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The cashew (Anacardium occidentale) is a tropical flowering tree that generates globally over 4 million metric tons of cashew nuts a year. Although the cashew nut is the most well-known product, other byproducts can produce additional value, including cashew apples, cashew nutshell liquid, cardanol, and cashew gum. Over the years, a fair amount of R&D has been done on cashew byproducts in order to increase their value for different applications. In order to stimulate further interest in the use of these products, a selective review of the applications and chemical modifications of these byproducts has been done in this Review. A particular emphasis has been made on the recent publications by authors on cashew gum and cardanol derivatives to show how the use of specific polymer reactions (e.g., ene reaction, aminohydrin formation, amine-formaldehyde reaction, and polysaccharide ether and ester formation) and physical processes (e.g., polymer blending, complex coacervation, microencapsulation, and electrospraying) can enhance the properties of these agro-based materials.

Cardanol acts to stabilize asphaltene particles in crude oil, but its derivative polycardanol, synthesized with BF3.O(C2H5)2 as initiator, exhibits divergent behavior, acting as both asphaltenes stabilizer and flocculant. This behavior could be related to structural differences in polycardanol samples. Therefore, in this work, we study the influence of some polymerization conditions (monomer purity, initiator concentration, and reaction time) on the structures and molar masses of the reaction products, and the reaction conversion. The materials were characterized by size exclusion chromatography and hydrogen and carbon nuclear magnetic resonance. When reacting with distilled cardanol, the conversion, the molar mass, and the homogeneity of structures increased as increasing initiator concentration in the range tested (1-3% m/m). For both monomers (different purity degrees), when using a lower initiator concentration (1% m/m), the product contained a larger amount of unreacted monomer and different structures were obtained due to the occurrence of rearrangements. The presence of triolefinic molecules in the monomer provoked crosslinked structures for higher initiator concentration (2-3% m/m). This study elucidated the differences among the reaction products of polycardanol.

People have been trying to find natural products that can replace rubber due to the land occupied by rubber planting and the environmental pollution caused by waste rubber. Herein, the linear poly-cardanol (LPCA) is obtained by undergoing a Friedel-Crafts alkylation reaction at 100 °C for 2 h at the catalyst of 5% of p-toluene sulfonate. The Mw of LPCA is about 4·104, and its polymeric degree is about 133. The weakening of 3009, 1263, and 1154 cm–1 in IR spectrum, the blue shift of UV absorption, the new chemical shifts of protons in 1H-NMR spectrum all certify the formation of LPCA. LPCA has obvious characteristics of elastomer. Its glass transition temperature (Tg) is –20.7 °C on the DSC curve. During the cocrosslinking of LPCA and liquid polyisoprene rubber (LIR), LPCA induces the crystallization of long LIR chain segments, which is confirmed by the transition peaks of the DSC curve in 40°C. This partial crystal structure is beneficial for LPCA/LIR blends to possess high strength. The tensile strength and the elongation at break of LPCA/LIR blend with 20% of LIR are about 2.04 MPa and 92%, respectively. LPCA possesses flexible alkyl chains and hydrophilic phenolic hydroxyl groups, so it can be used as a plasticizer just like LIR and compatibilizer at the same time. This study affords a possible way for renewable cardanol to replace rubber partially or completely.

In this paper, fire resistance of natural fabrics and their composites were experimentally investigated. Special interest was given to use bio based materials such as lignin, chlorophosphates, levulinic acid and cardanol in order to exploit their capability to be utilized as flame retardants. Dopamine hydrochloride was polymerized to polydopamine (PDA) and coated to jute fabric surface. Scanning electron microscope (SEM) and thermogravimetric analysis (TGA)/derivative thermogravimetric (DTG) analyses were performed to examine surface morphology and effect of PDA to degradation behaviour of jute fabrics. Real fire behaviour of non-coated and coated fabrics was observed with torch burn test. UL-94 horizontal flame propagation test was also utilized for composite samples. Limiting oxygen index (LOI) testing that measures the minimum amount of oxygen required for combustion, was carried out for assessing the ability of the composite samples for their ability against flammability. PDA was seamlessly coated on the surface of the jute fabrics with its surface-active feature without damaging the structure of the fabric as observed in the SEM images. With the support of this coating on the fabric surface, the increase of the decomposition temperature of the material can be clearly seen in TGA/DTG analyses and torch burn test showed the increase in the ignition time. UL-94 horizontal testing resulted in decrease in flame propagation rate of PDA coated composite samples. In addition to this, when the mass loss rates after combustion were examined, it was seen that there is a decrease in mass loss in the coated fabrics. Jute fabrics, a type of natural fabric, can be efficiently coated with PDA, and the fire retardant property of the PDA coating on natural fabrics has been clearly demonstrated.

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.

A series of lignin-based epoxy resins (LEPs) were prepared by the reaction of epichlorohydrin with lignin oligomers derived from partial reductive depolymerization of lignin. To overcome the high viscosity and brittleness defects in practical applications, the LEPs were blended with renewable epoxied cardanol glycidyl ether (ECGE) and then cured with methyltetrahydrophthalic anhydride (MeTHPA) to form high-performance epoxy thermosets. The effects of degree of lignin depolymerization, chemical composition of lignin oligomers and dosage of ECGE on thermal and mechanical properties of the cured products were investigated. The LEP/MeTHPA thermosets exhibited good thermal and mechanical properties. Especially, by separating monomer-rich fractions from lignin oligomers, the thermal and mechanical properties of the cured product were improved obviously. Notably, the incorporation of ECGE also possessed a positive effect on reinforcing and toughening the cured products. With 20 wt% ECGE loadings, the tensile, flexural and impact strength of the cured product reached the maximum value of 77 MPa, 115 MPa and 14 kJ/m2, respectively, which were equivalent to the commercial bisphenol A epoxy resins thermosets. These findings indicated that the novel bio-based epoxy resins from lignin oligomers and cardanol could be utilized as renewable alternatives for BPA epoxy resins.

