Neat Epoxy Research Articles

Synthesis and synergistic effect of cuprous(I) oxide nanoparticles and polyethyleneimine modified ammonium polyphosphate on enhancing the flame resistance of epoxy resin

Abstract In this study, cuprous(I) oxide nanoparticles (Cu2ONPs) and APP@PEI (polyethyleneimine-modified ammonium polyphosphate) materials were successfully synthesized and combined to create a flame-retardant system for the fabrication of epoxy (EP) resin with high flame resistance. The characteristic results revealed that the synthesized Cu2ONPs exhibited a particle shape with a size below 200 nm. The synthesized APP@PEI material possessed dimensions ranging from 10–20 micrometers, featuring a core–shell structure. The combination of Cu2ONPs and APP@PEI has proven to be an effective flame-retardant system, significantly enhancing the flame resistance of EP resin. The epoxy-based composite prepared with 2 wt% Cu2ONPs and 18 wt% APP@PEI demonstrated high flame resistance, achieving a V-0 rating (the highest rating according to the UL-94 method for evaluating the flame retardancy of materials) and a limiting oxygen index value of 36% (indicating the material’s self-extinguishing ability). This limiting oxygen index value was significantly higher than that of neat EP resin, which only reached 19%. The characteristic results of the flame-retardant epoxy-based composite demonstrated that both APP@PEI and Cu2ONPs were well dispersed in the EP resin and did not undergo structural transformation during the material preparation process. APP@PEI and Cu2ONPs enhanced the thermal degradation of EP-based composite materials at lower temperatures, exhibiting a faster degradation rate compared to EP resin. This augmentation facilitates the formation of a protective char layer on the surface of composite, thereby shielding it from direct flame exposure during combustion. Cu2ONPs played a role as oxidative catalysts, acting as Lewis acids. In addition to enhancing fire resistance, APP@PEI and Cu2ONPs have increased thermal conductivity, reduced impact strength, maintained tensile strength, and improved flexural strength of the composite material based on EP compared to neat EP resin.

Synthesis and properties of phenol/bisphenol A-liquefied Cryptomeria japonica wood-based epoxy resins and their glueability

Cryptomeria japonica Don. (Japanese cedar) was liquefied by a mixture of phenol and bisphenol A as the solvent under H2SO4 catalyst. The liquefied products could react with epichlorohydrin to prepare liquefied wood-based epoxy resin. The influence of different liquefied products on the properties of epoxy resins was investigated. GPC analysis showed that the average molecular weight of the liquefied woods and liquefied wood-based epoxy resins was between 864 and 1219, 1911 and 3450, respectively, with an increasing proportion of bisphenol A. DSC analysis illustrated that the isothermally cured resins could be further heated to promote post-cure. From DSC analysis, results showed that the enthalpy (ΔH) and the height of the exothermic peaks of LWER1, LWER2 and LWER3 resins were higher than those of the LWER4 resin, with the enthalpy of the LWER1 resin being the greatest. The latter can be attributed to the higher number of electron-withdrawing aromatic rings. TGA analysis showed that thermal degradation in all liquefied wood-based epoxy resins was different from the neat epoxy resin (ER), which indicated that the liquefied wood-based epoxy resins were a new copolymerized resin system. According to a glueability evaluation, the bonding strength of the phenol-liquefied wood-based epoxy resin (LWER1) was greater than that of the other resins. After a boiling water immersion test, the bonding performance of the phenol-liquefied wood-based epoxy resin (LWER1) was similar to that of the neat epoxy resin (ER). The results indicated that phenol-liquefied wood was a potential raw material for preparing BPA-free and biomass-based epoxy resins.

