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To investigate the real anchorage performance of basalt and glass hybrid fiber reinforced plastic (FRP) anchors in external corrosive environments. In this paper, a combination of experimental studies and finite element analysis was used. By carrying out pull‐out tests of basalt and glass hybrid FRP anchors under the synergistic effect of freeze–thaw cycles and alkaline environment, the effects of factors such as hole diameter, anchorage length, and mortar strength on their anchorage performance and durability were investigated. Critical corrosion time was introduced to determine the degree of corrosion of the anchor rods. After that, it combined with numerical simulation to reveal the degradation mechanism of the anchorage performance of hybrid anchors. The results showed that the best anchorage performance of basalt/glass hybrid FRP anchors was achieved when the hole diameter was 24 mm, the anchorage length was 175 mm, and the mortar strength was 45.5 MPa. The ultimate pull‐out load was up to 122.16 kN. When the time did not exceed the critical corrosion time, the ultimate load‐carrying capacity of basalt and glass hybrid FRP anchors increased by 9.3% compared to the uncorroded environment. Beyond the critical corrosion time, the ultimate load‐carrying capacity was reduced by 23.3% and the anchorage performance was degraded. In addition, the contact interface between the anchor and the mortar is the weak area of the anchoring structure, which should be focused on in the later design of the actual project. Highlights: Basalt/glass hybrid FRP anchors have good corrosion resistance.The anchoring performance of hybrid FRP anchors under the coupled environment is studied.Hole diameter and anchoring length have more influence on the anchor performance.The concept of critical corrosion time is put forward.The failure mechanism and coupling environment influence are revealed by FES. [ABSTRACT FROM AUTHOR]

Nowadays, additive manufacturing techniques such as the Fused Filament Fabrication appear to be among the most promising methods for enabling modern industry to produce components of high geometrical complexity. The main characteristic of this method is the deposition of thermoplastic polymers that can be further reinforced with chopped and/or continuous fibers that attribute to the product some unique structural characteristics. Nevertheless, the process is susceptible to a variety of defects that are derived from the fabrication process parameters, such as porosity, insufficient fiber impregnation with the polymer and fiber disorientation. On the other hand, since the applicability of the process depends on the development of numerical tools for assessing the effects of these defects, the accurate detection and quantification of them is a crucial part of it. In the present work, these defects are studied experimentally by implementing an X-ray computed tomography testing campaign. The manufacturing defects are identified using well-established techniques while a complete analysis of the distribution of porosity is presented for various zones of Onyx, Onyx/Carbon and Onyx/Glass fiber reinforced structures. Finally, the tendency of the overall pore content to increase with increasing number of continuous fiber reinforcement was identified as well as porosity variations in printing direction are presented. [ABSTRACT FROM AUTHOR]

In the current study, the effect of adding the encapsulated healing agent with neat polymeric and nanocomposite shells on the mechanical‐healing features of glass fibers/epoxy composite under various loads was investigated. Therefore, the microcapsules with urea‐formaldehyde (UF) nanocomposite shell containing the various weight fraction of silica nanoparticles (0, 1, 2, 3) were synthesized. After that, the flexural, tensile, and interlaminar shear strength (ILSS) samples were destructed by using the quasi‐static penetration method with the damaging force of 500, 1050, and 2900 N, respectively. The maximum healing efficiency in the flexural loads belonged to the composite with the 3 wt% nanosilica on the surface of microcapsules, which was 83.9%. Also, it was found the increment in the weight fraction of silica nanoparticles had a negligible effect on the healing ability of composite under tensile loading. Achieving 135.8% healing efficiency in the composite with the 2 wt% nanosilica under the shear loads can be one of the most important findings in this work. [ABSTRACT FROM AUTHOR]

In recent years, glass‐fiber‐reinforced plastic (GFRP) applications have expanded. This study elucidates the fatigue fracture mechanism of GFRP with different fiber orientations and experimentally clarifies the relationship between fiber orientation and fracture mechanism by using specimens with unidirectional simple fiber orientations. First, Static tensile and fatigue tests are performed on two types of specimens with fibers oriented in a single direction (parallel to the load axis and orthogonal to the load axis), and it is found that specimens with a single fiber orientation parallel to the load axis shows higher strength in both tests. Next, In the case of GFRP with fibers oriented parallel to the load axis, it is found that fatigue loading causes fatigue crack initiation at the fiber ends, followed by fiber localized debonding due to crack propagation at the fiber‐matrix interface and that the crack propagation rate gradually decreases and stops. Therefore, this suggests that the increase in fiber length of fibers oriented parallel to the load axis in GFRP leads to an increase in the crack propagation life at the fiber‐matrix interface, which leads to an increase in fatigue life. [ABSTRACT FROM AUTHOR]

