Search

The present work deals with analyzing the effect of silicon dioxide on mechanical and thermal stability of hybrid polymer composite. Compression molding is adopted to develop the hybrid composite with constant 0.5 wt.% of graphene and varying wt.% of silicon dioxide (2, 4 & 6 wt.%). Modified hummers method is used to synthesis graphene by chemical exfoliation of graphene from graphite flakes. Mechanical properties of developed composite is investigated using tensile, flexural, impact and interlaminar shear testing follow by fracture surface analysis of tested samples. Thermal stability is examined by thermogravimetric analysis and functional group confirmation is carried out using Fourier transform infrared spectroscopy (FTIR). Investigation over mechanical properties of fabricated composite reveals that addition of silicon dioxide up to 4 wt.% depicted higher flexural and tensile strength. Increment in silicon dioxide percentage improves the toughness of composite. FTIR results confirms the presence of asymmetric stretching vibrations due the after effect of hybrid fillers. Thermogravimetric analysis results depict that incorporation silicon dioxide increases the activation of energy of matrix from ~ 24.2 to 31.5 kJ/mol. [ABSTRACT FROM AUTHOR]

To simultaneously endow thermal conductivity, high glass transition temperature (Tg) and healing capability to glass fiber/epoxy (GFREP) composite, dynamic crosslinked epoxy resin bearing reversible β-hydroxyl ester bonds was reinforced with boron nitride nanosheets modified glass fiber cloth (GFC@BNNSs). The in-plane heat conduction paths were constructed by electrostatic self-assembly of polyacrylic acid treated GFC and polyethyleneimine decorated BNNSs. Then, the GFC@BNNSs were impregnated with the mixture of lower concentration (3-glycidyloxypropyl) trimethoxysilane grafted BN micron sheets, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate and hexahydro-4-methylphthalic anhydride, which accounted for establishing the through-plane heat transport pathways and avoiding serious deterioration of mechanical performances. The resultant GFREP composite containing less boron nitride particles (17.6 wt%) exhibited superior in-plane (3.29 W·m−1·K−1) and through-plane (1.16 W·m−1·K−1) thermal conductivities, as well as high Tg of 204 °C (Tg of the unfilled epoxy=177 °C). The reversible transesterification reaction enabled closure of interlaminar cracks within the composite, achieving decent healing efficiencies estimated by means of tensile strength (71.2%), electrical breakdown strength (83.6%) and thermal conductivity (69.1%). The present work overcame the disadvantages of conventional thermally conductive composites, and provided an efficient approach to prolong the life span of thermally conductive GFREP laminate for high-temperature resistant integrated circuit application. [ABSTRACT FROM AUTHOR]

This paper presents a study regarding the obtaining, characterizing and mechanically testing a new laminar composite material, consisting of epoxy resin reinforced with basalt plain fabric. The composites were obtained by manual lay-up, cross-link stage being developed by pressure molding in a hydraulic press. Rectangular plates were obtained and cut into samples with specific shapes, for the mechanical tests (tensile, three-point bending and compression). After testing, the fracture zone was analyzed using optical microscopy to observe the behavior of the composite following the mechanical stresses applied (fracture mechanism, voids presence and fiber delamination identification). Due to the low costs and non-hazardous nature, basalt fibers can be a serious competitor in the production of laminar composites that could successfully replace ordinary glass fiber composites. The mechanical properties in tensile, three-point bending, and compression of epoxy-resin-impregnated basalt fiber composites are comparable and even exceed those of widely used epoxy-resin-impregnated fiberglass composites. [ABSTRACT FROM AUTHOR]

Frontal polymerization (FP) is a self-sustaining reaction that relies on polymerization exothermicity and heat transfer. This study explores the inplane and in-depth FP mechanisms of continuous fiber-reinforced epoxy composites. First, the effects of initiator and diluent concentrations on the FP behaviors of neat epoxy resins were examined. It was found that the frontal velocity and frontal temperature of the neat resins increase with an increase of either the initiator concentration or the diluent content, depending on the polymerization enthalpy and curing kinetics. Then, the FP behaviors of continuous carbon fiber and glass fiber-reinforced epoxy woven composites were investigated. The results showed that the in-plane FP behavior of the composites was primarily controlled by the thermal conductivity and specific heat capacity of the continuous fibers, whereas the in-depth FP behavior mainly depended on the pores of the woven fabrics. Highlights • Frontal velocity and temperature of neat resins are controlled by the polymerization enthalpy and curing kinetics. • The in-plane FP behavior of continuous fiber reinforced composites is dependent on the thermal conductivity and specific heat capacity of the fibers. • The in-depth FP behavior of composite is determined by both the thermal conductivity of fibers and the pores of fabrics. [ABSTRACT FROM AUTHOR]

In this study, we compare the effect of various precursor‐based graphene oxide (GO) nanofillers on enhancing the mechanical performance of E‐glass fiber‐reinforced epoxy resin composites (EGFPs). GO derived from bituminous coal (BC‐GO) and graphite (Gr‐GO) were dispersed into an epoxy resin matrix. The resulting mixture was combined with E‐glass fiber mats using vacuum‐assisted resin infusion molding. Notable improvements (38.9% in flexural strength, 22.9% in tensile strength, and 21.6% in impact strength) were observed in BC‐GO‐reinforced EGFPs at 0.25 phr loading of BC‐GO. The improvements for Gr‐GO‐reinforced EGFPs were 28%, 9.3%, and 6.8%, respectively. XRD analysis of BC‐GO showed a diffraction peak at 2θ = 20.9°. Except for this peak, no other crystalline peaks were observed when BC‐GO was incorporated into EGFPs. FTIR spectra of both composite samples, with or without the nanofiller, were similar due to the spectral peaks overlap. TEM demonstrated the exfoliated morphology of BC‐GO in EGFPs. These findings underscore the potential of BC‐GO as a cost‐effective reinforcement for polymer nanocomposites across various industrial applications, including the development of lightweight and strong materials for aerospace and automotive industries, protective coatings, petroleum, and aerospace production systems. Highlights: BC‐GO demonstrates superior mechanical performance compared to Gr‐GO in EGFPs.0.25 phr BC‐GO improves 38.9% flexural, 22.9% tensile, and 21.6% impact strengths.Beyond 0.25 phr, BC‐GO and Gr‐GO showed a decline in mechanical enhancement.Role of particle size, loading & adhesion to matrix analyzed using XRD, FTIR, and DLS.Coal‐GO is an attractive alternative nanofiller for EGFPs. [ABSTRACT FROM AUTHOR]