In this work a corrosion protection material formed by commercial benzoxazine and polyaniline (PAni) for coatings applications was developed. PAni doped with a natural phenolic compound, cardanol, was used in the coating preparation, and conventional hydrochloric acid-doped PAni was also used for comparative purposes. Cardanol is a reddish-brown liquid obtained from the by-product of cashew nut processing. The presence of the aliphatic group and the hydroxyl of the cardanol, as well as the amine groups of the PAni, can enhance the corrosion barrier of a benzoxazine coatings. The anticorrosive properties of the coatings were evaluated by electrochemical impedance spectroscopy in 3.5% NaCl solution for a total period of 168 h. The coatings of benzoxazine filled with PAni showed better anticorrosion performance and adhesion strength on carbon steel substrate when compared to pristine benzoxazine and PAni doped with 3 wt% cardanol exhibits the best performances. This last result can be explained by both the presence of PAni and the better PAni dispersion within benzoxazine when doped with cardanol. In addition, the incorporation of cardanol-doped PAni in the benzoxazine reduced the cure temperature of the benzoxazine.

Sensors based on conductive hydrogels have received extensive attention in various fields, such as artificial intelligence, electronic skin, and health monitoring. However, the poor resilience and fatigue resistance, icing, and water loss of traditional hydrogels greatly limit their application. Herein, an ionic conductive organohydrogel (PAC-Zn) was prepared for the first time by copolymerization of cardanol and acrylic acid in water/1,3-butanediol as a binary solvent system. A very small amount of cardanol (1% cardanol of total monomers) could not only significantly improve the tensile strength (∼4 times) and toughness (∼3 times) of PAA but also improve its extensibility. Due to the presence of 1,3-butanediol, PAC-Zn showed outstanding tolerance for freezing (-45 °C) and drying (over 85% moisture retention after 15 days of storage in a 37 °C oven). Compared with ethylene glycol and glycerol as antifreeze agents used in organohydrogels, the addition of 1,3-butanediol endowed the organohydrogel with not only similar frost resistance but also better mechanical performance. Besides, PAC-Zn exhibited fast resilience (almost no hysteresis loop) and excellent antifatigue ability. More importantly, a PAC-Zn organohydrogel-based sensor could detect human motion in real time (wrist, elbow, finger, and knee joints), revealing its fast response, good sensitivity, and stable electromechanical repeatability. In conclusion, the multifunctional PAC-Zn organohydrogel is expected to become a potential and promising candidate in the field of strain sensors under a broad range of environmental temperatures.

Purpose The purpose of this study is to investigate the heat resistance and heat-resistant oxygen aging of 4-nitrophthalonitrile-etherified cardanol-phenol-formaldehyde (PPCF) to further use and develop the resin as the matrix resin of high-temperature resistant adhesives and coatings. Design/methodology/approach PPCF resin was synthesized by 4-nitrophthalonitrile and cardanol-phenol-formaldehyde (PCF). The structures of PPCF and PCF were investigated by Fourier transform infrared, differential scanning calorimetry and proton nuclear magnetic resonance. In addition, the heat resistance and processability of PPCF and PCF resins were studied by dynamic mechanical analysis, thermogravimetric analysis, scanning electronic microscopy (SEM), X-ray diffraction (XRD) techniques and rheological studies. Findings The results reveal that PPCF forms a cross-linked network at a lower temperature. PPCF resin has excellent resistance under thermal aging in an air atmosphere and that it still had a certain residual weight after aging at 500°C for 2 h, whereas the PCF resin is completely decomposed. Originality/value 4-Nitrophthalonitrile was introduced into PCF resin, and XRD and SEM were used to investigate the high temperature residual carbon rate and heat-resistant oxygen aging properties of PPCF and PCF resins.

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.

Polybenzoxazines obtained especially from green synthons are facing challenges of the requirement of high ring-opening polymerization (ROP) temperature of the monomer, thus affecting their exploration at the industrial front. This demands effective structural changes in the monomer itself, to mediate catalyst-free polymerization at a low energy via one-step synthesis protocol. In this regard, monomers based on disulfide-linked bisbenzoxazine were successfully synthesized using cystamine (biobased) and cardanol (agro-waste)/phenol. Reduction of the disulfide bridge in the monomer using dithiothreitol under mild conditions in situ transformed the oxazine ring in the monomer, via neighboring group participation of the -SH group in a transient intermediate monomer, into a thiazolidine structure, which is otherwise difficult to synthesize. Structural transformation of ring-opening followed by the ring-closing intramolecular reaction led to an interconversion of O-CH2-N containing a six-membered oxazine ring to S-CH2-N containing a five-membered thiazolidine ring and a phenolic-OH. The structure of the monomer with the oxazine ring and its congener with the thiazolidine ring was characterized by spectroscopic methods and X-ray analysis. Kinetics of structural transformation at a molecular level is studied in detail, and it was found that the reaction proceeded via a transient 2-aminoethanethiol-linked benzoxazine intermediate, as supported by nuclear magnetic resonance spectroscopy and density functional theory studies. The thiazolidine-ring-containing monomer promotes ROP at a substantially low temperature than the reported mono-/bisoxazine monomers due to the dual mode of facilitation of the ROP reaction, both by phenolic-OH and by ring strain. Surprisingly, both the monomer structures led to the formation of a similar polymer structure, as supported by thermogravimetric analysis and Fourier transform infrared study. The current work highlights the benefits of inherent functionalities in naturally sourced feedstocks as biosynthons for the new latest generation of benzoxazine monomers.

