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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.

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.

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.

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.

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.

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.

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 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...

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, ...

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 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 materials from natural resources have gained momentum worldwide. Present study concentrated and carried out to prepare six sets of cardanol-based biocomposites in combination with ...

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.

As a class of recyclable thermoset, vitrimers are generally constructed by introducing dynamic chemistry into various synthetic or biobased building blocks. Particularly, biobased vitrimers have aroused increasing interest because of the utilization of renewable resources. The wide range of constructing resources and the different mechanical properties of the resulting networks highlight the fusion of vitrimers with distinct mechanical properties in the recycling process. However, most vitrimers have only been investigated in terms of their own reprocessability, or fusion of identical polymer networks. Herein, we report the concept of melding two biobased vinylogous urethane vitrimers with distinct mechanical properties. Two distinct biobased vinylogous urethane vitrimers were prepared by reacting acetoacetate-modified cardanol with two different diamines (MXDA or PACM). It was found that these vitrimers can be successfully fused and that, after three rounds of hot pressing, the mechanical and thermal properties of the fused vitrimer are comparable to that of a homogeneous vitrimer prepared using premixed MXDA and PACM diamines, the ratio of which is the same as the two distinct vitrimers. This capability of fusing two distinct vitrimers also features a flexible window for targeting mechanical properties, which can be achieved by simply adjusting the ratio of these two vitrimers.

In the present work, amine-functionalized Prosopis juliflora carbon (APJC)-reinforced diphenyldiaminomethane-based cardanol benzoxazine (DDCBz) composites have been developed and characterized with a view to utilizing them for possible load-bearing and corrosion-resistant applications. Chemical structure of the DDCBz was ascertained using Fourier transform infrared, Proton nuclear magnetic resonance and Maldi mass spectroscopy. The 5 wt% APJC/DDCBz composites exhibit good hydrophobic character, thermal stability and mechanical properties compared to those of neat matrix and other wt% of APJC-reinforced composites. Similarly, glass transition temperature (Tg) and water contact angle of composites are enhanced according to their weight percentage concentration. Results from corrosion studies indicate that the mild steel specimens coated with DDCBz matrix and APJC/DDCBz composites offer enhanced corrosion resistance. Data obtained from different studies infer that the APJC-reinforced DDCBz composites possess an improved thermal stability, thermomechanical behaviour, hydrophobic characteristics and corrosion-resistant properties, which make them suitable for high-performance thermal and corrosion-resistant applications.

In the present work, chalcone benzoxazine (Chal-Bz) was co-polymerized with two bio-based benzoxazines namely cardanol (CrAb) and eugenol (EuAb) benzoxazine and coated over cotton fabric. The Chal-Bz/CrAb and Chal-Bz/EuAb blends coated cotton fabrics show water contact angle values of 163° and 156° respectively and their oil–water separation efficiency were observed found to be 97 and 96% respectively. In addition, the glycidoxypropyltrimethoxysilane (GPTMS) functionalized bio-silica in varying weight percentages (1, 3, 5, 7 and 10 wt%) was also reinforced with two co-polymerized blended matrices to obtain respective composites. The developed composites were studied for their dielectric, thermal and morphological behaviours. The values of dielectric constant of 10 wt% bio-silica reinforced Chal-Bz/CrAb and Chal-Bz/EuAb composites were found to be 2.1 and 2.3, respectively. Similarly the values of contact angle of 10 wt% bio-silica reinforced chal-Bz/CrAb and Chal-Bz/EuAb composites were 137° and 116°, respectively. Data obtained from different studies suggest that these bio-silica reinforced benzoxazine composites can be used in the form of coatings, adhesives, sealants and encapsulants for high performance micro-electronics insulation applications under adverse environmental conditions. Thermal assisted polymerization of chalcone based benzoxazine (Chal-Bz) with bio based benzoxazines cardanol-aniline based benzoxazine (CrAb) and eugenol-aniline based benzoxazine (EuAb)) for low k and oil–water separation application.

