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In this study, two kinds of fiber reinforced thermoset composites (glass and carbon fiber) were fabricated with almost same volume fraction and thickness and bonded with epoxy adhesives (ADs) with various weight contents of nano hexagonal boron nitride (nano-h-BN) (0, 1, 2 and 3 wt%). The single-lap shear (SLS) tests were conducted on bonded joints with ADs. The effects of nano-h-BN contents on the morphology and micro-structure of the epoxy ADs were studied by scanning electron microscope (SEM). The specimens with the glass fiber reinforced composites with 2-wt% nano-h-BN showed the highest results of SLS strength characteristics with an improvement of 23.6 % and 37.2 % in the SLS strength compared to the specimens with the glass fiber and without nano-h-BN in 0° and 90° directions. Furthermore, the specimens with the carbon fiber reinforced composites with 2-wt% nano-h-BN showed an improvement of 191.7 % and 78.3 % in the SLS strength compared to the specimens with the carbon fiber and without nano-h-BN in 0° and 90° directions. [ABSTRACT FROM AUTHOR]

Abstract Ramie fiber in combination with glass has proved to be excellent for making cost effective composite materials. They are prepared by hand layup method using E-glass and ramie fibers. The resin used in the preparation of composites was epoxy. Fiber reinforced composites were hybridised at two weight percentages (20% and 30%). Samples prepared were tested to evaluate its properties, such as tensile strength, flexural strength, impact strength, and scanning electron microscope (SEM). Scanning electron microscope analysis revealed the morphological features. HFREC (Hybrid fiber reinforced epoxy composite) exhibited better mechanical properties than the individual samples. [ABSTRACT FROM AUTHOR]

Abstract Owing to the outstanding properties of nano-Al 2 O 3 particles have incited material researchers to have a promising invasion in the field of fibrous polymeric composites. There is an uncertainty of nano-Al 2 O 3 /polymer interfacial stability at high temperature engineering applications. Current investigations explicate the effects of nano-Al 2 O 3 content on the mechanical behavior of glass/epoxy (GE) composites at various in-situ elevated temperatures. The flexural properties and viscoelastic behavior of the composites have been investigated and evaluated. The Weibull design parameters were analysed as a function of nano-Al 2 O 3 content and different test temperatures. Scanning electron microscopy analyses were carried out to understand various interfacial strengthening mechanism and micro-mechanism failures. These results indicated that incorporation of 0.1 wt% of nano-Al 2 O 3 in GE composites at room temperature could be considered an optimal value in flexural strength enhancement. The fracture surfaces demonstrated a combination of fiber pullout, interfacial debonding, matrix drainage and fiber imprints failure morphologies. Weibull analyses responded a reasonable agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Abstract Flax composites demonstrate superior damping properties to conventional fibres. These materials are already being utilised in some products but the mechanical properties they exhibit are too low for many structural applications. Hybridization of flax with higher strength fibres has been shown to yield materials, which balance damping and load carrying capabilities alongside improved environmental credentials for flax/carbon hybrids. However, the most used composite material is E-glass but the current literature does not facilitate the prediction of damping properties for these hybrid composites, where it is expected that they will behave differently due to the difference in material properties. The woven flax and E-glass fibres specimens embedded with epoxy resin are manufactured via resin infusion to understand the damping and mechanical properties possible from an industrial process and the dominant factors affecting them, rather than the relationships between individual variables and these properties. These experiments allow the hybrids to be profiled for the first time and it is observed that hybridization of flax and E-glass fibres results in an increase in damping, from 1.97% to 2.63% for the best hybrid, especially when the flax plies are placed on the outer skin, however the compromise in tensile properties is significant, from 473.28 MPa to 166.53 MPa. [ABSTRACT FROM AUTHOR]

