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The effect of Closite C93A nanoclay on the mechanical, thermal properties of diglycidyl ether bisphenol A (DGEBA) epoxy resin and epoxidized soybean oil (ESO) bioepoxy blend at various wt.% (10, 20, 30) cured with anhydride hardener (MHHPA) existence of 2-methylimidazole (2-MI) as an accelerator was investigated. The DGEBA/ESO blend systems optimized through the mechanical properties. The 20 wt.% DGEBA/ESO blend systems exhibited higher tensile and impact strength incorporation of 0.5–2.5 wt.% C93A nanoclay. The curing reaction of DGEBA blends and its nanocomposites with MHHPA, 2-MI was explored by non-isothermal differential scanning calorimetry (DSC). The thermal stability of DGEBA/20%ESO blend enhanced by loading of 2.5 wt.% C93A nanoclay which restrict the flexibility of chain and obstructed the decomposition process. The formation of exfoliated inside the clays in the DGEBA/ESO/2.5%C93A nanocomposites corroborated by X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis. [ABSTRACT FROM AUTHOR]

In this paper, different types of carbon-based fillers such as graphite powder (GP), expanded graphite powder (EGP), expanded graphite flakes (EGF), silane treated expanded graphite flakes (EGS) and exfoliated graphene nanoplatelets (GNPs) were used at 40 wt% loading level inside epoxy resin for comparative thermal conductivity enhancement analysis. Disc-shaped epoxy adhesive composite samples were manufactured by hand layup and mechanical mixing technique. The thermal conductivity (k) of epoxy composites was measured according to ASTM E1530 standard at 60 °C by steady-state heat flow meter technique. It was enhanced to 0.96 (∼5 times), 2.50 (∼13 times) and 3.21 W/mK (∼17 times) for 40GP + 0Ep, 40EGF + 60Ep and 40EGS + 60Ep epoxy adhesive composites at 40 wt.% of filler loading level inside low conducting (k ∼ 0.194 W/mK) epoxy resin, respectively. From scanning electron microscopy, we observed the formation of the heat-conducting network through GP, EGF and EGS inside the epoxy matrix. The lap shear strength (LSS) of the epoxy adhesive joint was increased at 40 wt% of GP filler added epoxy adhesive but it decreased at 40 wt% EGF filler loading inside the epoxy resin. Introduction of EGF inside epoxy resin has influenced negative impact on TGA analysis (thermal stability) of epoxy adhesive than GP at initial stages of thermal degradation. This indicates the commercial use of these epoxy adhesives for heat dissipation application of electronic packaging industry. [ABSTRACT FROM AUTHOR]

In this investigation, the fabrication of thermal conductive epoxy composite with the assimilation of synthesized expanded graphite (EG) decorated with copper compound nanoparticles [copper (Cu), copper(II) oxide (CuO) and copper(I) oxide (Cu2O) nanoparticles], has been reported wherein, Cu-compound was attached to EG surface by solid-state pyrolysis of copper(II) acetate (CA) monohydrate. The prepared hybrid filler was characterized by an x-ray diffraction technique and the Cu-compound nanoparticles size was 40.8 ± 17.67 nm. The microstructure and morphology of the distributed Cu-compound nanoparticles over the EG surface were characterized by transmission electron microscopy (TEM) and scanning electron microscopy. The Cu-compound nanoparticles decorated EG hybrid filler at 10 wt.% loading ((EG-CA (4)/Ep)10) demonstrated the thermal conductivity (TC) which is 11.8 times higher than the neat epoxy due to the formation 3D percolation heat-conducting networks. Further, decoration of Cu-compound on the EG surface resulted in higher TC as measured using a guarded heat flow meter technique. Lap shear strength of (EG-CA (4)/Ep)10 composite was tuned to 5.93 ± 0.27 MPa as characterized by a universal testing machine. The porosity of fabricated composites was decreased as Cu-compound attachment increases on the EG substrate. The thermo-gravimetric analysis revealed enhanced thermal stability of (EG-CA (4)/Ep)10 composite to 407°C at 50% weight loss consideration. The electrical resistivity of the composite was reduced with the addition of the EG filler system as confirmed from the super megaohmmeter. [ABSTRACT FROM AUTHOR]

