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The object of research is modified epoxy composite materials containing fibrous fillers treated in physical fields. The technological features of the development of tribotechnical epoxy composites, which must withstand the effects of elevated temperatures, have been considered. In this case, it is necessary to modify the structure of the epoxy polymer matrix, which is achieved as a result of the introduction of heat-resistant organosilicon varnish. Organosilicon varnishes and chopped fibers contain technological additives, which complicates the process of structuring epoxy composites and leads to the appearance of structural defects. Removal of technological additives and cleaning the surface of the aramid and glass fibers from lubricants is possible as a result of processing the components of the composition in physical fields. There is a need to study the influence of physical fields on the structuring processes of the epoxy system and the formation of the structure of epoxy composites with specified properties. Modified epoxy composites contain chopped aramid and glass fibers treated with ultrasound. The tribotechnical characteristics of epoxy composites were studied at a sliding speed of V=1.0 m/s with a change in specific load from 0.5 MPa to 1.5 MPa. The temperature in the tribocontact zone during frictional interaction rises to 100 °C with an increase in the specific load. An increase in the density of the surface layer of tribocontact of epoxy composites with fillers treated in physical fields was revealed. The practical recommendations have been compiled for the implementation of the treatment technology of components in physical fields, which ensures structuring of epoxy composites with high tribotechnical characteristics. [ABSTRACT FROM AUTHOR]

Objective: To measure the flexural strength (FS) of bulk-fill resin composites and assess their long-term water absorption and solubility properties with and without the inclusion of short glass fibres. Methods: One resin composite, everX Flow with fibres, and four commercially available bulk-fill composites without fibres, namely, PALFIQUE, Activa, SDR Plus, and Filtek Bulk Fill One, were tested. Six specimens (2 × 2 × 25 mm) were fabricated for each material and stored in water for 1 day and 30 days to measure the flexural strength using a three-point bending test. To evaluate water absorption and solubility, circular disks measuring 15 × 2 mm (n = 5) were immersed in water for 60 days, and their weights were recorded periodically. After 60 days, the specimens were dried for an additional 21 days to determine solubility. Results: Flexural strength values ranged from 101.7 to 149.1 MPa. Significant distinctions were observed among the resin composites at the onset of the study (p < 0.05). The highest FS value was identified in everX Flow, while ACT exhibited the lowest (p < 0.05). However, the flexural strength values exhibited a significant decrease with increased storage time (p < 0.05), except for ACT, which demonstrated a noteworthy increase. Concerning water absorption and solubility, ACT displayed the highest absorption, while the range of solubility varied from −0.88 to 5.8 μg/mm3. ACT also had the highest solubility, whereas everX Flow exhibited negative solubility. Significance: The addition of short fibres, along with potential differences in matrix composition, enhanced the flexural strength of everX Flow. However, the substantial reduction in flexural strength observed in everX Flow and SDR following exposure to water corroborates the manufacturers' recommendation to apply a conventional resin composite cap on these materials. [ABSTRACT FROM AUTHOR]

The performance/weight ratio of fiber reinforced polymer matrix composites makes them the material of choice for structural applications in many fields such as aerospace, aeronautics, automotive and civil engineering...etc. In polymer matrix composites, the fibers used as reinforcement are mainly synthetic fibers such as carbon and/or glass fibers. To ensure the low cost of using fiber-reinforced materials in motor vehicles, it is proposed to selectively incorporate carbon fibers to enhance glass fiber composites along the roadway, and to enhance glass fiber composites along the main load path. For this purpose, we conducted a behavioral study of hybrid epoxy thermoset polymer matrix laminates to highlight the influence of alternate hybridization of glass and carbon fibers on the physical-mechanical behavior of the materials.The results obtained show that the alternated hybridation of the fibers has a significant influence on the tensile properties; and it affected the density, hardness and flexural properties significantly. [ABSTRACT FROM AUTHOR]

This work investigates the effects of fibre content, fibre orientation, and frequency on the dynamic behaviour of flax fibre-reinforced polypropylene composites (FFPCs) to improve understanding of the parameters affecting vibration damping in FFPCs. The effects of fibre content and fibre orientation on the mechanical performances of FFPCs, along with fracture characteristics, are also investigated in this study. Laminates of various fibre contents and orientations were manufactured by a vacuum bagging process, and their dynamic and static properties were then obtained using dynamic (dynamic mechanical analysis (DMA) to frequencies of 100 Hz) and various mechanical (tensile and flexural) analyses, respectively. The findings suggest that of all the parameters, fibre orientation has the most significant impact on the damping, and the maximum loss factor (i.e., 4.3–5.5%) is obtained for 45° and 60° fibre orientations. However, there is no significant difference in loss factors among the composites with different fibre contents. The loss factors lie mainly in the range of 4–5.5%, irrespective of the fibre volume fraction, fibre orientation, and frequency. A significant improvement (281 to 953%) in damping is feasible in flax fibre/polypropylene composites relative to more widespread glass/epoxy composites. The mechanical properties of composites are also strongly affected by fibre orientation with respect to the loading direction; for example, the tensile modulus decreases from 20 GPa to 3.45 GPa at an off-axis angle of 30° for a fibre volume fraction of 0.40. The largest mechanical properties (tensile and flexural) are found in the case of 0° fibre orientation. For composites with fibre volume fractions in the range 0.31–0.50, tensile moduli are in the range 16–21 GPa, and tensile strengths are in the range 125–173 MPa, while flexural moduli and strengths are in the ranges 12–15 GPa and 96–121 MPa, respectively, making them suitable for structural applications. The obtained results also suggest that flax fibre composites are comparable to glass fibre composites, especially in terms of specific stiffness. The ESEM analysis confirms the tensile failures of specimens due to fibre debonding, fibre pull-out and breakage, matrix cracking, and inadequate fibre/matrix adhesion. The outcomes from this study indicate that flax fibre-reinforced composite could be a commercially viable material for applications in which noise and vibration are significant issues and where a significant amount of damping is required with a combination of high stiffness and low weight. [ABSTRACT FROM AUTHOR]

