Conventional Epoxy Research Articles

Epoxidized technical Kraft lignin as a particulate resin component for high-performance anticorrosive coatings

Deterioration of steel infrastructures is often caused by corrosive substances. In harsh conditions, the protection against corrosion is provided by high-performance coatings. The major challenge in this field is to find replacements for the fossil-based resins constituting anticorrosive coatings, due to increasing needs to synthesize new environmentally friendly materials. In this study, softwood Kraft lignin was epoxidized with the aim of obtaining a renewable resin for anticorrosive coatings. The reaction resulted in the formation of heterogeneous, solid, coarse agglomerates. Therefore, the synthetized lignin particles were mechanically ground and sieved to break up the agglomerates and obtain a fine powder. To reduce the use of fossil fuel-based epoxy novolac resins in commercial anticorrosive coatings, a series of formulations were prepared and cured on steel panels varying the content of epoxidized lignin resin. Epoxidized lignin-based coatings used in conjunction with conventional epoxy novolac resin demonstrated improved performance in terms of corrosion protection and adhesion properties, as measured by salt spray exposure and pull-off adhesion test, respectively. In addition, the importance of size fractionation for the homogeneity of the final coating formulations was highlighted. The findings from this study suggest a promising route to develop high-performing lignin-based anticorrosive coatings.

Investigation on One-Component Waterborne Epoxy Emulsified Asphalt (OWEEA) Used as Bonding Material

Due to the issue of weakened adhesion between ultra-thin surface overlays, higher demands have been placed on bonding layer materials in practical engineering. This study proposed a method for preparing a one-component waterborne epoxy resin-modified emulsified asphalt (OWEEA) and explored the impact of different ratios on its performance. The basic physical and mechanical properties of the OWEEA, as well as its rheological characteristics, were investigated through penetration tests, softening point tests, ductility tests, tensile tests, and dynamic shear rheological tests. Pull-out tests and shear tests considering different substrates were used to evaluate the interfacial bonding performance of the OWEEA as a bonding layer material, and comparative analysis was conducted with conventional waterborne epoxy resin-modified emulsified asphalt. Based on microscopic testing and analysis, the laws of physical and chemical changes and secondary curing characteristics of the one-component waterborne epoxy emulsion (OWE) during the modification of emulsified asphalt were elucidated. The results indicated that the OWE prepared in this study significantly enhanced the tensile strength and bonding properties of emulsified asphalt. The results showed that the tensile strength, bonding strength, and shear strength of the OWEEA increased from 0.15 MPa, 0.36 MPa, and 0.35 MPa to 0.55 MPa, 1.29 MPa, and 2.01 MPa, respectively. The modification effect of the OWEEA surpassed that of conventional waterborne epoxy emulsion, albeit with a certain reduction in elongation at break, reduced from 1551% to 98%. Furthermore, the OWEEA showed a distinct secondary curing phenomenon. The results of the SEM tests showed that high temperatures accelerated the formation of the crosslinked network structure of OWE, promoting its integration with emulsified asphalt and resulting in a more uniform and dense structure, significantly enhancing bonding strength in a short period. In the actual road construction process, laying hot-mix asphalt mixtures on the bonding layer can further enhance its curing effect and improve its bonding performance.

Mechanical recycling and electro‐thermal welding of epoxy vitrimer nanocomposites