Design and process‐induced defects in fiber‐reinforced polymers (FRPs) lead to fracture nucleation due to the stress concentrations. In addition to the degradation in mechanical properties, defects can accelerate aging of FRPs and limit their service life. Efforts to understand the impact of defects have largely focused on the mechanical performance of FRPs. However, their impact on aging performance has not yet been extensively investigated. Here, we report the effect of the meso‐scale (missing yarn) and micro‐scale (micro‐crack) defects on the hygrothermal aging behavior of FRPs. Missing yarn defects were generated by pulling‐out yarns in warp and weft directions of glass fabric. Then, micro‐cracks were induced in composite laminates by acoustic emission controlled tensile loading/unloading. After exposing samples to the hygrothermal aging, we found that meso‐scale defects deteriorate mechanical/thermomechanical performance, reaching 30% decrease in the flexural strength. Notably, even though increasing micro‐crack density reduces the moisture saturation time, the aging time is reported as a more predominant design parameter, deteriorating the mechanical performance for micro‐crack‐induced FRPs. [ABSTRACT FROM AUTHOR]

For enhancing impact characteristics, woven glass fiber epoxy laminates are reinforced with short fibers. The 6‐mm‐long slender fillers, when added up to 4% in the matrix, exhibit no influence on the flexural modulus, but at 2% they maximize the laminate's flexural strength. While the dissipation energy continues to increase up to 30 J of impact, the laminates' post‐impact load bearing capacity gets significantly affected beyond 20 J. The reinforced laminates exhibit better elastic response and enhanced damage resistance with as high as 50% reduction in the visible damage area as well as up to 35% increase in the damage initiation force. The degree of damage shows excellent correlation with the visible damage area. The distinct through thickness conical region, diverging from the impact site, is attributed to the presence of microcracks oriented along the fiber directions. The cone boundary, from where the interlaminar failure initiates, is largely the manifestation of transverse matrix cracks. While the damage cone with greater divergence indicates reduced impact resistance of the laminate, the orientation of transverse matrix cracks remains unaffected by the impact energy or the filler content. At low impact energies, the failure initiated from the fiber/matrix interfaces, coalesce to form the matrix cracks, which act as a precursor to the interlaminar failure. However, at high energy levels, several failure mechanisms simultaneously develop with no clear indication of the order of damage evolution. The short fibers enhance the laminate's impact resistance either by arresting the cracks or by developing tortuous crack path with high energy dissipation. [ABSTRACT FROM AUTHOR]

In this study, an effective microscale method based on the parametric modeling scheme of the finite volume method is improved to evaluate the effective thermal conductivity and localized thermal fields of the fiber‐reinforced composites. By comparing with the finite element method and experimental data, it is indicated that the proposed microscale method exhibits a high accuracy in solving their effective properties. On this basis, the mesh sensitivity and fiber volume fraction influence on the thermal conductivity are both investigated. The number of 36 × 36 sub‐cells is employed as the RVE model to balance the computational efficiency and simulating accuracy. In addition, affected by the thermal conductivity and microstructure of constituent materials, the heat flux distribution near the interface between phenolic resin matrix and glass fiber is relatively uniform. The study on the influencing factors of the volume fraction shows that the equivalent thermal conductivity increases slowly at the low volume fraction, while the growth rate of the equivalent thermal conductivity increases significantly at the high‐volume fraction. [ABSTRACT FROM AUTHOR]

Utilizing recycled or short fibers for making useful engineering composite component is a present research trend and requirement. Current research work explicates the effect of short carbon fibers (SCF) used as secondary reinforcement in woven glass/epoxy hybrid composites and evaluates their mechanical properties. Different concentrations (0.1, 0.3, and 0.5 wt%) of SCF were incorporated to assess the tensile, flexural, and interlaminar fracture toughness (Mode I and II) of the resulted composites. Composites with 0.1 wt% SCF showed 29.02% and 16.08% increment in the tensile and flexural strength, respectively. For Mode I and Mode II interlaminar fracture toughness tests, 0.1 wt% SCF‐GE samples showed the highest strain energy release rate. Double cantilever beam specimens were used for Mode I testing and an improvement of 13.49% in GIC value was observed. End‐notched flexure method was used for the Mode II tests, and 0.1 wt% SCF‐GE samples showed 20.45% increase in GIIC values. This paper explains the various reasons and mechanisms for obtaining such results. Scanning electron microscopy of the fractured surfaces was carried out to perceive the diverse failure micro‐mechanisms that could have been involved. [ABSTRACT FROM AUTHOR]

Fused filament fabrication (FFF) is one of the most commonly used additive manufacturing technologies. However, the applied material for commercial FFF is limited. Presently, though being one of the most used polymer materials, polypropylene (PP) is rarely used in FFF because of its serious warpage and shrinkage problems. This study investigated the impact of addition of short glass fibers (GF) and ethylene propylene diene monomer (EPDM) on the printability of polypropylene random copolymer (PPR) based FFF and mechanical properties of the printed samples, as well as other properties including rheology, thermal behaviors, and morphology. The results show that the modified PPR has excellent printability, as the printed samples are of good geometrical accuracy. The addition of GF can significantly improve the strength and modulus of the composite, but it also leads to serious decrease in toughness. EPDM addition can effectively improve the toughness of the composite, showing a complementary effect with GF. This work has important meaning in expanding the FFF applicable material and in broadening the application of PP. [ABSTRACT FROM AUTHOR]