In the present work, the hybrid siloxane-based cardanol-benzoxazine-epoxy (1:1 ratio) matrix (SBCBz-EP) capable of curing at substantially low temperature when compared with that of conventional benzoxazines was prepared and characterized. The matrix SBCBz-EP was reinforced with varying weight percentages (1, 3 and 5 wt%) of hydroxyl-terminated cyclotriphosphazene (HTCP) and the resulting hybrid composites were characterized by modern analytical methods, which can be used for paint-related applications due to their low-temperature curing behaviour. Data obtained from differential scanning calorimeter analysis infer that the glass transition temperature of the hybrid matrix (SBCBz-EP) and HTCP reinforced with 1, 3 and 5 wt% composites was 73°C, 75°C, 82°C, and 88°C, respectively. The polymerization temperature obtained for SBCBz-EP matrix and HTCP-reinforced hybrid composites was considerably lower than that of conventional benzoxazines. The present hybridization approach of benzoxazine and epoxy paves an avenue to alleviate the deficient characteristics of both industrially valuable resins namely high curing temperature and brittle behaviour of benzoxazines and also to improve thermal stability, mechanical strength and flame-retardant behaviour of epoxy resins. Data obtained from mechanical, dielectric, thermal stability and corrosion-resistant studies indicate that the properties of hybrid composites (HTCP/SBCBZ-EP) were enhanced to an appreciable extent according to the wt% of HTCP and it can be suggested that these hybrid composite materials can be used in the form of adhesives, sealants, encapsulants and water-resistant coatings for high performance industrial applications.

Cardanol is a bio-phenol used in the field of polybenzoxazine (polyBZ) due to its abundance, low cost, effectiveness, and ease of reaction. Its impact on the polymerization kinetic of benzoxazine as well as on the thermal stability has been hereby investigated. To this aim, three di-functional benzoxazine monomers (BZ) are synthesized by bridging with ethylene diamine either two phenols (di-phenol), one phenol and one cardanol (asymmetric card-phenol), or two cardanol moieties (di-cardanol). FT-IR measurements show that the presence of the cardanol aliphatic chain modifies the formation of hydrogen bonding network. These differences are highlighted in the chemorheology of polymerization, where the di-phenol BZ monomer shows an early vitrification explained by the formation of a high degree of H-bonding interactions during curing. An important feature of benzoxazines reactions, highlighted in this study, is that vitrification does not stop the polymerization process. Cardanol long alkyl side chain can cause a plasticizing effect and induces a lower degree of polymerization. This is observed through the decrease of the glass transition temperature (Tg) and the apparition of a β relaxation for cardanol-based polymers. Interestingly, the thermal stability is significantly improved for cardanol-based polyBZ, which can be the result of H-bonds reorganization in the system due to the cardanol aliphatic chains.

With the increase in demand for bio-based coatings with lower volatile organic compound (VOC) emissions, methacrylated cardanol (MACO) and triethoxysilane-functionalized cardanol (TSCO) have been investigated as bio-based reactive diluents for formulating alkyd coatings as a substitute for volatile solvents. The viscosity of the representative alkyd resin was significantly reduced through the use of cardanol-based reactive diluents (over 84% diluent efficiency at 30 wt% loading). Both MACO and TSCO were able to participate in the cross-linked network of the alkyd coating as confirmed by the gel content and cross-link density of the cured coating films. Moreover, the cross-link density of the alkyd coating was significantly improved by using TSCO as the reactive diluent, leading to a significant enhancement in mechanical strength and solvent resistance of the alkyd coating. This work will facilitate the adoption of cardanol as a renewable building block in the coating industry in order to produce greener alkyd coatings.