The synthesis of high-thermal-conductivity expanded graphite (EG) by a physical method from natural graphite flakes using zinc nitrate hexahydrate is described herein. This article establishes thermal conductivity studies of the epoxy composite system containing a hybrid of EG, a soft material, and micro-SiC, a hard material, with different filler fractions. To verify the texture and appearance, the filler materials were characterized by polarized light and scanning electron microscopy. The thermal conductivity of the fabricated hybrid epoxy composites was analyzed by a guarded hot plate meter technique. The electrical properties of the hybrid composite were evaluated by a four-point potentiometer. The single-lap shear strength of optimized composition was observed under a universal testing machine. The thermomechanical behavior and thermal stability of the hybrid composites were investigated through dynamic mechanical analysis and thermogravimetric analysis, respectively. The dispersive status and synergistic effect of the hybrid filler inside the epoxy matrix were studied through fracture surface analysis by scanning electron microscopy. With the addition of 15 wt.% EG and 15 wt.% micro-SiC to the epoxy resin, thermal conductivity of up to 2.24 W/mK was achieved for the hybrid composite, which was an 11.6-fold improvement over unaided epoxy. [ABSTRACT FROM AUTHOR]

Synthesized expanded graphite (EG) was decorated with Ag nanoparticles using solid-state decomposition by a simple 'mix and heat' technique. The epoxy composite was fabricated by a stir casting method with an ultrasonic procedure in order to enhance the thermal conductivity (TC). The morphology of filler (EG–Ag) studied under X-ray diffraction (XRD) technique and scanning electron microscopy (SEM) confirms the attachment of Ag nanoparticles on EG surfaces. The TC of the composite containing 10 wt% of EG–Ag hybrid filler (EG–Ag(10)-Ep(90)) measured using guarded heat flow meter technique was found to be 2.52 W/mK, which is almost 13-fold enhancement as compared to the neat epoxy. The thermo-gravimetric analysis (TGA) of EG–Ag(10)-Ep(90) confirmed thermal stability which enhanced from 289 to 327 °C at 5% weight loss, in N2 atmosphere. The improvement in TC was ascribed to the synergistic effect of micro-nano (EG–Ag) hybrid filler, in which Ag nanoparticles acted as 'spacer' between EG threads by reducing interfacial Kapitza resistance as evidenced from fracture surface analysis. After attaining 3D percolation limit, the hybrid composite at 10% filler fraction (EG–Ag) entered the electrical conductivity of the semiconducting range which was enhanced by fourteen orders from neat epoxy. [ABSTRACT FROM AUTHOR]

In the present study, TEIA bioresin was blended with the diglycidyl ether bisphenol A (DGEBA) epoxy resin in different ratios (i.e. 10, 20, 30, 40 mass%), cured with methylhexahydrophthalic anhydride curing agent in the presence of 2-methylimidazole catalyst. The optimized composition of DGEBA and TEIA bioresin blends system was employed as an adhesive strength. The adhesive strength of the TEIA-modified DGEBA epoxy resin blend system was increased from 4.14 to 6.31 MPa on an aluminium substrate compared to the DGEBA epoxy resin. The curing kinetics of non-isothermal, DGEBA epoxy resin and its bio-based blend systems were investigated employing differential scanning calorimetry. An increase in the peak temperature and reduction in a heat of curing as well as activation energy in DGEBA epoxy resin were observed with the addition of TEIA bioresin content. The activation energy (Ea) of the DGEBA resin and their bio-based blend system were obtained from Kissinger and Flynn–Wall–Ozawa methods. [ABSTRACT FROM AUTHOR]

Thermal management is an important parameter in an electronic packaging application. In this work, three different types of fillers such as natural graphite powder (Gr) of 50‐μm particle size, boron nitride powder (h‐BN) of 1‐μm size, and silver flakes (Ag) of 10‐μm particle size were used for thermal conductivity enhancement of neat epoxy resin. The thermal properties, rheology, and lap shear strength of the neat epoxy and its composite were investigated. The analysis showed that the loading of different wt% of Gr‐based fillers can effectively increase the thermal conductivity of the epoxy resin. It has also been observed that the thermal conductivity of the hybrid filler (Gr/h‐BN/Ag) reinforced epoxy adhesive composite increased six times greater than that of neat epoxy resin composite. Further, the viscosity of hybrid filler reinforced epoxy resin was found to be increased as compared with its virgin counterpart. The adhesive composite with optimized filler content was then subsequently subjected to determine single lap shear strength. The degree of filler dispersion and alignment in the matrix were determined by scanning electron microscopy (SEM) analysis. [ABSTRACT FROM AUTHOR]