In this work, bio-based hybrid coating using Ag-TiO2 (AgT) sol and cardanol epoxy (CE) was developed, coated over mild steel (MS) substrates and studied for its corrosion resistant efficiency. Initially, the AgT sol was prepared and successively surface-functionalized using 3-glycidoxypropyl-trimethoxysilane (GPTMS) using a sol–gel approach to achieve compatible with the CE matrix. The physico-chemical and antimicrobial properties of neat CE and CE composites with different wt% of GAgT (GAgTx/CE) were studied using various analytical techniques and microbial assays, respectively. Further, CE and the GAgTx/CE composites were coated over MS, and their corrosion resistant behavior against microbial co-culture medium (MCM) (i.e. nutrient medium amended with 3% w/v NaCl and inoculated with both Micrococcus luteus and Pseudomonas aeruginosa) was evaluated by electrochemical techniques at different periods. The results suggested that the presence of GAgT along with CE matrix provided enhanced hydrophobicity with low surface free energy, which consequently lowered the interfacial interactions between the microbes and MS substrates. The optimum loading of GAgT in CE was 3 wt.%, showing enhanced resistance as high as 1097 Ω even after 21 days in MCM and thus renders durable corrosion resistance. In addition, the zone of microbial inhibition and water contact angle (WCA, θW = 94) of 3% GAgT/CE was comparatively higher than the other coatings. Our results suggest that further different hybrid coatings using cardanol epoxy can be developed in order to exploit the full potential of bio-material with different substrates as desired for sustainable coatings in industrial applications.

Cashew nut shell liquid (CNSL) extract obtained using soxhlet extraction method with acetone as solvent has been used in the synthesis of Co (II) and Zn (II) metal complexes. The CNSL gave a molecular peak ion of 298g/mol-1 on a GC-MS, an indication that cardanol was more prominent than anacardic acid in the obtained extract. Physicochemical parameters such as saponification value (50.30 mgKOH/g), moisture content (5.10), iodine value (241.00 mgKOH/g), ash content (1.30) and pH (6.31) were equally obtained. The metal complexes of Co (II) and Zn (II) prepared with unmodified (UMCNSL) and aniline modified CNSL (AMCNSL) were characterized using UV-visible, FTIR, melting point and electrical conductivity. Some characteristic FTIR bands were observed for AMCNSL, UMCNCL, AMCNSL-ZnCl2.H2O (1612cm-1) and AMCNSL-CoCl2.6H2O (1612cm-1). The presence of C=N were confirmed in the metal complex of AMCNSL-ZnCl.H2O and AMCNSL-CoCl.6H2O but were not present in the UMCNSL-ZnCl.H2O and UMCNSL-CoCl.6H2O.

In this article, two kinds of phosphorus-containing cardanol-based acrylates were designed and synthesized. Firstly, a pre-polymer (PT-HCE) with three arms was synthesized using hydroxyethyl cardanol ether (HCE) and phosphorus oxychloride (POCl3) as raw materials. Then, the PT-HCE was acrylated to synthesize phosphate tris-hydroxyethyl cardanol epoxy acrylate resin (AEPT-HCE) and phosphate tris-hydroxyethyl cardanol photosensitive resin (APT-HCE). The structures of PT-HCE, AEPT-HCE and APT-HCE were characterized and the results showed that the photosensitive resins were successfully synthesized. In addition, AEPT-HCE and APT-HCE were used to prepare the flame-retardant UV/EB curing coatings. The properties of the coatings were tested, and the results revealed that different structures have a certain effect on Tg and tensile properties of the coatings. The cured films demonstrated excellent flame-retardant properties, showing flammability rating of V-0 in UL-94 test.

The upcycling of waste biomass into valuable materials by resource‐efficient chemical transformations is a prime objective for sustainable chemistry. This approach is demonstrated in a straightforward light‐driven synthesis of polyols and polyurethane foams from the multi‐ton waste products of cashew nut processing. The photo‐oxygenation of cardanol from nutshell oil results in the formation of synthetically versatile hydroperoxides. The choice of the workup method (i. e., reduction, hydrogenation, epoxidation) enables access to a diverse range of alcohols with tunable alkene and OH functions. Condensation with isocyanates to give rigid polyurethane foams provides a resource‐efficient waste‐to‐value chain that benefits from the availability of cardanol and installation of OH groups from aerial O2., A tough nut to crack: The upcycling of waste biomass into valuable materials is a prime objective for sustainable chemistry. The multi‐ton waste cashew nut shell liquid is used in the light‐driven synthesis of polyols with tunable OH contents and in the subsequent preparation of rigid polyurethane foams.