High wear rates and frictional coefficients have always been the primary reasons for limiting the service life of critical elements such as pumps, couplings, bushings, bearings and gears. The premature and erratic failures are costing the industries extensive amounts of money every year. Additionally, under severe service conditions, the wear resistance requirements are higher, which greatly hinders the application of neat thermoplastics in different sectors. Hence, it is vital to enhance the tribological characteristics of thermoplastics. The mechanical and tribological properties of Polyamide 6, Thermoplastic Polyurethane, and glass fibre reinforced (GFR) Polyadmide 6 Composites of variable fibre volume fractions were investigated. Pin specimens of Polyamide 6 reinforced with (25%, 33%, and 50%) by volume of fibres were fabricated by an injection moulding process. The specimens were tested for tensile, compression, hardness, and wear under dry abrasive conditions using a pin-on-disc setup. Furthermore, the samples were scanned using micro-computed tomography (micro-CT), and the worn-out samples were analysed using field emission scanning electron microscopy. The experimental results showed that the fibre volume fraction was inversely proportional to the wear resistance of the prepared composite materials. This research will enable the industry partners to supply cutting-edge technologies to the global oil and gas industry that not only minimizes the well running cost but also improves the well resilience. [ABSTRACT FROM AUTHOR]

In this work, basalt fibers (BF) have been investigated as possible natural and sustainable replacements for the common synthetic mineral filler—glass fibers (GF)—used in polyamide 66 matrix (PA66). Composites have been prepared at two different fiber concentrations (15 and 25 wt.%, respectively) by melt blending. The developed systems have been mainly characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), capillary rheology, and scanning electron microscopy (SEM). The kinetic parameters to thermal degradation through the Coats–Redfern method allowed us to attest a negligible effect of fiber type on thermal stability of the developed systems. Composites incorporating 15 wt.% of fiber content possessed the highest activation energy (≥230 kJ/mol). The introduction of BF and GF in PA 66 polymer, regardless of content, always led to an increase in crystallization and melting temperatures, and to a similar reduction in crystallinity degree and glass transition temperature. The shear viscosity of the basic polymer increased by the addition of fillers, particularly at low shear rate, with a pronounced effect in the case of basal fibers. A slightly higher shear thinning behavior of BF/PA66 with respect to GF/PA66 composites was confirmed by fitting the flow curves through the power law model. Finally, a worsening in fiber dispersion, by increasing the content in the matrix, and a weak compatibility between the two phases constituting the materials were highlighted through SEM micrographs. [ABSTRACT FROM AUTHOR]

Bumpers are essential components that shield passenger cars from slow-speed collisions. Automobiles have them mounted on the front and rear ends. It is believed that bumpers would be crucial in avoiding or restricting damage to automobiles. Various composite material combinations are being researched when a car frontal accident occurs in light of the impact requirements. By comparing it to the parent material, the unique hybrid fibre-metal laminate production clarifies problems such as deformation and stress. This research focuses on identifying the hybrid material composed of basalt fibre with aluminium and glass fibre combinations, inducing it with the properties of the existing parent material and fusing it together to form a laminated composite. It also focuses on identifying its specific features and mapping them with those of the existing ones. This project's peculiarity strives to give the best bumper with a range of deformation between 0.017378 m and 0.03114 m for the 38 MPa tensile strength with a maximum stress prediction of 2.424 × 102 MPa that shows advantageous in day-to-day operations, and this is done by comparing simulation results. [ABSTRACT FROM AUTHOR]

The application of pultruded fiber reinforced polymer (FRP) composites in civil engineering is increasing as a high-performance structural element or reinforcing material for rehabilitation purposes. The advantageous aspects of the pultrusion production technique and the weaknesses arising from the 0° fiber orientation in the drawing direction should be considered. In this direction, it is thought that the structural performance of the profiles produced by the pultrusion technique can be increased with 90° windings by using different fiber types. This paper presents experimental studies on the effect of FRP composite wrapping on the flexure performance of reinforced concrete (RC) filled pultruded glass-FRP (GFRP) profile hybrid beams with damage analysis. The hybrid beams are wrapped fully and partially with Glass fiber reinforced polymer (GFRP) and carbon fiber reinforced polymer (CFRP) composites. Hybrid beam specimens with 0° to 90° fiber orientations were tested under three- and four-point bending loads. Based on the experimental load–displacement relationship results, initial stiffness, ductility, and energy dissipation capacity were compared. The experimental findings revealed that the maximum load-carrying capacities of beams produced with pultrude profiles increased by 24% with glass wrapping and 64.4% with carbon wrapping due to the change in the damages. A detailed damage analysis is provided. Similarly, significant increases were observed in structural performance ratios such as initial stiffness and ductility ratio. [ABSTRACT FROM AUTHOR]

