Bio-based Epoxy Research Articles

A facile biomass-based coating for flax fabric toward plant fiber/biobased epoxy composite with enhanced fire safety

The natural abundance, biodegradability, and low density of plant fibers, together with biobased epoxy thermoset resin, have driven the increasing popularity of plant fiber/polymer composites (PFRPs) to wider applications in various industries. However, the striving for biomass-based flame retardants (FRs) treatment for PFRPs remained a bottleneck due to polymers’ inherent vulnerability against fire and the increasing environmental awareness. In this work, a facile two-step aqueous solution coating process was proposed for fabric surface treatment of flax fabric using fully biobased phytic acid and chitosan from polysaccharides. The treated flax fabric demonstrated self-extinguishing behavior when ignited and showed a decrease in peak heat release rate (PHRR) by 58% under combustion. The laminate produced by this treated flax fabric and biobased epoxy resin showed a decrease of PHRR by 36% and an increase of more than 200% for the time of torch fire burn-through, demonstrating intriguing flame retardance brought by only FRs treatment on flax fabric reinforcements. Various measurements were done to elaborate on the role of treated flax fabric in the flame retardancy of polymer composites.

Vanillin-derived bio-based epoxy resins containing dual dynamic Schiff base and disulfide bonds with reprocessability and degradability

Vanillin-derived bio-based epoxy resins containing dual dynamic Schiff base and disulfide bonds with reprocessability and degradability

Analysis of bio-based epoxy resins: Impact of amine hardeners on thermal, thermomechanical, optical and electrical properties of epoxidized resveratrol with high Tg

Epoxidized resveratrol (RES) has been cured with different amines in order to compare their possibilities to obtain high-temperature resistance of bio-based epoxy resins. Materials obtained from the bio-based monomer present glass transition temperatures (Tg) among the highest ever reported for an epoxy-amine curing system, with extremely high char residue, making them excellent candidates for extremely high-temperature applications. Particularly, epoxidized RES stoichiometrically cured with 4,4′-sulfonyldianiline (DDS) reached 297 °C, measured as the tan δ peak by DMTA, and two other materials, using 4,4′-methylenedianiline (DDM) and 4,4′-diaminodicyclohexylmethane (CAA) as curing agents, exceeded 300 °C. In fact, the material begins to degrade before the chains are fully relaxed, so they are thermosetting that never go completely into the rubbery state. Additionally, this resin improves the direct current (DC) insulating character (~1015 Ωcm) while decreasing the optical band gap (~2 eV) when compared to other epoxy resins available, which is of great interest for photovoltaic applications. Moreover, some of the materials presented a very high char residue proportion when heated (>40 wt% at 800 °C under nitrogen atmosphere), presenting good fire-retardant properties.

A multifunctional partially bio-based epoxy resin by renewable chitosan as reaction raw material: shape memory effect, bonding property, excellent degradability, and toughening performance

A multifunctional partially bio-based epoxy resin by renewable chitosan as reaction raw material: shape memory effect, bonding property, excellent degradability, and toughening performance

An Imine-Functionalized Silicone-Based Epoxy Coating with Stable Adhesion and Controllable Degradation for Enhanced Marine Antifouling and Anticorrosion Properties.

Biofouling and corrosion of submerged equipment caused by marine organisms severely restrict the rapid development of the marine industry. Traditional antifouling or anticorrosion coatings typically serve a sole purpose and exhibit limited degradability upon failure, rendering them inadequate for current demands. Herein, a novel imine-functionalized command-degradable bio-based epoxy coating (SAHPEP-DDM) with enhanced integrated antifouling and anticorrosion performances was synthesized utilizing 1,3-bis (3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and syringaldehyde. Compared with commercial epoxy resins (E51-DDM) and polydimethylsiloxanes (PDMS), the SAHPEP-DDM coating exhibits superior antifouling and anticorrosion properties due to the existence of -C=N- and Si-O-Si chain segments in the cross-linking network. The coating achieves resistance rates of 99.59 % and 99.20 % against E. coli and S. aureus, respectively, and shows promising resistance against algae and proteins, as well as excellent corrosion resistance in artificial seawater (with |Z|0.01 Hz and arc radius of about 1011 Ω and exceeding 1010 Ω respectively). The coating also exhibits excellent chemical resistance in organic solvents as well as neutral and alkaline environments. Moreover, its controlled degradation after coating failure can be achieved in acid aqueous solutions through temperature and acidity adjustments, facilitated by the presence of -C=N-. This work presents a novel degradable coating successfully coupled the dual functions of antifouling and anticorrosion coatings, avoiding the employment of intermediate coat, indicating vast potential for application in various marine engineering fields.