This research developed epoxy‐based glass fiber reinforced composite (GFRPs) containing multi‐scale fiber reinforcement comprising of silanized nanoclay (nano‐reinforcement) and compatibilized para‐aramid (PA) fibers (micro‐reinforcement) for enhanced impact strength and tensile‐flexural properties. VARIM technique was used for fabrication of GFRPs. Surface modification (silanization) of nanoclay was confirmed by FTIR and that of PA fibers was confirmed by SEM‐EDS and FTIR. Dispersion/morphology of nanoclay in the processed nanocomposites was determined by XRD and TEM analysis. Three different methods were used for the compatibilization of PA fibers. All methods exhibited a substantial increase in impact strength without a decrease in flexural/tensile strength. Nanocomposite containing 1.0 phr MAH treated PA fibers and 2 phr silanized nanoclay showed the highest improvement in impact strength (34% higher than the reference composite) along with minor improvements in tensile strength (6%), and flexural modulus (13%). SEM micrographs of the fractured surface of impact test samples were used to identify the mechanisms/reasons for the improved mechanical performance of the newly developed GFRPs. [ABSTRACT FROM AUTHOR]

Polymeric materials reinforced with synthetic fibres such as glass, carbon, and aramid provide advantages of high stiffness and strength to weight ratio as compared to conventional construction materials, i.e., wood, concrete, and steel. Despite these advantages, the widespread use of synthetic fibre-reinforced polymer composite tends to decline because of their high-initial costs, their use in non-efficient structural forms, and, most importantly, their adverse environmental impact. The banana fibres were chemically modified through contact with 10 wt % sodium hydroxide solutions for 45 minutes. Polymeric composites with different fibre lengths were prepared through the hand lay-up process at room temperature. Prepared composites exhibited better mechanical and thermal properties. The tensile strength increased with an increasing fibre length of the banana fibre in epoxy matrix composites, due to the stronger interfacial interactions between the treated fibres and the epoxy matrix. These effects occurred due to the morphological and chemical changes in the treated fibre surfaces, which promote better adhesion between the fibres and the epoxy matrix. [ABSTRACT FROM AUTHOR]

The thermomechanical properties of short glass fiber (GF) reinforced polypropylene random copolymer (PPR) composites are investigated. Four composites with different fiber content, namely 10, 15, 20, and 30 wt%, are prepared using melting mixing. For fibers up to 15 wt% the composites exhibit enhanced thermal stability as compared to the random polypropylene. The use of fibers also improve the mechanical strength of the matrix. In particular, PPR/GF30% demonstrates the highest Young modulus, yield strength, and storage modulus values, while PPR/GF10% has the best ductility among the composites. Incorporation of 10 wt% fibers also increases the yield strength and storage modulus of the PPR matrix by approximately 1.6 and 1.2 (for temperatures higher than 60°C) times, respectively. These results suggest that GF reinforced PPR is a composite suitable for advanced technological applications. [ABSTRACT FROM AUTHOR]

The stress interaction failure criterion was applied to three compression‐molded sheet molding compound (SMC) materials. Two are epoxy‐based compounds with randomly oriented carbon fiber tows, and the third material consists of glass fiber bundles randomly oriented in a vinyl ester resin. The failure surface was built using tensile test results at different orientations with respect to the flow direction, resulting in combined loads in the principal stress coordinate system. Three unknown variables arise from using only tensile strength values. Solving a system of three equations derived from the criterion function and using the failure values obtained from destructively testing at three different orientations, the unknown variables as well as the interaction strength components were determined. Results show good agreement for all three materials. Overprediction was found in some instances, attributed to the effect of fiber orientation distribution in the part, and to the complex interactions of the filled structures. To allow a more direct comparison between predicted and experimental data, the resulting failure surface was translated to the global coordinate system (σxx) and compared to the data derived from destructive tensile tests. Good agreement for all materials was observed, with underprediction noted for some orientations, attributed in part to the equation solving method and the nature of the mesostructures of the composites, where interactions between the tows, resin, mold walls, and fibers are present. The results of this work show that the methodology described permits the development of a failure surface for SMC materials when limited data is available. [ABSTRACT FROM AUTHOR]

