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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.

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.

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

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.

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.

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.

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.

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.

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, ...

In the present work, the surface behavior of cotton fabrics coated with a series of bio-based polybenzoxazines is explored. Herein, we report the design and synthesis of bio-based benzoxazine monomers (C-x) using cardanol (C) and seven different amines (x = ba, ha, dda, oda, ddm, jef, and fa). The molecular structures of the benzoxazine monomers have been confirmed using FTIR and NMR analyses. The microstructure of the polybenzoxazine-coated cotton fabrics observed from FE-SEM reveals that formation of rough nanostructure is influenced by molecular structure of monomers. Further, surface analysis shows that poly(C-dda)-coated cotton fabric offers superior water contact angle (WCA = 155° ± 3) with low sliding angle (6°). Also, poly(C-dda)-coated cotton fabric delivers the lowest surface energy (14.1 mN/m) and high resistance against acidic and alkaline media. Subsequently, oil–water separation investigation shows that the poly(C-dda)-coated cotton fabric yields 99% of separation efficiency with flux value of 7200 L/m2h. Thus, the cardanol-based polybenzoxazine-coated cotton fabrics prepared in the present work can find application in the field of oil–water separation due to their superior water-repellent nature.

This study represents the first attempt to prepare a novel cardanol-based plasticizer. Modified cardanol (MC, i.e., phosphorylated cardanol) containing nitrogen and phosphoric acid groups was synthesized and then incorporated into polyvinyl chloride (PVC) as the secondary plasticizer for partial substitution of dioctyl phthalate (DOP). The molecular structure of MC was characterized by Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance (NMR), and 31P NMR spectroscopy. The thermal degradation behavior, mechanical performance, and compatibility of MC were also investigated. The substitution of DOP with MC enables PVC blends to have higher thermal stability, tensile strength, and leaching resistance. The tensile strength is increased from 17.7 MPa for DOP/PVC blend (MC-0) to 25.7 MPa for MC/PVC blend (MC-4), and the elongation at break is increased from 256 to 432%, respectively. The microstructure of the tensile fractured surface was studied by scanning electron microscopy. The results show that the addition of MC allows PVC blends to have well-balanced properties of flexibility and strength and excellent migration resistance.

Cardanol is a kind of green industrial raw material, refined from cashew nut shell oil by advanced technology, which has shown potential for anticorrosion coating application. A new cardanol-based benzoxazine monomer (CB) was synthesized by Mannich condensation of a cardanol, paraformaldehyde, and cardanol aldehyde amine (Carala), which was prepared based on cardanol, paraformaldehyde, and triethylenetetramine, and finally, the cardanol-based benzoxazines containing amino group were modified by silane (CBSi). Cardanol, Carala, and CB were characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. Furthermore, the cured films have been evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. The result of DSC of CB and CBSi showed that curing behavior of CBSi was similar to that of CB; however, the enthalpy of polymerization reaction corresponding to CB and CBSi is 84.7 J g−1 and 91.3 J g−1, respectively, and exothermic enthalpy of CBSi is slightly higher than that of CB. TGA results illuminated that the thermal stability and char yield of cardanol-based polybenzoxazine could be enhanced due to increment of silane, and residual char yield at 700°C of CBSi30 is 13%. Especially, incorporation of silane could improve the water contact angle, which can increase from 78.7° to 98.9° when the ratio of γ-(2,3-epoxypropoxy) propytrimethoxysilane to CB increases from 0% to 30%.