Self-healing amine- and carboxy-cured bio-based epoxy vitrimers driven by the disulfide metathesis reaction

Self-healing amine- and carboxy-cured bio-based epoxy vitrimers driven by the disulfide metathesis reaction

Bio-Based Self-Healing Epoxy Vitrimers with Dynamic Imine and Disulfide Bonds Derived from Vanillin, Cystamine, and Dimer Diamine.

The condensation reactions of 4,4'-(ethane-1,2-diylbis (oxy)) bis(3-methoxybenzaldehyde) (VV) with cystamine, 1,6-hexamenthylene diamine, and a dimer diamine (PriamineTM 1075) produced three types of vanillin-derived imine-and disulfide-containing diamines (VC, VH, and VD, respectively). Thermal curing reactions of polyglycerol polyglycidyl ether with VD and mixtures of VC/VD and VH/VD produced bio-based epoxy vitrimers (BEV-VD, BEV-VC/VD, and BEV-VH/VD, respectively). The degree of swelling and gel fraction tests revealed the formation of a network structure, and the crosslinking density increased with a decreasing VD fraction. The glass transition temperature, tensile strength, and tensile modulus of the cured films increased as the VD fraction decreased. In contrast, the thermal degradation temperature of the cured films increased as the VD fraction increased. All the cured films were healed by hot pressing at 120 °C for 2 h under 1 MPa at least three times. The healing efficiencies, based on tensile strength after the first healing treatment, were 75-78%, which gradually decreased as the healing cycle was repeated. When imine-and disulfide-containing BEV-VC/VD and imine-containing BEV-VH/VD with the same VC/VD and VH/VD ratios were used, the former exhibited a slightly higher healing efficiency.

Biobased recyclable epoxy composites reinforced with carbon nanotubes for electromagnetic interference shielding and Joule heating

AbstractCurrent epoxy thermosets are facing various challenges such as resource scarcity, environmental concern, and limited functionalities. Here, we present a novel solvent free approach to fabricate multifunctional carbon nanotubes (CNTs) reinforced biobased and recyclable epoxy thermoset composites through precuring in an internal mixer followed by curing in an oven. The epoxy matrix, a covalent adaptable network (CAN) based on dynamic imine bonds, was synthesized from entirely biobased feedstocks, including glycerol triglycidyl ether, vanillin, and 1,10‐diaminodecane. The shear force during precuring facilitated dispersion of CNTs in CAN matrix, allowing for high CNTs loading (up to 20 wt%). The well‐dispersed CNTs not only reinforced mechanical properties of CAN but also introduced new functionalities like electrical conductivity, electromagnetic interference (EMI) shielding capacity, and Joule heating performance. The composite with 20% CNTs exhibited a tensile strength and Young's modulus of 78.1 MPa and 3.07 GPa, respectively, marking a 34.2% and 63.6% improvement over pristine CAN. It also demonstrated a high electrical conductivity of 35.3 S/m, resulting in a remarkable EMI shielding effectiveness (22.8 dB) and excellent Joule heating performance (reaching 131.7°C at 27 V input). Furthermore, these composites are thermally and chemically recyclable due to dynamic imine bonds, promoting sustainability and circular economy.

A novel bio-based epoxy resin curing agent of gluconic aldehyde amine for the preparation of epoxy resin film

To resolve the shortage of fossil resources, gluconic aldehyde amine (GAA) was prepared from glucose via Mannich reaction, and then was used to cure E901 epoxy resin to prepare glucose-based epoxy resin film (GAAF). Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy indicated the successful synthesis of GAA. With the increase of Mannich reaction temperature, the tensile strength and elongation at break of GAAF firstly increased and then decreased, as well as the thermal stability increased. The GAAF-60 sample exhibited maximum tensile strength of 47.5 MPa, which were higher than that prepared by petroleum-based phenolic amine and lignin-based phenolic amine, respectively. The synthesis of GAA presented a novel bio-based epoxy resin curing agent for the preparation of epoxy resin film.