Fiber-reinforced polymer composites are manufactured using various methods, with vacuum-assisted resin transfer molding (VARTM or VARIM). This study's primary focus lies in assessing how the orientation of sampling impacts the mechanical properties of glass fiber-reinforced pure and nanocomposites. 2 wt.% nano Al2O3- doped and non-doped composites were produced using the VARTM process. Tensile, flexural, and density test specimens were extracted from three distinct zones and two distinc direction those aligned horizontally to the resin flow (HRF) and those oriented vertically to the resin flow (VRF). Remarkably, results showed up to a 3.91% increase in values from samples in the third zone, particularly on the vacuum outlet side. To facilitate precise stress value comparisons across plates, uniform sample orientation and consistent zone selection are essential. [ABSTRACT FROM AUTHOR]

Composite materials made up of polymer matrix reinforced with synthetic fibers have gained popularity of late owing to their enhanced mechanical properties. However, very little work is reported to date on metals being used as filler material. Research gaps were obtained pertaining to the use of metallic fillers in synthetic fiber reinforced polymer composites. This paper demonstrates an attempt to fabricate composites made of Epoxy polymer matrix and E-glass fiber reinforcement with Mild Steel in its powdered form as fillers. Composites are prepared in varying weight percentages of the filler in the order of 2 wt. %, 4 wt. % and 6 wt. %. Hand layup method is employed for fabricating these composites which are later subjected to compression. Further, the samples are machined according to ASTM D3039 standard for tensile test and ASTM D256 standard for Izod impact test. Hardness test is also performed using a Shore D Durometer and these properties are compared with the unfilled samples. The results indicated that the weight percentage of the filler clearly influenced the mechanical properties of the developed composites. This study also revealed that the hardness and tensile strength of these composites improved with the incorporation of fillers up to 2 wt. % whereas, the impact strength improved up to 4 wt. %. Thereafter, there was a decline in their impact and tensile properties. However, hardness marginally increased beyond 4 wt. %. This area is open for research with regard to their usability under tribological, high temperature or magnetic conditions. [ABSTRACT FROM AUTHOR]

Glass fibers (GFs) are frequently employed as reinforcement fibers for polymer resins such as epoxy and polyester. The mechanical behaviors of GFs polymer composites are nevertheless constrained by weak interfacial adhesion between polymer matrix and GFs. Herein, we invented a cross‐linking modified sizing agent using polyethyleneimine and bisphenol A epoxy emulsion, and studied the effect of cross‐linking extent on GF surface characteristics and GF/epoxy interfacial adhesion. The treatment of GFs with cross‐linking modified sizing agent facilitated the formation of interpenetrating polymer networks in composites for strengthening interface interaction. The results show that the modified GFs have a rough surface and improved interfacial adhesion with epoxy matrix. When sizing agents with cross‐linking extent of the 23.0%, the GF/epoxy composites show advanced interfacial shear strength (IFSS) and transverse fiber bundle tension (TFBT) strength. This work demonstrates that the cross‐linking extent of sizing agent could regulate interfacial adhesion, which is a facile and promising strategy in reinforcing glass fiber polymer composites. Highlights: Crosslink the sizing agent to enhance GF mechanical properties was reported.GF surface energy was enhanced and thickness of GF/epoxy interphase increased.IFSS and TFBT strength of the GF/resin composites increased by 23.65% and 30.54%, respectively. [ABSTRACT FROM AUTHOR]

Glass fiber‐reinforced polymer‐matrix (GFRP) composites are used to manufacture devices such as radomes, electrical insulators, and radar‐absorbing structures, many of which are used in applications with strict mechanical and dielectric property requirements. As such, designs and properties of GFRP composite materials should be regularly improved to guarantee their safe operation and meet their constantly evolving application requirements. In this study, glass fiber (GF) particles and epoxy resin 128 (EP‐128) were used to manufacture high‐performance EP/GF‐X composites with GF particle contents ranging from 5% to 40%. An investigation into their mechanical and dielectric properties revealed that EP/GF‐20 composite specimens presented the best mechanical performance with their bending strength and modulus reaching 159.68 MPa and 6521.92 MPa, respectively, and an average dielectric constant of 4.862 within the 10–105 Hz frequency range. A theoretical analysis of the EP/GF‐X composite specimens' dielectric constants using classic dielectric models based on the Lichtenecker, Bruggeman, Jaysundere‐Smith, and Maxwell‐Garnett rule‐of‐mixture equations indicated that the dielectric model based on the Bruggeman rule‐of‐mixture equation provided the dielectric constants closest to the measured values with a maximum deviation of less than −0.321% for EP/GF‐40 composites. This study provides a feasible strategy to control the mechanical and dielectric properties of GFRP composites. Highlights: Glass fiber (GF) particles and epoxy 128 (EP‐128) resin were used to manufacture high‐performance glass fiber‐reinforced epoxy (EP/GF‐X) composites.The composite manufacturing process was carefully controlled to ensure uniform distribution and orientation of GF particles in the EP‐128 resin.The mechanical and dielectric properties of the manufactured EP/GF‐X composites were effectively tailored by controlling the content and distribution of GF particles in the EP‐128 resin matrix.The dielectric constants of the EP/GF‐X composites were measured experimentally and predicted using various theoretical dielectric models.The Bruggeman model provided the dielectric constants of the EP/GF‐X composites closest to the measured values. [ABSTRACT FROM AUTHOR]