As basalt fiber has better mechanical properties and stability than glass fiber, cross arms made of continuous basalt-fiber-reinforced epoxy matrix composites are capable of meeting the mechanical requirements in the event of typhoons and broken lines in coastal areas, mountainous areas and other special areas. In this paper, continuous basalt-fiber-reinforced epoxy matrix composites were used to fabricate the core rods and composite cross arms. The results verified that basalt fiber composite cross arms can meet the strict requirements of transmission lines in terms of quality and reliability. In addition to high electrical insulation performance, the flexural modulus and the flexural strength of basalt fiber core rods are 1.8 and 1.06 times those of glass fiber core rods, respectively. Basalt fiber core rods were found to be much better load-bearing components compared to glass fiber core rods. However, the leakage current and the result of scanning electron microscopy (SEM) analysis reveal that the interface bonding strength between basalt fibers and the matrix resin is weak. A 3D reconstruction of micro-CT indicates that the volume of pores inside basalt fiber core rods accounts for 0.0048% of the total volume, which is greater than the 0.0042% of glass fiber rods. Therefore, improving the interface bond between basalt fibers and the resin can further improve the properties of basalt fiber core rods. [ABSTRACT FROM AUTHOR]

The main objective of this study is to better understand the performance changes of naturally aged glass fiber-reinforced concrete (GFRC) and polypropylene fiber-reinforced concrete (PPFRC), especially the degradation of fibers, which is of great significance for evaluating the durability of structures using these two types of composite materials. The mechanical properties, water absorption, and microstructures of GFRC and PPFRC at a curing age of three years, including their compressive strength, full curves of water absorption, fiber-matrix interaction, and fiber degradation, were systematically studied, and the related properties were compared with those at the curing age of 28 days. The degradation of fibers after freeze-thaw cycles was also studied. The results revealed the following. The water/binder ratio (w/b) affects the rate of increase of the long-term compressive strength of naturally aged concrete. In general, the water absorption of fiber-reinforced concrete (FRC) at the curing age of three years was found to be significantly reduced, but with the increases of w/b and the fiber content to the maximum values, the water absorption of the specimens cured for three years was higher than that of the specimens cured for 28 days. Moreover, with the increase of the curing age, the optimal glass fiber (GF) contents for reducing the water absorption decreased from 1.35% to 0.90% (w/b = 0.30), and from 0.90% to 0.45% (w/b = 0.35), respectively. The GF surface was degraded into continuous pits with diameters of about 200 to 600 nm, and the surface of the pits was attached with spherical granular C-S-H gel products with diameters of about 30 to 44 nm. The freeze-thaw cycles were found to have no significant effect on the pits on the GF surface and the granular C-S-H gel products attached to the pits, but caused a portion of the cement matrix covering the GF to fall off. The interfacial bonding between the polypropylene fiber (PPF) and the cement matrix exhibited almost no change in the PPFRC after three years of curing as compared with that after 28 days of curing. Furthermore, the cement hydration gel on the PPF surface was not significantly damaged by 150 freeze-thaw cycles. [ABSTRACT FROM AUTHOR]

Novel fibre/powder (glass fibre (GF)-fumed silica (FS)) composite core materials with different fibre to powder ratios were prepared by wet papermaking process. The composite core materials and corresponding vacuum insulation panel (VIP) samples were characterised to obtain an insight into their microstructure, tensile strength, uniformity and thermal conductivity. The results show that the addition of fumed silica will alter the pore structure of the glass fibre core material, and reduce the average pore size, pore volume and porosity of the core material. Moreover, addition of fumed silica can increase the tensile strength of the core material to a certain extent, but it will diminish the uniformity. Further investigation conclusively shows that the addition of fumed silica has little effect on the thermal conductivity of VIP in low vacuum, but the thermal conductivity of VIP is significantly reduced with the increase of fumed silica content in high vacuum. Compared to glass fibre core VIP, the thermal conductivity of fiber/powder composite core VIP is more stable and the service life would be longer. [ABSTRACT FROM AUTHOR]

Continuous glass fiber reinforced polylactic acid (CGF/PLA) composites were prepared by 3D printing technology in this study. The multi‐roll melt impregnation mold was manufactured according to the melt impregnation model. CGF/PLA filament was prepared by a melt impregnation device, and then used to prepare CGF/PLA composite materials by the self‐modified 3D printer device. The full impregnation of the fibers was achieved by the action of the coverage angle of the tension roller in the impregnation mold. The effects of the total coverage angle, traction speed, fiber content, and impregnation temperature on the fiber impregnation effect and 3D printed product performance were studied. The bending strength, tensile strength, impact strength, and interlayer shear strength of the printed sample reached 312, 220, 154, and 14 MPa, respectively. The strategy in this study can effectively improve the impregnation effect of PLA resin on CGFs and promote the development and application of 3D printing technology in the field of high‐performance composite manufacturing. [ABSTRACT FROM AUTHOR]