A change in the length distribution of glass fiber was induced by mixing long glass fiber 30%‐ reinforced polypropylene composites with recycled composites of short glass fiber 30%‐reinforced polypropylene, and the improvement in mechanical properties was investigated. Changes in mechanical properties were confirmed as a function of the number of recycles and mixing ratio of the composites, and the average fiber length and length distribution of the glass fibers were analyzed using a three‐dimensional measuring machine. The tensile strength, flexural strength, flexural modulus, and impact strength of the blend of a once‐recycled composite of short glass fiber‐reinforced polypropylene and once‐recycled composite of long glass fiber‐reinforced polypropylene in a ratio of 40:60 were 99%, 102%, 100%, and 100% those of a virgin composite of short glass fiber‐reinforced polypropylene, respectively. In addition, the average length of the glass fiber of this blend was 0.305 mm, which was similar to that of the virgin composite of short glass fiber‐reinforced polypropylene (0.313 mm); furthermore, the distribution ratio of long fibers of length 1 mm or more was 5%. The length distribution of the glass fibers was significantly altered by the combination of the recycled composites and the long glass fiber‐reinforced composite; accordingly, the deteriorated mechanical properties of the recycled composites could be significantly recovered. [ABSTRACT FROM AUTHOR]

This article presents the experimental findings of tension‐tension stress‐controlled fatigue tests performed on low‐density sheet molding compound (LD‐SMC). LD‐SMC composite is a type of SMC including a polyester resin reinforced with chopped glass fibers bundles and hollow glass spheres. The coupled frequency‐amplitude affects the nature of the overall fatigue response, which can be controlled by the damage mechanisms accumulation and/or by the self‐heating. In fact, the self‐heating produced a material softening and decreased the fatigue lifetime. For fatigue loading at 80 Hz, self‐heating has been observed and yielded to a temperature rise to 65°C, which is more than a glass transition temperature of polyester. Thus, the polyester matrix is subjected to remarkable thermally activated modifications of its physical state. Multiscale damage analysis of the randomly‐oriented sample in fatigue showed that the first observed damage phenomenon corresponds to the debonding of the hollow glass microspheres occurring in the fiber depleted zones. [ABSTRACT FROM AUTHOR]

Light weighting has become an integral part of vehicle design. This strategy makes use of fiber‐reinforced thermoplastics, which can be injection molded into complex shapes. Composite design work requires knowledge of the orientation state throughout a part to predict properties like stiffness and strength. Although evolution models for the orientation state have been developed, each requires empirical parameters, and no standard method for obtaining these exists. This work continues efforts to find such a test, particularly for long (average length > 1 mm) glass fiber composites. Here, a polypropylene loaded with 30, 40, and, 50 wt% long glass fiber is subjected to startup of shear and nonlubricated squeeze flow (NLSF). The orientation evolution was reported for both flows and an attempt was made at fitting several orientation models to the data. The measured orientation evolution from startup of shear was slower than expected, and this slower evolution appears to result from the combination of the initial orientation state and fiber concentration. On the other hand, the measured orientation profile from NLSF was found to be essentially independent of fiber concentration. However, the NLSF orientation profile could not be replicated with a single set of parameters. Rather, shear‐like parameters made reasonable predictions in shear‐dominated regions, and extension‐like parameters made reasonable predictions in extension‐dominated areas, in concordance with results from short glass fiber composites. [ABSTRACT FROM AUTHOR]

Cold spray deposition of aluminum powders on polyethylene reinforced with glass fibers has been studied. Different processing conditions, including different stratifications of the fiber-reinforced polymer used as a substrate, have been investigated to better understand the deposition mechanism. The experimental campaign has been conceived and tailored to highlight the influence of several process parameters on the deposition of the first layer of particles. The results obtained allowed to highlight and clarify the influence of standoff distance and gas pressure and also gave some insights concerning the effect of the substrate stratification. Guidelines regarding the design of the manufacturing process have been also released. [ABSTRACT FROM AUTHOR]

Polypropylene (PP) is widely used in the automotive industry due to its excellent mechanical properties, good formability, and low cost. Herein, the spray‐free PP composites reinforced by graphene oxide@short glass fiber (GO@SGF) were fabricated by extrusion compounding and injection molding. Aluminum powder was used as spray‐free filling materials. The microstructure and composition of SGF and GO@SGF are investigated using scanning electron microscopy and X‐ray photoelectron spectrometer. The effect of GO@SGF on the mechanical properties of spray‐free PP composites was studied. The results showed that both tensile strength and modulus were effectively improved by incorporation of GO@SGF. This mainly attributed to the improved interfacial bonding between the reinforcements and matrix. [ABSTRACT FROM AUTHOR]

In the present study the effectiveness of two different biodegradable polymers, namely Polylactic acid (PLA) and ECOVIO (EC), a blend of a copolyester and PLA, as matrix materials for basalt fiber composites, prepared with the "film stacking method" has been investigated. Comparison with composites based on glass fiber mat has also been performed. The addition of basalt fibers, leads to a significant improvement in tensile and flexural strength and stiffness. The ECOVIO/basalt fiber composites exhibited the highest percentage enhancement, while the failure strain decreased dramatically. Therefore, the basalt fabrics appear to have a competitive mechanical performance with the glass fiber mats employed. [ABSTRACT FROM AUTHOR]

