Toughness Of Epoxy Composites Research Articles

Enhancing mechanical, thermo-mechanical and low velocity impact properties of epoxy methyl ricinoleate toughened epoxy composites by integrating microcrystalline cellulose

Enhancing mechanical, thermo-mechanical and low velocity impact properties of epoxy methyl ricinoleate toughened epoxy composites by integrating microcrystalline cellulose

Milled graphitic nanoparticle toughened epoxy composites via increased resistance to in-plane crack propagation

Fascinating features of 2D-based carbon materials like graphene have drawn increasing attention to fulfill the desire to enhance the fracture toughness of epoxy composites. However, challenges remain to improve their dispersibility in polymers and increase interaction ability. Thus, work is needed to synthesize alternative cost-effective 2D carbon nanofillers capable of delivering consistent performance as a reinforcer to monitor the fracture toughness of the epoxy composites. The present study demonstrates transforming graphite to ball-milled graphite (BMG) via an effective high-energy wet ball milling process. Herein a noteworthy size reduction is achieved for the BMG ranging from ∼217 to 227 nm. Microscopic investigation spotted an exfoliated 3D networked graphite nanosheet with nanopores. These BMGs were functionalized to attach amine-based silane moieties and were incorporated into the epoxy network. Consequently, even at higher loading levels, they showed their astonishing capability to enhance the crack far field resistance of nanocomposite resulting in significantly improved fracture toughness and energy to ∼2.31 MPa m1/2 and ∼11.30 kJ/m2, respectively. Improvement is ascribed to the better dispersing ability of BMG, which provides a consistent strong interfacial interaction with the epoxy network to modulate material resistance to fracture. Such environmentally friendly nanofillers must be industrially acceptable for synthesizing durable epoxy nanocomposite systems and can be utilized to prepare structural composites.

Mechanical wear and hydrophobicity behaviour of Digitaria ischaemum fibre-reinforced finger millet husk biosilica toughened epoxy composites

Mechanical wear and hydrophobicity behaviour of Digitaria ischaemum fibre-reinforced finger millet husk biosilica toughened epoxy composites

Effect of corn husk fiber length and diameter on load bearing, fatigue, and DMA properties of biosilica toughened epoxy composite

AbstractThis study examined how the diameter and length of corn husk fiber affects the mechanical, fatigue, and DMA properties of epoxy‐based composite material. As filler, biosilica, which is made from wheat husks, was used to make composites. By hand layup process, the composites were created and then characterized as per the ASTM standards. Results revealed that the N21 composite designation offered improved tensile and flexural strength, Izod impact and hardness up to 94 MPa, 137 MPa, 3.62 J, and 86 shore‐D. But compared to all composite designations, the composite designation N23 has the highest tensile and flexural strength, Izod impact, and hardness values, which are 134 MPa, 182 MPa, 4.84 J, and 88 Shore‐D, respectively. Similarly, the composite designation N21 gives improved fatigue life counts of 21,629 by adding 1vol. % of biosilica and fiber length of 70 mm and diameter of 200 μm. In the same way, the highest storage modulus and loss factor of 5.5 GPa and 0.3 were noted for composite N23. The fiber diameter of 200 μm and a length of 70 mm demonstrate effective load shearing phenomenon and bonding between the fiber and matrix. Overall, the lesser diameter fiber with a higher length outperformed and it is recommended for high‐performance composite making.

Tuning the microwave absorption characteristics of r-GO toughened epoxy composites via SiC-induced phase separation

Tuning the microwave absorption characteristics of r-GO toughened epoxy composites via SiC-induced phase separation

Influence of flax fiber orientation on mechanical, thermo-mechanical and interfacial adhesion properties of epoxidized methyl ricinoleate modified epoxy composite: A sustainable green composite for cleaner production