Polypropylene (PP) nanocomposites were prepared using bottom-up graphene oxide (BGO) functionalized with cardanol having a long alkyl group as a filler. BGO was prepared from citric acid and tannic acid, and then further functionalized with cardanol glycidyl ether (CGE), where CGE was synthesized by reacting cardanol with epichlorohydrin to produce cardanol functionalized BGO (CBGO). PP nanocomposites were fabricated by mixing PP and CBGO using twin-screw extruder, where the content of CBGO ranged from 0.5 to 5.0 wt%. PP nanocomposite containing 2.0 wt% of CBGO (PP/CBGO-2.0) showed the maximum mechanical properties. The effect of the alkyl group in CBGO on the mechanical properties was investigated by comparing the mechanical properties of PP/CBGO-2.0 with those of PP nanocomposite with 2.0 wt% BGO (PP/BGO-2.0). For example, the tensile strength and Young’s modulus of PP/CBGO-2.0 increased by 20.1% and 30.6%, respectively, compared to neat PP, while those of PP/BGO-2.0 increased by 14.7% and 25.0%, respectively.

Background Cashew nut shell is a by-product of cashew (Anacardium occidentale) production, which is abundant in many developing countries. Cashew nut shell liquor (CNSL) contains a functional chemical, cardanol, which can be converted into a hydroxyoxime. The hydroxyoximes are expensive reagents for metal extraction. Methods CNSL-based oxime was synthesized and used to extract Ni, Co, and Mn from aqueous solutions. The extraction potential was compared against a commercial extractant (LIX 860N). Results All metals were successfully extracted with pH0.5 between 4 and 6. The loaded organic phase was subsequently stripped with an acidic solution. The extraction efficiency and pH0.5 of the CNSL-based extractant were similar to a commercial phenol-oxime extractant. The metals were stripped from the loaded organic phase with a recovery rate of 95% at a pH of 1. Conclusions Cashew-based cardanol can be used to economically produce an oxime in a simple process. The naturally-based oxime has the economic potential to sustainably recover valuable metals from spent lithium-ion batteries. Graphic abstract

Cardanol, principal constituent of the technical cashew nut shell liquid, has applications as antioxidant and antibacterial, and these properties may be enhanced through encapsulation. In the present study, we isolated and purified cardanol, and nanoparticles (NPs) were produced by polyelectrolyte complexation using polysaccharide systems with chitosan, sodium alginate, and non-toxic Arabic gum, because they are biocompatible, biodegradable, and stable. We characterized the NPs for morphological, physicochemical, and antioxidant activity. The micrographs obtained revealed spherical and nanometric morphology, with 70% of the distribution ranging from 34 to 300 nm, presenting a bimodal distribution. The study of the spectra in the infrared region suggested the existence of physicochemical interactions and cross-links between the biopolymers involved in the encapsulated NPs. Furthermore, the NPs showed better antioxidant potential when compared to pure cardanol. Thus, the encapsulation of cardanol may be an effective method to maintain its properties, promote better protection of the active ingredient, minimize side effects, and can target its activities in specific locations, by inhibiting free radicals in various sectors such as pharmaceutical, nutraceutical, and biomedical.

Various naturally-based chemicals can be used directly as wood adhesives or are precursors for the synthesis of adhesive resins. Liquefaction and pyrolysis of wood yield various smaller chemicals derived from the different wood components, which then are used in the preparation of adhesives by replacing mainly phenol as raw material. The possible replacement of formaldehyde in aminoplastic and phenolic resins would solve the question of the subsequent formaldehyde emission. The multiple unsaturations of the triglycerides in vegetable oils enable polymerization for the direct synthesis of thermosets, as well as bases for polyfunctionalization and crosslinking. Natural polymers, such as poly(lactic acid)s (PLAs), natural rubber, or poly(hyhydroxyalkanoate)s (PHAs) are thermoplastics and can be used for various special applications in wood bonding, in case they can also be crosslinked. For other thermoplastic wood adhesives, such as PUR or PA, chemicals based on natural resources can at least replace a part or even all synthetic raw materials (monomers); these monomers derive from targeted decomposition of the wood material in biorefineries. Cellulose nanofibrils (CNFs) can be used as as sole adhesives or as components of adhesives. Hydrogen bonding has a key function in binder applications related to adhesion between cellulose nanoparticles and other materials. CNFs are able to establish strong bonding between wood particles/fibres through flexible and strong films by a simple drying process. Cashew nut shell liquid (CNSL) is a by-product of the cashew nut processing with cardanol (CD) as main component. CD-formaldehyde resins show improved flexibility compared to phenol-formaldehyde (PF) resins; CD can replace up to 40% of the phenol.

Skin pigmentation depends not only on melanosomes produced by melanocytes but also on the migration of melanosomes to adjacent keratinocytes and their distribution on the skin surface. The inhibitory effects of cardanol diene (CADI), a major phenolic compound extracted from cashew nut shell liquid (CNSL), on melanin transfer in B16F10-HaCAT co-culture cells and a crude extracted compound of cashew nut shell oil (CNCE) on melanin production in zebrafish were investigated. β-arbutin was used as a positive control. CADI inhibited the expression levels of the melanin phagocytosis-associated protein PAR-2 and filopodia-associated protein NMDAR1, and the effect was better than that of β-arbutin at the same concentration. To further study the inhibitory mechanism of CADI in melanin transfer, fluorescence microspheres were used to simulate melanin and co-culture with keratinocytes. The results indicated that CADI inhibited melanin transfer through suppressing keratinocyte phagocytosis, dendrite formation and filopodia three channels. We also found that CNCE inhibited melanin production in zebrafish and showed significant inhibitory effects on TYR, DCT and α-MSH. Thus, the natural components extracted from CNSL effectively inhibited skin pigmentation, providing insight into the application of new anti-melanin drugs in cosmetics and medicine.