The objective of the present work was to evaluate the antioxidant potential of a mixture of saturated, monoene, diene, and triene cardanols derived from the cashew nutshell liquid in naphthenic mineral oil. A mineral naphthenic oil sample was doped with the cardanols mixture at concentrations of 500, 2000, and 5000 mg/kg and evaluated using differential scanning calorimetry (DSC) and the accelerated oxidative method (PetroOXY), following ASTM standards (E2041-18, E1970-16, E537-12, and E698-18). The addition of cardanols increased the oxidative stability of the mineral oil by a factor of 4 to 5. To evaluate the antioxidant potential of each particular cardanol present in the mixture, structural analysis and specific antioxidant mechanisms were investigated by density functional theory (DFT). Each molecular structure was optimized with the hybrid functional B3LYP with a basis set 6-31G (d, p), and the antiradical mechanisms (HAT, SPLET, and SET-PT) were evaluated. The HAT was the best observed mechanism, standing out for the cardanol monoene that showed presented better antiradical activity. Concerning the global reactivity study, it was concluded that the increase of the unsaturations in the side chain of the molecules contributes significantly to their increased general reactivity. When evaluating the Fukui index, it was confirmed that, for the cardanol monoene, the reactivity prevails in the aromatic ring with an emphasis on oxygen and carbon 4, without the interference of the carbon chain. The results showed that the cardanol mixture may be applied as bio-antioxidant for naphthenic mineral oils. General scheme of the study

The two different benzoxazine (Bz) monomers were synthesized from two different bisphenol-AF (BF)- and bisphenol-S (BS)-based diamines with cardanol (CL) precursor, whose molecular structures were confirmed using spectroscopy tools. Further, 2.5 wt%, 5 wt% and 7.5 wt% of phenol-3-aminopropyltriethoxysilane benzoxazine-functionalized MCM-41 (APMS) were reinforced with cardanol-bisphenol AF core diamine-based benzoxazine (BFCL-Bz) and cardanol-bisphenol-S core diamine-based benzoxazine (BSCL-Bz) and cured, which leads to increased thermal stability. Successfully developed polybenzoxazines (PBz) nanocomposites dielectric properties were studied. It was observed that the incorporation of 7.5 wt% of APMS into BFCL-PBz polybenzoxazine results an ultra-low dielectric constant value of about 1.78 at 1 MHz, whereas the APMS/BSCL-PBz composites showed 2.16 for the same weight % concentration of APMS. This may be attributed to the presence of fluorine moieties in APMS/BFCL-PBz system. Data resulted from different studies, and it is concluded that the hybrid composites developed in the present work can conveniently be used in the form of adhesives, sealants and encapsulants for low k interlayer dielectric materials for high-performance microelectronics applications.

High-performance epoxy coatings were prepared by crosslinking commercial diglycidyl ether of bisphenol-A with silicon–sulfur containing di- and tetra-functional carboxyl curing agents based on cardanol. The curing agents were synthesized and products were analyzed by chemical, spectroscopic, and chromatographic techniques. In the next part, coatings were formulated by varying the ratio of epoxy resin to curing agents on equivalent basis, such as 1:0.6, 1:0.8, and 1:1. The coatings were applied on mild steel panels and cured at 150°C for 30 min. The resultant coatings were evaluated for performance properties including mechanical, chemical, optical, thermal anticorrosive, and flame retardant properties. It was observed that with an increase in concentration of silicon–sulfur containing curing agents, water contact angles of the coatings substantially increased. Moreover, electrochemical impedance spectroscopy, Tafel analysis, and salt spray studies revealed that anticorrosive properties of the coatings improved with an increase in concentration of silicon and sulfur. In spite of synergistic effect of silicon–sulfur, only marginal improvement in flame retardant properties was observed.

An environmentally compatible organic solar cell (OSC) has potential to build a global clean energy infrastructure for the world. However, much less attention has been focused on the structures sou...

Phenolic resin can include any of various synthetic thermosetting resins, such as Novolac, which is obtained by the reaction of phenols with simple aldehydes, such as formaldehyde. Phenolics can be...

Cardanol is a substituted phenol obtained from cashew nut shell liquid (CNSL) by the vacuum distillation. It is a feasible alternative to petrochemically derived phenol for many applications. Carda...

Photochromic molecules derived from bioresources and their hybrids with various carbon nanomaterials always resulted in devices with outstanding performance. Among different carbon nanomaterials su...