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Increasing environmental concern has put forward the use of flax fibers instead of glass fibers in composite materials. However, durability performances of these bio-fibers remain one of their main issues. This study focuses on the hydrothermal aging of flax fibers. Flax tows were immersed in distilled water at a temperature of 80 °C for different durations. The effect of the hydrothermal aging on mechanical properties of flax tows was evaluated. Results showed a strong decrease in the maximal strength and the stiffness by 31% and 49%, respectively, until one week of aging. Multi-scale analyses were realized to explain these evolutions. Morphological characterization highlighted a washing of fiber surfaces during the hydrothermal aging, extracting amorphous components as pectins, lignins and amorphous hemicelluloses from cortical tissues. We showed that this morphological evolution impacted the fiber crystallinity. Based on a mechanical analysis, we showed that amorphous components extraction may be at the origin of the material softening. Moreover, the amorphous phase in particular the natural binder pectin would play a major role in the fiber stiffness but does not modify the flaws at the origin of failure. [ABSTRACT FROM AUTHOR]

Asource of waste post-industrial continuous glass fiber reinforced polypropylene (PP/GF) tape was investigated by means of thermo-mechanical recycling into long fiber thermoplastic (LFT) composite material. The glass fiber content was initially 70 wt.% in the tape and diluted to 40 wt.% in the LFT. Different approaches were investigated to reduce the size of the material into processable dimensions while retaining the quality of the fibers. The resulting flakes were melt-processed and the mechanical behavior determined. Competitive mechanical performance was obtained in terms of stiffness, strength and toughness compared to commercial reference materials made of long fibers. [ABSTRACT FROM AUTHOR]

The deposition of steel powders on glass fiber reinforced polymer (GFRP) with the Cold Spray technique is investigated. Metallization of composite materials is still challenging when high-strength and dense powders, such as steel, are used due to excessive erosion of the polymer or disruption of the fibers during the deposition. To overcome these issues, low-pressure cold spray equipment has been used for the experimental campaign shown in this paper. Different coatings were obtained by using nitrogen as the carrier gas and different sets of pressure and standoff distance. Optimization of the process parameters, including the stratification of the laminate, has been carried out. Results of an initial study of the feasibility of the process and the influence of the different chosen spray conditions are exposed. In particular, the bonding mechanisms of steel powders and their morphology are discussed. [ABSTRACT FROM AUTHOR]

Fiber Reinforced Polymer (FRP) composites may be successfully used in numerous structural strengthening applications. One of these applications is as a confining material for reinforced concrete structural elements. Research has shown its effectiveness both in seismic retrofit of existing reinforced concrete columns as well as in new construction of concretefilled composite tubes as earthquake-resistant columns. Several researchers have conducted experiments and introduced analytical models, mostly empirical, fitted with relatively limited experimental data. These models can be used to predict the confined concrete strength of cylindrical specimens. In this article, a series of twelve analytical models are evaluated using a quite extensive experimental database. The database includes a total of 639 cylindrical concrete specimens confined with carbon or glass fibers. The evaluation of each model's performance was carried out using novel statistical methods. Generally, it was observed that the type of the fibers used does affect the analytical model's prediction accuracy. In general, newer models have higher efficacy compared to older ones, and the equations suggested by the Eurocodes provide safe design tools regardless of unconfined compressive concrete strength and type of confining material. Moreover, using this extended database an empirical model was developed, and its performance compared to that of the twelve models. The results indicate that the simple proposed model exhibits excellent all-around performance. [ABSTRACT FROM AUTHOR]

Surface defects cause the measured tensile strength of alkali glass fibers to be significantly lower than their theoretical values. Coatings can be used to “heal” surface flaws and to modify surface properties. In the present work, the nanocoating on alkali-resistant glass (ARG) fiber rovings was carried out by self-assembled monolayers (SAMs) of octadecyltrichlorosilane (OTS). The ARG roving was dipped into OTS nanosol, which deposited the organic–inorganic SAMs of OTS on the ARG surface. The assessment of changes in the fiber surfaces was characterized by scanning electron microscopy (SEM) and fluorescence microscopy, while the chemical changes were characterized by X-ray photoelectron spectroscopy (XPS). Furthermore, the influence of nanocoating on the tensile properties of ARG and OTS-treated ARG with and without an epoxy matrix was also studied. The SEM analysis revealed the formation of nanoscale layers on the ARG surfaces and the XPS confirmed the deposition of organic–inorganic monolayers. The tensile strength of ARG rovings with and without the epoxy matrix was improved significantly. The OTS treatment almost created a superhydrophobic nanocoating on ARG, which was confirmed by the sessile drop water contact angle, and the water absorption by the ARG/epoxy composites reduced. [ABSTRACT FROM AUTHOR]

Glass fiber-reinforced polypropylene composites often replace the conventional materials due to their special or unique mechanical properties. As the applications of these composites increase for a number of industries, drilling of these composites is inevitable for subsequent composite product manufacturing stage. In the drilling of composites, the thrust force is induced during the drilling operation; as a result, it causes damage. This damage is characterized by the delamination factor, which depends on the machining parameters such as speed of the spindle, feed rate, and drill diameter. The study on the delamination in the drilling of glass fiber-reinforced polypropylene is limited and has been carried out comprehensively. The effect of machining parameters on delamination in the drilling of glass fiber-strengthened polypropylene (GFR-PP) composites is studied through the Box–Bhenken design. Response surface method, along with the desirability analysis, is used for modeling and optimization of delamination factor in the drilling. The result proves that the models are effectively used to forecast the delamination in the drilling of GFR-PP composites. Also, the result indicates that the foremost issue that influences the delamination is the feed rate. [ABSTRACT FROM AUTHOR]