AbstractVitrimers constitute a new class of recyclable thermosets based on the incorporation of associative dynamic covalent bonds, such as disulfide bonds, into the crosslinked matrix. These reversible bonds usually require excess dynamic bonds to confer proper self‐healing and recycling capabilities to the thermoset. In that way, we manufacture epoxy resins cured with 4‐aminophenyl disulfide (AFD) in a stoichiometric ratio, and with 10 and 20 wt% of AFD excesses to analyze the effect of composition on resin properties. Beyond the neat vitrimers analysis, we manufacture nanocomposites doped with carbon nanotubes (CNT) to obtain electroactive vitrimers. These epoxy resins and nanocomposites can be mechanically recycled by milling and hot‐pressing. The recycled nanocomposites conserve partially CNT integrity and dispersion. Even more, recycled nanocomposites with AFD excesses maintain the mechanical strength of the pristine nanocomposites. Vitrimer nanocomposite samples can be also electrically welded, due to their heating by the Joule effect, through a relatively low voltage application, and therefore with low energy consumption, to obtain a monolithic specimen. In summary, the manufactured epoxy vitrimers and nanocomposites are recyclable and sustainable epoxy materials, which can be processed and reprocessed using technologies easily implementable, fast, and with low energy consumption.Highlights Electroactive and re‐processable vitrimer nanocomposites are manufactured. Nanocomposite vitrimers show conductivities similar to conventional epoxies. Bond exchanging temperatures can be reached by Joule heating. CNT addition enhances disulfide exchanges and thermo‐mechanical recyclability. Electrothermal welding of vitrimer nanocomposites is successfully tested.

Enhanced electromechanical coupling in Pb(ZrTi)O3 piezoelectric composite via poly(vinylidene fluoride‐trifluoroethylene) clamping

AbstractThis study presents an advanced two‐step hot‐pressing process for fabricating the 1‐3 type Pb(ZrTi)O3/poly(vinylidene fluoride‐trifluoroethylene) (PZT/P(VDF‐TrFE)) piezoelectric composite sheets, demonstrating significant potential for nondestructive evaluation and information storage applications. The engineered columnar architecture within these composites induces a two‐phase clamping effect, which, upon polarization, facilitates the elongation of PZT and suppresses its lateral vibrations, thus enhancing the electromechanical coupling effect as verified by COMSOL simulations. A notable dielectric constant of 2200 at 100 Hz and a coupling coefficient of 0.725 was achieved with specific geometric modifications to the PZT/P(VDF‐TrFE) sheets. These findings suggest that P(VDF‐TrFE) as a polymer matrix exceeds the performance of conventional epoxy matrices, offering a novel approach to designing 1‐3 type piezoelectric composites.Highlights P(VDF‐TrFE) effectively drives the elongation strain of internal PZT columns. COMSOL simulation clarifies the clamping effect of piezoelectric P(VDF‐TrFE). PZT/P(VDF‐TrFE) shows a higher kt of 0.725 than that of pure PZT samples.

Fatigue performance of carbon fiber‐reinforced polymer strengthened single‐edge cracked steel plates: Effects of adhesive property and CFRP arrangement

AbstractCarbon fiber‐reinforced polymer (CFRP) is increasingly used to improve the fatigue behavior of damaged steel structures due to its advantages, including high strength and convenient processing. However, several issues, such as the effects of the adhesive property and CFRP arrangement, still need to be studied. In this study, a total of 20 single‐cracked steel specimens were tested under fatigue load, including two unstrengthened specimens, six single‐sided strengthened specimens, and 12 double‐sided strengthened specimens. The failure mode, fatigue life, crack propagation pattern, and interface damage development were obtained from experiments. The results show that epoxy resin structural adhesives (adhesives Araldite 420 and J133C) have the best bonding properties with CFRP. For the conventional epoxy adhesives, Araldite 420 and J133C can considerably improve fatigue life, which increased by more than 44.84 times to unstrengthened specimens. CFRP plate strengthening can significantly improve the fatigue life of single‐edge cracked steel plates. For the double‐sided strengthened specimens, the fatigue life can be improved by 6.93–44.84 times that of unstrengthened specimens. For the single‐sided, the fatigue life can be improved by 2.24–2.77 times. Properties of epoxy adhesive have a more significant effect on fatigue life compared to the thickness of the CFRP plate due to debonding.Highlights Ductile epoxy adhesives are most conducive to improving the fatigue behavior of CFRP strengthened steel plates. The fatigue life of steel plates can be improved by increasing the thickness of CFRP plates and using double‐sided CFRP strengthening. Interface debonding is the main failure mode of CFRP plates strengthening single‐edge cracked steel plates under fatigue.