Abstract Fiber reinforced sandwich composites are frequently used today. The inability to recycle these frequently used materials ensured that the repairs of these materials became more important. There are a several different methods developed on this area, but most of them are basically based on the patch repair method. In this study it is aimed to improve the efficiency of repair with newly proposed patch types to be applied during the patch repair process, which is used in the repair of sandwich composites. Sandwich composite plates were made of glass fiber, PVC foam and epoxy resin with vacuum assisted resin infusion method. Prepared specimens were subjected to the three-point bending test taking into consideration parameters such as specimen width, damage diameter and the results were evaluated. As a result, it has been seen that the proposed methods significantly affect the efficiency of patch repair. Highlights • This study aimed to improve the efficiency of sandwich composite repair with newly proposed patch types. • Improvement studies were carried out to repair a damaged sandwich composite using the minimum number of repair plies. • Patch type repair method was applied and three different types of patches are proposed on this method for improving strength. • All specimens were subjected to three-point bending tests under the parameters of specimen width, damage diameter. • As a result, the quality of the repairs has got improved with the modifications which applied to the patch type repair. • Load carrying capacity of developed methods increased the repair strength according to the conventional patch repair method. [ABSTRACT FROM AUTHOR]

Recently, researchers have been attempting to enhance the mechanical and tribological characteristics of thermosetting epoxy composites by incorporating inorganic nanoparticles and ensuring their uniform distribution throughout the matrix. This study characterises ball-milled ilmenite (FeTiO 3 -size of 63 nm) and silicon dioxide (SiO 2 -size of 67.5 nm) fillers added to epoxy in proportions of 0:0, 2.5:2.5, 5:5, and 7.5:7.5% by weight. A liquid ultrasonic technique is used to blend the fillers with the epoxy, and compression moulding is used to fabricate the composite. Mechanical tests were performed based on ASTM standards. Tensile strength, tensile modulus, flexural strength, flexural modulus and elongations at break(tensile and flexural test) of 5:5 wt % are 30.54%, 12.2%, 32.22%, 28.98%,23.78% and 23.53% higher than neat sample respectively. Shore "D" hardness and Izod's impact strength are 4.65% and 98.93% higher at 5:5 wt % than neat sample respectively. Specific wear rate decreased from 2.6 × 10−11 m3/Nm (neat GFRP: 0 wt % glass fibre reinforced polymer composite) to 0.7 × 10−11 m3/Nm at 5:5 wt % filler. Nanoparticles lowered the coefficient of friction by around 16.66%, 60.42%, and 33.33% at sliding distances of 100 m for 2.5:2.5, 5:5, and 7.5:7.5 wt % respectively with the neat sample. A 5:5 wt percent resulted in 76.68% less wear volume loss than pure GFRP. Field emission scanning electron microscopy (FESEM) analysis revealed element distributions, particle size, pullout of fibers, damaged interfaces, filler dispersion, voids, wear debris, interfacial debonding, and cavities. Thus, this approach enhances GFRP composite's mechanical, tribological, and structural properties. [Display omitted] • Characterization of ball-milled ilmenite (FeTiO3) and silicon dioxide (SiO2) fillers (0:0, 2.5:2.5, 5:5, and 7.5:7.5 wt.%) blended by ultrasonic liquid process and manufactured by compression moulding. • The mechanical tests were conducted according to ASTM standards. At 5:5 wt%, GFRP composites have better tensile strength, modulus, flexural strength, elongations at break, Shore "D" hardness, and Izod's impact strength than pristine samples. • Filler-incorporated, produced composites have lower specific wear rate, coefficient of friction, and wear volume loss at 100 m sliding distance than pure GFRP composites. • Field emission scanning electron microscopy (FESEM) reveals the morphology of fractured and worn surfaces in samples. • EDS Mapping predicts the Distribution of Elements in the developed composite. [ABSTRACT FROM AUTHOR]

The interfacial properties for three different glass fiber (GF) mats were evaluated by examining permeability through combining the results of wettability and interlaminar shear strength (ILSS) testing. Three types of GF mats were studied: (1) unidirectional (UD), (2) bidirectional (BD, 0/90°), and (3) randomly-chopped (RC). Single fiber tensile tests were used to compare the fibers in the 3 mats, forty single fibers were extracted from each mat. FE-SEM was used to study damages on the GF in each of the mat types. Fibers from the UD mat exhibited the best mechanical properties and less damage was observed with the FE-SEM. Vacuum assisted resin transfer molding (VARTM) was used to manufacture glass fiber reinforced composite (GFRC) specimens, with the three different mat types. The permeability of the different GF mats was measured, during manufacture of the GFRC, and related to the spreading of the epoxy resins in the GF mats. Short beam tests were performed as a measure of interfacial properties and related to the observed permeability and spreading. GFRC manufactured with UD GF mat exhibited the best interfacial and mechanical properties and displayed the least physical damage while GFRC manufactured with BD GF mat had the poorest interfacial and mechanical properties while exhibiting the most visible damage. The UD GF mat also displayed the smallest change in contact angle and the best permeability. The longitudinal fiber pattern in the UD GF mat apparently promotes capillary effects leading to an increase in wetting rate. This study demonstrates that GF mat pattern affect the interfacial and mechanical properties as well as matt permeability and resin spreading. [ABSTRACT FROM AUTHOR]