The protective performance of graphene/polymer composite coatings largely depends on the interface design in resin matrix. Herein, we report the synthesis of bio-based cardanol epoxy modified graphene oxide (GODN) nanomaterial and its application in epoxy coatings for the achievement of fine interface toward high performance anticorrosion composite coatings. The chemical composition of prepared GODN nanomaterial was investigated by FTIR, Raman and XPS spectra, respectively. The presence of cardanol epoxy attached on GO surface promotes the formation of chemical bonds between GO and epoxy resin, providing strong interfacial interaction and enhanced adhesion. Electrochemical results revealed that the GODN1%/EP composite coating exhibits high impedance (4.38 × 108 Ω cm2) even after 45 days immersion. Compared with pure EP coating, the localized corrosion reaction of GODN1%/EP coating can be inhibited under defected interface. The enhanced protective performance of GODN/EP composite coating was attributed to two aspects: (1) the impermeable GO greatly suppressed the penetration of aggressive ions and (2) the attached cardanol epoxy chains effectively improved the interfacial interaction and thus inhibited the crack propagation.

New thermoset composite material made from cardanol-based resin blended with microfibrillar cellulose was compared to petroleum-based vinyl ester and glass-fiber-reinforced unsaturated polyester in terms of mechanical, thermal, rheological and surface properties of produced polymers and composites. The bio-sourced material was less resistant than the commercial vinyl ester but comparable to the unsaturated polyester resin. Microfibrillar cellulose increased the tensile strength and modulus but increased the resin viscosity and decreased the mixture homogeneity. The bio-sourced and commercial resins displayed similar hydrophobic behavior, and cellulose slightly decreased composite hydrophobicity. The glass transition temperature of the bio-sourced material was comparable to that of the unsaturated polyester. Thermal decompositions of composites and thermoset polymers were also similar. Cellulose and cardanol thus may be adequate as sustainable components in the composite materials industry.

Plasticized polyvinyl chloride (PVC) has been widely used in the world. Petroleum-based plasticizers especially phthalates have been the most common plasticizers used in PVC. However, the global petroleum resources are becoming scarce gradually, and the hygienic requirements for plasticizers are increasing. Owing to the negative impact of petroleum-based plasticizers on human health and the environment, their use has been restricted in the USA, the European and so on. Biomass renewable resources have wide range of sources and low prices, and the chemicals obtained from them have various structures, which can provide a huge platform to design novel PVC plasticizers with the aim of replacing traditional phthalate plasticizers. Many bio-based PVC plasticizers, such as vegetable oil-based plasticizers, cardanol-based plasticizers, lactic acid-based plasticizers, waste cooking oil-based plasticizers, polyester plasticizers, hyperbranched plasticizers and so on, have been extensively studied. We have reviewed recent research progress on different types of novel bio-based PVC plasticizers and assorted them by raw materials and chemical structure. Through in-depth analysis of the relationship between the chemical structure and the plasticizing performance, the efficiency of plasticizers may be predicted before they have been designed. This review will be beneficial for the development of bio-based plasticizers by pointing out the research and application direction.

Purpose The purpose of this paper is to use the bio-based resource as the starting material for the synthesis of azo dye. Cardanol is one of the most used bio-based resources for carrying out the synthesis of various compounds having numerous end applications. The study presents an attempt to develop an azo dye from Cardanol having end applications in pH-responsive dyes. Design/methodology/approach The cardanol was sulfonated to block the para position by which ortho positioned hydroxyl group after diazotization and coupling will provide necessary pH-sensitivity. The diazotization of two naphthalene derivatives, i.e. 1-naphthol-8-amino-3,6-disulfonic acid (H-acid) and 7-amino-4-hydroxy-2-naphthalene sulfonic acid (J-acid) was carried out using the standard practice, and the diazotized compounds were coupled with the sulfonated cardanol. The obtained dyes were characterized by Fourier transform infrared, nuclear magnetic resonance, carbon-hydrogen-nitrogen-sulfur analysis and hydroxyl value. The colour properties were checked using UV-vis spectrophotometry and density functional theory, while thermogravimetric analysis was used for the thermal degradation studies of both the dyes. Findings Water-soluble cardanol-based azo dyes were prepared successfully having good thermal stability, and the obtained results are being presented in this paper. Originality/value The originality lies between the use of cardanol as a bio-based resource for the synthesis of azo-dye and the obtained azo-dye has the pH-sensitivity.

Energy efficiency and resource utilization are considered to be necessary for sustainable development. Organic phase change materials (PCMs) as an effective thermal energy storage tool have attracted great interest, but non-renewable ingredients, low stability and their unsafe nature largely restrict their sustainability. Herein, a series of bio-based benzoxazine-derived PCMs were developed, in which green preparation, efficient energy conversion, and safe utilization can be simultaneously achieved. Through the Mannich condensation reaction, novel PCMs can be easily synthesized with good yield and high atom economy by combining natural 3-pentadecylphenol (a cardanol derivative) and amine sources. The resulting PCMs exhibited adjustable latent heat (48.78–147.02 J g−1) by altering raw materials, which are close to their commercial unsustainable counterparts. As an example, C-aa-12 also showed considerable recycling ability after 100 times repeated use. In addition, due to the designed structure, as-prepared PCMs also possessed more excellent properties of thermal stability (Td50% was increased by 65.1%) and flame retardancy (HRR was reduced by 39.4%) compared with traditional ones, making them promising in a wider application field.