Potential of epoxy coating containing ionic liquid as anti-corrosion coating: Evaluation of barrier properties

Barrier properties of innovative epoxy coatings containing 10 or 20 phr of phosphate/phosphonium ionic liquid (IL) were investigated using mainly electrochemical impedance spectroscopy. The impedance diagrams revealed quasi-pure capacitive behavior and the impedance modulus at low frequency, related to corrosion resistance, remains at around 1012 Ω cm2 during immersion time in 0.1 M NaCl solution. The capacitances were graphically extracted from Cole–Cole representations, and the resistances were determined using R//C electric equivalent circuits. Both epoxy–IL coatings were free of porosity and impeded the hydration of the matrix. The results were also compared to those of conventional epoxy coatings, for which hydration occurs owing to their porosity. Results indicate that this new epoxy–IL coating system would offer excellent anticorrosion protection for metallic substrates.

Static and Impact Properties of Flax-Reinforced Polymers Prepared with Conventional Epoxy and Sustainable Resins.

The study assessed the tensile, flexural, and impact properties of composite materials reinforced with flax fibers, employing three distinct resin types. The composite laminates were fabricated using three commercial resins: a conventional epoxy resin, an epoxy resin with a 31% weight concentration of bio-renewable content, and a recyclable methyl methacrylate infusion resin. This aims to assess if there exists a commercially available alternative to the traditional epoxy resin that can reduce the overall carbon footprint of composite materials. To investigate the influence of humidity on the mechanical behavior of the flax layers, a drying treatment was applied to the fibers before the infusion process. Micro-computed tomography analysis revealed that heat treatment resulted in a reduction of porosity, although it did not affect the mechanical response of the composite laminates. Moreover, laminates produced with non-recyclable and sustainable resins exhibited no significant change in tensile and flexural modulus. In contrast, those produced with recyclable resin demonstrated a slight reduction in the strengths of the composite laminates. Conversely, out-of-plane impact tests and repeated impact tests indicated that composites prepared with recyclable and bio-epoxy resin formulations present superior damage resistance to repeated impact compared to traditional epoxy resin.

Effects of the chain length of nonaromatic epoxy resins on thermomechanical and optical properties: experiments, and ab initio and molecular dynamics simulations.

Epoxy resin has been extensively used in the field of advanced electronic materials as an adhesive and encapsulant owing to its excellent material properties. However, recently, there has been a demand for further improvement in heat resistance, high transparency, environmental resistance, and enhanced handling properties for high-brightness light-emitting diodes. Conventional aromatic epoxy resins lack light resistance; therefore, a colorless and transparent epoxy resin without aromatic rings is desirable. In this study, tris(2,3-epoxypropyl) isocyanurate (TEPIC) was used as a nonaromatic epoxy resin, and three types of TEPIC with different side-chain lengths were prepared. The ultraviolet (UV)-visible absorption properties of TEPIC were evaluated using time-dependent density functional theory, and the practicality of the numerical prediction of light resistance was verified. TEPIC yields a UV absorbance spectrum with a lower intensity than those of conventional aromatic epoxy resins, suggesting that TEPIC is expected to have high light resistance. In addition, their thermomechanical properties and the influence of molecular structure were evaluated using both molecular dynamics (MD) simulations and experiments. The MD simulation and experimental results were in good agreement, indicating that the long side chains of TEPIC suppress triaxial deformation-induced failure and improve ductility instead of decreasing strength and stiffness. In addition, the longer side chains form a dense molecular structure with less free volume. These results indicate that numerical approaches can be used to predict various properties of epoxy resins and interpret them from the molecular structure. Accordingly, these approaches can be used to aid the material development process.