The paper deals with analysis of relationships between the microgeometry and mechanical properties of fiberglass i.e. epoxy resin composites with random fibers distribution. The mechanical properties (e.g. a flexural modulus E f , taking into account shear effects) of the material were determined in bending by Short Beam Shear Tests (SBST). Microgeometry of the structure was characterized on the basis of microscopic images of test specimens. The paper proposes a new measure of irregular reinforcement distribution expressed as an area ratio of the matrix surrounding the single fiber to the circuit of the fiber. The measure, denoted by G AB , is expressed in microns. In particular the relationship between the results obtained in the test samples with random distribution of fibers and theoretical regular structures of square (K) and hexagonal (H) type is presented. Specimens of the investigated composite (E-glass fibers and Epidian 5 epoxy resin), supplied by industrial partner, were cut out from raw material of helicopter blades girders. The obtained experimental results for the analyzed composite corresponded to approximation by the theoretical model of the square (K) type. The results can be used to estimate the flexural elastic modulus E f of the unidirectional composites with irregular arrangement of fibers, made manually or using the molding apparatus. Based on those results, it can be concluded that the square distribution model (K) is appropriate for numerical estimation of the strength composites properties reinforced with glass fibers of circular cross-section, having the diameter in the range of 10–16 μm. [ABSTRACT FROM AUTHOR]

This study aims to improve the web crippling performance of pultruded glass fibre-reinforced polymer (GFRP) C sections using fibre-reinforced epoxy composite (FEC). The strengthened GFRP C sections were subjected to two loading conditions: interior-two-flange (ITF) and exterior two-flange (ETF). The parameters considered were bearing lengths, FEC strengthening length and thicknesses. Two failure modes, namely web-flange junction failure and web buckling failure were observed for the pultruded GFRP C sections under ETF loading conditions as the bearing length changed. While the combination of the web-flange junction and FEC crushing failures were observed under ITF loading conditions at 20 mm and 50 mm bearing lengths. Furthermore, the average web crippling capacity of strengthened GFRP C sections improved by up to 426 % and 488 %, in comparison to control samples under ETF and ITF loading conditions, respectively. The average web crippling capacity of pultruded GFRP C sections increased up to 45 % when the bearing length increased from 20 mm to 50 mm. The finite element (FE) outcomes showed an agreement with experimental results in the context of failure patterns, load-displacement profiles and web crippling capacities. Finally, equations were proposed to estimate the web crippling capacity of pultruded GFRP C sections strengthened with FEC. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive experimental investigation on the fatigue response of glass-filled epoxy composites when subjected to cyclic loading. Rod-shaped particulate glass fibers in a volume fraction of 0%, 5%, 10% and 15% are reinforced in the epoxy matrix. The mechanical behavior of the resulting composite is studied under monotonic tensile loading and tension–tension cyclic fatigue loading. The undergoing damage mechanisms leading to the crack initiation and its propagation are studied using the in-situ low cycle fatigue testing. The crack initiation behavior and the crack initiation life are found to be affected by different crack initiation sites such as the epoxy-fiber interface, the matrix and the fiber itself. Fractography reveals that the crack coalescence, crack propagation and the failure are largely affected by the varying volume fraction of glass fibers. The specimen with 10% volume fraction is found to exhibit the maximum fatigue life under the applied cyclic loading. • Rod-shaped glass fibers in varying volume fraction are used in the epoxy matrix. • Composites are subjected to monotonic and cyclic tension–tension loading. • Epoxy, the fiber and their interface are identified as the crack initiation sites. • Fibers act as crack nucleation sites resulting in coalescing the microcracks at the interface. • The specimen with 10% volume fraction exhibited the maximum fatigue life. [ABSTRACT FROM AUTHOR]