Due to the high interest in the use of glass/epoxy laminates in aerospace applications, aviation, and as cryogenic tanks, it is crucial to understand the behavior of composites under challenging environmental conditions. Polymer composites are exposed to low temperatures, including cryogenic temperatures, which can lead to the initiation of microdamage. This paper investigates damage initiation/accumulation and its influence on the properties of cross-ply woven glass fiber epoxy composites at low temperatures compared to room temperature conditions. To evaluate the influence of a low-temperature environment on the mechanical performance of glass fiber reinforced epoxy composite (GFRP) laminates, three types of test campaigns were carried out: quasi-static tensile tests and stepwise increasing loading/unloading cyclic tensile tests at room temperature and in a low-temperature environment (−50 °C). We demonstrated that the initial stiffness of the laminates increased at low temperatures. On the other hand, there were no observed changes in the type or mechanism of developed damage in the two test conditions. However, the reduction in stiffness due to the accumulated damage was more significant for the laminates tested at low temperatures (~17% vs. ~11%). Exceptions were noted in a few formulations where the extent of damage at low temperatures was insignificant (<1%) compared to that at room temperature. Since some of the studied laminates exhibited a relatively minor decrease in stiffness (~2–3%), we can also conclude that the formulation of matrix material plays an important role in delaying the initiation and formation of damage. [ABSTRACT FROM AUTHOR]

The effect of incorporation of micron sized aluminum trihydrate, multi‐walled carbon nanotubes, and graphene nano platelets into glass fiber reinforced epoxy matrix is investigated using dynamic mechanical analysis. The objective of the investigation was to develop polymer central core of high temperature low sag transmission conductor. The effect of individual and hybrid carbon fillers on the viscoelastic properties of the epoxy composites is investigated and discussed. The storage modulus of the glass reinforced epoxy increases by 20% at room temperature due to incorporation of carbon nanofillers. In glass transition region, the increase is higher between 40% and 60% and it varies up to 90% in the rubbery region. Key attributes of carbon filler addition are limited enhancement of storage modulus at room temperature, higher enhancement over glassy, glass transition, and rubbery regions. The carbon fillers extend the temperature range of the glassy region. The cross‐link density, filler efficiency, and degree of entanglement of fibers are estimated to understand the implications of the carbon fillers on the viscoelastic properties. The loss modulus peak of glass epoxy composite increases from 2800 to 3900 MPa with carbon fillers and the increase in glass transition temperature is 47°C. Incorporation of carbon fillers leads to increase of damping factor peak from 0.2 to 0.28. Cole–Cole plots have established the inherent heterogeneity of epoxy systems due to the presence of carbon fillers. Prediction models for storage modulus and damping factor have been proposed to highlight the influence of geometry and size of carbon filler. [ABSTRACT FROM AUTHOR]

To alleviate the environmental pollution caused by waste wind turbine blades and provide new ideas for recycling, the thermochemical characteristics of four basic components of composite materials commonly used in wind turbine blades were studied in this paper. Thermogravimetric experiments in different atmospheres and heating rates, and thermogravimetric‐infrared combined experiments were carried out. The results show that the reaction of epoxy resin and thermoplastic polyurethane was easy and deep in N2 and CO2. Except for glass fiber, the other three components showed different combustion characteristics in air. The maximum reaction rates and activation energy of resin‐based components in N2 increased with increasing heating rate. The pyrolysis products of the four basic components all contained CO2 and CO, and some aromatic substances could be generated during the thermal transformation of epoxy resin and thermoplastic polyurethane. It can be concluded that the thermal transformation properties of the basic components of the composite material of wind turbine blades can be used to treat the waste blades, making the resin as the matrix material undergo a thermal transformation reaction and recover the fiber. This is to effectively guarantee the green and sustainable development of wind power generation. [ABSTRACT FROM AUTHOR]

Over decades, composite materials have grown at a very steady rate, allowing them to progressively penetrate and conquer current markets. Modern composite materials in the materials world are reaching new heights by putting a firm foot in every single one of them. There is a market available that goes from a simple product that is utilised every day to an extremely sophisticated material. Attempts are made to comprehend the demands of the ever-expanding natural composite business by examining the current literature on diverse natural fiber-based composites. The conclusion is that by successfully fusing vegetable natural fibres with polymer matrices, the mechanical properties of the composite have improved in comparison to the matrix material. These filters are inexpensive, non-toxic, and simple to recycle. [ABSTRACT FROM AUTHOR]

In a multi-component system, the interfacial interactions between the various components trigger the behavior of the composite under external loading and thus determine the bulk properties of the material. In the present work, composite laminates made from TiO2 modified epoxy reinforced with glass fiber are subjected to thermal loading and the effort is made to analyze the interfacial interactions through the experimental values of storage modulus, loss modulus and tan delta. The loading of TiO2 nanoparticles in the epoxy resin is varied to also understand the effect of nanoparticle addition on the interfacial interactions through DMA. The addition of TiO2 nanoparticles helped to increase the storage and loss modulus by improving the rigidity of the polymeric chain. To understand the effect of varying the loading of TiO2 nanoparticles and to gauge the optimum wt.% addition of such nanoparticle, Tan delta, the degree of entanglement and the coefficient of the effectiveness of the nanofiller is found and the results indicate that the laminates successfully withstand the applied thermal load when the TiO2 loading is kept at 2 wt.%. This optimum nanoparticle loading wt.% is further validated through the adhesion factor which is found with the help of Tan delta values. [ABSTRACT FROM AUTHOR]

In the present work, the mechanical and morphological characterization of bamboo-glass fiber-nanoclay epoxy hybrid composites is carried out. Materials are prepared using a hand lay-up process with different wt.% of bamboo fiber, glass fiber, nanoclay, and epoxy. As per ASTM standards, fabricated composite laminates are cut and tested for tensile and flexural properties. The bamboo fiber epoxy composites (BFEC) display the tensile and flexural strength of 137 and 170 MPa, respectively. Hybrid composites, viz. bamboo-glass fibers epoxy composites (BGFEC), display improved tensile (180–240 MPa) and flexural (225 to 320 MPa) strengths compared to BFECs. Glass fiber epoxy composites (GFEC) display maximum tensile (265 MPa) and flexural (360 MPa) strengths among all the composites. Furthermore, the addition of nanoclay improves the tensile (by 6 to 8%) and flexural (by 8 to 10%) strengths of epoxy, BFEC, BGFEC, and GFECs. SEM analysis is conducted for fractured tensile specimens to understand the reasons for specimen failure. [ABSTRACT FROM AUTHOR]