The main objective of this review is to discuss the recent research on polymer-based surface coatings contributing to the protection against marine biofouling based on the knowledge available in literature, supplemented by means of figures, mechanism illustrations, mathematical models, and equations. A need for studies on the mathematical behavior of such coatings is emphasized, composed of quantitative evaluation of foul-release performance of coatings using mathematical equations of the concerned parameters. Apart from the synthesis of protective polymeric coatings, understanding the relationship between characteristics of coating materials and accompanying foul-release and antifouling mechanism is important. In this regard, efforts have been made to equally evaluate, simulate, and measure the appropriate performance of the coatings. By examining the physicochemical and mechanical properties of the polymers, adhesion behavior has been found to be one of the prerequisites for the success of polymeric coatings for marine applications. The potential development of a broad spectrum of methods used to evaluate the foul-release performance of polymeric coatings depending on adhesion behavior of fouling organisms with the coatings has been discussed. From the analysis of the factors affecting degradation of coatings, environmental interference is declared a key factor for complete degradation of polymeric coatings. This review opens up new research directions to improve the adhesion performance of polymeric coatings for ship hulls designed with tunable viscoelasticity by the incorporation of elastomeric polymers (like polydimethylsiloxane) into stiff polymers (like epoxy resins) with and without the utilization of additives, modifiers, and nano-fillers. In addition, it provides methods to improve the foul-release performance of such coatings that work on adhesion behavior of biofouling species attached to the coating surface. [ABSTRACT FROM AUTHOR]

The effect of hybrid filler on newly developed thermal conductive epoxy adhesive has been reported in this paper. The hybrid filler containing hexagonal boron nitride (h-BN) and graphite (Gr) with the mass ratio of 1:1 was loaded in to the epoxy resin with different wt% ratio (10:90, 20:80, 30:70, 40:60, 50:50 and 60:40). The corresponding thermal conductivity of adhesives was measured using guarded heat flow meter technique which enhanced up to 2.025 W/mK with the loading of 60 wt% of hybrid filler. Lap shear strength of the adhesive containing 40 wt% of hybrid filler was higher than the pristine epoxy resin thereby confirming reinforcing effect of hybrid filler into the epoxy matrix. Afterward, the shear viscosity of uncured epoxy resin filled with hybrid fillers were analyzed by using parallel plate rheometry. Strong shear thinning behavior was exhibited at higher hybrid filler loading. Further, lower loss factor and higher Tg values were observed with increase in the hybrid filler (h-BN/Gr) loading thereby confirming the higher cross linking density and lower mobility of epoxy chain. Thermal stability of hybrid Gr/BN-epoxy composite adhesives was studied using thermo gravimetric analyzer. Scanning electron microscopy confirmed the uniform deposition of hybrid filler on to the surface of epoxy resin. [ABSTRACT FROM AUTHOR]

Abstract: Petroleum based epoxy resins exhibit various excellent properties such as adhesion, mechanical performance, electrical insulation and chemical resistance. There is wide concern towards depletion of non‐renewable resources, climate change and finding renewable alternatives for petroleum based materials to reduce the emission of greenhouse gases. This review mainly draws attention towards the utilization of renewable resource based epoxy resin derived from lignocellulosic biomass, furan, tannins, itaconic acid, rosin acid and bio‐oil etc. Without altering the mechanical and thermal properties much, epoxy resins derived from renewable materials have been widely investigated. The last two decades have witnessed an exponential growth in using bio‐derived products, which has been driven by the need to replace petroleum based materials, reduce fuel consumption and lower the overall environmental impact. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

In the present investigation, epoxidized soybean oil‐based toughened epoxy composites were developed using unidirectional sisal fibers mat aligned at [0°/0°]s and [0°/90°]s orientations. Stiffness and strength of the [0°/0°]S laminated composite are increased by 17% and 121%, respectively, as compared with the [0°/90°]s oriented composite. Simialrly, Notched impact strength and critical strain energy release rate (KIC) of [0°/0°]s laminated composite were also highly improved by 19.5% and 33.4%, respectively, with respect to [0/90] laminated composite. Dynamic mechanical analysis of [0°/0°]s oriented composite showed high storage modulus and broadened loss tangent curve revealing a strong influence of fiber orientation on damping behavior. The fibre–matrix adhesion in both the biocomposites is confirmed by scanning electron microgrphs of the impact fractured specimens. Contact angle and work of adhesion are measured to investigate the hydrophilic nature of epoxy, its blend, and composite toward water. POLYM. COMPOS., 39:2065–2072, 2018. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The development of new polymer-based conductive adhesives with specific performances and improved conductivity are increasingly critical for thermally interface material (TIM). Epoxy resins have been widely used as a common interface material for conductive adhesives due to its well-known ability to accept wide range of fillers possibly derived from carbon, metallic or ceramic sources. These conductive fillers with high inherent thermal conductivity, together with a possibility to characterize and manipulate the system, leads to the production of thermally conductive adhesives with higher knowledge content for a number of electronics applications. [ABSTRACT FROM AUTHOR]