Renewable natural fibers have been better eco-friendly reinforcing agents for plant oil toughened epoxy composites in order to achieve the desired properties for structural applications. In the current work, epoxy methyl ricinoleate (EMR) synthesized from castor oil was used to modify epoxy to tailor the stiffness-toughness balance. For the first time, an epoxy/EMR blend has been used to fabricate the composite. The fiber pull-out test showed a 17% increment in interfacial shear strength on adding 20% EMR to epoxy and hence this modified epoxy was reinforced with UD (Unidirectional) mat at three different orientations i.e. [0/0], [0/90] and [90/90]. The [0/0] orientation laminates displayed the highest tensile, flexural, and impact strength with an increment of 120%, 151% and 858% respectively as compared to epoxy/EMR copolymer, whereas [0/90] orientation laminates showed superior translaminar fracture toughness and critical strain energy release rate with an increment of 216.5% and 494% respectively. Different theoretical models and a combination of classical lamination theory and modified rules of mixture were adopted to fit with the obtained experimental tensile strength and modulus values of appropriate laminates. Thermogravimetric and dynamic mechanical analysis confirmed the desired thermal stability and damping ability of the composites. Scanning electron microscope (SEM) morphology of the fractured surface and Water Contact Angle (WCA) of the surface of composites were studied to explain the fiber-matrix interface mechanism and wettability of the samples respectively. The results demonstrated that the EMR Modified Epoxy Composite can be an alternative to synthetic epoxy composites in automobile and structural applications. • Less viscous and reactive epoxy methyl ricinoleate (EMR)bio-resin is synthesized • High performance bio-composite using 20%EMR/epoxy as matrix was fabricated. • Effect of fiber inter-ply orientation on various mechanical properties was studied. • Failure mechanisms were validated with by Scanning Electron Microscope (SEM).

Pear cactus fiber with onion sheath biocarbon nanosheet toughened epoxy composite: mechanical, thermal, and electrical properties

Pear cactus fiber with onion sheath biocarbon nanosheet toughened epoxy composite: mechanical, thermal, and electrical properties

Simultaneously improving the flame retardancy and toughness of epoxy composites with hyperbranched phosphorus-containing polysiloxane functionalized halloysite nanotubes

Development of high-performance thermosets with simultaneously improved flame retardancy, toughness and strength but unaffected glass transition temperature (Tg) has been a great challenge. In this work, hyperbranched phosphorus-containing polysiloxane functionalized halloysite nanotubes (HBPPSi-HNTs) were synthesized to prepare flame-retarding, mechanically-strong and tough epoxy composites. The tensile and impact strengths of the composites with 5.0phr HBPPSi-HNTs were improved by 23.7 % and 48.8 % respectively compared with the neat epoxy resin. The epoxy composites also exhibited excellent flame-retardancy due to the instantaneous gas-phase and condensed-phase flame retardant behavior of HBPPSi-HNTs. The composite with 10.0phr HBPPSi-HNTs passed UL-94V-0 rating, with an LOI value as high as 42.6 %. And compared with neat epoxy resin, the peak of heat release rate (PHRR), total heat release (THR), total smoke production (TSP) and CO generated per second (COY) were reduced by 50.1 %, 32.6 %, 30.1 % and 39.5 %, respectively. This work presented a general approach to prepare epoxy composites with simultaneously improved flame retardancy and mechanical properties without sacrificing the glass transition temperature.

Adhesion of Silica and Block Copolymer Toughened Epoxy Composites

Adhesion of Silica and Block Copolymer Toughened Epoxy Composites

Effect of nanosilica on mechanical, thermal, fatigue, and antimicrobial properties of cardanol oil/sisal fiber reinforced epoxy composite

AbstractSisal fiber reinforced nanosilica and cardanol oil toughened epoxy composites were prepared and characterized in this present work. The main aim of this study was to understand the importance of adding cardanol oil and nanosilica to sisal‐reinforced epoxy composites in enhancing the load bearing, thermal stability, and antimicrobial properties. The composites were fabricated by the hand layup process and specimens were cut using a water jet machine. The composites were tested using the respective ASTM standards. The results found that the blending of cardanol oil makes the epoxy less brittle and the composites are environment friendly. Similarly, nanosilica with sisal fiber in cardanol oil blended epoxy composites showed improved mechanical properties. The highest tensile strength and modulus were found to be 56% and 64% than pure epoxy resin. The maximum impact resistances and hardness values observed for the composites are 6.48 J and 91 shore‐D. Moreover, improved fatigue life counts were observed for composite designation ECN2, which contains 1.0 vol% of nanosilica, but also a decrement in it if the volume percentage was increased to 2.0. The antimicrobial properties improved with the increment of nanosilica and cardanol oil content. These eco‐friendly, mechanically toughened biocomposites could be used in drug and food storage, automotives, drones, structural, and sports goods as well as in household appliances manufacturing.