The siloxane based flexible cardanol benzoxazine was synthesised using cardanol, 1,3-bis(aminopropyl) tetramethyldisiloxane and p-formaldehyde through solvent free method and was characterised by different analytical techniques. A new fangled nanocomposites of amine functionalised rice husk ash silica reinforced siloxane based flexible cardanol benzoxazine were developed and their molecular structure, molecular weight, morphology, cure behaviour, thermal stability, dielectric character and corrosion resistant behaviour were carried out by appropriate test methods. Data obtained from differential calorimetric analysis and experimental cure process infer that the siloxane based cardanol benzoxazine cures at 110 °C, which is significantly lower temperature when compared to that of conventional benzoxazines cure between 220 and 280 °C. Results from dielectric and corrosion resistant studies indicate that these renewable hybrid composite materials can be conveniently used in the form of adhesives, encapsulants, sealants and potting compounds for high performance, low k materials in microelectronics and as coatings to protect steel surfaces from corrosion and microbial deterioration.

Cardanol glycidyl ether, epoxidized acetylated castor oil methyl ester, and epoxidized soybean oil were grafted on polyvinyl chloride (PVC) chains to obtain flexible PVC materials. The structure and properties of graft modification of PVC materials were investigated. The glass transition temperature of graft modification of PVC with cardanol glycidyl ether, epoxidized acetylated castor oil methyl ester, and epoxidized soybean oil was 42.1 °C, 43.8 °C, and 37.9 °C, respectively. The mechanical properties illustrated that graft modification of PVC materials were more flexible than PVC. The extraction tests showed that the modified PVC materials presented no migration in n-hexane and can be used to prepare flexible PVC products with high requirements of durability. The internal plasticizing mechanism was also discussed according to the free volume theory.

Renewable resource based polyol derived from undecylenic acid, a by-product of castor oil, was successfully synthesized by three consecutive reactions: methylation, thiol-ene addition, and amidation. The biobased polyol is a sulfur- and nitrogen-containing polyol. The structure was confirmed by FTIR, NMR, and mass spectroscopic techniques. The undecylenic acid based polyol was used as a polyol along with phosphated cardanol-based polyol in the preparation of polyurethane coatings. The obtained polyurethanes were assessed for their properties by various techniques such as thermogravimetric analysis (TGA), dynamic mechanical and thermal analysis (DMTA), Universal testing machine (UTM) and electrochemical study. Interestingly, the biobased polyol improved mechanical property such as toughness of the material when it was incorporated in different weight percentages to the phosphated cardanol-based polyol. Moreover, the synergistic effect of the phosphorous and biobased polyol with the elements - sulfur and nitrogen, enhanced the anti-corrosion and antimicrobial natures of the polyurethane coating. The corrosion rate was drastically decreased from 3.0 × 10–4 to 1.8 × 10–7 mm per year for the prepared polyurethane coatings.

The sustainable biomass cardanol grafting onto neoprene (CR) rubber was carried out successfully at room temperature by covalently binding to CR via click chemistry to realize the internal plasticization of CR rubber. The structure of the synthesized product was characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance, and differential scanning calorimetry and thermogravimetric analysis demonstrate a lowering of the glass transition temperature of the CR-propargyl ether cardanol as compared to CR. This confirms the plasticization effect of the cardanol when grafted onto CR. The cardanol as an internal plasticizer also has a good thermal stability and almost near-zero migration.

The physico-mechanical and thermo-mechanical properties of meta-pentadecenyl phenol (cardanol) functionalized acrylonitrile–butadiene rubber (CGNBR) composites containing sodium montmorillonite clay were determined via studies on the functionalization of NBR by grafting cardanol onto its backbone main chain in the latex stage using benzoyl peroxide as a free radical initiator. Results show an improvement in technical properties for functionalized NBR nanocomposites over the NBR nanocomposite. Air and ASTM 3 oil aging studies at 100 °C confirmed an increase in tensile strength and a decrease in elongation at break for CGNBR compared to the dioctyl phthalate plasticized NBR nanocomposite. Fire and flame retardancy studies showed an increased limiting oxygen index for functionalized NBR over the NBR nanoclay composite. Results delineate the method of preparation and characterization of functionalized NBR and oil plasticized NBR nanoclay composites to achieve an improved oil resistance effect for functionalized NBR over NBR nanocomposite.