[Display omitted] • Screw pine fiber was hybridized with the glass fiber in vinyl ester resin matrix. • Preparation of dispersed and skin core composite by a simple rule of mixture. • Evaluation of shear strength based on the fiber volume fraction. • The vol.% of both the Screw pine and glass fiber plays an important role. • Glass fiber contributes to the improvement of shear property of composite. To evaluate the shear property, screw pine fibers are hybridized with glass fibers in a vinyl ester resin matrix. Two types of screw pine/glass fiber reinforced vinyl ester hybrid composites were created (dispersed and skin-core). A hydraulic compression molding method was used to create composites with a total fiber loading of 35.12 vol%. The shear property of composites was evaluated based on their form. After tests, scanning electron microscopy was used to conduct fractographic studies on the fracture surface of the hybrid composite specimen. Furthermore, neat resin samples and Screw pine alone composites were prepared and tested for comparison. The results revealed that the addition of glass fiber increased the shear property of composites. In both types of composites, the composite with 18.59 vol% Screw pine fibers and 16.53 vol% glass fibers has a high level of shear property. However, the skin-core type composites outperformed the dispersed type composites. [ABSTRACT FROM AUTHOR]

ABSTRACT Chicken feather fibers (CFFs) have potential application in light weight composites. We investigated the physical properties of epoxy polymer composites reinforced with CFFs and glass fibers. CFFs or hybrid fiber (glass fiber and CFFs) composites reduced the density upto 30-40% when compared with glass fiber reinforced composites. The CFF composites has a storage modulus of about 3.5 GPa and a flexural strength of about 50-80 MPa. The hybrid fiber composite has better mechanical properties than CFF composites while having increased bio-based content. This study demonstrated a new way to utilize CFFs. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44013. [ABSTRACT FROM AUTHOR]

The dynamic response of open-ended cylindrical glass fiber composite shells subjected to internal blast loading is studied in the current paper. The experimental observation on response characteristics of cylindrical glass fiber shells is presented, in which failure modes of composite structures are especially concerned. It is found that dynamic buckling may occur in the inner steel liner, which may consequently cause delamination and fiber fracture of the outer glass fiber shell and thus limits the blast loading resistant capability of glass fiber explosion containment vessels. The other failure mode is obvious circular plastic expansion of the inner steel liner and fiber fracture of the outer fiber shell. There exists an interesting case that hoop winding fibers fail but fibers with a winding angle do not fail, based on which the hybrid filament wound method for cylindrical composite containment vessels is proposed. The current study may contribute to further understanding on the design and application of glass fiber composite explosion containment vessels (CECVs). [ABSTRACT FROM AUTHOR]

This paper explores the fracture properties of a novel and sustainable glass-fiber reinforced composite, the matrix for which is formed through the aqueous, anoxic, room-temperature carbonation of (waste) metallic iron powder along with other minor ingredients. A comparison of the properties of this binder with Ordinary Portland Cement pastes, which constitutes one of the most common and economic ceramic matrices is also provided. The iron-based binder system exhibits fracture parameters (fracture toughness, K IC S and critical crack tip opening displacement, CTOD C , determined using two parameter fracture model, TPFM) that are significantly higher when compared to those of the OPC systems in both the unreinforced and glass fiber reinforced states. The beneficial influence of the unreacted metallic iron particles of large aspect ratio, on the fracture parameters of iron-based binders are elucidated. The strain energy release rates show trends that are in line with the fracture parameters from TPFM. The elastic and inelastic components of strain energy release rate are separated in an effort to capture the fundamental toughening mechanisms in these systems. The fracture parameters determined using a non-contact, digital image correlation technique are found to relate well to those obtained from TPFM. [ABSTRACT FROM AUTHOR]

ABSTRACT The focus of this study is to experimentally investigate the mechanical properties of fiberglass reinforced composite with various aspect ratios and loading fractions in the quasi-static and low-velocity impact loading conditions. In this study, short fiberglass reinforced polycarbonate composite materials were fabricated via a solution mixing method and characterized for their tensile properties by varying both fiberglass loading fraction and aspect ratio. The tensile properties including tensile toughness of the fiberglass reinforced composites were characterized and compared. It was observed in this study that the toughness of the composite was dramatically improved whereas the tensile strength and Young's modulus were moderately enhanced over the neat polymer, which were measured to be only up to 15% and 70% increase, respectively. The low-velocity impact behaviors of the fiberglass composites were also investigated and compared to the tensile toughness of the corresponding composites. Besides, the effect of thickness on their low-velocity impact properties was investigated. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40821. [ABSTRACT FROM AUTHOR]