A novel renewable resource based tri-functional epoxy resin from itaconic acid (TEIA) was blended with petroleum based epoxy resin (DGEBA) and fabricated at different ratios. Then, it was by thermally cured with methylhexahydrophthalic anhydride (MHHPA) in presence of 2-methylimidazole (2-MI) catalyst. The tensile, modulus, strength of virgin epoxy resin (41.97 MPa, 2222 MPa) increased to 47.59 MPa, 2515 MPa, respectively, with the addition of 30% of TEIA. The fracture toughness parameter, critical stress intensity factor (KIC) revealed enhancement of toughness in the TEIA bio-based blends system. The thermomechanical properties of TEIA (tri-functional epoxy resin from itaconic acid) modified petroleum-epoxy networks were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The fracture morphology was also studied by the scanning electron microscopy and atomic force microscopy respectively. [ABSTRACT FROM AUTHOR]

Currently, the utilization of renewable resources for sustainable technology is in the renown of consumer as well as industrial attention, especially, chemical industries because of their availability, low cost, credentials toward environmental issues such as lower ecotoxicity, CO2footprints, and inbuilt biodegradability. These natural properties are being taken advantage of in research and development, with vegetable oil-, furan-, lignin-, rosin-,vanillin-, and itaconic acid-derived biobased epoxy resin being used in various applications including paints, coatings, adhesives, and biomedicine. The present review mainly focuses on the utilization of natural resources for the synthesis of biobased epoxy and its curing agents. [ABSTRACT FROM AUTHOR]

A trifunctional epoxy resin from itaconic acid (TEIA) was synthesized from a renewable resource-based itaconic acid by allylation of itaconic acid to form diallyl itaconate by using m-chloroperoxybenzoic acid as oxidizing agents followed by epoxidation of allylic C═C bond of diallyl itaconate methylhexahydropthalic anhydride as curing agent in the presence of 2-methyl imidazole as a catalyst. The chemical structure of the synthesized resins was confirmed by Fourier transform infrared and nuclear magnetic resonance (1H-NMR and 13C-NMR) spectroscopy analysis. The mechanical, thermal, and rheological performances of the TEIA were also investigated and compared with diglycidyl ether of bisphenol A and a plant-based epoxidized soybean oil bioresin cured with the same curing agent. The higher epoxy value of 1.02, lower viscosity (0.96 Pa s at 25°C), higher mechanical, and higher curing reactivity toward methylhexahydropthalic anhydride of TEIA as compared with epoxidized soybean oil and comparable with diglycidyl ether of bisphenol A demonstrated significant evidence to design and develop a novel bio-based epoxy resin with high performance to substitute the petroleum-based epoxy resin. [ABSTRACT FROM AUTHOR]

Castor-oil-based polyurethane (PU), epoxy (glycidol) terminated polyurethane (EPU), and hydroxy terminated poly (dimethyl siloxane) (HTPDMS) modified EPU (EPDMS) were synthesized. The PU and EPU were synthesized with polyol:diisocyanate and polyol:diisocyanate:glycidol ratio of 1:1.2 and 1:3:3, respectively, whereas EPDMS was prepared by the incorporation of 5 wt.%, 10 wt.%, 20 wt.%, and 30 wt.% of HTPDMS into the EPU. The structural modification of EPDMS was confirmed by solid-state CP/MAS C and Si NMR spectroscopy. The results of a tensile test revealed that the EPDMS with 10 wt.% loading of HTPDMS (EPDMS10) exhibited considerable enhancement in the tensile strength and modulus. The scanning electron microscope analysis was performed to understand the increased phase heterogeneity of the samples. [ABSTRACT FROM AUTHOR]