Unlocking the potential of functionalized cottonseed oil for the production of biobased epoxy foams

Nowadays, polymer foams are present in various areas of modern life. Having valuable and versatile features, they are utilized for insulation, packaging, sound absorption, cushioning and many other applications. Most of the commercially available polymer foams, whether rigid or flexible, are made from petrochemicals. Among these porous polymers, polyurethanes derived from highly hazardous isocyanates are dominant. Replacement of such foams with more environmentally safe materials holds great significance in the context of sustainability policy. Therefore, the utilization of molecules derived from biomass for the production of porous polymer foams is of considerable importance. This work focuses on the development of thermoset flexible foams based on plant oil, namely cottonseed oil. The polymeric matrix of the foams was prepared by the reaction of epoxidized cottonseed oil (ECO) with a cyclic anhydride in the presence of a catalyst, whereas the gaseous phase was generated by the addition of a chemical blowing agent. The morphology of the prepared foams was characterized using Scanning Electron Microscopy, while the internal structure of the foams was studied via Micro-Computed Tomography. The thermomechanical properties of foams were evaluated by Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). Possessing flexibility, softness, high porosity and shape memory ability, the prepared foams can be considered as potential cost-effective and eco-friendly options for flexible foams market: furniture, carper underlay, bedding.

Exploring strategies for valorizing wood processing waste: advancing sustainable, fully lignocellulosic biocomposites

This study presents the design and synthesis of bio-composites exhibiting high properties, wherein both the matrix and filler originate from wood biomass. Notably, no additional hardener compounds or treatments/modifications of the lignocellulosic filler were employed. Thermosetting materials were developed by homopolymerizing a bio-based aromatic epoxy monomer, the resorcinol diglycidyl ether (RDGE), with different percentages, from 1 wt% to 30 wt% of natural wood processing side-product, such as spruce bark powder (SB), which was used as such without additional treatments and modifications. The DSC analyses revealed enhanced reactivities with the bio-filler content, resulting in a reduced reaction temperature range and maximum reaction temperature. These findings provide evidence of the chemical interaction between the functional groups from spruce bark and the epoxides groups. The obtained fully based lignocellulosic materials show high E' values from 2.4 GPa to 2.5–3.5 GPa (glassy state) and from 64 MPa to 99–156 MPa in the rubbery region. The damping factor of the bio-composites with 1–10 wt% SB have shown an increase of the α transition temperature from 92 °C to 94–97 °C. The excellent filler/matrix interface and optimal adhesion between them were confirmed by SEM analysis.

Recent Development of Functional Bio-Based Epoxy Resins.

The development of epoxy resins is mainly dependent on non-renewable petroleum resources, commonly diglycidyl ether bisphenol A (DGEBA)-type epoxy monomers. Most raw materials of these thermoset resins are toxic to the health of human beings. To alleviate concerns about the environment and health, the design and synthesis of bio-based epoxy resins using biomass as raw materials have been widely studied in recent decades to replace petroleum-based epoxy resins. With the improvement in the requirements for the performance of bio-based epoxy resins, the design of bio-based epoxy resins with unique functions has attracted a lot of attention, and bio-based epoxy resins with flame-retardant, recyclable/degradable/reprocessable, antibacterial, and other functional bio-based epoxy resins have been developed to expand the applications of epoxy resins and improve their competitiveness. This review summarizes the research progress of functional bio-based epoxy resins in recent years. First, bio-based epoxy resins were classified according to their unique function, and synthesis strategies of functional bio-based epoxy resins were discussed, then the relationship between structure and performance was revealed to guide the synthesis of functional bio-based epoxy resins and stimulate the development of more types of functional bio-based epoxy resins. Finally, the challenges and opportunities in the development of functional bio-based epoxy resins are presented.

Bio-based liquid crystal epoxy resins: Toughening and strengthening of conventional epoxy resins with strategically extended spacer layers

Liquid crystal epoxy resin, as an ideal toughening agent, combines the features of liquid crystal ordering and network cross-linking, which can effectively optimize the comprehensive performance of blended epoxy resins and achieve an ideal balance of rigidity and toughness. Here we successfully synthesized rigid and flexible bio-based liquid crystal epoxy resin (THBR-EP) by finely tuning the length of alkyl side chains. Using aromatic diamine as curing agent, a homogeneous network without phase separation was constructed by taking advantage of the different activity but good compatibility with ordinary epoxy resins, which significantly improved the toughness of the blended system. Specifically, only a small amount of THBR-EP(2.5 wt%) was required to exhibit a maximum impact strength of 48.8 kJ/m2. Moreover, the increase in system toughness was accompanied by a benign improvement in flexural strength, modulus and thermal stability. The ordered structure of the liquid crystals and their good compatibility with the resin matrix enhanced the ability to inhibit crack extension and energy dissipation. The feasibility to simultaneously achieve effective toughening and other property improvements of common resins broadens the application of resins under various demanding scenarios.