The mechanical properties of composites produced without additives are limited by the matrix and fibers of constructed material. To increase the mechanical properties, micro or nano size particles can be added to the composite. In this study, A l 2 O 3 particles with a purity of 98% and a size of 0–50 μm were added to the epoxy material in the ratios of 1%, 2%, 3%, 4% and 5% by weight to optimize the parameter in order to enhance the mechanical properties of [110P/163 T/195T]s stacking sequenced woven composites. Tensile fatigue tests were performed with a computer-controlled fatigue test device with a 100 kN load cell, by applying R = 0.1 load ratio, 6 Hz frequency, and sine wave load form. Fatigue tests were conducted at different load levels. As a result, increase between 119%-2441% was observed in the fatigue cycle of micro- A l 2 O 3 reinforced woven composite materials compared to non-particles added epoxy woven composites. The highest damping rate was observed as 57.528 in 1% micro- A l 2 O 3 , and the lowest damping rate was observed as 26.312 in composite with no Al2O3 particles. The micro-structure morphologies of micro-Al2O3 reinforced woven composites were observed by SEM. [ABSTRACT FROM AUTHOR]

For commercial civil applications of laminated composite material, characterizations to forecast the interlaminar shear behavior and viscoelastic response across a wide temperature range are essential. In this study, the interlaminar shear strength (ILSS) of glass/epoxy (GE) composites dispersed with binary nanofillers nanosilica‐multilayer graphene (NS‐MLG) and nanosilica‐nanoclay (NS‐NC) was analyzed at an in‐situ testing temperature of 20, 70, and 110°C. Further, the viscoelastic property of the composites was studied using a dynamic mechanical thermal analyzer (DMTA) in the temperature range of 35–165°C. An increase in the ILSS value of around 9% and 10% was observed at room temperature for GE/MLG‐NS and GE/NC‐NS, respectively, compared to control GE composites. In contrast, the trend was seen to change at higher temperatures. There was a slight decrement in the storage modulus (E′) of GE/MLG‐NS and GE/NC‐NS composites in the glassy region compared to control GE composites. The mean Tg of the GE composite (control) was nearly 107.3°C when the E′ decline onset temperature was taken into account, but after the addition of MLG‐NS, it was 10.1°C below. The mean Tg of GE/NC‐NS was determined to be 106.3°C, and in the glass transition as well as rubbery regions, it was observed to compete with the E′ value of the control GE composites. Fractography was done using micrographs obtained from environmental scanning electron microscope (ESEM). Traces of polymeric material found at the fiber surface certified the improved interfacial adhesion between glass fiber and polymer in the matrix‐modified composite samples. [ABSTRACT FROM AUTHOR]

The intention of this research is to recapitulate the two different fillers like E glass fiber and nanocarbon fiber, which were utilized to fabricate the polymer matrix composites by the assistance of epoxy resin. The mechanical compression molding was influenced to produce the polymer-based nanocomposites under consideration of optimal process parameters. There are three different weight fractions E glass fiber (40%, 45%, and 50%), nanocarbon fiber (10%, 15%, and 20%), and epoxy concentrations (30%, 40%, and 50%), respectively, that were used to produce the polymer matrix composites. Those processing parameters were designed by the L9 Taguchi with DOE technique to conduct the mechanical tests like tensile strength and hardness properties. The signal-to-noise ratios were successfully accomplished to identify optimal process parameters for improving the individual responses. The ANOVA and interaction was additional supports to enhance the mechanical properties. The scanning electron microscope was used to examine the fracture surfaces at the tensile fracture specimens with optimal conditions. Moreover, the maximum mechanical characteristics were attained by the increasing of nanocarbon fiber in the processed polymer matrix composites. [ABSTRACT FROM AUTHOR]

In the current study, the nano-composites of unidirectional carbon and glass fiber reinforcedepoxy resin with multi-walled carbon nanotubes (MWCNTs) were separately prepared by hand lay-up and hot pressing of fiber epoxy prepregs. Three types of MWCNT derivatives (parentCNT, low carboxylated CNT (LCCNT) and higher carboxylated CNT (HCCNT)) were dispersed into the epoxy resin/fiber composites. The improved mechanical properties observed in the three component composites could be attributed to the uniform dispersion of CNTs in epoxy/ fiber matrices, nanosize of the additives and the improved interfacial interactions between the composite components. The COOH functional groups could also be effective in the increase of mechanical traits because they induce the amphiphilic nature into CNTs for better dispersion and to generate the better glass fiber/epoxy (E/G) and carbon fiber/epoxy (E/C) interactions. HCCNT led to the best mechanical properties among all the samples due to its higher carboxyl content. HCCNT also changed the curing peak of epoxy in DSC and improved its thermal stability. For instance, the final residual mass for E/HCCNT was 15.4% at 600 °C compared to 13.92% for the pure epoxy while the values of 17.55 and 16.48% were observed at 500 °C for E/HCCNT and epoxy, respectively. The observed effect of COOH functionality on the void formation within the composite and on the better CNT dispersion in the matrix can be considered as an important observation for investigating the E/C/CNTs nanocomposites. [ABSTRACT FROM AUTHOR]

Silicon fillers have recently been employed as a multifunctional material to improve polymer composites' dielectric strength and mechanical strength, widely used to fabricate high-performance structural components. However, the mechanical strength was altered by adding silicon filler particles, leading to machining challenges that caused issues with quality and surface characteristics due to brittle fracture of silicon particles and related damage. The silicon filler 0, 3, 5, and 10% filled polymer matrix glass fibre reinforced composite was fabricated, and then abrasive water jet machining was used to investigate the machinability of the fabricated composite by considering silicon concentration, water jet pressure (WP), standoff distance (ND), traverse speed (ST). The machinability of the composite was established for quality-affecting responses such as kerf taper angle (KTA) and surface roughness (Ra). Silicon-filled polymer composites exhibit a higher dielectric constant than epoxy-glass fibre composites. An increase in silicon filler fraction decreases the surface roughness (Ra) and kerf taper angle (KTA), specifically at 5% of silicon filler, resulting in better machining quality. In contrast, 10% silicon filler increases those two responses to a high level, resulting in lower usage in considered applications due to more direct interaction between silicon filler and garnet abrasive grains. Increasing water jet pressure (WP) and decreasing standoff distance (ND) and traverse speed (ST) improve the machinability of silicon-filled composites. An SEM study of the surface topography reveals smooth cutting and finishing at high water jet pressure (WP) and 5% silicon particles. [ABSTRACT FROM AUTHOR]

