = Sc,Y, La)-MgO-CaO-Al 2 O 3 -SiO 2 , were studied in detail, covering rare earth (RE) effects on high temperature viscosity, liquidus temperature and crystalline phases, softening and glass transition temperature, and speciation reactions of aluminum (AlO x , x = 4, 5) and silicate network (Q n , n  = 4, 3, 2) using 27 Al and 29 Si MAS NMR and Raman spectroscopic methods. Rare earth oxides (RE 2 O 3 ) were shown to have a dual functionality, i.e., decreasing melt viscosity like a network modifier depolymerizing glass network, but increasing viscosity at low temperature, i.e., glass softening temperature (T soft ) and transition temperature (T g ), strengthening the glass network functioning like Al 2 O 3 . Liquidus temperature (T Liq ) was found to be sensitive to the type of RE 2 O 3 modifications in terms of their ionic field strength (IFS); Sc 3+ of the highest IFS increased, but La 3+ of the lowest IFS decreased T Liq . Effect of Y 3+ (intermediate IFS) on T Liq resembles Sc 3+ only at higher concentration. The overall results suggest that RE ions of different IFS have different “true” solubility limits in the host glass matrix, above which RE 2 Si 2 O 7 crystallizes. All of the glasses with and without RE 2 O 3 contained predominately four-fold coordinated aluminum, AlO 4 ; yet replacement of CaO by RE 2 O 3 increased AlO 5 according to 27 Al MQMAS NMR spectroscopic measurements. Raman spectroscopic results suggested that depolymerization of the silicate network. [ABSTRACT FROM AUTHOR]

Thermal-bonded airlaid nonwoven webs consisting of fiber glass and polyester bicomponent fibers were manufactured, and then multilayer webs were formed into composite panels using compression molding technique. The consolidation process was optimized and the effect of bulk density on air permeabilites, mechanical properties, and thermal resistance was studied. Increasing binder amount and bulk density improved the flexural and tensile strength. Thermal resistance of the panels were found to be very dependent on the bulk density such that the resistance increased exponentially with an initial increase in density, then leveled off and decreased linearly with further increment in density. Depending on the composition and bulk density, the panels provided thermal resistance between 0.52 and 0.88 Km2/W, tensile strength between 2 and 7 MPa, and flexural strength between 600 and 3500 kPa. The findings revealed that airlaid nonwoven panels can be designed to use as structural thermal insulation materials in constructions. [ABSTRACT FROM PUBLISHER]

Pd-Ag nanoparticles with different Pd/Ag ratio were deposited onto fiber glass by using the technique of surface self-propagating thermal synthesis (SSTS) and characterized by X-ray photoelectron spectroscopy (XPS), atomic absorption spectroscopy (ААS), and EXAFS spectroscopy. The samples reduced in hydrogen exhibited the formation of Pd-Ag alloy whose tentative structure and composition were suggested. Thermally scheduled reduction of Pd-Ag catalysts in hydrogen made the Ag atoms partially oxidized. Reported are the catalytic properties of synthesized Pd-Ag samples in selective hydrogenation of acetylene. [ABSTRACT FROM AUTHOR]

Copyright of Revista ADM is the property of Asociacion Dental Mexicana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Forming of fiberglass shells by a winding method for the purpose of detecting the criticalities is analyzed. The quantitative assessments of criticalities are introduced as a finite set of indexes that are the multipurpose criticality functions. The optimal parameters for forming the fiberglass conic shell are found with respect to the criticality criterion. [ABSTRACT FROM AUTHOR]

The study investigates the effects of salt concentration on some mechanical properties of thermoset polyester resin without reinforce and polyester resin reinforced with random fiber glass mat. The volume fraction of the composite material varies in (15%, 25%, 35% and 45%). The two types of material were immersed for (40) days in different salt concentrations ratio (15%, 35% and 55%). The environment consists of salt 99.9% and 0.008% magnesium carbonate and potassium iodide. The study depends on the experimental results of impact test and tensile test to describe the mechanical properties of polyester resin and composite material. It is found that the fracture toughness of composite material increases at approximate ratio of (2.9%) while the polyester resin increases at approximate of (2.25%) due to increasing the salt concentration in water with ratio (40%), so that the fracture toughness increases with approximate ratio (3%) due to increase in the volume fraction ratio from (15%) to (45%). The elastic modulus of composite material increases with ratio of (14.9%) and (90.29%) for polyester due to increase in the salt concentration ratio in the water at approximate ratio of (40%). The elastic modulus increases at ratio of (13.73%) , the yield stress of polyester increase at ratio (50.32%) and yield stress of composite material increases at ratio (55%) as a results of increase in the volume fraction ratio from (15%) to (45%).