Low dielectric constant and highly intrinsic thermal conductivity fluorine‐containing epoxy resins with ordered liquid crystal structures

AbstractEpoxy resins with a high dielectric constant and low intrinsic thermal conductivity coefficient cannot meet the current application requirements of advanced electronic and electrical equipment. Therefore, novel fluorine‐containing liquid crystal epoxy compounds (TFSAEy) with fluorinated groups, biphenyl units, and flexible alkyl chains are first synthesized via amidation and esterification reactions. Then, 4,4′‐diaminodiphenylmethane (DDM) is used as a curing agent to prepare the corresponding fluorine‐containing liquid crystal epoxy resins. The obtained dielectric constant (ε) and dielectric loss (tan δ) values of TFSAEy/DDM at 1 MHz are 2.54 and 0.025, respectively, which are significantly lower than those of conventional epoxy resins (E‐51/DDM, 3.52 and 0.038). Additionally, the intrinsic thermal conductivity coefficient (λ) of TFSAEy/DDM is 0.36 W/(m·K), 71.4% higher than that of E‐51/DDM (0.21 W/(m·K)). Meanwhile, the corresponding elastic modulus, hardness, glass transition temperature, and heat resistance index of TFSAEy/DDM are 5.73 GPa, 0.35 GPa, 213.5°C, and 188.7°C, respectively, all superior to those of E‐51/DDM (3.68 GPa, 0.27 GPa, 107.2°C, and 174.8°C), presenting potential application in high‐heating electronic component packaging and printed circuit boards.

Interfacial coordination-assisted construction of mechanically robust, fluorescent and intumescent flame retardant epoxy resins

Conventional intumescent flame retardant epoxy resins (EP) are challenged by the weak interfacial interaction between the fillers and matrix, and particularly the introduction of desired functionality. To address this issue, herein, interfacial coordination reaction is facilely utilized to assist the construction of highly fire-safety EP with robust mechanical strength and blue-fluorescence. For demonstration, nicotinic acid-nickel chelate (NicNi) decorated ammonium polyphosphate (NicNi@APP) was strategically prepared by the in-situ growth of NicNi particles on the surface of APP. It is crucial that during the curing of epoxy system, the coordination environment of Ni2+ was gradually changed alone with the interfacial coordination reaction of DETA and NicNi@APP. Consequently, the as-cured EP was not only equipped with the blue-fluorescence possibly due to the clustering-triggered emission (CTE), but also possessed high mechanical strength. Besides, EP containing 6 wt% NicNi@APP achieved a V-0 rating under UL-94 tests, and got a limiting oxygen index (LOI) of 32.6 %. What’s more, its peak of heat release rate (PHRR), total heat release (THR), total smoke production (TSP) during combustion decreased by 84.3 %, 69.8 % and 68.7 % respectively as compared to EP. Generally, this work provides a feasible strategy for the preparation of multifunctional epoxy resin with high performance.

Evaluation of the injection and plugging ability of a novel epoxy resin in cement cracks

Sustained casing pressure (SCP) is a crucial issue in the oil and gas production lifecycle. Epoxy resins, exhibiting exceptional compressive strength, ductility, and shear bonding strength, have the potential to form reliable barriers. The injectivity and sealing capacity of the epoxy resin is crucial parameters for the success of shallow remediation operations. This study aimed to develop and assess a novel solid-free resin sealant as an alternative to Portland cement for mitigating fluid leakage. The investigation evaluated the viscosity, compressive strength, and brittleness index of the epoxy resin sealant, as well as its tangential and normal shear strengths in conjunction with casing steel. The flow characteristics and sealing abilities of conventional cement and epoxy resin were comparatively analyzed in cracks. The results showed that the application of a viscosity reducer facilitated control over the curing time of the epoxy resin, ranging from 1.5 to 6 h, and reduced the initial viscosity from 865.53 to 118.71 mPa⋅s. The mechanical properties of the epoxy resin initially increased with a rise in curing agent content before experiencing a minor decrease. The epoxy resin containing 30% curing agent exhibited optimal mechanical properties. After a 14-day curing period, the epoxy resin's compressive strength reached 81.37 MPa, 2.12 times higher than that of cement, whereas the elastic modulus of cement was 2.99 times greater than that of the epoxy resin. The brittleness index of epoxy resin is only 3.42, demonstrating high flexibility and toughness. The tangential and normal shear strengths of the epoxy resin exceeded those of cement by 3.17 and 2.82 times, respectively. In a 0.5 mm-wide crack, the injection pressure of the epoxy resin remained below 0.075 MPa, indicating superior injection and flow capabilities. Conversely, the injection pressure of cement surged dramatically to 2.61 MPa within 5 min. The breakthrough pressure of 0.5 PV epoxy resin reached 7.53 MPa, decreasing the crack's permeability to 0.02 D, a mere 9.49% of the permeability observed following cement plugging. Upon sealing a 2 mm-wide crack using epoxy resin, the maximum breakthrough pressure attained 5.47 MPa, 3.48 times of cement. These results suggest that epoxy resin sealant can be employed safely and effectively to seal cracks in the cement.