ABSTRACT A semicrystalline copolyimide derived from 3,3′,4,4′-biphenyltetracarboxylic dianhydride ( s-BPDA), 1,3-bis-(4-aminophenoxy)benzene (TPER), and 4,4′-oxydianiline (4,4′-ODA), end capped with phthalic anhydride (PA), was synthesized. Glass fiber reinforced composite was also prepared by impregnating powdery glass fiber with poly(amic acid) followed by solution imidization techniques. This copolyimide displayed a glass transition temperature of 202°C and a melting temperature of 373°C by differential scanning colorimeter (DSC). Crystallization and melting behaviors were investigated under nonisothermal and isothermal crystallization conditions. Double exothermic peaks were found by DSC when the copolyimide was cooled from the melt and multiple melting behaviors can be observed after the coployimide had been isothermally crystallized at different temperatures. Mechanical properties were investigated by dynamical mechanical analysis (DMA) and tensile experiments. The samples were cured at different temperatures and then tested at different temperatures. Results indicated that the copolyimide and the composite showed excellent mechanical properties. Additionally, this copolyimide also showed lower melt viscosity by rheological analysis. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40345. [ABSTRACT FROM AUTHOR]

The aim of this study was to obtain and investigate new biomedical glass fiber resin cements with improved mechanical properties and radiopacity, using alkaline-resistant (AR) glass fibers. New light-curing, self-curing, and dual-curing resin cements were obtained from AR glass fibers and BaSO4 powder mixed with 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)-phenyl]propane and triethyleneglycol dimethacrylate monomers at different weight ratios, such as 5/20/75, 10/20/70, 20/20/60. The newly obtained cements were investigated for mechanical properties-compressive yield strength (CYS), compressive modulus (CM), diametral tensile strength (DTS)-as well as for radiopacity. Slight increases in CYS, CM, DTS and improved radiopacity with increasing amount of glass fibers were observed. The mechanical properties were found to increase in the order light-curing < self-curing < dual-curing. SEM images support the reinforcement of resin cements by glass fibers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

The compressive property of a single basalt fiber in basalt/epoxy and basalt/PCBT composite was investigated by nano-indentation with the application of conical-pyramidal Berkovich tip. The nano-indentation test involved a load from 30 mn to 200 mn. Every indent was produced on section of a single fiber. Area function was selected according to the depth of the indent. The results showed that compressive modulus and hardness of basalt fiber is higher than those of glass fiber and carbon fiber in the same matrix. The modulus of basalt fiber behave differently when embed in different matrixes. [ABSTRACT FROM AUTHOR]

We investigated the mechanical and physical characteristics of composites composed of polyacetal alternatively called polyoxymethylenePOM and cellulose fiber CelF derived from wood pulp 10–52 wt 9.3–50.1 vol without any fiber surface treatment. The modulus, deflection temperature under load, and thermal conduction coefficient of the POMCelF composites were effectively enhanced with increasing CelF content, and the composites had an advantage of specific modulus compared to glass fiber GFfilled POM. The flexural modulus of POMCelF 40 wt 38.2 vol was measured to be about 6 GPa, which was comparable to that of POMGF 20 wt 12.1 vol . In the composites, the CelFs were distributed randomly as monofilaments, and the debonding of the interface between the fibers and POM matrices in the fracture faces was confirmed as less by scanning electron microscopy observation. The POMCelF composites possessed lower specific wear rates than the POMGF composites, and they had damping behaviors near that of neat POM. No clear dependence of the melt flow index of the base POM on these characteristics was observed, except on Charpy impact strength. The composites studied here were unique in their performance and ability to be designed in accordance with specific demands, and they could be potential replacements for mineralfilled and GFfilled POM composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [ABSTRACT FROM AUTHOR]

To research the relationship between epoxy and fiber inherent property and mechanical properties of composite, we prepared a series of composites using three kinds of high mechanical performance epoxy resins as matrices and reinforced by the same volume fraction (5%) of short carbon and glass fiber. Their mechanical properties were investigated from the perspective of chemical structure and volume shrinkage ratio of epoxy. We analyzed their tensile strength and modulus based on the mixing rule and Halpin-Tsai equation, respectively, and studied the morphology of impact test samples by scanning electron microscope. The results show that chemical bonds formed between matrix and fiber are the most important factor to improve the mechanical properties of composite. High volume shrinkage ratio is also helpful when the fiber surface was coarse. Otherwise, the tensile strength is more sensitive to interface than the tensile modulus. It is concluded that the mechanical properties of composite are strongly affected by the chemical structure of epoxy resin, the volume shrinkage ratio of cured matrices, and properties of fiber surface. [ABSTRACT FROM AUTHOR]

A comparative quantitative life cycle assessment (LCA) should consider the eight environmental impact classification factors listed in ISO/TR 14047:2003. This paper reports on the energy requirement for production of flax fibers to be used as reinforcement in composite materials. Data are compiled from a number of published sources. Only 5% of the harvested plant mass is converted into long fibers, while the other 95% could be regarded as waste; the respective coproducts (short fiber for paper manufacture, shives for animal bedding, and dust for fuel) can be collected, processed, packaged, and sold. The analysis here assumes that these coproducts are disposed of at a cost that covers the postseparation handling and hence they are not included in the flax burdens. The analysis suggests that sliver (postcarding fiber) has an embodied energy comparable to glass fiber reinforcement mat at approximately 55 GJ/tonne. Spinning fibers to produce yarn for weaving dominates the embodied energy. In the event that best agricultural practice is taken into account, and that some energy usage is apportioned to coproduct, then the claim that flax is a sustainable “green” alternative may be justified for random mat reinforcement. If the fiber is spun to yarn, then the embodied energy for flax exceeds that of the glass fiber equivalent. [ABSTRACT FROM AUTHOR]