In the present work, imidazole core mono-amine (ima) was synthesized and used with cardanol (C) and bisphenol-F (BF) to obtain corresponding benzoxazines (C-ima and BF-ima) respectively. Similarly aniline (a) was used as amine precursor for synthesis of benzoxazines (C-a and BF-a) of cardanol (C) and bisphenol-F (BF) respectively for the purpose of blending and comparative studies with ima based benzoxazines. Benzoxazines (C-ima, C-a, BF-ima and BF-a) matrices and blends were prepared using both monofunctional and bifunctional benzoxazines in different weight percent (25/75 wt%, 50/50 wt% and 75/25 wt%) ratios and were characterized using different analytical techniques. From DSC analysis, it was observed that the curing temperature obtained for imidazole based benzoxazines (C-ima and BF-ima) was significantly lower than that of benzoxazines (C-a and BF-a) made using conventional aniline. Similarly, the blends prepared using ima based benzoxazine possess the lower curing temperature, with enhanced thermal stability and char yield than those of conventional cardanol-aniline benzoxazines to an appreciable extent. Hybrid blend composites were developed by reinforcing varying weight percentages (1, 3, 5, 7 and 10 wt%) of GPTMS functionalized bio-silica with selected blends (50:50) of imidazole based benzoxazines (C-ima and BF-ima) and their properties were studied. Data obtained from different studies, suggest that these hybrid composites possess an enhanced thermal stability, higher values of Tg, improved hydrophobic behavior, higher value of char yield and lower dielectric constant than those of neat matrices and blended matrices. It is concluded that the imidazole amine based benzoxazines (C-ima and BF-ima) blends and hybrid composites developed in the present work possess better properties than those of conventional benzoxazine based materials, hence it is suggested that these blends and composites can be used for high performance thermal and dielectric applications.

An attempt has been made in the present work to develop hybrid blended composites using epoxy resin (PETEP) derived from waste polyethylene terephthalate (PET) bottles and bio-phenolic (cardanol)-based benzoxazine (CBz) reinforced with functionalized bio-carbon (f-PJC) obtained from Prosopis juliflora (PJ) for high performance applications. The molecular structure, thermal properties, thermo-mechanical behaviour, morphology, surface properties, and corrosion resistance of the composites were studied by different analytical methods, and the obtained results are reported. Dynamic mechanical properties such as the storage modulus (2.591 GPa), loss modulus (1.299 GPa) and cross-linking density (5.1 × 107 J mol−1 K−1) were improved in the case of the 5 wt% f-PJC/PETEP–CBz composite compared to those of the PETEP–CBz blended matrix and the f-PJC/PETEP–CBz composites with other weight percentages. Among the studied bio-carbon-reinforced hybrid composites with different weight percentages, the 5 wt% f-PJC/PETEP–CBz composite shows a higher value of char yield (38.37%), with an enhanced glass transition temperature of 285 °C and an improved water contact angle of 111.3°. Results obtained from corrosion studies infer that these hybrid composites exhibit improved corrosion resistance behaviour and effectively protect the surface of mild steel specimens from corrosion. It is concluded that the present work can be considered as an effective method for utilizing waste products and sustainable bio-materials for the development of high performance value-added hybrid composites for thermal and corrosion protection applications.

This paper reports the development of the first vitrimer based on polybenzoxazines containing disulfide bonds and cardanol. The synthesis of the monomer was carried out following a sustainable process, without any solvent and purification. The novel polybenzoxazine can be recycled, reshaped and (re)processed, thanks to a fast relaxation process (18 seconds at 120 °C) and low activation energy (64.5 kJ mol−1). Furthermore, the benzoxazine vitrimer shows significant and healable adhesive properties over short times and at low temperatures. These features support it also being considered in additive manufacturing applications, with the possibility of applying 3D printing technology, extending its application to many fields of materials.