Enhance the mechanical properties of epoxy resin reinforced with functionalized graphene oxide nanocomposites prepared by atom transfer radical polymerization

AbstractInspired by the strengthening effect of nanoparticles and the toughening effect of block polymers, we prepared a block polymer filler with graphene oxide (GO) as the main body by surface initiate atom transfer radical polymerization (SI‐ATRP). In the side groups of the main molecular segment of this block polymer, glycidyl methacrylate (GMA) fragment and N‐(3,4‐bis([tert‐butyldimethylsilyl]oxy)phenethyl)methacrylamide (DOPAmTBDMS) fragment can promote dispersion and toughening respectively. The molecular structure was characterized by Fourier transform infrared and X‐ray photoelectron spectroscopy. After the modified GO was added to the epoxy composite, the mechanical properties of the composite could be significantly improved. The toughness of epoxy composites was enhanced by crack deflection of the matrix. When the added amount of modified GO was 0.25 wt%, the flexural strength reached 151 MPa, which was 37.27% higher than pure epoxy composite. The tensile strength and izod impact strength were increased by 50.56% and 69.89%, respectively. These are attributed to the strengthening and toughening effects of GO and the side groups on it. This research had potential application value in the field of resin fillers and in combination with carbon fiber, metal and other materials.

Characterization of prickly pear short fiber and red onion peel biocarbon nanosheets toughened epoxy composites

AbstractIn this research, the role of prickly pear short fiber and red onion peel wrinkled biocarbon nanosheets toughened epoxy resin composite was investigated. The main aim of this research was to find the effectiveness of adding biocarbon along with prickly pear fiber in the load‐bearing, thermal and electrical conductivity behavior of the epoxy resin composite. The biocarbon nanosheets were prepared for this present investigation from red onion peel waste using the pyrolysis process. The composites were characterized by American society of testing and materials (ASTM) standards and compared with previous results. The highest tensile strength and flexural strength were observed for 3 vol.% of biocarbon nanosheets up to 60% and 40% respectively than pure epoxy. Izod impact toughness and hardness values also increased with the inclusion of reinforcements by 5 vol.% around 93% and 90% correspondingly. Similarly, relative permittivity and dielectric loss enhanced about to 6.4 and 0.74 for 5 vol.% of biocarbon nanosheets. The thermal conductivity also improved with the addition of biocarbon nanosheets and maximum values up to 0.42 W/mK. This enhanced dielectric, mechanical, and thermally active composites might be employed as a microwave shielding material in electronic devices, automotive, and industrial applications for communications equipment that require shielding material with good mechanical properties.

Enhancement of mechanical and dynamic mechanical thermal characteristics of woven glass fabric–reinforced multi-nanoparticle–filled toughened epoxy composites

In recent years, high-performance nanocomposite materials emerge as an alternative to traditional materials owing to their impressive mechanical properties and lightweight characteristics. However, enhancements on various characteristics of this type of material were still under investigation for numerous novel structural applications. The current research study has highlighted the effect of various nanofillers incorporation in glass fabric–reinforced toughened epoxy composite on the enhancement of mechanical and dynamic mechanical characteristics. Two different nanosized filler particles (Al2O3 and TiO2) were selected for applications of higher strength. The composite laminates were fabricated by using the vacuum bagging method, and curing processes were performed at room temperature. The test outcomes revealed that better tensile strength and maximum flexural strength were perceived with the S4 composite sample (Al2O3 + TiO2 nanofillers). It has been observed that the existence of both Al2O3 and TiO2 nanofillers enhances the interlaminar shear strength (ILSS). The overall result of dynamic mechanical thermal analysis indicated that the inclusion of multi-nanoparticle fillers in the toughened epoxy composite showed better results than the traditional composite. The maximum tensile strength, flexural strength, shear strength, and micro-hardness of Al2O3 and TiO2 nanofiller-infused epoxy composites (S4) were 101 MPa, 5.68 MPa, 19.7 Mpa, and 46 Hv.