Experimental studies on thermal and FTIR characterisation of bio-degradable neat neem gum and epoxy resin for composite material applications

This article aims to assess the suitability of natural neem gum in various composite material applications in place of epoxy resin. The assessment was done by thermal characterisation, experimental study and comparative analysis of thermal behaviour, Fourier transform IR spectroscopy (FTIR) characterisation and comparison of functional groups and mechanical properties of neat epoxy and neat neem resins. To study and compare thermal behaviour differential scanning calorimetry (DSC), thermogravimetric (TG) and relative derivative TG (DTG) analysis were conducted. The glass transition temperatures, exothermic and endothermic peaks, curing of thermosetting epoxy and crystallisation of polymeric neem, value of % cure and mass change or mass loss concerning temperature of both the resins were experimentally determined and comparative analysis was conducted to find the suitability of neem resin in composite material applications in place of epoxy resin. Functional groups of neem gum were identified and mechanical properties such as bond strength, toughness, rigidity and ductility were characterised and compared with that of epoxy resin by conducting FTIR.

Experimental and numerical assessment of the flexural response of banana fiber sandwich epoxy composite

Recently, most service or product-oriented industries have been focusing on their activities to uphold the green and sustainable environment protocol owing to the increased environmental pollution. Concerning this issue, industries are now concentrating on developing recyclable or waste materials products. This research advocates developing and validating a banana fiber sandwich composite to promote the beneficial usage of bio-waste. The composite sandwich specimens were fabricated with resin-impregnated woven banana fiber mat as a skin, and the core was reinforced with three different weight percentages (5, 7.5 and 10%) of chopped banana fiber. The sandwich specimens were pressed into a three-point bending test to validate the structural integrity. The flexural characteristics like flexural strength and modulus were examined experimentally, whereas the key strength indices like flexural stiffness and core shear modulus were evaluated analytically. Post-fracture surfaces were studied through a scanning electron microscope to investigate the failure mechanism. The experimental and analytical results indicate that 10% banana fiber content in the sandwich core increases the flexural strength and flexural modulus to 225% and 147%, respectively, compared to the neat epoxy core. The numerical simulation was also performed through FEA to validate the experimental findings. The numerical results are in good concurrence with the experimental one.

A novel high-performance coating with hybrid nanofiller reinforcement for superior self-cleaning, anti-icing, and corrosion resistance properties

A novel self-cleaning superamphiphobic nanocomposite coating with excellent corrosion protection, anti-icing, and mechanical properties has been developed through the integration of hybrid graphene nanoplate (GNP) and silica nanoparticle (NS) reinforcement, coupled with surface modification using fluorinated particles and polydimethylsiloxane (PDMS). The GNP/NS hybrid nanofiller imparts superior corrosion barrier performance and mechanical strength to the coating. The surface modification led to impressive contact angles of 168° for water and 150° for hexadecane. While sliding angle consistently displayed less than 10° for both fluids, signifying the coating's exceptional superamphiphobic characteristics. The coating demonstrates exceptional anti-icing performance, with significantly delayed ice formation and reduced ice adhesion. Moreover, the coating exhibits remarkable stability and durability, even after long-term exposure to corrosive and harsh weathering environments. Electrochemical impedance spectroscopy (EIS) measurements confirmed the coating's superior corrosion resistance; the impedance plot of developed coating remained unchanged and exceeded 1010 Ω/cm2 across various exposure durations, whereas the neat epoxy started with a lower impedance value that progressively diminished over the exposure period. Tensile tests revealed a 75% increase in tensile strength, 63% improvement in failure strain, and an 11% increase in Young's modulus compared to the neat epoxy. Additionally, to comprehensively elucidate the mechanisms underpinning the developed nanocomposite coating, this study utilized a range of advanced analytical methods, including SEM, EDX, XRD, FTIR, and hardness tests. The developed nanocomposite coating shows promising potential as a reliable, long-lasting protective solution for metal structures in civil, mechanical, and aerospace engineering applications.

Surface-Modified Electrospun Glass Nanofibers from Silane Treatment and Their Use for High-Performance Epoxy-Based Nanocomposite Materials.

