Search Results (22)

Sustainable bio-based epoxy technology is developed by using bio-based epoxy materials instead of conventional fossil-derived ones. Significant progress in new bio-based epoxy material development on bio-based epoxy resins, curing agents, and additives, as well as bio-based epoxy formulated products, has been achieved recently not only in fundamental academic studies but also in industrial product development. There are mainly two types of bio-based epoxy resins: conventional epoxy resins and novel epoxy resins, depending on the epoxy resin building-block type used. Bio-based conventional epoxy resins are prepared by using the bio-based epichlorohydrin to replace conventional fossil-based epichlorohydrin. Bio-based novel epoxy resins are usually prepared from epoxidation of renewable precursors such as unsaturated vegetable oils, saccharides, tannins, cardanols, terpenes, rosins, and lignin. Typical bio-based curing agents are bio-based polyamines, polyamides, amidoamines, and cardanol-based phenalkamine-type curing agents. Cardanol is a typical bio-based reactive additive available commercially. Certain types of partially bio-based formulated epoxy products have been developed and supplied for use in bonding, coating, casting, composite, and laminating applications. Full article

In this study, a novel bio-based oxazine resin was synthesized through the reaction of naturally renewable materials: cardanol and furfurylamine. The molecular structure of the target product was confirmed via comprehensive characterization techniques, including Fourier-transform Infrared Spectroscopy (FT-IR), Gel Permeation Chromatography (GPC), Mass Spectrometry (MS), and Nuclear Magnetic Resonance (NMR). Differential Scanning Calorimetry (DSC) revealed that the curing process of cardanol-furfurylamine oxazine (CFZ) exhibited three exothermic peaks (~140, ~240, ~270 °C), which not only helped to optimize the processing conditions but also effectively enhanced the material properties. In the modification experiments, CFZ had been blended and cured with benzoxazine (BZ) at the mass ratios of 2:98, 5:95, 10:90, 20:80, and 40:60. Dynamic Mechanical Thermal Analysis (DMTA) further showed an elevated Loss Factor (tan δ) peak of CFZ-BZ resin, suggesting significantly enhanced toughness. Notably, when the content of the CFZ resin in the composite reached only 5%, the storage modulus achieved its maximum value, highlighting that minimal addition of CFZ resin can optimize the rigidity of the composite, which would drastically reduce material costs and simplify the process. Impact strength testing demonstrated that the impact resistance of CFZ-BZ resin was 6.42 times higher than that of pristine BZ. By integrating renewable materials with rational molecular design, this novel oxazine resin synergistically combines high-temperature resistance, superior toughness, and efficient modification at low loading, positioning it as a promising candidate to replace conventional petroleum-based resins in aerospace, renewable energy, and electronic packaging applications. Full article

This study investigates the impact of an increased bio-content on the mechanical properties of bio-based epoxy resins. Cardanol-based epoxy and novolac resins (65% and 84% bio-content, respectively) were combined with two commercial cardanol-based epoxy systems to achieve higher total bio-contents. Quasi-static tensile tests showed that resin blends with up to 40% bio-content maintain tensile properties comparable to traditional formulations, with a glass transition temperature (T_g) suitable for automotive requirements. The results highlight that an increased bio-content enhances flexibility and viscoelastic behavior. Additionally, the tests showed that epoxy resins with a high bio-content represent a sustainable alternative with reduced environmental impact. This work benchmarks novel cardanol-based epoxy formulations with existing bio-based systems, supporting their industrial application. Full article