Use of composite laminates is found in various applications such as aircraft and automotive, sports, rocket parts and civil structures. Resin system of the polymer composites enacts a crucial role of binding the reinforcements properly to provide good mechanical properties. The presence of any kind of filler alters the properties of resin system which in turn also alters the mechanical behaviour of composite laminate. In the present work an attempt has been made to enhance the mechanical performance of glass fibre epoxy composites by embedding nano calcium carbonate particles in resin system. These particles were added in different weight fractions like 1, 3 and 5% and the response of GFRP nano composites were recorded under flexural and shear loads. Composite laminates with 3% wt. of nano particles have shown considerable improvement among the other laminates. [ABSTRACT FROM AUTHOR]

ABSTRACT: Three kinds of compatibilizers, ethylene–ethyl acrylate copolymer (EEA), ethylene–ethyl acrylate–glycidyl methacrylate copolymer (EAG), and ethene–maleic anhydride–glycidyl methacrylate copolymer (EMG), were introduced to PA6/PET/GF blends for the first time to study the effect of different compatibilizers on composite. EEA, EAG, and EMG showed different effect on the properties of PA6/PET/GF blends. An observation of the GF–resin interface by scanning electronic microscope indicated EAG and EMG enhanced the adhesion of resin to GF, while EEA exhibited no improvement. Differential scanning calorimetry analysis showed that both EMG and EAG increased the degree of crystallinity of the PA6/PET/GF blends, whereas EEA declined. According to dynamic mechanical analysis, EAG, and EMG remarkably increased the storage modulus of composites. For the composites at a given GF content of 30 wt %, EMG increased the tensile strength from 140.6 to 156.3 MPa. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46429. [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]

ABSTRACT A two-step process for preparing glass fibers (GFs) reinforced β-nucleated PP composites was designed and developed. The complementary approach combined GFs reinforcement and β-nucleating agents regulation using N, N′-dicyclohexyl-2,6-napthalene-dicarboxamide (TMB-5) in the presence of maleic anhydride grafted polypropylene (PP- g-MA) through extrusion blending. The influence of TMB-5 and GFs on the mechanical properties and crystallization behavior of PP was studied by mechanical test, wide-angle X-ray diffraction, differential scanning calorimetry, and scanning electron microscopy. A distinct complementary effect of GFs and β-nucleating agent TMB-5 on mechanical properties and crystallization behavior of PP was observed. Results showed that addition of 20 wt % GFs and 0.1 wt % TMB-5 into PP matrix with the two-step process could lead to significant increase to its mechanical properties: specifically 64.8% improvement in tensile strength, 107.1% enhancement in flexural modulus, and 167.7% increasement in notched impact strength compared to that of neat PP. Furthermore, with the combination of TMB-5 and GFs, not only led to promoted interfacial adhesion, but also significantly improved overall comprehensive mechanical properties. The complementary process provided an alternative approach for the development of PP with balanced toughnesss and stiffness. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45768. [ABSTRACT FROM AUTHOR]

For the assessment of the damage kinetics during the instrumented Charpy impact test (ICIT), the acoustic emissions (AEs) were recorded and the transient signal of the acoustic sensor was analyzed with the wavelet transform (WT). Based on the results discussed in this paper, an assessment of the resistance against stable crack initiation of glass fiber reinforced materials with the help of AE measurements under impact conditions is possible. [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]

Probing the wetting properties of microfibers by polymer resins is of significant interest for the rational design of composite materials. Here, we demonstrate the measurement of contact angles on wetted micron scale fibers by imaging the fluid meniscus with telecentric optics at a spatial resolution of 4 μm followed by automated image analysis. The meniscus is described as a catenary in the zero gravity approximation and by fitting this to the measured profile, the contact angle is obtained at the intersection between the fluid and the fiber surface. The method is validated by measuring agreement between contact angles for the PMMA/H 2 O system for fibers with diameters 20–800 μm and for sessile drops. The ability of the method to discriminate contact angles for a series of commercial glass fibers against epoxy resin is successfully demonstrated. AFM imaging shows that the surface topography of the fibers does not have a simple relationship with the variation in contact angles. Contact angle goniometry by imaging of micron scale fibers appears as a viable alternative to Wilhelmy type measurements and the measurement principle could readily be extended to dynamic wetting experiments. [ABSTRACT FROM AUTHOR]