Present study deals with the development of aligned multi-walled carbon nanotubes (MWCNT) and vapour grown carbon fibers (VGCF) reinforced epoxy adhesive system used as an alternative to Pb/Sn soldering element. The alignment of MWCNTs was carried out in a specific designed instrument exerting of an external electric field. Solution casting technique was used for the fabrication of epoxy adhesive system incorporated with aligned MWCNT and VGCF. Scanning electron microscopy and Atomic force microscopy was carried out to determine the degree of alignment of MWCNTs. Owing to the formation of continuous path for the flow of electrons, 3 wt% of aligned MWCNT with 3 wt% of VGCF reinforced epoxy adhesive achieved about five orders of magnitude higher in the thermal conductivity compared to pure epoxy. Further, the experimental results showed that the shear strength of epoxy/3% MWCNT/3% VGCF adhesive system was 112% higher than the strength of pure polymer, emphasizing the advantages of aligned MWCNT on stiffness and strength. Dynamic Mechanical Analysis and Thermo-gravimetric analysis was carried out to study the thermo-mechanical and thermal degradation behaviour of epoxy adhesive formulations. [ABSTRACT FROM AUTHOR]

This study focuses on synthesis of waterborne epoxy (WBE) derived from epoxidized soybean oil (ESO) and its compatibility with water-dispersible curing agent Pripol 1009, which is a bioderived long-chain dimer acid. The reaction parameters involved in the synthesis of WBE from ESO have been optimized based on physicochemical properties like hydroxyl value, epoxy equivalent value and degree of solubility of WBE. The WBE obtained after 5 and 6 h of reaction time was found to be of optimum composition with balanced physicochemical properties. The mechanical, thermal and physicochemical properties of WBE obtained after 6 h of reaction time revealed relatively better performance characteristics as compared to ESO. [ABSTRACT FROM AUTHOR]

In the present study, waterborne epoxy (WBE) was prepared and the parameters involved in the synthesis of WBE have been optimized based on physicochemical analysis. A dextrin-based curing agent (DCA) was synthesized from dextrin and trimellitic anhydride at variable molar ratios, reaction temperature, reaction duration, and solvent. Furthermore, the optimized composition of DCA and WBE system was used as adhesive in wood bonding. A comparative analysis of DCA-cured-bonded system was studied with phenol-formaldehyde (PF)-bonded adhesive system. From all the analyses, the performance characteristic WBE–DCA adhesive system was found comparable with that of PF-bonded system. [ABSTRACT FROM AUTHOR]

Epoxy resin is modified with epoxy methyl soyate synthesized from soybean oil to toughen the matrix and reduce the viscosity of resin system. Unidirectional sisal fibers in mat form were incorporated at different orientations of [0/0] and [0/90] as reinforcement in epoxy blend having more toughened nature. Highly improved strength and modulus of the [0/0] laminated composite revealed strong interfacial region of matrix for binding the fibers. Further, notched impact strength of the composites was found to be more than 700% higher compared with modified epoxy blend. Dynamic mechanical analysis depicted an improvement in the storage modulus and higher damping factor of the [0/0] sisal fiber laminated composite, which confirms better damping properties under vibrating conditions. The fiber-matrix interfacial adhesion in the composite was confirmed by scanning electron microscopic analysis of the fractured specimens. Contact angle and atomic force microscopic studies were carried out to reveal the hydrophilic nature. [ABSTRACT FROM AUTHOR]

The present study highlights the structure and property relationships of epoxidized castor oil (ECO) toughened Diglycidyl Ether of Bisphenol A (DGEBA) epoxy nanocomposites. Toughened epoxy systems have been prepared by an addition of 10-40wt% ECO to the DGEBA epoxy resin. Nanocomposites were prepared by mixing small amounts of Cloisite 30B (C30B) clay and 3-aminopropyltriethoxysilane to the DGEBA/ECO blends. The chemical structure of toughened systems was confirmed using proton nuclear magnetic resonance and fourier transform infrared spectroscopy. The triethylenetetraamine-cured DGEBA/ECO/C30B (8:2:0.1) nanocomposites exhibited tensile strength (50 MPa), tensile modulus (1.7 GPa), flexural strength (120 MPa), flexural modulus (3.02 GPa), and elongation (19%). The fracture toughness (critical intensity factor, KIC) and fracture energy (critical energy release rate, GIC) of DGEBA/ECO/C30B (8:2:0.1) system found to be higher than the other systems (2.5 MPa.m½ and 1.8 kJ/m2 for KIC and GIC, respectively). The thermal stability and heat of reaction of DGEBA/ECO blends increase with the addition of C30B clays that were analyzed using thermogravimetric analysis and differential scanning calorimetry. Rheological characterizations of uncured samples revealed a pronounced effect of the C30B clay on the DGEBA/ECO blend systems that exhibited a shear-thickening behavior. On the other hand, the dynamic mechanical properties also revealed that the addition of C30B clays to the DGEBA/ECO blend a significant enhancements in viscoelastic and cross linking density behavior. Scanning electron microscope analysis was used to study the fractured morphology of DGEBA, DGEBA/ECO, and its nanocomposite systems. [ABSTRACT FROM AUTHOR]