This paper presents the behavior of composite panels based on glass fiber unidirectional fabrics and a bi-component epoxy resin under ballistic impacts that characterize two threat levels: FB2 and FB3, according to EN 1523:2004. The tested panels had characteristics kept in narrow ranges: thickness 18.26 ± 0.22 mm, mass ratio fabrics/panel 0.788 ± 0.015, surface density 27.51 ± 0.26 kg/m2. After testing the panels, the failure mechanisms of the panel were evidenced by scanning electron microscopy and photographs. Here the authors present a finite-element model at meso scale that was used for evaluating if the composite, initially tested at level FB2 (9 mm FMJ, v0 = 375 m/s), could withstand the higher level of impact, FB3 (projectile type 0.357 Magnum and impact velocity of v0 = 433 m/s). Simulation was performed in Explicit Dynamics (Ansys), keeping the same target but changing the projectile for the two different levels of threat. The results of the simulation were encouraging for making tests at level FB3, indicating the importance of alternating actual tests with simulations in order to achieve better protection with reduced surface weight. The simulation illustrated differences in impact duration and number of layers broken on the panel for each level. Validation of the model was based on the number of broken layers and the dimension of the delamination zone between the last two layers. Scanning electron microscopy was used for identifying failure mechanisms at the micro and meso scale. We found that damage to the composite was intensively dependent on impact velocity, this being quantitatively evaluated using the number of layers broken, the effect of delamination on separating layers and the deformation of the last layer. [ABSTRACT FROM AUTHOR]

Glass fiber/polymer composites find extensive application in marine industry; however, the durability of theses marine structures has always been a matter of concern owing to their continuous exposure to harsh marine environment. The objective of this study is to consolidate and analyze the work that has been carried out so far, primarily focusing on the influence of the marine‐environment characteristics on water absorption and its subsequent impact on the mechanical properties of glass fiber reinforced composites. It is found that immersion time and operational temperature are the two prominent factors that influence the durability of these polymer composites. Moisture causes reversible changes such as plasticization and irreversible changes such as hydrolysis, cracking, and crazing which subsequently exerts a detrimental effect on the physical, chemical, and mechanical properties of epoxy resins. During the initial stage of water absorption, the moisture content increased rapidly with the immersion time, and then it increased slowly as the immersion time stretched until the moisture content in the specimen reached a saturation level. Prolong exposure in water not only led to a substantial deterioration in static mechanical properties; it also altered the mode of failure from a brittle matrix‐ductile fiber to ductile matrix‐brittle fiber. [ABSTRACT FROM AUTHOR]

The addition of fillers to polymer composites induces a positive influence on the mechanical and tribological properties of the hybrid composites. These properties can be validated for possible uses such as automobile, construction, shipping, aerospace, sports equipment, electronics, and biomedical domains. In the present research, epoxy matrix reinforced with nylon-6 fibers and glass fibers were prepared using the solution blend technique. Alumina nanoparticles are added as fillers to enhance the properties of epoxy hybrid composites. The large surface area of interaction of nanofillers exhibits better adhesion between matrix and fibers of composites, and it significantly affects the various properties of composites. The tribological characteristics of fabricated epoxy hybrid composites were evaluated under various parameters and conditions. The results revealed that the addition of nanofiller significantly reduces the wear loss of epoxy hybrid nanocomposites. The wear resistance of epoxy hybrid composites increased with increase in addition of nanofiller up to 1.0%, and it slightly decreased with the further addition of filler. The Taguchi analysis was carried out for the least coefficient of friction and specific wear rate. The analysis found that the specific wear rate and coefficient of friction mainly depend on load, followed by speed and nanofiller. The fractured and worn surface of Al2O3-filled epoxy hybrid composites was analysed using SEM. [ABSTRACT FROM AUTHOR]

Investigations into polymer composites are mainly focused on properties dependent on glass fiber reinforcement and particulate fillers. In the present study, the effect of the binder was examined. The specimens were produced with two types of epoxy resin, with similar numbers of glass mat layers and similar proportions of quartz powder added. However, one group was fabricated with an emulsion binder in the glass mats and another group with a powder binder. Attention was concentrated on the tribological properties of the as-prepared composites, though their strength was examined as well. The hardness of the Sikafloor matrix was found to be much more sensitive to the applied binder than that of the MC-DUR matrix. No direct correlation between the microhardness and the specific wear rate was observed and increasing the particulate filler proportion did not cause a direct increase of the specific wear rate. In particular, the highest specific wear rate, around 350 J/g, was reached for both matrices with a 1% quartz addition when the emulsion binder was applied, while in the case of the powder binder it was with 6% quartz with the MC-DUR matrix, and there was no quartz addition with the Sikafloor matrix. The highest microhardness, HV0.5 = 25, in turn, was reached for the mats with the emulsion binder in the Sikafloor matrix with an addition of 10% quartz powder, while the highest friction coefficient was exhibited in the composite with the MC-DUR matrix, when 1% of the quartz powder and the emulsion binder were applied. [ABSTRACT FROM AUTHOR]

To further improve the preparation efficiency and properties of bamboo fiber reinforced polymer composites (BFRPs) fabricated by the vacuum-assisted resin transfer molding (VARTM) process. Here, the bamboo fiber/glass fiber mesh reinforced polymer hybrid composites (BGRPs) were fabricated by VARTM to determine the effects of three fiber stacking sequences (namely, GBBGBBG, BGBGBGB, and BBGGGBB; B: bamboo fiber, G: glass fiber mesh) on the physical and mechanical properties, as well as void characteristics of BGRPs (i.e. BGRP-1, BGRP-2, and BGRP-3). The results showed that the incorporation of glass fiber meshes could shorten the injection time of epoxy resin and improve the mechanical properties of BFRPs. BGRP-1 exhibited the lowest water absorption (1.31%) and the highest shear strength (15.55 MPa). Glass fiber meshes on the surface and bottom of BGRP-1, respectively, served as buffer layers to retard mechanical damage, so that BGRP-1 had the best drop hammer impact properties. BGRP-2 represented the highest flexural strength and flexural modulus of 92.22 MPa and 6.69 GPa, respectively. The mechanical properties of BGRP-3 were inferior to those of BGRP-1 and BGRP- 2, and more voids were observed in the middle of BGRP-3 in micro-CT slices induced by inadequate epoxy resin impregnation on bamboo fibers. [ABSTRACT FROM AUTHOR]