3D printing technology has shown capabilities in producing radical shapes with unique infill patterns and configurations to enhance fiber reinforced polymer composites. The ability to use 3D printing technology to inherently transform FRP failure and post-peak behavior is an unexplored area that can provide a new class of FRP with improved failure behavior. In this study, four designs are developed with combinatorically angled fiber reinforced layers and manufactured using 3D printing technology that demonstrated a ductility up to 29%. The designs enable a gradual load transfer mechanism between different FRP layers demonstrating characteristic load drops and up to 8% strain at failure. Damage in combinatorically angled Glass Fiber Reinforced Polymers (GFRP) composite layers were observed to be mostly sequential compared with the abrupt broom-like failure in high strength FRP composite. 3D printed GFRP composite with Design 4 showed a yield-like plateau leading to a failure strain of 4.2% after reaching its ultimate strength of 260 MPa which is comparable to Grade B steel. The response of a 3D printed high strength GFRP composites was compared with high strength glass FRP composites manufactured using conventional methods. This comparison showed that increase in fiber volume fraction of 3D printer filament can improve mechanical response of resulting composites. This work demonstrates a pathway to manufacture the next generation of structural FRP composite systems with enhanced ductility and inherent mechanism for energy dissipation. • Precise fiber control was achieved through 3D printing to prepare combinatorically angled FRP. • Load fractions for delayed FRP failure mechanism was achieved by controlling axial stiffness. • Evident reductions in strength and elastic modulus with increase in fiber angle was observed. • The FRP composite allowed a post-peak yield-like plateau with about 4.2% strain at failure. • Fiber volume fractions of 3D printed composites were lower than conventional composites. [ABSTRACT FROM AUTHOR]

ABSTRACT Improvement of mechanical and thermal properties is always the goal of high-performance general plastic for engineering applications. Herein, isotactic polypropylene/glass fiber/tetrapod-shaped zinc oxide (iPP/GF/T-ZnOw) composites are developed via melt-extrusion on twin-screw extruder. To improve the distribution of T-ZnOw in iPP matrix, T-ZnOw is first modified by various silane coupling agents and its structure is characterized by scanning electron microscopy, Fourier transform infrared spectra, and X-ray diffraction (XRD). The optimized treatment condition is determined via comparison of activation index. The introduction of GF and T-ZnOw could improve the mechanical properties including tensile strength, elastic modulus, flexural strength, flexural modulus, and impact strength, indicating that the surface modification and compatibilizer could enhance the interfacial interaction of iPP/GF/T-ZnOw composites. Moreover, XRD and differential scanning calorimentryresults show that T-ZnOw as a novel β-nucleating agent could induce the formation of β-crystal and the existence of GF counteracts the formation of β-crystal induced by T-ZnOw. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44217. [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]

ABSTRACT Binary blends of polypropylene (PP) and ethylene-octene copolymer (EOC) are prepared by continuous electron-induced reactive processing at various mass ratios of the blend components and various doses without adding of any grafting agents. The influence of mass ratio and dose is investigated in order to get the optimum processing behavior of toughened PP as well as optimum properties of resulting fibers. It is found that toughened PP with a PP/EOC blend ratio of 97.5-2.5 mass % can be used advantageously as a matrix component for the process of online spinning of glass fiber/toughened PP hybrid yarns. Such hybrid yarns belong to one of the most advanced production methods for the manufacturing of fiber reinforced thermoplastic composites with an increased mechanical performance. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44011. [ABSTRACT FROM AUTHOR]

ABSTRACT To explore the effect of short glass fiber reinforcement (SGFR) on the mechanical properties of polyethersulfone (PES), microstructural characterization has been performed by positron lifetime technique. The free volume distribution of SGFR-PES composites derived from CONTIN-PALS2 program exhibits the narrow full width at half maximum (FWHM) indicates the strong interaction between polymeric chains of PES matrix and SGF. The positron lifetime parameters of SGFR-PES composites are correlated with the mechanical properties viz., Tensile strength (TS), Young's modulus (YM) and elongation at break (EB). The decreased positron lifetime parameters, improved mechanical properties and reduced crystallinity of SGFR-PES composites are attributed to the improved chemical and physical interaction between the functional groups of both SGF and PES matrix. This is clearly evident from the FTIR (Fourier Transform Infrared Spectrometry) studies. The hydrodynamic interaction parameter (h) show negative values, suggest the improved interaction in SGFR-PES composites by the generation of excess friction at the interface. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43647. [ABSTRACT FROM AUTHOR]

ABSTRACT The incorporation of carbon nanofiber (CNF) into glass fiber (GF) composites is a potential route to extend polymer composite service-life and enhance mechanical properties. Under nonstatic conditions, only limited information concerning water uptake and contaminant release properties of nanocomposite materials is currently available. Polyester composites containing GF and oxidized CNF were immersed in water for 30 days under nominal pressure at 23 °C, below the polymer's glass-transition temperature. Water was analyzed and changed every three days to simulate water chemistry regeneration similar to exposures in flowing systems. Composites with oxidized CNF had greater water sorption capacity and leaching rates than CNF-free composites. The total mass of organic contaminant released correlated with the amount of water sorbed by each composite ( r2 = 0.91), although CNF dispersion was found to vary greatly within composites. The greatest and least contaminant release rates were found for the polyester-CNF and the polyester-GF composites, respectively. While volatile aromatic resin solvents and stabilizer compounds were detected, their concentrations declined over the 30 day exposure period. We hypothesize that the hydrophilic nature of the oxidized CNF increased the water sorption capacity of the polyester composites. Additional studies are warranted that examine the impact of this phenomenon on composite mechanical and long-term durability properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43724. [ABSTRACT FROM AUTHOR]