Miscanthus floridulus-based intumescent flame retardant by green self-assembly for fully biological EP composites with commendable flame retardancy, smoke suppression and mechanical properties

The design of fully biological epoxy resin (EP) composites with high performance is highly desirable driven by green and sustainable development due to their renewable and sustainable nature. Herein, an efficient intumescent flame retardant based on Miscanthus floridulus (MF-based IFR) was devised for bio-epoxy composites by a green self-assembly method. The resulting composites with 15 wt% MF-based IFR demonstrated outstanding flame retardancy, effective smoke suppression, and favorable mechanical properties. The enhanced flame retardancy demonstrated the V-0 rating of UL-94 and the 26.4 % of limiting oxygen index (LOI) due to the dual-phase flame-retardant mechanism. Compared to pure EP, the EP composite with 15 wt% MF-based IFR exhibited reductions of 71.90 %, 61.85 %, 55.0 %, and 60.94 % in peak heat release rate (pHRR), total heat release rate (THR), smoke release rate (SPR), and smoke growth rate (TSP), respectively. Additionally, compared to unmodified MF, the composites with 15 wt% MF-based IFR displayed increasing of 3.35 %, 11.26 %, and 10.24 % in tensile, bending, and impact strengths, respectively, attributed to the enhanced interface compatibility. This study provides a straightforward, cost-effective, and efficient strategy for producing fully bio-based epoxy composites with high performance, expanding their potential applications.

Cross-Linking Reaction of Bio-Based Epoxy Systems: An Investigation into Cure Kinetics.

The cure kinetics of various epoxy resin mixtures, comprising a bisphenol epoxy, two epoxy modifiers, and two hardening agents derived from cardanol technology, were investigated through differential scanning calorimetry (DSC). The development of these mixtures aimed to achieve epoxy materials with a substantial bio-content up to 50% for potential automotive applications, aligning with the 2019 European Regulation on climate neutrality and CO2 emission. The Friedman isoconversional method was employed to determine key kinetic parameters, such as activation energy and pre-exponential factor, providing insights into the cross-linking process and the Kamal-Sourour model was used to describe and predict the kinetics of the chemical reactions. This empirical approach was implemented to forecast the curing process for the specific oven curing cycle utilised. Additionally, tensile tests revealed promising results showcasing materials' viability against conventional counterparts. Overall, this investigation offers a comprehensive understanding of the cure kinetics, mechanical behaviour, and thermal properties of the novel epoxy-novolac blends, contributing to the development of high-performance materials for sustainable automotive applications.

Straw Tar Epoxy Resin for Carbon Fiber-Reinforced Plastic: A Review.

The massive consumption of fossil fuels has led to the serious accumulation of carbon dioxide gas in the atmosphere and global warming. Bioconversion technologies that utilize biomass resources to produce chemical products are becoming widely accepted and highly recognized. The world is heavily dependent on petroleum-based products, which may raise serious concerns about future environmental security. Most commercially available epoxy resins (EPs) are synthesized by the condensation of bisphenol A (BPA), which not only affects the human endocrine system and metabolism, but is also costly to produce and environmentally polluting. In some cases, straw tar-based epoxy resins have been recognized as potential alternatives to bisphenol A-based epoxy resins, and are receiving increasing attention due to their important role in overcoming the above problems. Using straw tar and lignin as the main raw materials, phenol derivatives were extracted from the middle tar instead of bisphenol A. Bio-based epoxy resins were prepared by replacing epichlorohydrin with epoxylated lignin to press carbon fiber sheets, which is a kind of bio-based fine chemical product. This paper reviews the research progress of bio-based materials such as lignin modification, straw pyrolysis, lignin epoxidation, phenol derivative extraction, and synthesis of epoxy resin. It improves the performance of carbon fiber-reinforced plastic (CFRP) while taking into account the ecological and environmental protection, so that the epoxy resin is developed in the direction of non-toxic, harmless and high-performance characteristics, and it also provides a new idea for the development of bio-based carbon fibers.