As a new and promising reinforcing filler, electrospun glass nanofibers (EGNFs) have attracted attention in the field of polymer composite materials. However, the reinforcing effectiveness of surface-modified EGNFs using different silane coupling agents in epoxy resin is still not quite clear. In this research, a series of silane coupling agents with increasing chain lengths in the order of methyl trimethoxysilane (MTMS), (3-aminopropyl) triethoxysilane (APTES), (3-glycidyloxypropyl) trimethoxysilane (GPTMS), and dual silane coupling agent APTES-GPTMS were employed to carry out surface treatment on the EGNFs. The pristine and silane functionalized EGNFs were then incorporated into epoxy resin as reinforcing fillers at low loading levels, i.e., 0.25 wt.%, 0.5 wt.%, and 1 wt.%, and the mechanical properties of the resultant epoxy nanocomposites, including strength, stiffness, ductility, and toughness, were evaluated. A commercial product of glass nanoparticles (GNPs) was used as a control to compare the reinforcing effectiveness of the EGNFs and the GNPs. This study revealed that the EGNFs could provide significant reinforcing and toughening effects at ultra-low loading (0.25 wt.%) in epoxy nanocomposite materials. Furthermore, surface modification of the EGNFs with silane coupling agents with long chain lengths, e.g., by using dual silane coupling agents, APTES-GPTMS, could enhance the interfacial bonding between the EGNFs and the epoxy matrix and further increase the mechanical performance of the EGNF-reinforced epoxy nanocomposite materials. Through this research, we realized epoxy nanocomposite materials with much-improved mechanical properties, i.e., 37%, 24%, 18%, 57% improvement in strength, stiffness, ductility, and toughness, respectively, with respect to those of the cured neat epoxy material with an ultra-low loading (0.25 wt.%) of APTES-GPTMS-EGNFs. Our research paves the road for developing lighter and stronger epoxy nanocomposite materials with EGNFs.

Mechanical and Sound Absorption of Rice Straw Fiber Reinforced Bio-Epoxy Composites for Lightweight Components in Rail Vehicles

The study explores the possibility of using rice straw fiber reinforced bio-epoxy composites as lightweight components for rail vehicles, which is in line with the current sustainability demands in transportation. The analysis covers various mechanical properties such as tensile strength, modulus and impact strength. Furthermore, the study focuses on testing the sound absorption coefficient of the composites, examining their ability to absorb sound energy across frequencies crucial for rail environments. The investigation also explores the effect of NaOH treatment on fiber-matrix compatibility, highlighting the ideal treatment parameters to prevent any unintended structural modifications. Despite having lower tensile strengths than neat epoxy, the composites display improved mechanical behavior and sound absorption properties. The study highlights the potential of these composites to contribute to sustainable rail solutions, promoting both performance and eco-conscious design. With their superior mechanical properties and sound absorption, these composites could lead to a shift in material preferences in the rail industry, paving the way for a sustainable paradigm in rail vehicle design.

Thermal degradation and flame spread characteristics of epoxy polymer composites incorporating mycelium

Although bioderived flame retardants are environmentally sustainable and less toxic, their impact on the thermal stability and flammability of polymers remains poorly understood. In this study, we assessed the influence of mycelium on the thermal stability and flame spread characteristics of epoxy through thermogravimetric analysis, Fourier transform infrared spectroscopy, the UL94 flammability test, and scanning electron microscopy. We observed a decrease in the maximum mass loss rate temperature when mycelium was incorporated into epoxy, indicating an earlier onset of thermal degradation. The inclusion of mycelium increased char yields above 418 °C due to mycelium’s inherent char-forming ability. However, mycelium did not alter the thermal degradation pathway of epoxy. Furthermore, according to the UL94 test results, the incorporation of mycelium reduced the flame spread rate compared to that of neat epoxy. These findings contribute to our understanding of the interaction between bioderived flame retardants and polymers paving the way for the development of more sustainable fireproofing materials.

Assessment of synthesis conditions on the corrosion inhibitive features of ZIF-67 MOF

Metal-organic frameworks (MOFs) have indeed attracted substantial interest owing to their distinctive features and diverse applications, such as corrosion protection. In this work, using two synthesis methods, namely co-precipitation (CZ67) and solvothermal (SZ67), a cobalt-based zeolitic imidazole framework (ZIF-67) was developed as an essential family of MOFs. The results of the characterization confirmed that ZIF-67 particles were synthesized successfully. According to the results of XRD, FE-SEM, TEM, ICP-OES, TGA, and BET analysis, the SZ67 has a higher surface area and higher stability in solution compared to CZ67. In addition, CZ67 and SZ67 were introduced in epoxy coatings to form CZ67/EPC and SZ67/EPC. The SZ67/EPC exhibited greater corrosion inhibition activity than the CZ67/EPC. After 24 h of exposure to the salty media, the|Z|at the low frequency for the scratched SZ67/EPC (119,500 Ω.cm2) reached 1.1 and 5.7 times of that for the CZ67/EPC and Neat epoxy coatings, respectively. Furthermore, SZ67/EPC demonstrated superior barrier anticorrosion properties during immersion for forty days. The corrosion protection and adhesion performance of SZ67/EPC surpassed the rest of the coated samples after salt spray exposure.