Recently, the growth of the recyclability of carbon fiber reinforced polymer (CFRP) composites has been driven by environmental and circular economic aspects. The main aim of this research work is to investigate the strength retention of a bio-based vitrimer composite reinforced with carbon fibers, which offers both recyclability and material reusability. The composite formulation consisted of an epoxy resin composed of diglycidyl ether of bioshpenol A (DGEBA) combined with tricarboxylic acid (citric acid, CA) and cardanol, which was then reinforced with carbon fibers to enhance its performance. Differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy were performed to analyze the chemical composition and curing behavior of the vitrimer. Mechanical testing under tensile loading at room temperature was carried out on epoxy, vitrimer, and associated carbon fiber reinforced composite materials. The results demonstrated that the DGEBA/CA/cardanol vitrimer exhibited thermomechanical properties comparable to those of an epoxy cured with petroleum-based curing agents. It was observed that the maximum tensile strength of vitrimer is about 50 MPa, which is very close to the range of epoxy resins cured with petroleum-based curing agents. Notably, the ability of the vitrimer composite to be effectively dissolved in a dimethylformamide (DMF) solvent is a significant advantage, as it enables the recovery of the fibers. The recovered carbon fiber retained comparable tensile strength to that of the fresh carbon composites. More than 95% strength was retained after the first recovery, which confirms the use of fibers for primary and secondary applications. These research results open up new avenues for efficient recycling and contribute to the overall sustainability of the composite material at an economic level. Full article

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. Full article

This paper presents a study of the flammability and thermal decomposition products of glass fiber-reinforced epoxy resin (GFRER) with the addition of cardanol-based phosphorus-containing benzoxazine monomer (CBz) and graphene and their combinations in different proportions (up to 20 wt.%). The addition of CBz alone or in combination with graphene resulted in an increase in the limiting oxygen index (LOI) and self-extinguishing in the UL-94 HB test. The flame-retardant samples had better tensile mechanical properties than the sample without additives. The differential mass-spectrometric thermal analysis (DMSTA) of the thermal decomposition products of GFRER without additives and with the addition of CBz and graphene was carried out. CBz addition promoted the thermal decomposition of high-molecular-weight products of epoxy resin decomposition in the condensed phase and at the same time decreased the time of release of low-molecular-weight thermal decomposition products into the gas phase. Graphene addition resulted in an increase in the relative intensities of high-molecular-mass peaks compared to GFRER without additives. Full article

The green and environmentally friendly cardanol epoxy resin has a bright application prospect, but its insufficient thermal/mechanical properties seriously hinder its application. Adding nanoclay to polymer matrix is an effective method to enhance the thermal/mechanical properties of material, but the dispersion and compatibility of nanoclay in epoxy resin remain to be solved. In this work, active Girard’s reagent clay (PG-clay) and non-active Girard’s reagent clay (NG-clay) were prepared by using acethydrazide trimethylammonium chloride (Girard’s reagent) as the modifier, and cardanol epoxy resin/G-clay nanocomposites were synthesized by the “clay slurry composite method”. The results showed that both PG-clay and NG-clay were dispersed in the epoxy matrix in the form of random exfoliation/intercalation, which effectively improved the thermal/mechanical properties of the composites. Tg of the cardanol epoxy resin has raised from 19.8 °C to 38.1 °C (4 wt.% PG-clay). When the mass fraction of clay is 4%, the tensile strength of the non-reactive NG-clay increases by 128%, and the elongation at break also increases by 101%. Simultaneously, the active PG-clay can participate in the curing reaction of epoxy resin due to the amino group, forming a chemical bond between the clay layer and the resin matrix and establishing a strong interfacial force. The tensile strength of the composite is increased by 970%, and the elongation at break is also increased by 428%. This research demonstrates that the cardanol epoxy resin/G-clay nanocomposite stands as a highly promising candidate for bio-based epoxy resin materials. Full article

Bio-based vitrimers present a promising solution to the issues associated with non-renewable and non-recyclable attributes of traditional thermosetting resins, showcasing extensive potential for diverse applications. However, their broader adoption has been hindered by the requirement for catalyst inclusion during the synthesis process. In this study, a cardanol-based curing agent with poly-hydroxy and tertiary amine structures was prepared by a clean synthetic method under the theory of click chemistry. The reaction of a cardanol-based curing agent with diglycidyl ether of bisphenol A formed catalyst-free, self-healing, and recyclable bio-based vitrimers. The poly-hydroxy and tertiary amine structures in the vitrimers promoted the curing of epoxy-carboxylic acid in the cross-linked network and served as internal catalysts of dynamic transesterification. In the absence of catalysts, the vitrimers network can achieve topological network rearrangement through dynamic transesterification, exhibiting excellent reprocessing performance. Moreover, the vitrimers exhibited faster stress relaxation (1500 s at 180 °C), lower activation energy (92.29 kJ·mol⁻¹) and the tensile strength of the recycled material reached almost 100% of the original sample. This work offers a new method for preparing cardanol-based epoxy vitrimers that be used to make coatings, hydrogels, biomaterials, adhesives, and commodity plastics in the future. Full article