The effect of nanoclay addition in Glass Fiber Reinforced Epoxy (GFRE) composites on impact response was studied. The epoxy nanocomposite matrix with 1.5 and 3.0 wt% loading of I.30E nanoclay was produced by high shear mixing. Hybrid GFRE nanoclay composite plates were manufactured by hand layup and hot pressing techniques using electrical grade-corrosion resistant (E-CR) glass fiber mats. The laminates were then subjected to low-velocity impact with energies between 10 and 50 J. Addition of nanoclay was found to improve peak load and stiffness of GFRE. Nanoclay loading of 1.5 wt% resulted in optimum properties, with 23% improvement in peak load and 11% increase in stiffness. A significant reduction in physical damage was also observed for hybrid nanocomposite samples as compared to GFRE. This was mainly attributed to transition in damage mechanism due to nanoclay addition. Clay agglomeration in samples with 3.0 wt% loading contributed towards limiting the improvement in impact resistance. [ABSTRACT FROM AUTHOR]

In this work, flame-retardant glass fiber reinforced epoxy composites (FGRE) were successfully prepared via adding a novel phenylphosphonate-based flame retardant, N, N '-diamyl- p -phenylphosphonicdiamide (P-MA) into GRE. FGRE12 showed high LOI value of 33%. Meanwhile, FGRE12 passed V-0 rating in UL 94 test and the peak of heating release rate (pHRR) decreased by 54% in comparison with that of GRE. The flame-retardant efficiency of P-MA in GRE was compared with that in epoxy matrix (EP). Moreover, the influences of P-MA on mechanical and thermal stability properties of GRE were studied systemically. Dynamic mechanical analysis (DMA) studied the influence of P-MA on viscoelasticity of GRE. Fiber push-in test and three-point-bending test were used to evaluate the influence of P-MA on the EP matrix/fiber interface strength and interlamilnar shear strength, respectively. In addition, nanoindentation test was used to study the hardness and Young's modulus of EP matrix. The above results showed that the addition of P-MA did not affect the hardness of epoxy matrix and interfacial strength (epoxy matrix/glass fiber). The influence of P-MA on thermal stability of GRE was studied by thermalgravimetric analysis (TGA). These results would be very important in designing new generation multifunctional epoxy-based composite materials. [ABSTRACT FROM AUTHOR]

Electrospun glass nanofibers (EGNFs) are emerging fillers to improve mechanical properties of polymer matrix composite materials. However, questions concerning their reinforcing effectiveness in comparison with other nanoscale fillers such as glass/silica nanoparticles (GNPs) are still to be answered because reinforcing mechanisms for conventional fiber reinforced polymer composites might not be applicable at distinctive nanometer scale. Herein a comparative study on reinforcing effect of EGNFs and their conventional counterpart GNPs was carried out for the first time. Four types of glass nanofillers, including pristine EGNFs and GNPs as well as amino surface-functionalized EGNFs and GNPs were investigated to make epoxy matrix nanocomposites at ultra-low loading level (≤0.5 wt%). Mechanical properties of these glass nanofiller reinforced epoxy composites were investigated and corresponding reinforcing and toughening mechanisms at nanometer scale were discussed. Due to shape factor (aspect ratio), EGNFs demonstrated much more pronounced reinforcing and toughening effectiveness and completely outperformed GNPs in all cases despite much lower specific surface area. This research provided meaningful data to fully understand the merit of EGNFs as reinforcing filler in polymer nanocomposites and paved the road for designing and modeling next-generation polymer matrix composite materials. [ABSTRACT FROM AUTHOR]

This work describes the study to investigate and compare the mechanical and thermal properties of raw jute and glass fiber reinforced epoxy hybrid composites. To improve the mechanical properties, jute fiber was hybridized with glass fiber. Epoxy resin, jute and glass fibers were laminated in three weight ratios (69/31/0, 68/25/7 and 64/18/19) respectively to form composites. The tensile, flexural, impact, density, thermal and water absorption tests were carried out using hybrid composite samples. This study shows that the addition of jute fiber and glass fiber in epoxy, increases the density, the impact energy, the tensile strength and the flexural strength, but decreases the loss mass in function of temperature and the water absorption. Morphological analysis was carried out to observe fracture behavior and fiber pull-out of the samples using scanning electron microscope. [ABSTRACT FROM AUTHOR]