Constructing interfacial barrier from tribo-positive shell microcapsules to suppress space charge in thermochromic phase change composites for smart electronics

Thermochromic phase change composites (TPC) exhibit versatile functions under electrothermal stimuli, which are extensively applied as packaging, insulation and circuit components in considerable advanced smart electronics. However, space charge accumulation under DC voltages is still a critical and universal issue for the serious deterioration of functionalities and life-span of TPC and electronics. This study presents a novel strategy of suppressing space charge in thermochromic phase change epoxy composites (TPCE) by constructing interfacial barrier from tribo-positive shell thermochromic phase change microcapsules. The strong tribo-positive melamine-formaldehyde (MF) shell of microcapsules can establish negative charge barriers in the interfaces between microcapsules and epoxy matrix through triboelectrification, which is directly verified by Kelvin probe force microscopy. Pulsed electroacoustic measurement results exhibit the space charge accumulation in TPCE under an extreme electric field strength of 50 kV/mm and an elevated temperature of 70 °C can be significantly diminished by 39.3% compared to that of neat epoxy resin after incorporating merely 1 phr MF shell microcapsules, affirming the effect of interfacial barrier on space charge inhibition. The interfacial barrier could improve the charge carrier dissipation and mitigating the space charge accumulation as confirmed by hopping conduction analysis. Moreover, DC breakdown strength of TPCE can also be enhanced by 12.3% and 6.1% with 1phr microcapsules at 30 °C and 70 °C compared to that of neat epoxy resin owing to the suppressed space charge. The results provide a potential approach of designing high-performance thermochromic phase change composites for smart electrical and electronic devices.

Effect of Surface Modification on Corrosion Resistance, Mechanical and Electrical Properties of Epoxy Resin-Based Nanocomposites

The epoxy resin-based nanocomposites have been used to overcome the drawback of epoxy resin such as brittle, low impact resistance, poor stress cracking and poor corrosion resistance in the aggressive environment by incorporating inorganic nanoparticles into the high cross-linked structure of epoxy resin. However, the main problem of these composites is the agglomeration of nanoparticles which influences the worst dispersion in the epoxy matrix and leads to poor properties of the composite. Therefore, this work aims to study the effect of nanoparticle additions, i.e. ZrO2 nanoparticle and SiO2 nanoparticle including waste glass powder (WGP) which is an alternative inorganic filler, on properties of the epoxy resin-based nanocomposite. The particle surface of each filler was also modified with 3-glycidoxypropyltrimethoxysilane (GTPMS) in order to achieve better dispersion in the disk-shaped bulk composites. The chemical property of modified fillers was characterized by Fourier transform infrared spectroscopy (FT-IR). The physical properties, mechanical properties, water absorption and corrosion resistance of all composites are then investigated. The results revealed that the incorporations of ZrO2, SiO2, and WGP with GPTMS surface modification into epoxy resin-based nanocomposite exhibit better performance in mechanical properties, water absorption and corrosion resistance than the unmodified surface of ZrO2, SiO2, and WGP additions. Although, both modified- and unmodified surfaces of fillers for the epoxy resin-based nanocomposites show improvement in all properties compared to the neat epoxy resin but the electrical properties of epoxy resin-based nanocomposites with unmodified fillers and GPTMS-modified fillers do not show a significant effect on any electrical properties.