Modification of bisphenol a type epoxy resin by biobased magnolol epoxy

Modification of bisphenol a type epoxy resin by biobased magnolol epoxy

Biomimetic 3D printing: Cocoon-like silk reinforcements from discarded cocoons for hemispherical composite components

Silkworm cocoons serve as the primary raw material for silk fabric production. However, due to stringent quality requirements for silk products, only high-quality cocoons are selected, while defective ones such as spotted cocoons are relegated to low-value textile fillers or direct landfilling. To enhance the value of discarded cocoons, this study combines continuous fiber 3D printing technology with traditional molding techniques, using discarded cocoons as raw materials to create high-performance hemispherical composite materials that mimic the natural structure of silkworm cocoons, thereby achieving efficient resource reuse. Additionally, a novel random path algorithm for 3D printing was developed to address the issue of uneven fiber orientation in the manufacturing of curved composite materials. The vacuum bag molding method was utilized to combine silk-like hemispherical fiber-reinforced bodies with resin, producing hemispherical composites with a high fiber content. Extensive tensile testing on longitudinally and laterally cut cocoon fiber samples was conducted to explore the mechanical behavior in various directions, revealing unique anisotropic properties. Further tensile testing on homemade silk yarn confirmed the material's high strength and excellent toughness. Scanning Electron Microscopy (SEM) analysis demonstrated good interfacial bonding between the silk and bio-based epoxy resin within the composites. Compression tests indicated a maximum load capacity of 6717 N, showcasing exceptional impact resistance and superior energy absorption in projectile impact tests. Even under extreme loads, the hemispherical composites maintained a substantial intact area, highlighting their structural integrity advantages. This study not only breathes new life into industrial waste but also provides a new direction for the manufacturing sector to achieve a greener and more sustainable development path.

Catalyst-free gallic acid-based epoxy vitrimers with reprocessability and high glass transition temperature

General approaches for preparing epoxy vitrimers required lots of catalysts to accelerate transesterification to form the cross-linked network and the residual catalyst not only resulted in toxicity but also poor compatibility with other components. Herein, a green and facile strategy for preparing gallic acid epoxy resin (GA-EP) was developed under catalyst-free condition using renewable gallic acid, xylitol and hexahydro 4-methylphthalic anhydride (MHHPA) as feedstocks. The results indicated that the bio-based epoxy vitrimer had higher glass transition temperature (122 °C), satisfactory mechanical, thermal and degradation properties compared to neat Bisphenol A-based epoxy vitrimer. Furthermore, recycled GA-EP was ground into powder and added to the fresh resin to investigate its reusability. Compared to the original, the recycled epoxy vitrimer system demonstrated comparable performance, except for minor reductions in glass transition temperature (Tg) and modulus, likely stemming from the inherent inhomogeneity of the reprocessed material. This work provides a new approach to the production of high Tg bio-based epoxy vitrimers without adding any catalyst.

Exploring anti-corrosion properties and rheological behaviour of tannic acid and epoxidized soybean oil-based fully bio-based epoxy thermoset resins

This research explores the physicochemical attributes of a fully bio-epoxy thermoset aimed at serving as an anti-corrosion coating for safeguarding carbon steel structures in marine environments. Throughout this investigation, various epoxy thermosets formulations, based on epoxidized soybean oil (ESO) and tannic acid (TA), were synthesized by adjusting the initial ratios of epoxide:hydroxyl groups (epoxy:OH). These formulations were subsequently applied onto carbon steel substrates and subjected to thermal curing at moderate temperatures (170 °C) to evaluate their anti-corrosion effectiveness using electrochemical impedance spectroscopy (EIS). The examination of the total impedance values derived from EIS Bode diagrams (>106 Ω) revealed a notable anti-corrosion efficacy that endured over several months of immersion in 3.5 wt% NaCl solutions. In addition to electrochemical assessment, a rheological analysis was conducted to determine the optimal curing temperature for each formulation and to track the evolution of their mechanical properties throughout the curing process. Furthermore, the progression of corrosion at the coating-metal interphase was quantified using samples featuring artificially created notches to facilitate rapid water penetration, reaching the protected surface. Moreover, cross-cut and pull-off adhesion tests were conducted on coatings cured with various epoxide:hydroxyl ratios, yielding exceptional results on carbon steel substrates. Overall, a great potential for anti-corrosion protection has been demonstrated on the developed fully bio-based coatings with tuneable mechanical properties, regarding the initial component ratio, to reach the specific requirements for specific applications.