The mutual exclusiveness between strength and toughness restricts the engineering application of glass fiber/epoxy composites requiring both high strength and suitable toughness. Inspired by natural nacre, a hetero-structural montmorillonite−multiwalled carbon nanotube (Mt−MWCNT) hybrid was coated on the curved surface of glass fibers to construct a nacre-like interface layer, consisting of Mt as "brick", MWCNTs as "anchor" and initial epoxy resin as "mortar". MWCNTs were employed for guaranteeing the effective separation of Mt nanosheets and strong interfacial interactions among the Mt, matrix and fiber. The enhanced dispersion degree of Mt−MWCNT hybrids and strongly bonded interface layer were established, and synergistic effects of Mt and MWCNTs on the strength and toughness of composites were also demonstrated. Compared with pure glass fiber/epoxy composite, interlaminar shear strength and work of break of resulting composites were improved by approximately 28% and 189%, respectively; meanwhile, such composite exhibits higher storage modulus in the glassy region and superior thermal stability. This work demonstrates a practical and effective strategy for fabricating high-performance yet low-cost fiber-reinforced composites through the nature-inspired interface. [Display omitted] • A nacre-inspired interface layer consisting of Mt as "brick", MWCNTs as "anchor" and epoxy resin as "mortar" was constructed. • A "Mt-MWCNTs/epoxy" interface layer was designed to efficiently reinforce GF/EP composites. • The simultaneous improvements in both strength and toughness were obtained for GF/EP composites. [ABSTRACT FROM AUTHOR]

The optimum condition of glass fiber/epoxy composites was investigated according to mixing ratio of two epoxy matrices. Novolac type epoxy and isocyanate modified epoxy were used as composites matrix. Based on chemical composition of mixing matrix, optimum mixing ratio of epoxy resins was obtained through FT-IR instrument. In order to investigate thermal stability and interface of epoxy resin, glass transition temperature was observed by DSC instrument, and static contact angle was measured by reflecting microscope. Change of IR peak and T g was conformed according to different epoxy mixing ratios. After fabrication of glass fiber/epoxy composites, tensile, compression, and flexural properties were tested by UTM by room and high temperature. The composites exhibited best mechanical properties when epoxy mixing ratio was 1:1. [ABSTRACT FROM AUTHOR]

Inspired by biological systems in which damage triggers an autonomic healing response, a polymer composite material that can heal itself when cracked has been developed. In this work, compression and tensile properties of a self-healed fibre reinforced epoxy composites were investigated. Microencapsulated epoxy and mercaptan healing agents were incorporated into a glass fibre reinforced epoxy matrix to produce a polymer composite capable of self-healing. The self-repair microcapsules in the epoxy resin would break as a result of microcrack expansion in the matrix, and letting out the strong repair agent to recover the mechanical strength with a relative healing efficiency of up to 140% which is a ratio of healed property value to initial property value or healing efficiency up to 119% if using the healed strength with the damaged strength. [ABSTRACT FROM AUTHOR]

This study investigates the thermal barrier efficiency of five commercially available ceramic nano and micro particles deposited on the surfaces of glass fibre-reinforced epoxy composites (GRE). Two approaches of application of deposition of ceramic particles have been undertaken, firstly where the ceramic particles were dispersed in a phenolic resin binder and applied on a GRE surface by a K-bar coater and the second where extra ceramic particles were sprayed on the first coating while the resin was partially cured to enable the surface to be completely covered by ceramic particles, leaving no resin exposed. The thermal barrier efficiency of these coatings was evaluated from the cone calorimetric parameters at incident heat fluxes of 35 and 50 kW/m 2 as well as from temperature gradient through the samples’ thicknesses, measured by inserting thermocouples on the exposed and back surfaces during the cone tests. The morphology and durability of the coatings to water absorption, peeling, impact and flexural loading were also studied. The results showed that the surface layers of all coated samples were uniform and there was a strong adhesion between the coating and the substrate. Moreover, they did not adversely affect the mechanical properties of GRE composite while improving the mechanical property retention of GRE composites after exposure to heat. [ABSTRACT FROM AUTHOR]