Phytic acid oligomers as bio-based crosslinkers for epoxy and polyol resins

AbstractIn recent years, the chemical industry is not only striving to produce the best possible products for various applications, but the new products should ideally be based on renewable resources. The ideal case of "cradle to cradle" is generally not achievable in the coatings industry, as maximizing product life and preventing product degradation in the environment is usually one of the main goals of the coatings industry. Therefore, if the coatings industry wants to act sustainably, its efforts should be focused on renewable raw materials. This paper presents a process that makes the renewable raw material phytic acid easily accessible for conventional epoxy and polyol resin coating systems through hydrophobization- and oligomerization. Phytic acid, as a phosphorus reservoir in plants and with beneficial properties for corrosion protection and as a flame retardant, could be a new base for various coatings. In this work, a simple one-pot oligomerization of phytic acid with green mono- and difunctional alcohols is investigated. The aim of this work is to create a phytic acid hardener system based on renewable raw materials that can produce coatings with solvent-based epoxy and polyol binders as well as water-based epoxy binders. The successful reaction was observed by infrared, 1H-NMR, and 31P-NMR spectroscopy and the acid equivalent weight was determined by conductivity titration. The renewable curing agent was then used equivalently with different binder systems to prepare coatings. Crosslinking and glass transition temperature were monitored using oscillatory rheology. The coatings were applied to glass plates and the pendulum hardness was measured. A simple heating test followed by 31P-NMR and IR spectroscopy was also performed to demonstrate the stability of phytic acid under reaction conditions.

A sustainable alternative? A comparative life cycle assessment of epoxy adhesives

AbstractIn response to the imperative of eco‐friendly material substitution, a comparative cradle‐to‐gate life cycle assessment (LCA) of two epoxy adhesives is presented: a traditional epoxy resin and an innovative self‐curing epoxy derived by epoxidizing poly‐beta‐myrcene (a constituent of Chios Mastic natural resin). Employing ReCiPe 2016 indicators and standard normalization, our study reveals that epoxidized poly‐beta‐myrcene outperforms conventional epoxy in 9 of 18 assessed midpoint indicators, with minimal impact in 7, and marginally higher impact in 2. The superiority of epoxidized poly‐beta‐myrcene extends to all three ReCiPe Endpoint protection areas. Atom economy and the E‐factor are also considered and related to the LCA results. Furthermore, the evaluation demonstrates epoxidized poly‐beta‐myrcene's remarkable environmental favorability compared to a literature bio‐based epoxy across multiple CML‐IA‐baseline indicators. In summary, epoxidized poly‐beta‐myrcene emerges as a promising, ecologically sensitive alternative to current conventional and bio‐based epoxy options.

Biobased boronic ester vitrimer resin from epoxidized linseed oil for recyclable carbon fiber composites

In the last decades fiber-reinforced polymer composites (FRPC) have seen an enormous growth however, at the end of their lifetime, FRPC made of epoxy resins cannot be easily recycled because of the permanently crosslinked structure of the resins. Since the fibrous reinforcements usually have high costs, the possibility of developing recyclable FRPC is very advantageous both from environmental and economical point of view.To address this increasing need of the market, we developed a recyclable, environmentally friendly vitrimer resin from epoxidized linseed oil and a boronic ester cross-linker. Using the vitrimer as a matrix, carbon fiber-reinforced composites, with mechanical performance similar to the ones prepared with a conventional epoxy resin, were obtained. Moreover, the composites could be conveniently recycled under mild conditions by reversible hydrolysis of the boronic ester crosslinks using aqueous EtOH, recovering both the carbon fiber reinforcement and the vitrimer matrix.