Synergistic toughening on hybrid epoxy nanocomposites by introducing engineering thermoplastic and carbon-based nanomaterials

In this study, epoxy-anhydride thermoset was initially modified with polyethersulfone (PESU) at 0‐15 wt% loading. The various mass ratios at 0.50 wt% total content of graphene nanoplatelets (GNPs)/carbon nanotubes (CNTs) were further introduced to comprehensively study the simultaneous incorporation of different tougheners on morphological, thermal, and mechanical properties of engineering thermoplastic modified epoxy. The binary blend of PESU/epoxy reveals two-phase morphologies due to reaction induced phase separation, showing particulate morphology at 5 wt% PESU and co-continuous morphology at 10‐15 wt% PESU. It was found that the presence of PESU at 5 wt% not only improved thermal stability but also provide the optimum mechanical properties, showing 35% and 40% increasing in tensile strength and fracture toughness, respectively. From fracture surface analysis, crack deflection from the PESU dispersed particles was observed as a main toughening mechanism for this binary blend. With introducing GNPs and/or CNTs, hybrid nanocomposite based on 5 wt% PESU modified epoxy matrix showed similar morphology and thermo-mechanical properties to the binary blends. Additionally, the remarkable Young's modulus were observed in all hybrid PESU/carbon-based nanofillers toughened epoxy composites. PESU and GNPs dispersed phase contribute greatly in enhancing fracture toughness (KIc) of hybrid PESU/nanofillers system. KIc of PESU/epoxy blends with 0.5 wt% GNPs was measured at 0.86 MPa m1/2, counting as ∼60% and ∼18% improvement from pristine epoxy and 0.5 wt% GNPs modified neat epoxy, respectively. Apart from crack deflection of PESU, GNPs cluster effectively deviates and bifurcates the crack path, indicating the synergistic effect on PESU/GNPs epoxy nanocomposite. Interestingly, these two tougheners also dominates the toughening mechanism in PESU/GNPs/CNTs epoxy nanocomposites. Meanwhile, the influence of CNTs on fracture toughness was not clearly demonstrated on hybrid nanocomposite system.

Impact of reduced graphene oxide on microstructure evolution in m-caproamine/imidazole toughened epoxy composites – Synergia of viscoelastic and microwave absorption properties

The present study investigates the effect of reduced graphene oxide (r-GO) on the microstructure evolution, damping, and microwave absorption performance of the caproamine (CA) toughened epoxy /imidazole (m-CA/ER/MI/r-GO) system. The X-ray diffraction analysis revealed good dispersion levels of r-GO featuring intercalation of r-GO into galleries of polymer chains. The effective role of r-GO in tuning the microstructure was confirmed from SEM, AFM and TEM analysis and the consequence of this is reflected in the dynamic mechanical characteristics. The m-CA/ER/3 wt% r-GO composites achieved an outstanding microwave absorption performance with a reflection loss of −51.6 dB (99.999% microwave absorption) at 9.51 GHz and an effective absorption bandwidth of 2.48 GHz when compared to m-CA/ER composite. The microwave performances are justified with the attenuation constant, impedance matching ratio, and the dielectric loss mechanisms operating in the composites. Hence, the developed m-CA/ER/r-GO will serve as a potential multifunctional composite with synergetic thermomechanical properties and excellent microwave absorption performance.

Bio-based epoxy functionalized MQ silicone resins: from synthesis to toughened epoxy composites with good mechanical properties, thermal resistance and transparency

A series bio-based eugenol silicone resins are synthesized, and EG-1.2MQ shows its good promise as a new green multifunctional additive to well balance the toughness, mechanical properties, transparency, and other properties.