Compositional Influence of Synthesized Magnetic Nanoparticles on Epoxy Composites: Dielectric, Magnetic, and Optical Characteristics

Epoxy nano-magnetic composites exhibit remarkable and promising properties by synergistically combining the properties of epoxy resin and magnetic nanofillers. The current study deals with the synthesis of Fe3O4, NiFe2O4, and CoFe2O4 nanoparticles and their respective nanoparticles-doped epoxy composites, as well as the structural, optical, and dielectric characterization of the resultant nano-composites. To investigate the surface morphology of the synthesized nanoparticles, field emission electron microscopy (FESEM) analysis was employed. By measuring electron diffraction spectroscopy (EDS), the presence of various chemicals was verified. X-ray diffraction (XRD) was used to determine the structural details of the synthesized nanoparticles and nanoparticles-doped epoxy composites. The structural chemistry and surface functionality of the nano-epoxy composites were investigated using Fourier transform infrared spectroscopy (FTIR). The magnetic properties of the synthesized nanoparticles and nanoparticles loaded epoxy composites were also studied using a vibrating sample magnetometer (VSM). UV–visible reflection spectroscopy was also carried out to find the optical properties of the synthesized nanoparticles, neat (undoped) epoxy, and nanoparticles-doped epoxy composites. Dielectric spectroscopy measurements of nanoparticles-doped epoxy composites were performed using an Agilent E4980A precision LCR (Inductance Capacitance Resistance) meter with an Agilent 16451B-test fixture LCR and vector network analyzer (VNA) in the frequency span of 10 kHz to 2 MHz and 200 MHz to 20 GHz, respectively. The influence of the synthesized nanoparticles on the neat (undoped) epoxy composites and the results in view of future applications are fully discussed.

Impact-dynamic properties of aromatic hyperbranched polyester/RTM6 epoxy nanocomposites

Present study investigates the influence of aromatic hyperbranched polyester (AHBP) nanofillers on the impact-dynamic properties of RTM6 epoxy. The strain rate dependence of the energy absorption capacity of neat RTM6 epoxy and RTM6 nanocomposites with filler weight ratios of 0.1%, 1%, and 5% was determined through compression testing. Additionally, static and dynamic tensile tests were performed on these materials. Universal testing machines were used for the quasi-static tests, split Hopkinson bar setups for the high-strain rate experiments. Furthermore, dynamic single-edge notch bending (SENB) tests were conducted to measure fracture toughness using an adapted split Hopkinson compression bar setup. In addition to global deformation measurements, full-field deformation measurements were also performed in all experiments using the digital image correlation (DIC) technique. The results indicate that the energy absorption capacity, tensile strength, fracture strain, and toughness are significantly influenced by both strain rate and filler content of the RTM6 epoxy.

Effect of incorporating carbon- and silicon-based nanomaterials on the physico-chemical properties of a structural epoxy adhesive

Various carbon-based (i.e. carbon nanofibres (CNF), cellulose nanocrystals and graphite nanopowder) and silicon-based nanomaterials (i.e. silica nanopowder and MMT nanoclay) were incorporated into neat structural epoxy (NE) adhesive (Sikadur®-30) at 0.5, 1.0 and 1.5% by weight and mixed using a simple and cost-effective approach to produce the nanomaterial-modified epoxy adhesives (NMEAs). The impact of incorporating these nanomaterials into the NE on its chemical composition was investigated using Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy. X-ray diffraction (XRD) measurements were also used to identify the changes in the physical structure (i.e. the degree of crystallinity) that may occur in the NE with the addition of nanomaterials. Furthermore, the microstructure of the NE and NMEAs (in terms of the degree of dispersibility of the nanoparticles through the matrix) was investigated through scanning electron microscopy (SEM) analysis. A porosity analysis was also conducted across all samples. The results obtained from various tests were correlated to investigate the changes that occurred in the different properties of the matrix and the corresponding nanocomposites effectively and more critically. The SEM images showed some particle agglomeration, which increased with increasing wt%. An increase in the % porosity ratio of all nanocomposites over that of the NE was also observed, accompanied by a decrease in crystallinity compared to the NE. As per the FTIR spectroscopy, the chemical bonds in the NE and carbon-based NMEAs were observed to have different intensities, which were changed in the NMEAs, with the type and wt. % of the nanomaterials. No new bonds were formed by incorporating any of the nanomaterials (i.e. carbon- and silicon-based), except when adding 1.0 wt% CNF, where a bond at 1710 cm−1 was observed indicating a new CO stretching bond. As shown by Raman spectroscopy, all CNF and graphite NMEAs exhibited higher ID/IG values than those of the corresponding pristine materials.