Bio-Oil-Based Epoxy Resins from Thermochemical Processing of Sustainable Resources: A Short Review

Epoxy is the most prevalent thermosetting resin in the field of polymer composite materials. There has been a growing interest in the development of bio-based epoxy resins as a sustainable alternative to conventional petrochemical epoxy resins. Advances in this field in recent years have included the use of various renewable resources, such as vegetable oils, lignin, and sugars, as direct precursors to produce bio-based epoxy resins. In the meantime, bio-oils have been produced via the decomposition of biomass through thermochemical conversion and mainly being used as renewable liquid fuels. It is noteworthy that bio-oils can be used as a sustainable resource to produce epoxy resins. This review addresses research progress in producing bio-oil-based epoxy resins from thermochemical processing techniques including organic solvent liquefaction, fast pyrolysis, and hydrothermal liquefaction. The production of bio-oil from thermochemical processing and its use to inject sustainability into epoxy resins are discussed. Herein, we intend to provide an overall picture of current attempts in the research area of bio-oil-based epoxy resins, reveal their potential for sustainable epoxy resins, and stimulate research interests in green/renewable materials.

Review of thermal conductivity in epoxy thermosets and composites: Mechanisms, parameters, and filler influences

Rapid development of energy, electrical and electronic technologies has put forward higher requirements for the thermal conductivities of epoxy resins and their composites. However, the thermal conductivity of conventional epoxy resins is relatively low, which could cause major heat dissipation issues. Therefore, the thermal conductivity enhancement of epoxy resins has long been a hot research topic in both academia and industry. In recent years, many promising advances have been made at the technical and mechanistic levels. This review includes the different approaches, the thermal conduction mechanisms implied, and the main research progresses. The research and academic achievements are mainly focused on the development of intrinsically liquid crystal epoxy resins and their composites, and the addition of fillers on amorphous epoxy resins. Finally, the challenges and prospects for thermal conductive epoxy resins are provided. Notably, this review can provide a more comprehensive understanding of thermally conductive epoxy resins and a guideline for the cutting-edge development direction of thermally conductive epoxy resins.

A biobased epoxy vitrimer/cellulose composite for 3D printing by Liquid Deposition Modelling

Conventional epoxy polymers are obtained from oil-based resources and their structure is formed by permanent covalent crosslinks. Therefore, this class of materials is now considered non environmentally friendly as they are neither renewable nor reprocessable and recyclable. In this study, we prepared a vitrimeric material based on an epoxy-functionalised cardanol cured with a biobased polycarboxylic acid. In the presence of a zinc-containing catalyst, a soft polyester with a Tg = −13 °C was obtained; its reprocessability by a chemical method was demonstrated to be feasible without any relevant change in properties once a second curing cycle was completed. The vitrimeric polyester was then used in combination with cellulose powder for the preparation of a sustainable and biobased composite. The matrix/filler mass fraction was tailored to obtain a composite paste with suitable rheological properties for 3D printing via Liquid Deposition Modelling (LDM). Preliminary printing tests were successful, and the vitrimeric printed parts were then thermally cured retaining the shape. The suitability of the vitrimeric composite for additive manufacturing was thus confirmed: the new material can provide a solution to 3D printing of recyclable thermosetting biobased polymers.