Mechanical, wear, and drop load impact behavior of glass/Caryota urens hybridized fiber‐reinforced nanoclay/SiC toughened epoxy multihybrid composite

AbstractHigh toughness epoxy resin hybrid composites were prepared using nanoclay, SiC, and glass‐caryota intra ply fibers. The main aim of this research was to study the effect of adding Caryota urens natural fiber from biomass as a potential fiber along with synthetic glass fiber in load‐bearing and wear properties of nanoclay and silicon carbide (SiC) particle toughened epoxy composite. The intra‐ply glass‐caryota fiber, silicon carbide, and nanoclay were surface‐treated using 3‐Aminopropyltrimethoxysilane. The composites were prepared using the hand lay‐up method. The tensile result shows that the addition of 1 vol% of the silicon carbide particle along with nanoclay in intra‐ply glass‐caryota fiber‐reinforced epoxy composite gives improved results than other composite designations. The wear properties show that the addition of silicon carbide of 1.0 vol% gives a lower specific wear rate of 0.024 mm3/Nm. Similarly, the composite, which contains 1.0 vol% of silicon carbide and nanoclay gives higher penetration resistance and energy absorption. In all properties, the addition of silicon carbide modifies the values significantly. This high toughness intra‐ply glass‐caryota fiber‐reinforced silicon carbide/nanoclay toughened epoxy resin composite could be used in automotive, sports components, domestic appliances, and structural body applications.

Investigation of mechanical and thermal insulating properties of wool fibres in epoxy composites

The purpose of this study is to investigate a novel exploitation approach for a mass livestock byproduct, namely sheep wool fibres. In order to fulfil this aim, wool fibre toughened epoxy composites with an amount of 2.4, 4.1 and 5.7 phr were prepared via the hot press method. Initially, mechanical assessment of the composites was executed, in order to evaluate their mechanical integrity. The flexural and shear strength tests showed that the wool fibre-epoxy composites maintain their mechanical properties for up to 4.1 phr and no degradation is detected. Subsequently, the thermal properties were tested. Thermogravimetric analysis proved that adding wool fibres as toughening agent in epoxy matrix can prolong the endurance of the material while reaching high temperatures. The coefficient of thermal conductivity decreased by 30% compared to neat epoxy, something that is also confirmed through simulation, proving that wool fibre-epoxy composites can be considered as a promising insulating material, while exploiting a natural waste.

The nanoeffeсt in epoxynanocomposites

It was shown that the distribution of silica nanoparticles (silicon dioxide) and the size of inhomogeneities (heterogeneity level) in the epoxy oligomers and epoxy nanocomposites effect on the structure and properties of epoxy composites.It was established that the maximum value of epoxy composites impact strength is achieved only when the particles of the optimal size (~ 150 nm) are formed in their structure from silica nanoparticles of different grades (BS-50, BS-100 and BS-120), sizes and specific surface.The nano effect in dispersed-filled epoxy composites caused by the formation of clusters of silica nanoparticles of size ~ 150-190 nm was discovered and proved for the first time. It is accompanied by an increase in impact strength by ~2 times and proves the high efficiency of nanoparticles for creating impact-resistant plastics.It was shown that monolithic ultrafine particles of powdered quartz (silicon dioxide) with a particle diameter of ~150 nm lead to an increase in the toughness of epoxy composites by only ~20% and are much less efficient than nanoparticles.

Effects of surface-modified pineapple fibre-reinforced micro B4C and CTBN rubber particle toughened epoxy hybrid composites in mechanical, impact damage, thermal and water absorption behavior

In this present work, the drop load impact damage, mechanical, thermal and water absorption behaviour of surface-modified pineapple fibre reinforced micro boron carbide (B4C) and carboxyl-terminated acrylonitrile butadiene (CTBN) rubber toughened epoxy composites are studied. The principal aim of this research is to unveil the effects of surface modification and the role of adding microparticles into the resin matrix. The natural fibre and microparticles were surface-treated by an amino silane (3-Aminopropyl)trimethoxysilane (APTMS). The silanization process was done in aqueous solution. The epoxy hybrid composites were prepared using hand lay method. The impact damage results revealed that addition of surface-modified CTBN micro rubber along with pineapple fibre and micro B4C improved the damage resistance. Similarly, the mechanical and thermal results revealed that additions of surface-modified B4C and CTBN rubber microparticles improved the tensile, flexural and Izod impact damage behaviour with better thermal stability. The contact angle of the hybrid composites showed a higher contact angle, which shows higher hydrophobicity. The fractography images showed improved bonding and effective dispersion of microparticles in the matrix. These mechanical, thermal and impact damage resistance composites are highly sought after in structural, hybrid vehicles and mini-aircraft applications.