Mesoscale models have been successfully used to simulate impact on fabrics and composites at ordnance velocities. There are many advantages of the mesoscale models: 1) individual components of the model (e.g. yarns) can be easily tested to check if they capture the important physics of the problem, 2) the components of the model often have simple material models (e.g. a yarn is often linear elastic up to failure), and 3) a multi-tier validation with material and ballistics tests at meso- and macroscale levels can be performed. The authors have successfully developed mesoscale models for a glass fiber reinforced composite (S-2 glass fiber with epoxy resin) that were validated by unconventional composite tests (e.g., torsion, out-of-plane delamination). In this paper the models are exercised at impact velocities ranging from 2 to 5 km/s. The original material models have simple constitutive laws (linear-elastic and elasto-plastic) that, in principle, have limited validity for hypervelocity impact. Therefore, modifications are made to better model the high-rate behavior of the epoxy resin matrix. The simulation results capture complicated damage mechanisms that might provide insight into future experimental data. [ABSTRACT FROM AUTHOR]

Abstract: A multiaxial fatigue damage model for fibre reinforced polymer composite materials is presented. The model combines (i) fatigue-induced fibre strength and modulus degradation, (ii) irrecoverable cyclic strain effects and (iii) inter-fibre fatigue. The inter-fibre fatigue aspect is based on a fatigue-modified version of the Puck multiaxial failure criterion for static failure. The model is implemented in a user material finite element subroutine and calibrated against fatigue test data for unidirectional glass fibre epoxy. A programme of uniaxial fatigue tests on quasi-isotropic glass fibre epoxy laminates is presented for validation of the novel fatigue damage methodology. The latter is successfully validated across a range of stress levels. [Copyright &y& Elsevier]

Abstract: Within this work the ablation behaviour of both carbon and glass fibre reinforced epoxy resin was assessed when ablated by a nanosecond-pulsed laser source emitting radiation in the ultra-violet spectrum. The investigation focussed on the influences of pulse overlap, focus spot diameter and resulting fluence on process quality and machining time.Results showed that ns-pulsed UV-lasers are capable of machining both types of fibre reinforced composites, while achieving good quality surfaces without burn marks or otherwise heat-damaged areas. [Copyright &y& Elsevier]

Abstract: The effects of halogen-free flame retardants (FR) such as intumescent ammonium polyphosphate (APP) and melamine cyanurate (MC) on the flammability and mechanical properties of epoxy/glass fiber composite systems were studied. Overall, intumescent APP shows better flammability results compared with MC. The composite with 5vol.% APP performed sufficiently well in the UL-94 test and LOI, whereas 20vol.% MC is required to achieve similar results. The addition of 1vol.% MC into 4vol.% APP had shown some improvement on the composite flame resistance. The composite attains the maximum flexural strength at 15vol.% while the dynamic mechanical analysis shows that the addition of flame retardants increased the storage modulus but did not change the glass transition temperature Tg . [Copyright &y& Elsevier]

Abstract: Bi-directional and chopped E-glass fiber reinforced epoxy composites are fabricated in five different (15, 20, 25, 30 and 35) wt% in an epoxy resin matrix. The mechanical characterization of these composites is performed. The three body abrasive wear behavior of fabricated composites has been assessed under different operating conditions. Abrasive wear characteristics of these composites are successfully analysed using Taguchi’s experimental design scheme and analysis of variance (ANOVA). The results obtained from these experiments are also validated against existing microscopic models of Ratner-Lancaster and Wang. It is observed that quite good linear relationships is held between specific wear rate and reciprocal of ultimate strength and strain at tensile fracture of these composites which is an indicative that the experimental results are in fair agreement with these existing models. Out of all composites fabricated it is found that tensile strength of bi-directional E-glass fiber reinforced composites increases because of interface strength enhancement. Chopped glass fiber reinforced composites are observed to perform better than bi-directional glass fiber reinforced composites under abrasive wear situations. The morphology of worn composite specimens has been examined by scanning electron microscopy (SEM) to understand about dominant wear mechanisms. [Copyright &y& Elsevier]