The current study focuses on the investigation of the synergetic effect of graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs) on the flexural properties, hardness and water absorption characteristics of glass fiber reinforced polymer (GFRP) laminated composite materials. The laminated composite materials were fabricated with various configuration of filler reinforcements using vacuum assisted hand lay-up technique. Further, micromechanical analysis was performed using Halpin-Tsai model to investigate the synergistic effect of CNT/GNP hybrid glass fiber reinforced epoxy nanocomposites. It was observed that the CNT and GNP reinforced hybrid composite exhibited highest value of flexural strength and hardness; the respective values being 38% and 29% higher in comparison to the neat epoxy composite. Furthermore, among GNP and CNT, the composite containing former reinforcement exhibited better mechanical properties. The composites containing nanoparticles also exhibited better water uptake characteristic, where the weight gain for hybrid composite was 1.004%, whereas, for neat epoxy composite, the weight gain was 1.210%. This was attributed to the ability of nanofillers to restrict the intermolecular movement of the surrounding GFRP composites, which delays the relaxation of polymer chains, thereby reducing the diffusion of tiny molecules through the composites. It was also observed that the addition of GNPs has a strong effect on the elastic properties of the hybrid glass fiber reinforced epoxy nanocomposite than the addition of CNTs. [ABSTRACT FROM AUTHOR]

Today, advanced materials like fibrous composites are widely used in the industry due to their favorable strength-to-weight ratio, corrosion resistance and many other suitable properties. Buckling phenomenon may occur in a thin composite structure subjected to high compressive loads. Moreover, the buckling strength of polymer based composites such as glass/epoxy decreases due to sunlight radiation. In this research, the effect of adding zinc oxide (ZnO) nanoparticles as a reinforcement to the matrix material of glass/epoxy composite on the critical buckling load of the beam specimens is investigated experimentally. In addition, samples are exposed to simulated sunlight irradiation and the effect of adding nanoparticles is investigated. Rectangular composite beams are made and reinforced with 1 wt. % of ZnO nanoparticles. Beams are clamped under tensile testing machine for buckling test. Compressive load is applied to the beams in the longitudinal direction and force-displacement graphs are plotted. Results indicate that the addition of ZnO nanoparticles into the epoxy resin increases the critical buckling load of these beams. As the results show, the critical buckling load of ZnO reinforced glass/epoxy specimens increases by %39.4 with respect to that of glass/epoxy samples. Moreover, to investigate the effect of adding nanoparticles after sunlight irradiation, some samples were placed in the accelerated weathering system for 24 h. Buckling test results represent a remarkable increase in the amount of critical buckling load for ZnO/glass/epoxy specimens even after the irradiation. SEM images of the break section of ZnO reinforced glass/epoxy specimens illustrate homogeneous dispersion of ZnO nanoparticles in the epoxy resin. [ABSTRACT FROM AUTHOR]

The fabrication of carbon fiber‐reinforced polymer composites generates vast amounts of waste carbon fiber. In the present work, these waste carbon fibers were added in varying contents (0.1, 0.3, and 0.5 wt%) to glass fiber/epoxy (GE) composite as short carbon fibers (SCFs) to improve its ambient and elevated temperature mechanical performance. The flexural and tensile behavior of the SCF modified GE composites were assessed at 30, 50, 70, and 110°C. The most significant improvement in mechanical performance was achieved by adding only 0.1 wt% of SCF into GE composite across most of the temperatures. At elevated temperatures, all the SCF‐modified GE composites showed superior mechanical performance over the control GE composite. An important correlation between SCF content in GE composite and elevated temperature mechanical performance enhancement has been discussed. Differential scanning calorimetry was performed to understand the effect of SCF addition on GE composite's glass transition behavior. Fractography was conducted to study the various failure mechanisms at ambient and elevated temperatures. [ABSTRACT FROM AUTHOR]

The objective of the present work is to understand how the main constituents of sizing modify the interfacial strength, the mechanical properties of epoxy composites as well as their durability. In this study, two model interphases between E‐glass fibers and epoxy resin were designed and studied in terms of adhesion and mechanical strength from nano to macroscale. The first one is made from a reactive sizing of APTMS silane coupling agent and DGEBA pre‐polymer film‐former. The other one contains a non‐reactive MTES silane and neutralized DGEBA film‐former. The sizings were evidenced by SEM/AFM observations and XPS spectroscopy. The characterization of the prepared composites by AFM nano‐mechanic mode, micromechanical tests revealed the effect of the sizing chemistry on the interfacial properties between glass fibers and matrix. The interfacial strength is more important for the composites reinforced with APTMS‐DGEBA sized fibers than those prepared with MTES‐BGEA sized fibers. In each case, an interphase area of around 200 nm width is detected at fibers vicinity. In this area, the elastic modulus is more than 25% lower than the bulk matrix modulus. [ABSTRACT FROM AUTHOR]

Natural fiber composites (NFC) exhibit good specific mechanical properties in comparison to synthetic fiber composites (SFC). The study investigates interlaminar glass (G) fiber hybridized jute (J) and flax (F) reinforced epoxy composites designated as JGGJ, GJJG, FGGF, and GFFG along with their virgin counterparts. Composite laminates of four plies are manufactured by hand-layup followed by compression molding to investigate tensile, flexural, and interlaminar shear properties. Further the effect of hybridization is also investigated for modal frequencies and damping ratio obtained from experimental modal analysis. Glass fiber hybridization as extreme layers shows significant improvement in flexural and shear properties as compared to tensile. Glass fiber reinforcement, as core layers improve the damping by 155.55% and 101.31% for JGGJ and FGGF, respectively, over pure glass epoxy. However with increase in bending stiffness of GJJG and GFFG, the bending modal frequency is improved. Also, the modal frequency and damping ratio increases following a power-law variation with a decrease in the free length. Finite element and analytical validations are presented to the experimental frequencies and flexural modulus, respectively. These studied hybrid composites can serve as semi-structural members like interior trim panels in automotive applications that possess significant strength and dissipate in-service vibrations effectively. [ABSTRACT FROM AUTHOR]