A novel bioresin, epoxidized soybean oil was synthesized by in situ method and was characterized employing FTIR and NMR. The bioresin was blended with epoxy (DGEBA) at different ratios as reactive diluents for improved processibility and toughened nature. The composition with 20 wt% bioresin exhibited improved impact strength to the tune of 60% as compared to virgin epoxy. Fracture toughness parameters critical stress intensity factor ( K) and critical strain energy release rate ( G) were evaluated using single edge notch bending test and demonstrated superior enhancement in toughness. Dynamic mechanical, thermal, thermo mechanical and fracture morphological analyses have been studied for bio-based epoxy blends. Curing kinetics has been evaluated through DSC analysis to investigate the effect of bioresin on cross-linking reaction of neat epoxy with triethylenetetramine as curing agent. [ABSTRACT FROM AUTHOR]

This article is designed to review the developments in synthesis, modifications, and properties of epoxy monomers derived from both petroleum and renewable resources. It begins with the enhancement in epoxy monomer properties such as mechanical, thermal, adhesive, barrier, etc. by addition of flexible polymer and elastomers. It also explains the role of organic/inorganic fillers on epoxy monomers to achieve the desired properties for outdoor applications. The effects of chemical/physical treatments on fiber are reviewed and their improvements with epoxy monomers are also observed. The authors also suggest for further improvement of epoxy monomers to obtain various eco-friendly high-performance applications. [ABSTRACT FROM AUTHOR]

The non-isothermal curing kinetics of diglycidyl ether of bisphenol-A (DGEBA) and bio-based epoxy resin (ESO) both cured with methyl hexahydrophthalic anhydride (MHHPA) curing agent in the presence of 2-methylimidazole as catalyst (2-MI) was investigated using differential scanning calorimetry (DSC) at three different heating rates 5, 10, 15 °C/min. The peak temperature was found to be dependent on the heating rates and the structure of anhydride as well as molar ratio of epoxy groups to MHHPA and catalyst. The activation energy ( E a ) was determined by Kissinger and Ozawa methods. The two kinetic parameter m and n were obtained by Sestak–Berggren autocatalytic model. The curve obtained by the predicted values of the non-isothermal Malek method matched perfectly with the experimental data for DGEBA, ESO and their blend. [ABSTRACT FROM AUTHOR]

The present research is based on a comparative study of anhydride cured biobased and petroleum-based epoxy network. The effect of epoxidized soybean oil (ESO) bioresin on petroleum-based epoxy (DGEBA) at varying compositions cured with methylhexahydrophthalic anhydride (MHHPA) as curing agent and 2-methyl imidazole (2-MI) as the catalyst has been investigated. The tensile strength of virgin epoxy (42.94 MPa) increased to 48.62 MPa with the addition of 20% of ESO. The fracture toughness parameters; critical stress intensity factor (KIC) and critical strain energy release rate revealed enhancement of toughness in the biobased blends. Differential scanning calorimetry studies confirmed an enhancement in the peak temperature and a reduction in the heat of curing in virgin epoxy on incorporation of ESO content. The thermomechanical and fracture morphological properties of virgin epoxy, ESO, and its biobased blends were investigated by thermogravimetric analysis, dynamic mechanical analysis, atomic force microscopy, and scanning electron microscopy, respectively. [ABSTRACT FROM AUTHOR]

The petroleum based diglycidyl ether of bisphenol A (DGEBA) epoxy resin is one of the most extensively used epoxy resins for various industrial applications such as paints, coatings, adhesives, and structural applications, owing to its excellent mechanical and thermal properties, low curing shrinkage, and good chemical resistance. However, the serious drawbacks in terms of brittleness or poor fracture energy significantly restricted its extensive utilization. Various renewable resources based flexible chains were used to blend with DGEBA for toughening and to significantly improve the fracture properties without sacrificing the mechanical properties. This review mainly focuses on toughening of DGEBA with various renewable polymers and the effect of its concentration on its toughening mechanism. [ABSTRACT FROM AUTHOR]