The phenalkamines (PK) derived from cardanol oil can be used as a bio-based crosslinker for epoxy coatings as an alternative for traditional fossil amines (FA). First, the reaction kinetics of an epoxy resin with four PK and FA crosslinkers are compared by differential scanning calorimetry, illustrating a fast reaction rate and higher conversion of PK at room temperature in parallel with a moderate exothermal reaction. Second, the performance of coatings with various concentrations of PK and PK/FA ratios indicates good mixing compatibility between crosslinkers resulting in higher hardness, scratch resistance, hydrophobicity, and abrasive wear resistance of coatings with PK. The superior performance is confirmed over a broad range of resin/crosslinker ratios, facilitating the processing with viscosity profiles depending on the PK type. Although fossil- and bio-based crosslinkers have different chemical structures, the unique linear relationships between intrinsic mechanical properties (i.e., ductility and impact resistance) and coating performance indicate that the degree of crosslinking is a primary parameter controlling coating performance, where PK simultaneously provides high hardness and ductility. In conclusion, the optimization of the processing range for bio-based PK as a crosslinker for epoxy coatings delivers suitable processing conditions and superior mechanical performance compared to traditional amine crosslinkers. Full article

Cardanol, a waste from the food industry and widely produced (1 Mt/y), has been used as a chain stopper during the polycondensation of short oil alkyd resins in order to replace benzoic acid. Then, phosphorylated cardanol has been added in order to both reduce solvent content and bring flame-retardant (FR) properties to the alkyd resins. The renewable carbon content of the formulations has been increased up to 23%. The impact of the introduction of phosphorylated cardanol molecules on the drying time and flexibility has been studied as well as the thermal and flame-retardant properties by differential scanning calorimeter, thermogravimetric analysis and pyrolysis-combustion flow calorimeter. The most effective flame-retardant coating that was associated with excellent FR properties and excellent coating properties has been obtained with phosphate-cardanol added at 2%wt of P. Indeed, the film properties were closed to the classical alkyd resin, the solvent content was reduced by 50% and the pHRR decreased by 42% compared to the reference alkyd resin. Full article

Epoxy resin has a versatile set of applications due to its excellent properties. However, its easily flammable property limits further applications. A bio-based flame retardant, cardanyl diphenylphosphate (CDPP), was successfully synthesized via condensation reaction between cardanol and diphenyl phosphoryl chloride. The chemical structure of CDPP was confirmed via ¹H nuclear magnetic resonance and Fourier transform infrared spectroscopy. To overcome the flammable property of epoxy resin, different amounts of CDPP were incorporated into the epoxy resin. The thermal stability of epoxy resin with CDPP was reduced due to its phosphorus component, which had a relatively weak bond. Meanwhile, the measured char residue of epoxy resin with CDPP was increased compared to its calculated value, which indicated that CDPP promoted the formation of char residue. The limiting oxygen index of epoxy resin with CDPP was enhanced as the amount of CDPP increased from 22.1% for EP0 to 32.7% for EP10. The maximum value of the heat release rate per unit area and total heat release values of EP10 decreased by 23.23% and 12.02%, respectively, as compared to those of EP0. Additionally, single lap shear strength confirmed the improvement in the adhesion property of EP5. The lap shear strength increased to 7.19 MPa for EP5 compared to 6.27 MPa for EP0. This behavior might be due to the higher polarity of the phosphorus components. Based on the findings gathered in the present study, the incorporation of a bio-based flame retardant (CDPP) in epoxy resin has the potential for improving flame retardancy and adhesion property, which will be promising for the industrial area. Full article