This study investigates the influence of reduced graphene oxide (rGO) coated glass fabrics on the strain sensing and the mechanical characteristics of fiber‐reinforced composites. Graphene oxide was applied in two thicknesses (threefold and fivefold coatings) onto a fabric using a padder mangle machine followed by thermal reduction and infused with an epoxy to manufacture rGO‐enhanced composite. The tensile modulus and flexural strength of the rGO‐enhanced composites with threefold coating were improved by 27% and 6.2%, respectively, compared with the equivalent composite manufactured without rGO. The normalized resistance (ΔR/R0) of composites increased by 0.89% and 3.48% under a cyclic tensile force of 1000 and 4000 N. The magnitude of ΔR/R0 was stable within 30 cycles suggesting a consistent strain sensing performance with a gauge factor of 15.55. The electrical response of the rGO‐enhanced composite was evaluated using a new industrial standard for sensors, by assessing calibration curves. The composite showed low hysteresis and low electrical viscosity which make these materials suitable for industrial piezoresistive strain sensors. [ABSTRACT FROM AUTHOR]

High performance glass fiber reinforced epoxy composites are in greater demand in several industrial applications, from civil structures to aviation industry. The epoxy has highly cross-linked structure and is found to be high performance polymer. Further, carbon nanofillers such as multi-walled carbon nanotubes (MWCNT), graphene nanoplatelets (GNP) and thermally stable microfiller aluminium trihydrate (ATH) are being used to improve the thermal properties. GNP and MWCNT posses high aspect ratio and specific surface area contributing to improvement in thermal properties of composites. In spite of this, there are difficulties connected with nanofiller addition, such as dispersion and interaction. The fabricated nanocomposites are based on ECR glass fiber and epoxy resin by adding GNP, MWCNT and ATH fillers using pultrusion process assisted by ultrasonication. For the purpose of comparison, composites containing only MWCNT, GNP and ATH were also tested. The XRD and SEM were used to study the fillers dispersion and interaction. The thermogravemetric analysis(TGA) was carried out to determine the thermal stability of composites. From the thermal analysis result, it is found that the epoxy-MWCNT-GNP-ATH composite has enhanced thermal stability due to the addition of ATH micro filler. [ABSTRACT FROM AUTHOR]

In sandwich composites, interfacial bonding between face sheets and core has to be strengthened to prevent debonding. In this work, sandwich composites with polyurethane core and glass fiber reinforced epoxy face sheets were prepared by vacuum infusion process. Chopped fibers of glass, carbon, and kevlar with length 12 mm were introduced between core and face sheets during fabrication in order to improve face‐core bonding. The influence of chopped fibers is investigated by testing flexural, compressive, shear, and fracture toughness properties of prepared specimens according to ASTM standards. Sandwich specimens with chopped glass fibers exhibited, superior interfacial bonding between the face and the core and hence improved the mechanical properties of sandwich composite. The chopped glass fiber embedded sandwich composite has an increased flexural strength of 32.77% and compressive strength of 21.43% when compared with plain sandwich composite. In addition, the shear strength and fracture toughness behavior of specimens with chopped glass fibers are superior when compared to other chopped fibers incorporated in the interfacial region. The interfacial region between skin and core was investigated using scanning electron microscopy (SEM). Chopped glass fibers in the interfacial region showed better adhesion property along with the epoxy. [ABSTRACT FROM AUTHOR]

Reinforcing fibers, nanofillers, matrix materials, and manufacturing techniques all have a role in the mechanical characteristics of hybrid composites. MWCNTs-reinforced E-glass/Kevlar/epoxy composites are appropriate fillers for structural applications. The impact of different concentrations of MWCNT fillers (0.4%, 0.8%, and 1.2% wt) on the mechanical characteristics of hybrid composites has been studied. Tensile and bending strength, as well as hardness, were measured in compression-molded composites. The effects of compression pressure, mold temperature, and applied pressure on hybrid (0.8% MWCNT) were investigated. When it came to composite tensile and bending strength, compression pressure was the most important factor, closely succeeded by mold temperature and pressure period. Compression molding were optimized, resulting in a tensile strength of 183 MPa, a bending strength of 158.3 MPa, and a hardness value of 23.8 HV. [ABSTRACT FROM AUTHOR]

Water invasion induced aging and degradation of the unidirectional glass fiber reinforced epoxy resin (UGFRE) rod is inferred as the primary reason for the decay-like fracture of the composite insulator. In this paper, the moisture diffusion processes in the UGFRE from different directions at various test humidities and temperatures are studied. The moisture diffusion of the UGFRE sample obeys the Langmuir diffusion law under the humidity conditions of 53%, 82% and 100% at 40 °C. In deionized water, the moisture diffusion of the UGFRE sample also obeys the Langmuir diffusion law when the invading direction is vertical to the glass fiber. However, when the water invades the UGFRE sample, parallel with the glass fiber, the weight loss caused by composite degradation should not be neglected. A modified Langmuir model, taking Arrhenius Theory and the nonlinear aging characteristic of the composite into consideration, is proposed and can successfully describe the moisture diffusion process. Both the glass fibers and epoxy resin will degrade in the deionized water. The glass fibers show better resistance to degradation than the epoxy resin. The epoxy resin degrades from the glass fiber/epoxy resin interface and become fragments. For composite insulators, the water invasion through the ends should be avoided as far as possible, or the degradation of the UGFRE rod will result in decay-like fracture. [ABSTRACT FROM AUTHOR]

The present study is focused on investigating the mechanical properties of hybrid polymer composites. The reinforcement materials are animal bone (ox) particulate and E-glass fiber. The matrix material is epoxy resin. The following combinations are considered for investigation: (a) bone particulate weight percent (20%, 30%, and 40%), (b) E-glass fiber weight percent (20%, 30%, and 40%), and (c) bone particulate (10%, 20%, and 30%) and E-glass fiber (30%, 20%, and 10%) with epoxy resin 60% by weight percent. The test specimens are prepared as per the required ASTM standard for tensile, compressive, and flexural tests. The test results show that maximum tensile and compressive strength observed in 40% of E-glass fiber with 60% of epoxy matrix, correspondingly, is 254.964 MPa and 37.52 MPa. The maximum flexural strength observed in E-glass fiber reinforced composites is 250.43 MPa. [ABSTRACT FROM AUTHOR]