The production of graphene oxide (GO) in large amounts for commercialization in the chemical industry has been limited because harsh and tedious process conditions are required. In this study, a novel carbon nanomaterial called 'bottom-up graphene oxide (BGO)' could be easily prepared for the first time by heat treatment of the mixture of citric acid (CA) and tannic acid (TA) with different weight ratios for the first time. BGO3 prepared using a 50/50 weight ratio of CA/TA was found to have an average lateral size of 250.0 nm and an average thickness of 7.2 nm, and it was further functionalized with cardanol to prepare cardanol functionalized BGO3 (CBGO3) to be used as a filler for the polypropylene (PP) nanocomposite, where cardanol was used to increase the compatibility between BGO3 and PP. The improved mechanical properties and thermal stability of PP nanocomposites containing CBGO3 could be ascribed to the intrinsic mechanical properties of the carbon nanomaterial and the increased compatibility by the attached cardanol on BGO3.

In this study the performance as well as emission tests were conducted on Kirloskar diesel engine (a single-cylinder 5.2 kW) using Cardanol as a bio-diesel. Cardanol was produced from cashew nut shell liquid (CNSL) blended with Honge methyl ester in addition of diesel. The bio-fuel blends 5C5H (5% cardanol + 5%Honge oil + 90% diesel),5C10H, 5C15H and 5C20H were prepared and tested at various loads (0%, 20%, 40%, 60%, 80% and full load conditions) and results are compared with diesel at 205 bar injection pressure and 17.5 compression ratio. The experimental results showed that at full load, the brake thermal efficiency of 5C5H is 29.35% which is similar to that of diesel i.e., 31.05%. The lower emissions of CO, HC except NOx are encouraging to recognize 5C5H as an optimized fuel blend for a compression ignition engine.

Tese (doutorado)—Universidade de Brasília, Faculdade de Saúde, Programa de Pós-Graduação em Ciências Farmacêuticas, 2022. A incidência de infecções fúngicas graves tem afetado significativamente milhares de pessoas nos últimos anos, principalmente pacientes imunocomprometidos, ocasionando cerca de 1,6 milhão de óbitos anualmente. Atualmente, os medicamentos antifúngicos apresentam limitações que incluem efeitos adversos e resistência a patógenos. Estudos com moduladores epigenéticos da classe dos inibidores de histona desacetilases têm sido explorados como estratégia terapêutica ou sinérgica juntamente com agentes antifúngicos. Este trabalho descreve a síntese e caracterização de dois novos inibidores da histona desacetilase, LDT536 (25) e LDT537 (26), elaborados a partir de cardanol e ácido anacárdico. Avaliou-se a atividade antifúngica em células planctônicas e formação de biofilme de fungos patogênicos – Candida albicans, Candida tropicalis, Cryptococcus neoformans e Sporothrix brasiliensis – bem como a toxicidade in vitro em células RAW264.7 e in vivo no modelo de G. mellonella. Os testes de suscetibilidade contra células planctônicas mostram que as concentrações inibitórias mínimas (CIMs) variaram de 32-64 µg/mL para o composto 25 e de 8-64 µg/mL para o composto 26. Em seguida, a interação sinérgica entre os antifúngicos azólicos (fluconazol, voriconazol e itraconazol) e o composto 26, o que levou a uma diminuição das concentrações de azóis de 2 para 256 vezes. Em relação à ação sobre os biofilmes, observou-se reduções de mais de 50% para C. albicans (4 µg/mL) e S. brasiliensis (16 µg/mL). Em ensaios de toxicidade in vitro, em células RAW 264.7, o composto 25 apresentou citotoxicidade na concentração máxima de 200 µM (53,07 µg/mL), enquanto 26 foi citotóxico em 6,25 µM (2,02 µg/mL). Finalmente, os compostos não apresentaram toxicidade no modelo in vivo de Galeria mellonella até uma concentração de 1200 µg/mL. Os resultados indicam potencial atividade antifúngica e antibiofilme dos compostos LDT536 (25) e LDT537 (26) planejados como candidatos a agentes terapêuticos sustentáveis e de baixo custo elaborados a partir dos lipídios fenólicos presentes no líquido da casca da castanha de caju. The incidence of severe fungal infections has significantly affected thousands of people in recent years, especially immunocompromised patients causing a high number of deaths. Currently, antifungal drugs have limitations that include adverse effects and pathogen resistance. Studies with epigenetic modulators of the histone deacetylase inhibitors class have been explored as a therapeutic or synergistic strategy along with antifungal agents. This work describes the synthesis and characterization of two new histone deacetylase inhibitors, LDT536 (25) and LDT537 (26), designed from cardanol and anacardic acid. We also evaluate antifungal activity in planktonic cells and biofilm formation of pathogenic fungi – Candida albicans, Candida tropicalis, Cryptococcus neoformans and Sporothrix brasiliensis – as well as the in vitro toxicity in RAW 264.7 cells and in vivo in G. mellonella model. The susceptibility tests against planktonic cells showed the minimum inhibitory concentrations (MICs) ranged from 32-64 µg/mL for compound 25 and from 8-64 µg/mL for compound 26. Then, we evaluated the synergistic interaction among antifungal azoles (fluconazole, voriconazole, and itraconazole) and compound 26, which led to a decrease in azole concentrations from 2 to 256 times. Regarding the action on biofilms, we observed reductions of more than 50% for C. albicans (4 µg/mL) and S. brasiliensis (16 µg/mL). In in vitro toxicity assays, in RAW 264.7 cells, compound 25 showed cytotoxicity at the maximum concentration of 200 µM (53.07 µg/mL), while 26 was cytotoxic at 6.25 µM (2.02 µg/mL). Finally, the compounds showed no toxicity in the in vivo model up to a concentration of 1200 µg/mL. The results indicate potential antifungal and antibiofilm activity of the compounds LDT536 (25) and LDT537 (26) planned as candidates for sustainable and low-cost therapeutic agents designed from the phenolic lipids present in the cashew nut shell liquid.