A novel bio-based benzoxazine (Ca-g) surfactant was synthesized via a Mannich reaction using renewable glycine and cardanol as raw materials. The structure of Ca-g was characterized by NMR, FT-IR, and elemental analysis. Styrene containing emulsions and polystyrene (PS) latex were prepared based on the Ca-g surfactant. These results showed that the Ca-g surfactant exhibited high efficiency for stabilizing styrene emulsions. An addition of only 1.7 (w/v)% stabilized the high internal phase emulsion (HIPE) with a styrene volume fraction up to 90%. More interestingly, HIPE exhibited pH-sensitivity and could be formed at pH values from 9.0 to 12.0. Furthermore, PS particles were obtained via HIPE polymerization. In addition, the in vitro cytotoxicity of Ca-g and its triglyceride emulsion was also investigated. Ca-g showed lower cytotoxicity against the HeLa cell line. A stable triglyceride-in-water emulsion stabilized by Ca-g was prepared. The bio-based Ca-g surfactant may have potential use in cosmetics and daily cleaning products.

The high rigidity and brittleness of traditional thermosetting resin based on bisphenol epoxy limits its many potential technical applications. Here, a novel tertiary amine containing cardanol-based epoxy resin (NC-514-DEA) was synthesized by reaction of diethanolamine (DEA) with cardanol epoxy resin (NC-514). Moreover, NC-514-DEA modified graphene oxide (GOND) was prepared and used as a reactive nano-reinforcing filler for epoxy composites. The results show that, compared with neat epoxy resin, the fracture toughness of the epoxy composite with 0.5 wt% GOND is increased by nearly 10%, and the friction coefficient is reduced from 0.567 to 0.408, demonstrating the best performance among specimens. The improved mechanical and wear resistance properties of prepared composites were attribute to the synergistic effect of NC-514-DEA and GO, which inhibited the generation and propagation of cracks by enhancing the interfacial interaction and distributing stress. In addition, the synthetic process of GOND is green, simple and efficient, providing a novel way for designing epoxy composite materials with many potential applications.

The present study aims to evaluate the anticonvulsant and antioxidant activity of the alkylated cardanol in mice, as well as the possible mechanisms involved. Albino mice were used. The pentylenetetrazol, picrotoxin, and pilocarpine were used to induce seizures clonic. The effect of selective receptor antagonist GABAA on anticonvulsant activity was investigated with flumazenil. The antioxidant activity was evaluated by the formation of lipid peroxides, nitrite content, and concentration of reduced glutathione. The largest dose of alkylated cardanol increased the latency of the first seizure induced by pentylenetetrazol acting on the GABAergic receptors. The treatment did not alter body weight and did not cause death in animals. It was observed a reduction in locomotor activity and motor coordination. Treatment reduced the level of lipid peroxidation and contents of nitrite and increased levels of GSH in the hippocampus and frontal cortex. Alkylated cardanol showed a protective effect against convulsions induced in mice.

The bio-based polymer blend of polylactic acid (PLA)-polybutylene adipate-co-terephthalate (PBAT) incorporated with cashew shell biomass synthesized cardanol oil (CARD) was prepared by solution casting method. The various formulations were prepared with PLA/PBAT(90/10) polymer blend containing 1%, 3%, and 5 wt.% of cardanol oil. All the prepared PLA/PBAT films were subjected to characterization techniques such as surface morphology, Fourier transform infrared spectroscopy, mechanical, thermal stability, X-ray diffraction, film color, opacity, wettability, and antimicrobial properties. The FTIR and XRD results confirmed the effective miscibility and molecular interactions of cardanol oil in PLA/PBAT blend. Further, the results of TGA analysis showed thermal stability improvement in PLA/PBAT bio-based film by the addition of cardanol oil. The homogeneous distribution of cardanol oil droplets on the PLA/PBAT blend was confirmed by observed SEM and TEM images. The mechanical result proved that the addition of 5 wt.% of cardanol oil into the PLA/PBAT blend increases the elongation at break. Moreover the bio-based PLA/PBAT film shows good barrier against water vapor and a poor barrier against oxygen permeability. The presence of cardanol oil in the PLA/PBAT matrix helps to enhance the optical and wettability properties of prepared bio-based film. Finally, it is proved from the investigational results that the PLA/PBAT/cardanol biodegradable films may be recommended to use in food packaging applications wherever high flexibility, water vapor barrier, thermal stability, antibacterial resistance, and less water absorption properties are required.