Thermo-mechanical and insulating robust epoxy vitrimer for fully recyclable fiber reinforced composites relied on salen agent

Environmental concerns raise the urgent demand of recyclable materials for electrical and electronic applications. Epoxy and its glass fiber reinforced composites are the most widely used materials in these areas, but are generally unrecyclable. Herein, we reported a recyclable epoxy vitrimer and its glass fiber reinforced composite by using salen agent and DGEBA-type epoxy to ensure its molecular design flexibility and industrial adaptability. Comparing with the conventional amine-cured epoxy, the obtained epoxy vitrimer shows a higher glass transition temperature of 140 °C, a superior tensile strength of 86.7 MPa and an enhanced breakdown strength (180 MV m−1). Furthermore, based on the reversible imine-imine and amine−imine exchange reactions, the epoxy vitrimer could be recycled by both mechanical and chemical methods. An admirable recycling efficiency was achieved based on electrical properties. Moreover, its corresponding glass fiber reinforced composites could be recycled in a closed-loop way while the reclaimed fabric was comparable to its origin. This study demonstrates the potential application of salen agent to develop fully recyclable electrical insulating component and opens a window to further improve the material properties of epoxy vitrimer based on the great design flexibility of salen agent.

Synergistic Effect of Nanoparticles: Enhanced Mechanical and Corrosion Protection Properties of Epoxy Coatings Incorporated with SiO2 and ZrO2.

This research paper presents the fabrication of epoxy coatings along with the hybrid combination of SiO2 and ZrO2. The epoxy resin is incorporated with SiO2 as the primary pigment and ZrO2 as the synergist pigment. The study delves into the adhesion, barrier, and anti-corrosion properties of these coatings, enriched with silica and zirconium nanoparticles, and investigates their impact on the final properties of the epoxy coating. The epoxy resin, a Diglycidyl ether bisphenol-A (DGEBA) type, is cured with a polyamidoamine adduct-based curing agent. To evaluate the protective performance of silica SiO2 and zirconia ZrO2 nanoparticles in epoxy coatings, the coated samples were tested in a 3.5% NaCl solution. The experimental results clearly demonstrate a remarkable improvement in the ultimate tensile strength (UTS), yield strength (YS), and Elastic Modulus. In comparison to using SiO2 separately, the incorporation of both ZrO2 and SiO2 resulted in a substantial increase of 43.5% in UTS, 74.2% in YS, and 8.2% in Elastic Modulus. The corrosion test results revealed that the combination of DGEBA, SiO2, and ZrO2 significantly enhanced the anti-corrosion efficiency of the organic coatings. Both these pigments exhibited superior anti-corrosion effects and mechanical properties compared to conventional epoxy coatings, leading to a substantial increase in the anti-corrosion efficiency of the developed coating. This research focuses the potential of SiO2 and ZrO2 in hybrid combination for applications, where mechanical, corrosion and higher adhesion to the substrates are of prime importance.

Design for disassembly of composites and thermoset by using cleavable ionic liquid monomers as molecular building blocks

Aircraft, automotive industries and the increasing numbers of wind turbine blade lead to a huge amount of carbon fiber reinforced polymers requiring to be recycled and/or reused in a closed loop supply chain or circularity of materials. Herein, we have designed and synthesized a tetra-epoxidized imidazolium ionic liquid (Tetra-IL) monomer containing ester-cleavable groups. This monomer was incorporated as a molecular brick platform into conventional epoxy-amine networks in order to tailor the physical properties as well as the end-of-life of the resulting networks. Thus, the introduction of only 10% of IL-based comonomers significantly reduced the gel time by 85% opening perspectives in the field of fast-cure epoxy resins. Overall, all the networks designed in this work presented high thermal stability (>350 °C), higher Tg included between 180 and 230 °C combined with hydrophobic behavior. Increasing the amount of IL monomer in the networks improved the homogeneity of thermosets and wettability of the epoxy resins with the carbon fibers (CF). Most importantly, the use of Tetra-IL led to the development of degradable networks under mild conditions within a brief timeframe (4.5 h) and allowing to recover the carbon fibers. In summary, this study highlighted the great potential of IL-based comonomers as molecular brick into conventional epoxy thermosets as a promising strategy to tailor the physical properties versus sustainability/degradability for the development of high-performance thermosets and composites.