This work is an attempt to develop bio-based eco-friendly poly(benzoxazine-co-urethane) [poly(U-co-CDL-aee)] materials using cardanol-based benzoxazines (CDL) and hexamethylene diisocyanate (HMDI) to check their self-healing ability and thermal properties. CDL monomers were synthesized using cardanol, amino ethoxyethanol (aee) or 3-aminopropanol (3-ap), and paraformaldehyde through the Mannich reaction. Later, CDL-aee or CDL-3-ap monomers were copolymerized with a urethane precursor (HMDI), followed by ring-opening polymerization through thermal curing. The thermal properties of poly(U-co-CDL) were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The self-healing behavior of the bio-based poly(U-co-CDL) was checked by applying a mild external pressure. The results revealed that the developed poly(U-co-CDL) showed repeatable self-healing ability due to supramolecular hydrogen-bonding interactions. Further, the self-healing ability of poly(U-co-CDL) was studied using density functional theory (DFT). From the above results, the developed material with superior self-healing ability can be used in the form of self-healing coatings and composites for various applications with extended shelf-life and reliability.

Janus particles with obvious chemical compartition can perform their functions independently, so they have attracted much attention in biomedical materials. Herein, a mesoporous silica/silver Janus nanoparticle modified with cardanol (C-MSN@Ag) was designed and synthesized

This paper is aimed at studying the thermal properties of poly(lactic acid), PLA with different plasticizers. Plasticized PLA was obtained by mixing and extruding PLA with 20 mass% of neat cardanol, epoxidized cardanol acetate (ECA) and poly(ethylene glycol) (PEG) 400. The glass transition of completely amorphous samples, melting and crystallization behavior of plasticized PLA were analyzed by differential scanning calorimetry. Results obtained show that, below Tg, a higher enthalpy relaxation occurs for PLA plasticized by cardanol derivatives. This is indicative of a faster mobility of PLA chains below Tg, when cardanol derivatives are used as plasticizers. On the other hand, an opposite behavior was observed for the crystallization studies. In facts, a much faster crystallization was found for PLA plasticized by PEG, which in turn indicates a much higher mobility of PLA chains above Tg compared to PLA plasticized by cardanol derivatives. Mechanical properties obtained on completely amorphous samples show that PLA plasticized by ECA is characterized by lower modulus, which is indicative of a more efficient plasticization. On the other hand, the thicker crystals formed during crystallization of PLA plasticized by ECA involve a more relevant increase in the modulus in semicrystalline samples.

Oilsands are suspended fine solids in bitumen in which asphaltenes become adsorbed on the surfaces of these particles, reducing the quality of the oil and hence generating higher costs for the oil industry. Since some polymers containing specific functional groups are able to interact with asphaltenes, it can be expected that these kinds of polymers are able to reduce the amount of asphaltene adsorbed. In this work, the performance of three (co)polymers, with different molar ratios of cardanol and styrene was evaluated in the adsorption process of a model system (pentane insoluble asphaltenes—C5I in kaolinite) monitored by ultraviolet–visible spectrometry. Kaolinite and asphaltene were characterized by scanning electron microscopy with energy dispersive X-ray spectroscopy and the wettability of these samples was measured with a goniometer, before and after the adsorption process. The increase in polymer concentration (from 0.025 to 0.2%w/v) reduced the amount of adsorbed asphaltenes on kaolinite. Polycardanol homopolymer presented the best performance, indicating the important role of the hydroxyl group and pendent hydrocarbon chain on the adsorption of asphaltenes on kaolinite. The results evidence the potential of polycardanol, obtained from a renewable source, in the extraction process of bitumen from oil sand.

The current research work presents an attempt to develop an antimicrobial agent from the bioresource cardanol which can be embedded in the polymer matrix to develop a UV curable coating. The brominated cardanol (BC) was synthesized from liquid bromine (Br2) and cardanol followed by the reaction with triethylamine (TEA) to synthesize quaternary ammonium cardanol (AC). Further, the reaction with glycidyl methacrylate (GMA) gives a UV curable antimicrobial agent (AA). This AA was incorporated in the epoxy acrylate UV curable system in various proportions along with the photoinitiator and coated onto a wooden substrate. The Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies and elemental analysis results revealed that the desired product has been formed. An antimicrobial test was performed with three types of microorganisms viz., bacteria, yeast, and fungi. The test results showed that the antimicrobial performance of the coatings was increased with the significant inhibition percentage values of 81.59% for gram-positive bacteria (Staphylococcus aureus), 77.12% for gram-negative bacteria (E. coli), and 73.82% for yeast (Candida albicans). Also, there was a decrease in the growth% value of the fungi (Aspergillus niger) as the concentration of AA in the system was increased. The mechanical properties of all the coatings were similar. There was a decrease in the Tg as well as in the degradation temperature of the coating films as the concentration of AA was increased, but the char yield got increased, as well. The sample with 20 wt% of AA showed the maximum amount of char yield (11.49%).