Abstract: A new radiation-resistant epoxy resin system was developed that has low viscosity and long working time at 45°C. The system consists of triglycidyl-p-aminophenol (TGPAP) epoxide, isopropylidenebisphenol bis[(2-glycidyloxy-3-n-butoxy)-1-propylether] (IPBE) epoxide and diethyl toluene diamine (DETD). Boron-free glass fiber composites of epoxy resin with different ratio of TGPAP/IPBE/DETD were prepared by vacuum press impregnation. The ratio of TGPAP/IPBE affected the working time and the viscosity at the impregnation. The mechanical properties of the composites at 300K and at 77K were measured before and after 60Co γ-ray irradiation of 1MGy at ambient temperature. The γ-ray radiation scarcely affected the properties of the composites. [Copyright &y& Elsevier]

Abstract: Bamboo fiber reinforced epoxy matrix composites filled with different weight proportions of red mud (a solid waste generated in alumina plants) are fabricated. The mechanical properties of these composites are evaluated and are then compared with those of a similar set of glass–epoxy composites. The solid particle erosion characteristics of the bamboo–epoxy composites have been studied and the experimental results are compared with those for glass–epoxy composites under similar test conditions available in the published literature. For this, an air jet type erosion test rig and Taguchi orthogonal arrays have been used. The methodology based on Taguchi’s experimental design approach is employed to make a parametric analysis of erosion wear process. This systematic experimentation has led to determination of significant process parameters and material variables that predominantly influence the wear rate of the particulate filled composites reinforced with bamboo and glass fiber, respectively. The comparative study indicates that although the bamboo based composites exhibit relatively inferior mechanical properties, their erosion wear performance is better than that of the glass fiber reinforced composites. It further indicates that the incorporation of red mud particulates results in improvement of erosion wear resistance of both the bamboo and glass fiber composites. [Copyright &y& Elsevier]

Abstract: The term “self-sensing composites” is sometimes used to describe the case where the reinforcing glass fibres in advanced fibre-reinforced composites are used as the sensors for chemical process-monitoring (cure monitoring). This paper presents conclusive evidence to demonstrate that reinforcing E-glass fibres can be used for in situ cure monitoring. The cure behaviour of an epoxy/amine resin system was compared using evanescent wave spectroscopy via the reinforcing E-glass fibres and conventional transmission Fourier transform infrared spectroscopy. This paper also reports for the first time that evanescent wave spectroscopy via E-glass fibres can be used to detect the presence of silane coupling agents. Preliminary results indicated that the cure kinetics on the E-glass fibre surface, as observed using evanescent wave spectroscopy, were influenced by the silane coupling agent. [Copyright &y& Elsevier]

• Epoxy/vinyl ester interpenetrating polymer network showed a significant improvement in the mechanical performance of GFRP composites w.r.t. GE and GVE composites. • The highest creep resistance of the GEVIPN composite was observed at a reference temperature of 30 °C. GEVIPN composite exhibited superior flexural performance at 30 °C but showed poor properties at 90 °C, over GE and GVE composites. GEVIPN composite exhibited a better damping ability as compared to GE and GVE composites. • Interfacial strengthening and weakening mechanisms of experimented composites are demonstrated. Fiber reinforced polymer (FRP) composites have become promising materials of modern times and find numerous applications in critical engineering fields including aerospace, marine and automobile sector. Due to their increasing demand, it becomes apparently essential to employ advanced techniques, which can predict the long-term behavior of such materials in various in-service conditions. Epoxy and vinyl ester based composites are most commonly used in structural FRP composites. As each polymer has its own advantages and disadvantages, hybridization or blending of different polymers is a trending technology to improve the performance of resulting FRP composite. The present article aims at comparing the performance of glass fiber reinforced epoxy-vinyl ester interpenetrating polymer network (GEVIPN) composite with that of the base materials, i.e. glass fiber reinforced epoxy (GE) and glass fiber reinforced vinyl ester (GVE) composites. Flexural testing has been conducted at various in-situ temperatures (30 °C, 60 °C and 90 °C) where GEVIPN composite showed highest properties at 30 °C. The lifetime prediction of the composite materials has been carried out using accelerated deformation and time-temperature superposition (TTSP) principle. It was observed that GEVIPN composite showed highest creep resistance as compared to the other two composites at lower temperature, whereas opposite trend was observed at elevated temperature. At 30 °C, GEVIPN composite showed positive reinforcement efficiency for ∼385 days with respect to GE and ∼46.27 years with respect to GVE. Similar studies were done for the other reference temperatures. Following this, fractography analysis of the fractured surface was done under FESEM to identify the failure mechanisms and draw a comparison between the composites. [Display omitted] [ABSTRACT FROM AUTHOR]