The new requirements in different sectors, such as aerospace, automotive and construction, for lightweight materials have led to an increase in demand for composite materials suitable for use in high rate production processes, such as plastic injection. This makes it necessary to look for matrices and reinforcements that, in addition to being compatible with each other, are also compatible with the injection process. It is in this area of research where the work presented here arises. To meet the two requirements mentioned above, this study contemplates a battery of composite materials obtained by combining PA66 and fiberglass, in different proportions and configuration, both for the preparation of the matrix and for reinforcement. For the elaboration of the matrix, two options have been evaluated, PA66 and PA66 reinforced at 35% with short glass fibre. To obtain reinforcement, six different options have been evaluated; two conventional fiberglass fabrics (each with different density) and four hybrid fabrics obtained from the previous ones by adding PA66 in different configurations (two over-stitched fabrics and two other fabrics). The different composite materials obtained were validated by means of the corresponding adhesion, peeling and resistance tests. [ABSTRACT FROM AUTHOR]

Abstract: This study evaluated the effects of synthetic and steel fibers on the bond properties of high-strength concrete and fiber-reinforced polymer (FRP) reinforcing bars. Direct bond tests were performed to evaluate the bond performance of 9-mm-∅ carbon fiber-reinforced polymer (CFRP) and 13-mm-∅ glass fiber-reinforced polymer (GFRP) reinforcing bars in three types of high-strength concrete with varying amounts of steel (20 and 40kg/m3) or synthetic (4.55 and 9.1kg/m3) fiber. The bond strength increased with the compressive strength of the high-strength concrete. The type and amount of fiber also affected the bond strength. The specimens with 40kg/m3 steel fiber had the highest bond strength. The larger FRP bars tended to have stronger bonds, regardless of the strength of the concrete and type or amount of fiber. The relative bond strength was determined to analyze the effect of the type and amount of fiber; it increased as more fiber was added. Overall, the specimens with 40kg/m3 steel fiber had the best bond performance. [Copyright &y& Elsevier]

Abstract: A model simulating the tensile behavior of fabric–cement composites is presented to relate the properties of the matrix, fabric, interface and the damage parameters to the overall mechanical response of the composites. Crack spacing parameters measured during tensile tests are used to define the damage parameters, and related to the stiffness degradation as a function of the applied strain. This procedure is integrated in composite laminate theory using an incremental approach to model the uniaxial tensile response. Two approaches of linear and nonlinear fabric bridging models are used. The model is capable of using interface parameters for different fabrics, matrix properties, and processing parameters. Simulation results are studied by means of parametric simulation and a validation of a variety of experimental observations which vary the matrix formulation with flyash, changes in pressure after casting, and fabric type. [Copyright &y& Elsevier]

Mechanical fatigue response of fiber-reinforced polymeric (FRP) composites is essential to better understand the durability of composite materials systems and to develop design specifications. Currently, the fatigue response of multi-directional glass composite materials is not well-understood and much needs to be done to understand their behavior under fatigue loading. In this study, three glass fabric FRP composite material coupons and systems are tested at constant low-amplitude fatigue loading. Experimental results show that for a given FRP material and load configuration, the energy loss per cycle due to fatigue damage is linear from about 10-90% of the fatigue life of the FRP composite material. The energy loss per cycle is determined to be a characteristic value of the constituent materials, and is found to vary with the induced fatigue strain levels by a power law. Based on the experimental results, a fatigue life prediction model is proposed, with internal strain energy as damage metric, to predict the useful life of FRP composites. The experimental and predicted fatigue lives at various strain levels are compared (S-N curves) and the model is found to be conservative. [ABSTRACT FROM AUTHOR]

The static and dynamic mechanical properties of banana and glass woven fabric-reinforced polyester composites have been determined with special reference to the effect of fiber volume fraction, layering pattern, and the weaving architecture. Even though articles related to natural fiber composites are abundant in the literature, work on natural fiber textile composites is found to be rare. Composites with high tensile strength can be obtained using banana and glass in the fabric form, using two layers of the fabric. The impact strength of the composites increases with the number of layers and the fiber volume fraction. By incorporating the fabric, the G′ curve shows an improved rubbery plateau indicating that the incorporation of the fabric induces reinforcing effects in the polyester matrix. The storage modulus has been found to be the highest for composites with four layers of the fabric. In all the composite samples, the relaxation peak of polyester is visible as peak in G″ at about 98°C. In the case of composites with four layers of the fabric, two peaks and one shoulder are seen. Increase in the number of layers made a second relaxation peak visible. The damping peaks have been found to be lowered by the incorporation of more number of layers. [ABSTRACT FROM AUTHOR]

The mechanical properties of composites based on different natural fibers and glass fibers using unsaturated polyester and modified acrylic as matrix are evaluated. In spite of the several works done in natural fiber composites, there are very few results on acrylic as matrix. Fabrication of the composites is done by means of vacuum infusion. Flexural, tension, and impact test are conducted on the composites. Ignition, thermal degradation, and water absorption are determined. Jute composite with unsaturated polyester resin as matrix showed the best results on flexural and tensile strengths and the lowest in impact energy, because of the strong interphase developed. Flax composites show higher impact energy than the other natural fiber composites, due to the existence of the effective energy dissipation mechanisms, like pull-out and axial splitting of the fibers. Scanning electron micrograph confirmed this fact. None of the samples resisted the five-second exposition to the flame on the ignition test. All of them were completely consumed, and flax composites burned the longest. [ABSTRACT FROM AUTHOR]