Revolutionizing epoxy performance: A new flame retardant with phosphorus and maleimide for enhanced cure behavior, thermal stability, flame retardancy, and mechanical properties

AbstractA novel phosphorus‐based maleimide, tris[4‐(2,5‐dioxopyrrol‐1‐yl)phenyl] phosphite (TDPPI), was employed as a flame retardant in epoxy with moderate transparency, enhanced thermal stability, and improved mechanical strength. SEM studies ascertained the uniform dispersion of TDPPI and its compatibility with the epoxy. Differential scanning calorimetry showed that the epoxy compounded with 2.5 wt% of TDPPI achieved 100% curing with the glass transition temperature of 43.8°C. The thermogravimetric study revealed that the presence of 2.5 wt% of TDPPI in epoxy increased the residual mass found at 600°C by 23%. The epoxy thermoset compounded with 2.5 wt% of TDPPI passed the Underwriter's Laboratory (UL‐94) test with V‐1 classification and achieved the limiting oxygen index of 30.7% with a reduced burning rate of about 58.7%. At 1.5 wt% of the TDPPI, the resulting epoxy thermoset exhibited an enhancement in the tensile strength (23%), Young's modulus (37%), flexural strength (9%), and Izod impact strength (37%) relative to the neat epoxy. In conclusion, 2.5 wt% of TDPPI is adequate for imparting flame retardancy to epoxy composites with improved mechanical strength because of the maleimide‐phosphorus synergistic effect.Highlights TDPPI is a phosphorus and maleimide containing flame retardant. TDPPI improves thermal stability, flame retardancy and mechanical strengths. Only 2.5 wt% of TDPPI is required for epoxy to achieve high flame retardancy. Maleimide presence lowers phosphorus requirement for epoxy flame retardancy. TDPPI is a promising new flame retardant material for epoxy.

Open-hole fatigue testing of UD-GFRP composite laminates containing aligned CNTs using infrared thermography

The present study aims to characterize the open-hole fatigue (OHF) behavior of unidirectional glass fiber-reinforced polymer matrix (UD-GFRP) epoxy composites containing aligned multi-walled carbon nanotubes (MW-CNTs) locally reinforcing the composite in the vicinity of the hole. The performance of these multi-scale composites has been compared with that of composites containing randomly oriented MW-CNTs around the hole. UD-GFRP containing neat epoxy (without MW-CNTs) as a matrix were the control samples in the study. Infrared thermography has been used to investigate the damage evolution in composites during the OHF tests. MW-CNTs, aligned perpendicular to the loading direction, improved the fatigue strength of the UD-GFRP composites by over 12% compared to the control samples. Fractography results are also presented in support of the findings from fatigue testing. Infrared thermography is presented as a method to rapidly determine the high cycle fatigue strength of the OHF specimens.

Enhancement of thermal and mechanical properties of polymer composite using a novel milled bamboo filler

AbstractThis work presents the thermal and mechanical characterization of epoxy composites reinforced with different fillers developed by modifying thermo‐mechanically extracted bamboo micron fibers. The modification of bamboo fibers was done by adding carbon nanoparticles to their surface and also by making powdered fillers using the process of ball milling. A decrease in water absorption in case of surface coated bamboo fibers was observed. The glass transition behavior was enhanced for composites filled with milled bamboo fillers as compared to neat epoxy. Better mechanical properties were observed for composites reinforced with milled bamboo fillers compared to that of composites filled with bamboo fibers. The highest tensile strength (90.258 MPa) was observed for composites reinforced with 5 wt% of milled bamboo fillers depicting an increase of 93.01% compared to that of neat epoxy (46.762 MPa).Highlights Bamboo fibers were modified with a sizing agent and carbon nanoparticles. A novel “milled bamboo filler” was produced and incorporated in composites. Thermal properties of epoxy composite were enhanced by the novel filler. Tensile strength of the composite was significantly enhanced. The novel filler has the future scope of application in various composite products.