In this article, we report the effects of hybridization and fiber-surface modification on the properties of hybrid composites prepared from recycled polypropylene (RPP), coupling agents, oil palm empty fruit bunch (EFB), and glass fibers through a twinscrew extruder and an injection-molding machine. The surface of the EFB fibers was modified with different concentrations (10-15 wt %) and temperatures (60-90°C) of alkali solutions. The structure and morphology of the fibers were observed with the help of Fourier transform infrared spectroscopy and scanning electron microscopy. Different types of composites were fabricated with untreated, alkali-treated, and heat-alkali-treated fibers. Comparative analysis of the mechanical, structural, morphological, and thermal properties of the composites was carried out to reveal the effects of treatment and hybridization. The analysis results reveal that composites prepared from the alkali-treated (in the presence of heat) fibers show improved mechanical, thermal, and morphological properties with a remarkably reduced water absorption. Additionally, the crystallinity of RPP also increased with the development of biaxial crystals. The improvement of various properties in relation to the structures and morphologies of the composites is discussed. [ABSTRACT FROM AUTHOR]

ABSTRACT Two types of long jute fiber pellet consisting of twisted-jute yarn (LFT-JF/PP) and untwisted-jute yarn (UT-JF/PP) pellets are used to prepare jute fiber-reinforced polypropylene (JF/PP) composites. The mechanical properties of both long fiber composites are compared with that of re-pelletized pellet (RP-JF/PP) of LFT-JF/PP pellet, which is re-compounded by extrusion compounding. High stiffness and high impact strength of JF/PP composites are as a result of using long fiber. However, the longer fiber bundle consequently affects the distribution of jute fiber. The incorporation of 10 wt % glass fibers is found to improve mechanical properties of JF/PP composites. Increasing mechanical properties of hybrid composites is dependent on the type of JF/PP pellets, which directly affect the fiber length and fiber orientation of glass fiber within hybrid composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41819. [ABSTRACT FROM AUTHOR]

ABSTRACT The effect of glass fiber (GF) on the electrical resistivities of polyoxymethylene (POM)/maleic anhydride-grafted polyethylene (MAPE)/multiwalled carbon nanotube (MWCNT) composites is investigated. The POM/MAPE/MWCNT composites at a MWCNT loading of 0.75% are nonconductive because most of MWCNTs are isolated in the MAPE islands, and their electrical resistivities decrease significantly after the addition of GF because of the formation of MAPE-coated GF structure, which facilitates the formation of conductive paths and was confirmed by field emission scanning electron microscopy (FESEM). The formation of MAPE-coated GF structure is attributed to the interaction between GF and MAPE during melt compounding, as contrasted by the uncoated GF using high-density polyethylene (HDPE) instead of MAPE. Nonconductive POM/5-20% MAPE/0.75% MWCNT composites become conductive upon the addition of 20% GF. This preparation method for conductive materials can be generalized to POM/5-20% maleic anhydride-grafted polypropylene (MAPP)/0.75% MWCNT composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41794. [ABSTRACT FROM AUTHOR]

ABSTRACT The effectiveness of using interleaved nylon veils to increase the interlaminar toughness of glass fiber reinforced, low-styrene emission unsaturated polyester resin composites has been investigated. Samples were manufactured by a hand lay-up technique followed by compression moulding. Nylon 66 veils were used, with the veil content varying from 0% to 4% by weight. Double cantilever beam, short beam shear, and three point bend tests were performed. The increasing levels of nylon veil content improved the interlaminar toughness of the composites, which was characterized by critical strain energy release rate ( GIC). The maximum GIC for crack propagation of a nylon interleaved composite increased by almost 170% over the baseline glass fiber reinforced composite. Dynamic Mechanical Analysis revealed an increase in the damping parameter of up to 117%. Image analysis via Digital Image Correlation and Scanning Electron Microscopy revealed increased fiber bridging between adjacent plies as a key reason for these improvements. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41462. [ABSTRACT FROM AUTHOR]