• Glass fiber forest was developed on the fabric surface by simple brushing and abrading. • The fabric surface brushing increased the fracture toughness of the composite. • Increase in toughness occurred due to fiber bridging caused by the glass fiber forest. • Increase in toughness due to abrading is strongly dependent on the fiber strength. To increase the interlaminar fracture toughness of the glass fiber/epoxy composite, a glass fiber forest surface was developed on the surface of the glass fiber fabric, which acts as interleaf in the matrix of laminates. The glass fiber forest (GFF) was produced manually through a simple brushing and abrading of the glass fiber for 5 times, 10 times, 20 times and 30 times in both weft and warp direction of the glass fiber fabric. Due to developing of GFF surface, the mode I interlaminar fracture toughness G I of glass fiber epoxy composite was increased depending on brushing and abrading times. For 5, 10 and 20 times, increase in G I was about 13.76%, 14.43% and 16.63%, respectively. While for 30 times brushing, G I increased up to it's highest value of 22.61% with a moderate loss of about 25.585% in the in-plane tensile strength. Observation of the surface highlighted that glass fiber forest formed on the fabrics developed a 3-D fiber network in matrix between the laminates region. Mechanism analysis showed that increase in toughness occurred due to fiber bridging caused by the glass fiber forest implanting in fabrics, presenting same through-thickness reinforcing mechanism. [ABSTRACT FROM AUTHOR]

Fiber fracture is a major contributor for the initiation of failure in fiber-reinforced polymer composites. The purpose of this study was to identify where damage occurs when a fiber fractures in a composite. Because this dynamic event occurs in less than 100 1ns, obtaining experimental evidence has been prohibitively difficult. Here, we report a novel method using a model composite, comprised of a spirolactam-based mechanophore-functionalized epoxy resin with a single embedded glass fiber. The ductile epoxy matrix is loaded under tension, which transfers load through interfacial shearing to the embedded brittle fiber, causing the fiber to break into segments. Fluorescence lifetime imaging microscopy (FLIM) is used to visualize regions of mechanophore activation and quantify changes in the dye's local environment such as relaxations on the nanosecond timescale. FLIM of these single fiber fragmentation test (SFFT) samples reveals localized damage zones in the epoxy matrix, not only at the point of fiber fragmentation, but also at distances remote from the fracture site that extend radially into the matrix up to two fiber diameters. The average mechanophore lifetime in the bulk epoxy is (1.5 ± 0.5) ns and in the damage regions is (0.75 ± 0.15) ns. This new data reveals the existence of polymer matrix yielding, which occurs during the fiber fracture event, and agrees with a dynamic model that predicts yielding behavior in the matrix during fracture. These results suggest that the damage from fiber fracture is more extensive than previously recognized. This new approach can be used to elucidate damage in other mechanical tests. The subsequent insights into composite damage mechanisms promises to dramatically accelerate the development of tough, durable, and damage tolerant composites. [ABSTRACT FROM AUTHOR]

This study aims to provide an algorithmic solution to create convertible products, which is then used to fabricate composite components. The shortest optimization path is adapted to this specific conversion problem. The first task was consecutive subcritical water processing and enzymatic hydrolysis optimized by response surface methodology, whereas the second task focused on lignin added composite material to fabricate reinforcement composite and reduce resin rate. The maximum fermentable sugar amount was obtained as 310.9 g/kg under the optimized conditions of 150 bar, 150.9 °C at a flow rate of 8 ml/min for 45 min. Subsequent to subcritical water extraction, remaining solids were processed with enzymes to breakdown cellulose for conversion into simple sugars that can be fermented into biofuels and chemicals, where the highest sugar concentration of 429.45 g/L was reached. Finally, lignin was mixed with epoxy resin at 3 different ratios to fabricate lignin-based glass fiber reinforced composite material. • Subcritical water process was optimized for fractionation of spruce into fermentable sugars and lignin. • Lignin was mixed with epoxy resin to fabricate lignin-based glass fiber reinforced composite material. • The lignin added at low ratios provided increased ductility and strength. • The reversible state was observed by the increase of the lignin ratio in the epoxy. • Lignin-based composite material can be utilized for manufacturing of wind turbine blades. [ABSTRACT FROM AUTHOR]