Comparative study of carbon and glass fiber reinforced polymer composites for the confinement of concrete columns

This study deals with the comparison of unconfined concrete specimens with carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) confined concrete specimens using epoxy as matrix. Initially, CFRP, GFRP and epoxy laminates were prepared for the analysis of various mechanical properties like tensile strength, flexural strength and fracture toughness. From the test results, CFRP and GFRP laminates exhibit better properties than neat epoxy laminate. Axial compressive strength, energy absorption characteristics, failure modes of the confined specimens are analyzed. Comparing with unconfined specimens, it is noticed that the axial load carrying capacity of GFRP confined specimens increased by 23%. While the CFRP confined specimen is compared, a considerable enhancement of 57% was noticed with a confinement effectiveness of 1.57. It is observed that confinement by the FRPs can also increase the fracture energy and ductility index significantly, which can avert the catastrophic failure of the structures.

Physical and mechanical properties of graphene and h‐Boron nitride reinforced hybrid aerospace grade epoxy nanocomposites

AbstractVarying graphene nanoplatelet (GNP) and hexagonal boron nitride (h‐BN) based fillers were integrated to an aerospace grade epoxy resin typically used as matrix to obtain or repair structural parts of aerospace platforms. The three‐roll milling approach was used for this purpose. Five cycles were performed for the mixing while the gap between rollers was 50 μm. Microstructure and thermal properties of the nanocomposites were studied. Moreover, mechanical and transport (electrical as well as thermal) performances were investigated. Results show that certain fillers yield multifunctional properties, that is, enhanced flexural strength by up to 69% in combination with high electrical conductivities with orders of magnitude of approximately and improved thermal conductivities up to 9.3%. For instance, the hybrid nanocomposite sample produced with 0.5 wt% GNP and 0.5 wt% h‐BN added to the epoxy matrix exhibits an electrical conductivity which increased fold, a flexural strength increased by 69% and thermal conductivity increased by 7% in comparison the neat epoxy. Hence, in this study it was demonstrated that these properties can be engineered and tuned effectively for aerospace applications like lightweight avionic chassis which have specific requirements like thermal and electric conductivity which naturally leads to the possible usage of GNP and h‐BN in an epoxy. Correspondingly, presented results are of relevance for novel thermal interface materials with tailored electrical properties.

A novel epoxy adhesive with ground rubber tire powder and carboxylated multiwalled carbon nanotubes

AbstractThe present study was an attempt to improve the toughness, mechanical and adhesion properties, and thermal stability of a two‐phase epoxy DGEBA/Resole phenolic resin through the use of carboxyl‐modified multi‐walled carbon nanotubes (c‐MWCNTs) and ground rubber tire (GRT) powder. The effect of a hybrid reinforcement containing GRT and c‐MWCNT blend on the mechanical properties, thermal stability, and microstructure of the epoxy‐phenolic adhesive were evaluated by tensile test, TGA, and FESEM, respectively. The formulated adhesive was utilized in a lap joint metal to a composite in order to peruse the adhesion features, where the composite was an epoxy resin reinforced with carbon fibers and the metal was stainless steel 316 L. According to the tensile test, there were 32% rise in tensile strength, 27% rise in modulus, and a 64% rise in toughness with adding 0.5% wt c‐MWCNTs and 15 phr waste GRT powder to the epoxy‐phenolic matrix. Furthermore, adding 1% wt c‐MWCNTs of nanoparticles and GRT powder has resulted in a 15% increase in lap shear strength. It also can be seen that thermal stability for the formulated samples has experienced an upward trend compared to the neat epoxy composite.Highlights Epoxy adhesives based on GRT Powder, c‐MWCNTs particles and phenolic resin have been successfully prepared. The hybrid uses of GRT Powder and c‐MWCNTs particles can synergistically increase the tensile and lap shear strength The addition of c‐MWCNT nano particles and GRT Powder in an epoxy adhesive can have a dramatic rise in the toughness system compared to the neat epoxy adhesive. Maximum degradation temperature of the produced newly adhesive has increased considerably in contrast with the neat epoxy adhesive.