Flax fibers are particularly relevant in composite fabrication due to natural availability and mechanical properties close to glass fibers. We explore flax fiber-containing epoxy-amine (DGEBA/DETA) polymers with wide industrial applicability. Flax fibers impact the glass transition temperature (DSC), with a T g drop of 67 °C at 30 wt% loading. For deeper insight, we develop here an original mixing calorimetry approach to follow in situ DGEBA/fibers and DETA/fibers interphases. DGEBA does not interact quantitatively with flax fibers while DETA/fibers interaction is significantly exothermic and directly related to fibers content. DETA/water interaction only accounts for 25% of total heat effect. Experiments run by contacting DETA with each of the main components of flax fibers (cellulose, hemicelluloses, lignin) point out systematic exothermic effects. Considering their mean proportion in flax fibers, the sum of enthalpy contributions agrees well with the overall effect measured with entire fibers. The main contribution (58%) arises from cellulose. XRD analyses and literature considerations allow concluding on the direct implication of DETA molecules with cellulose chains, resulting in T g decrease. This work clarifies the chemical role of flax fibers in DGEBA/DETA thermosets, down to the molecular-scale, and highlights that mixing calorimetry is a powerful tool to follow interphase formation in situ. We develop a mixing calorimetry approach to follow in situ interphase formation between flax fibers and DGEBA or DETA. DETA/fibers interaction is particularly exothermic. Each component of flax fibers leads to exothermic effects, cellulose giving the most prominent enthalpy contribution. DETA interacts with cellulosic chains, which limits the amount of "reactive" amino functions for polymerization and decreases the T g value. [Display omitted] • Addition of flax fibers in epoxy-amine mixture leads to T g decrease (67 characters). • Mixing microcalorimetry does not show interaction between DGEBA and flax fibers (84 characters). • DETA/fibers interaction is significantly exothermic (63 characters). • Cellulose, hemicellulose, lignin and water reacted exothermically with DETA (76 characters). • Cellulose is responsible for 58% of the heat effect despite its crystallized state (83 characters). [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]

Highlights: [•] We suggested a section of a new module that would apply a large section. [•] We developed a new FRP composite girder that is filled with concrete. [•] It was confirmed the composite effect from confining concrete. [ABSTRACT FROM AUTHOR]

ABSTRACT This research work investigates the tensile strength and elastic modulus of the alumina nanoparticles, glass fiber, and carbon fiber reinforced epoxy composites. The first type composites were made by adding 1-5 wt % (in the interval of 1%) of alumina to the epoxy matrix, whereas the second and third categories of composites were made by adding 1-5 wt % short glass, carbon fibers to the matrix. A fourth type of composite has also been synthesized by incorporating both alumina particles (2 wt %) and fibers to the epoxy. Results showed that the longitudinal modulus has significantly improved because of the filler additions. Both tensile strength and modulus are further better for hybrid composites consisting both alumina particles and glass fibers or carbon fibers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39749. [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]

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]

The physical–mechanical properties of mineral fibers manufactured from scoria obtained from two deposits in Armenia are studied. It is shown that the slag fibers can be used as an alternative to the widely used glass fibers. Their elastic modulus is identical to that of S-composition glass fibers and their strength is close to that of E-composition glass fibers. The elastic-strength properties of the composites exceed the corresponding indices of materials based on basaltic and andesite-dacite fibers. [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]

Study on the effect of concentration of maleated polypropylene (MAPP), dicumyl peroxide (DCP), nanoclay (NC), and aspen fiber loading on the mechanical properties of Aspen-PP composites has been undertaken with the objective to protect or increase the impact strength without losing or weakening the tensile strength. The central composite design of Statgraphic plus is used to determine the optimum concentration of additives and to maximize both the impact as well as tensile strength properties to be superior to that of pure PP. Finally, the material price of PP composites with an optimal composition of filler (aspen fiber and NC), coupling agent (MAPP), and initiator (DCP) is compared to that of pure PP and PP reinforced with glass fibers. [ABSTRACT FROM AUTHOR]

Polypropylene composites have emerged as alternative materials for a wide range of applications requiring advanced mechanical and thermal properties including automotive and structural engineering. The choice of suitable polypropylene reinforcing agent enables higher flexibility, lightweight, mechanical strength and low production cost. This paper reports on the fabrication of short glass fibre reinforced random polypropylene by melt mixing. The mechanical and thermal properties of the random polypropylene/E-glass fibre composites exhibited a strong dependence on the fibre size varying from 1 mm to 0.3 mm and the various fibre contents, namely 10, 15, 20 and 30 wt%. Activation energy analysis suggested hindering of crystallization due to the presence of the fibres. However, a maximum yield strength of 29.4 MPa was measured for the 10 wt% fibre reinforced composites with an average fibre length of 1 mm. Furthermore, use of shorter fibres (average length of 0.3 mm) and a filler loading of 10 wt% resulted in a maximum elongation at break of 654%. Enhanced stiffness was also observed for fibre content up to 15%. These results suggest that the use of short glass fibres will allow the development of cost-effective and robust polypropylene composites adequate for a wide range of modern applications. [ABSTRACT FROM AUTHOR]

In this study, we compare the effect of twin‐screw extrusion processing on the attrition of wood fibers (WFs) with glass fiber. The effects of process variables and screw design on fiber length were investigated by performing a range of dead‐stop experiments where the extruder was stopped, opened‐up, and compound removed from the screw elements. Fibers, chemically extracted from the polypropylene matrix, were analyzed for length and width using a commercial fiber analyzer. It was found that WF length attrition and composite properties were less affected by screw design and twin‐screw processing conditions (feed rate and screw speed) than glass fiber. Length weighted fiber length and X50 length (a measure used in particle size analysis) were equally correlated with process conditions and composite performance for both fiber types. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48551. [ABSTRACT FROM AUTHOR]