The mechanical behavior of multilayer satin-weave glass fabric-reinforced plastics under elastic deformation is investigated. Different experimental procedures for determining elastic characteristics of composite materials are analyzed. The effect of material cooling down to 77 K on its mechanical behavior is examined. [ABSTRACT FROM AUTHOR]

A new nondimensional number (η) to predict the dominant failure mechanism of fiber reinforced composites under compression loading is presented. Results from previous experimental investigations on the failure of glass fiber reinforced and carbon fiber reinforced vinylester matrix composites, respectively, were used to motivate and develop η. Experimental results available in the open literature are used to compare the predictions of η. This number can be used as a design tool to develop new composite materials with a preferred failure mode. The exercise of developing such a number provides insight into parameters that control the compressive strength of fiber reinforced composite materials. [ABSTRACT FROM AUTHOR]

Composite materials based on polycaprolactone reinforced with long glass fibres were prepared by using two processing technologies: continuous melt impregnation (extrusion/calendering) and film stacking. The effect of processing variables on the impregnation of glass fibres was studied, modelled and correlated to the mechanical properties of the composites. Materials prepared by using the calendering technology showed different mechanical properties depending on melt temperature, roll temperature and the speed of rotation. The fibre impregnation obtained by using the film stacking process was correlated to the moulding temperature and to the viscosity of the polymeric matrix. [Copyright &y& Elsevier]

Abstract: In a composite ecodesign approach, flax fibers could be good candidates for glass fiber substitution. However, their use in industrial applications could be restricted due to their scattered mechanical properties. In this study, we compared tensile properties of 50 batches of flax (Linum usitatissimum) fibers, cultivated in France between 1993 and 2011. Thus, 2954 fibers were tested in the same conditions according to the XP T 25-501-2 standard. Reliable specific data are suggested to be a basis for design calculation. [Copyright &y& Elsevier]

The use of fiber-reinforced polymer (FRP) composite materials are continuously growing in civil infrastructure due to their high strength, low weight, and manufacturing flexibility. However, FRP is characterized by sudden failure and lacks ductility. When used in construction, gradual failure of FRP components is desired to avoid catastrophic structural collapse. Due to its mechanical orthotropy, the behavior of FRP relies significantly on fiber orientation and stacking sequence. In this paper, a novel multi-angled glass fiber reinforced polymer (GFRP) composite laminate showing pseudo ductile behavior is produced using 3D-printing. This is accomplished by varying fiber orientation angles, stacking sequence, and thickness of lamina. Single-angled GFRP composite specimens were 3D-printed with different fiber orientation angles of 0°, 12°, 24°, 30°, 45°, and 90° using continuous and fused filament techniques. The tension test results of the single-angled specimens were then used to aid the design of multi-angled laminate for potential progressive failure behavior. A 3D finite element (FE) model was developed to predict the response of the experimental results and to provide insight into the failure mechanism of the multi-angled laminate. The experimental observations and the FE simulations show the possibility of producing pseudo ductile FRP-by-design composite using 3D-printing technology, which leads the way to fabricate next-generation composites for civil infrastructure. [ABSTRACT FROM AUTHOR]

The polyamide-based composite materials are widely employed in various industrial domains. Along with the numerous advantages of these engineering materials, an important sensitivity to hygrothermal conditions represents a major drawback. Hence, this study aims to thoroughly evaluate the variation of physical and mechanical properties in moist and thermal environments of three stacking sequences. An extensive tensile testing campaign is performed in order to create a rich experimental database. It is therefore preceded by a proper establishment of desiccation/absorption protocol for the composite material. The results demonstrate that the humid ageing parameters are highly affected by the temperature. The mechanical response is dependent on the glass transition temperature, or T g - T criterion, due to the occurring material plasticisation as a result of absorbed moisture. The shear modulus, the shear yield stress and strength deteriorate with the increase of temperature and moisture content. The changes of properties for the longitudinal and transversal orientations are not considerably pronounced. [ABSTRACT FROM AUTHOR]

Glass fiber/polyimide aerogel composites are prepared by adding glass fiber mat to a polyimide sol derived from diamine, 4,4′‐oxydianiline, p‐phenylene diamine, and dianhydride, 3,3′,4,4′‐biphenyltetracarboxylic dianhydride. The fiber felt acts as a skeleton for support and shaping, reduces aerogel shrinkage during the preparation process, and improves the mechanical strength and thermal stability of the composite materials. These composites possess a mesoporous structure with densities as low as 0.143–0.177 g cm−3, with the glass fiber functioning to improve the overall mechanical properties of the polyimide aerogel, which results in its Young's modulus increasing from 42.7 to 113.5 MPa. These composites are found to retain their structure after heating at 500 °C, in contrast to pure aerogels which decompose into shrunken ball‐like structures. These composites maintain their thermal stability in air and N2 atmospheres, exhibiting a low thermal conductivity range of 0.023 to 0.029 W m−1 K−1 at room temperature and 0.057to 0.082 W m−1 K−1 at 500 °C. The high mechanical strengths, excellent thermal stabilities, and low thermal conductivities of these aerogel composites should ensure that they are potentially useful materials for insulation applications at high temperature. [ABSTRACT FROM AUTHOR]