The combination of awareness of harmful industrial processes, environmental concerns, and depleting petroleum-based resources has spurred research in developing sustainable materials from renewable sources. Natural bio-based polymers have replaced synthetic polymers because of growing concern about environmental sustainability. As a result of heating and distilling cashew nutshell liquid (CNSL), cardanol has emerged as a promising bio-retrieved component that can be used to make bio-based epoxy. The current work intends to investigate the mechanical properties of three kinds of cardanol-based bio-based epoxies in anticipation of widespread use. Vickers hardness, tensile and flexural strength are used to characterize mechanical properties. Additionally, a water absorption test is carried out to examine the weight gain properties of all the bio-based epoxy variants selected. FormuLITE 2 (FormuLITE 2501A + FormuLITE 2401B) exhibited the highest Vickers hardness, tensile and flexural strength among the three variants. Moreover, it exhibited a water absorption rate nearly equivalent to that of the conventional LY556/HY951, and thus, FormuLITE 2, the bio-based epoxy resin having 34% of bio-content blended with conventional epoxy, proves to be the best option out of the selected bio-based epoxies to be used further as the matrix material for the fabrication of biocomposites. Full article

Novel phosphorylated cardanol molecules based on phosphonate (PO₃CR) and phosphate (PO₄CR) functions were synthetized. Those molecules have two main actions which are described in this article: the reduction in volatile organic compounds (VOC) and the development of flame retardant (FR) properties conferred on alkyd resins used as coatings for wood specimen. Phosphorylated cardanol compounds have been successfully grafted by covalent bonds to alkyd resins thanks to an auto-oxidative reaction. The impact of the introduction of PO₃CR and PO₄CR on the film properties such as drying time and flexibility has been studied and the thermal and flame retardant properties through differential scanning calorimeter, thermogravimetric analysis and pyrolysis-combustion flow calorimeter. These studies underscored an increase in the thermal stability and FR properties of the alkyd resins. In the cone calorimeter test, the lowest pHRR was obtained with 3 wt% P of phosphate-cardanol and exhibited a value of 170 KW.m⁻², which represented a decrease of almost 46% compared to the PO_xCR-free alkyd resins. Moreover, a difference in the mode of action between phosphonate and phosphate compounds has been highlighted. The most effective coating which combined excellent FR properties and good coating properties has been obtained with 2 wt% P of phosphate-cardanol. Indeed, the film properties were closed to the PO_xCR-free alkyd resin and the pHRR decreased by 41% compared to the reference alkyd resin. Full article

Many manufactured articles are made of composite materials often bonded by a phenolic resin. Through a D-optimal design, we optimized a method to characterize phenolic resins after the extraction process by GC-MS analysis. The study was conducted on three different phenolic resins and four manufactured articles with the same inorganic composition and different analyzed binders. Moreover, three cardanol resins that differ in their production systems were analyzed to see if there were differences between them. Through Soxhlet extraction with dichloromethane or acetone, it is possible to differentiate the raw materials through characteristic compounds and to identify them in the manufactured articles. Full article

For this present paper, we performed a life-cycle analysis and an evaluation of the mechanical properties of an epichlorohydrin/cardanol adhesive in a neat and a nano-filled form. Six different potentials and the cost of the adhesives were derived and compared with those of a commercial epoxy resin. Overall, the neat adhesive was found to be more environmentally friendly and to have a lower production cost. However, the addition of carbon nanotubes increased both the environmental footprint and the cost. The evaluation with regards to the mechanical properties was performed through a comparison of bulk properties and joint properties with the respective average values of commonly used structural and nonstructural adhesives from the literature. It was found that for all properties except for the Young’s modulus the novel adhesive had values greater than the average values of the cosmetic adhesives and for most properties it had values close to the average values of the structural adhesives. Moreover, the presence of the carbon nanotubes enhanced the mechanical properties of the adhesive except for the tensile strength. Full article