The objective of the current research work is to prepare a difunctional reactive dispersing agent derived from cardanol which can be used as an alternative for dimethylol propionic acid (DMPA) in waterborne polyurethane dispersion synthesis. The novelty of the research lies between the use of bio-based resource and utilizing the sulfonic acid group as an anionic dispersible group. The cardanol was sulfonated using oleum followed by the reaction of the hydroxyl group of phenol with the epichlorohydrin (ECH). The obtained product was then hydrolyzed to generate double functionalities which can be introduced in the PU backbone through a chemical reaction with a diisocyanate. The obtained intermediates and product were characterized using hydroxyl values, epoxy equivalent weights (EEW), CHNS analysis, FTIR and 1H-NMR analysis. The typical acetone process was used for the preparation of WPUDs, and the cured films were further analyzed for the various coating properties in which thermal properties showed significant improvements with the incorporation of HESC to the PU system along with the increased char yield and glass transition temperature (Tg), whereas the mechanical properties did not show any improvements, which could be attributed to the bulky structure of HESC and increased rigidity in the polymeric network. The detailed synthesis, characterizations and obtained results are presented and discussed here.

This study aims to evaluate the behavior of Cardanol/SiO2 nanocomposites in the inhibition of the asphaltene damage based on the coreflooding test at reservoir conditions. The nanocomposite design was performed in Part I (https://doi.org/10.1021/acs.energyfuels.0c01114), leading to SiO2 nanoparticles functionalized with different mass fractions of cardanol on the surface of 5 (5CSN), 7 (7CSN), and 9% (9CSN). In this part of the study, the nanocomposite/reservoir fluid interactions were evaluated through interfacial tension measurements and nanocomposite/rock surface interactions using water imbibition and contact angle measurements. Results showed that the designed nanocomposite leads to a reduction of interfacial tension of 82.6, 61.7, and 51.4% for 5CSN, 7CSN, and 9CSN regarding silica support (SN). Whereas, the reduction of the Si-OH functional groups from SiO2 nanoparticles due to the increase of the cardanol content affects the effectiveness of the wettability alteration for 7CSN and 9CSN. Nevertheless, when 5CSN is evaluated, the system is altered from an oil-wet to a mixed-wet state. Coreflooding tests at reservoir conditions were performed to evaluate the oil recovery after asphaltene damage, after damage removal and nanofluid injection, and after induction of a second asphaltene damage to check inhibition. Results show that the selected nanocomposites at a dosage of 300 mg·L-1 enhance the oil recovery in comparison with the baseline conditions via the reduction of the interfacial/surface forces at the pore scale and wettability alteration. It is worth to remark that this improvement remains after the second asphaltene damage induction, which proves the high inhibitory capacity of the designed nanocomposite for the asphaltene precipitation/deposition. Also, the use of the nanocomposites favors the oil recovery more than 50% compared to the asphaltene damage scenario.

In the present paper, the effects of hygrothermal ageing on the bulk mechanical properties and lap-shear strength of the novel bio-based epichlorohydrin/cardanol adhesive have been studied by tensi...

Plasticizers that enable flexible polyvinyl chloride (PVC) are usually combustible, restricting the application of PVC in fire-prone scenarios. In this context, intrinsically flame-retardant plasticizers displaying dual function continue to be the focus of intensive research. Despite their efficiency, the majority of these dual-functional plasticizers previously reported contain halogen elements, which, once ignited, emanate toxic and potentially carcinogenic substances, along with toxic gases and smoke, polluting the environment, damaging the biota, and threatening human health. Here, we report a strategy to obtain a halogen-free, intrinsically flame-retardant PVC bio-plasticizer that harnesses the phenolic hydroxyl of naturally occurring cardanol and covalent attachment of an organophosphate moiety. When combined with di-(2-ethylhexyl) phthalate (DOP), the organophosphate-containing cardanol is qualified as a co-plasticizer, while endowing the PVC materials with flame retardancy. Unlike inorganic flame-retardants, the engineered cardanol is compatible with PVC such that the mechanical properties of the PVC materials are not compromised. The rationale underlying the present effort may provide guidance for developing sustainable alternatives to halogen-containing plasticizers to address the sustainability challenge now confronting PVC industry.

Biobased benzoxazine composites were designed and prepared using renewable bio-phenol (cardanol), newly synthesized 9, 10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO)-urea diamine and eco-friendly borassus aethiopum flower carbon (ABAFC) reinforcement through appropriate experimental conditions. The molecular structure of the DOPO-urea diamine and DOPO-urea diamine-based cardanol-benzoxazine monomers was confirmed using spectral analysis. The biobased benzoxazine matrix and varying weight percentages (1, 3 and 5wt.%) of the bio-carbon-reinforced composites were characterized by different analytical techniques. Result obtained from different studies showed that the glass transition temperature, percentage char yield and contact angle values were increased with the increase in weight percentage of bio-carbon reinforcement. Further, it was also ascertained that the results obtained from corrosion studies using hybrid bio-carbon-reinforced cardanol-benzoxazine composites as the coating materials for steel specimen act as efficient protecting materials. Thus, the overall results suggested that the DOPO urea diamine-based cardanol-benzoxazine composites reinforced with bio-carbon can be used for high-performance corrosion-resistant coating applications.

1,3-Dioxolan-4-one (DOX) chemistry was exploited for the synthesis of poly(lactic acid) (PLA)-based copolymers. A new DOX monomer, bearing the naturally occurring carvacrol (CarvDOX) as a pendant, ...