Fiber reinforced polymer (FRP) composites possess excellent specific strength, specific stiffness and controlled anisotropy for which these are extensively used in various engineering applications, like automobile industries, aerospace industries, marine industries, space industries, electronics industries and many more. Glass fibers (GF), carbon fibers (CF) and aramid fibers (AF) are common reinforcements for polymer matrix composites (PMCs). High mechanical properties and wear resistance behaviour of glass fiber reinforced composites are the premises for the current experimental research on the effect of fiber orientation on the tensile strength of the polymeric composite materials. The glass fiber reinforced epoxy resin composite was prepared by wet lay-up method, followed by thermal treatment. [ABSTRACT FROM AUTHOR]

Effect of hybridization on dynamic mechanical properties of calotropis procera/glass fiber reinforced epoxy hybrid composites was investigated. The hand layup method was used to fabricate composites by varying fiber reinforcement of calotropis procera and glass fiber composition at 5, 10, 15, and 20 wt%. Dynamic mechanical analysis of composites was carried out in the temperature range of 25°C–180°C at the frequency of 1 Hz. Study revealed a marginal shift in glass transition temperature for fiber reinforced composites compared to neat epoxy which indicates the higher temperature resistance of the fiber reinforced composites. The higher interfacial bonding was revealed by the damping ratio analysis with the increase in glass fiber reinforcement in the hybrid composites. The hybrid composites exhibited increase in storage and loss modulus with increase in glass fiber content. Scanning electron microscopy was carried out to study the fracture surface morphology of the composite specimens. [ABSTRACT FROM AUTHOR]

In this study, a continuous glass fiber-reinforced composite is manufactured using the vacuum assisted resin transfer molding (VARTM) process. The composite is manufactured from an S-glass fiber acting as reinforcement and an epoxy resin as matrix. Unlike a traditional E-glass fiber reinforcement, S-glass fibers give higher stiffness and provide easier manufacturability due to the value of the refractive index of S-glass lying within the range of refractive indices of the epoxy resin. The epoxy resin is synthesized Epon 826, Epalloy 5200, and hexahydropthalic anhydride and tailored to match refractive indices of the S-glass fibers. After synthesis of the resin, composite panels are manufactured from the synthesized epoxy resin and S-glass fibers with a bi-directional [0°/90°] 8-harness satin weave. VARTM process was utilized to manufacture the composite panels. Composite panels are visually inspected for transparency, and tensile, flexural, and impact testing is performed. Mechanical tests showed consistent results for tensile modulus, tensile strength, flexural modulus, flexural strength, and impact damage resistance. [ABSTRACT FROM AUTHOR]

Surface tuned GO sheets are considered the opportune pothunter for the reinforcement of conventional glass fiber reinforced composites (GFRCs). Herein, we have tried to disseminate the effects of N-(2-Aminoethyl)-3-aminopropyltrimethoxysilane functionalized GO (GO-AEAPTS) and pristine GO sheets on thermo-mechanical properties of epoxy/glass fiber composites. Fourier Transform-infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), dynamic light scattering (DLS) and transmission electron microscope (TEM) were used to characterize the GO sheets. Multiscale composites integrated with GO-AEAPTS (1.5 wt%) provided maximum gain in all the studied properties i.e., interlaminar shear strength (ILSS), impact strength and thermal conductivity were improved by ~ 55, ~ 24 and ~ 70%, respectively. Storage modulus and glass transition temperature increased by ~ 44% and 14 °C, over the neat GFRC. In addition, GO-AEAPTS composites exhibited higher coefficient of effectiveness and crosslink density than those of GO counterparts. These property enhancements were credited to the homogeneous distribution of GO sheets, strong interfacial interactions (interfacial covalent interactions and hydrogen bonding) between GO-AEAPTS and epoxy resin as well as good fiber/matrix compatibility. Such multiscale composites with functional properties can outperform conventional counterparts with improved safety and reliability of structures and reduce maintenance costs. [ABSTRACT FROM AUTHOR]

The article discusses the fabrication, mechanical characterization, and heat resistance of nano ZnO‐TiO2‐filled glass fiber‐reinforced LY556 epoxy composites, with focus on the synergistic effect of ZnO and TiO2 nanofillers. The fabrication of the composite laminates is achieved by the addition of the nanofillers in different wt% ranging from 1 to 5 wt%. The composites are prepared using simple hand layup technique followed by curing under vacuum. The 3D atomic force microscopy scans indicated even distribution of the nanofillers up to 2 wt% loading. Severe agglomeration of the nanofillers is evident for 3 to 5 wt% loading. The surface roughness, microhardness, flexural strength, tensile strength, and impact strength of the composites indicate a relationship with dispersion, wt% loading, and the wettability of the nanofiller with the LY556. In general, it is found that the incorporation of hard nanofillers favored the improvement of impact strength to a greater extent compared to tensile and flexural strengths. Detailed analysis of the obtained mechanical property values favors an optimum 2 wt% incorporation of the selected nanofillers to obtain improvement in various strength values of the fabricated composites. The thermal stability of the fabricated composites improved through the incorporation of ceramic nanofillers. [ABSTRACT FROM AUTHOR]

In this study the experimental investigation of mechanical behaviour of Multi-Walled Carbon nanotubes (MWCNTs) and Aluminium Oxide (Al2O3) reinforced with EGlass/ Epoxy nanocomposites at 0.5%, 1.5% and 2.0% of weight rated with 225 GSM, 300 GSM and 450 GSM glass fibres were studied. Test specimens were prepared at the standardof ASTM D638 for tensile specimen ASTM D256 for impact specimen. Testspecimens were prepared at the ratio of MWCNTs: Al2O3 is 1:4. 1.5 wt. % of Multi- Walled CNTs filledE-Glass/Epoxy nanocomposites showed improved mechanical properties than glass fiber reinforced epoxy composites.450 GSM reinforced glass fiber epoxy composites containing 1.5wt. % of MWCNTs improved 36.27 % of higher tensile value and 28.57 % of impact value than the glass fibre reinforced epoxy composites. 225 and 300 GSM reinforced glass fibre epoxy composites with 1.5 wt. % of MWCNTs composites also has improved tensile and impact value than glass fibre reinforced epoxy composites. But, overall 450 GSM reinforced fibre nanocomposites showed enhanced mechanical properties than the other GSM reinforced nanocomposites. This proves Multi- Walled Carbon Nanotubes is a successful reinforcement for E-Glass/Epoxy matrix and it improves its properties and performance. [ABSTRACT FROM AUTHOR]