Silanized graphene oxide (SiGO) was synthesized and characterized using KH570 as a modifier on graphene oxide (GO). Subsequently, high performance silanized graphene oxide/cardanol based be...

The present investigation deals with the latex stage functionalization of carboxylated acrylonitrile butadiene rubber (XNBR) by chemically grafting cardanol onto its backbone main chain to impart multifunctional characteristics to it. The grafting of cardanol onto XNBR in the latex stage has been accomplished successfully using benzoyl peroxide (BPO) as a free radical initiator. Cardanol grafted XNBR (C-g-XNBR) exhibited an increase in molecular weight (7.5%) with an increase in PDI (polydispersity index). The optimum grafting parameters were found to be of 1 phr BPO with 15 phr cardanol at a reaction temperature of 80 °C and a reaction time of 10 h using “Taguchi methodology”. The maximum percentage grafting (PG) and grafting efficiency (GE) were estimated to be 13.8 and 92.8%, respectively at the optimum combination of the reaction parameters. Differential scanning calorimetry and dynamic mechanical analysis results exhibited a decrease in Tg value for the functionalized elastomer. Thermogravimetric analysis displayed an increase in the thermal stability of C-g-XNBR. MTT [3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide] assay and hemolysis studies proved that functionalized rubber as biocompatible. Moreover, functionalized XNBR exhibited a potential bactericidal effect against Staphylococcus aureus and Escherichia coli strains. Fire and flame retardancy study revealed an increased LOI (limiting oxygen index) for C-g-XNBR.

Owing to the natural abundance, variety of structural features, and highly specific functions, natural monomers render themselves as potential candidates for production of high performance functional polymers. The emerging concept of the biorefinery and development of new biosynthetic routes to synthesize a versatile and broad spectrum of natural monomers and polymers continues to gain momentum. The production of high quality polymers from renewable feedstocks requires innovative chemical modifications and catalytic transformations to achieve higher yields in an efficient manner. A fresh look into monomers available from natural resources such as terpenes, rosin, glycerol, furans, tannins, suberin, their derivatives and miscellaneous monomers may inspire future applications with impactful biobased materials. There are also many areas that require urgent discussion and review pertaining to recent developments in the field; this includes monomer sources that give molecules having special structural features. In particular, cardanol, a naturally occurring low-molecular-weight compound is unique as it contains a phenolic head group and a hydrocarbon chain with different degrees of unsaturation. This molecule possesses functional groups that are amenable for classical chemical modification, which is instrumental in developing a wide range of functional monomers and polymers. A large number of soft and hard materials have been developed from cardanol-based monomers. During the past, a large number of industrial grade materials have been developed from plant-based monomers, including development from microbial and fermentation processes (i.e. lactic acid). This review provides a comprehensive study and survey on recent developments on monomers and polymers derived from urushiol and cardanol based monomers and polymers, vegetable oil-based monomers and polymers, microbially produced monomers and polymers. These all represent emerging fronts giving a vast scope while highlighting important potential material and reagent opportunities.

With the aim to reinforce polylactide (PLA) mechanical properties, poly(acrylonitrile-butadienestyrene) (ABS) is considered as a polymer of choice. However, PLA and ABS are immiscible, leading to blends with weak properties. Cardanol is a lipid phenolic known to compatibilize these two polymers thanks to its reaction with ABS, but does not react with PLA and restricts its use to the modification of ABS. In this work, we investigated the effect of cardanol-based compatibilizers able to react by reactive extrusion with both PLA and ABS. In a first approach, cardanol unsaturations were epoxidized (CardE), hoping to react with PLA, while cardanol phenolic group would react with ABS. This compatibilizer was efficient as attested by ABS nodules size reduction and dispersion within PLA, in addition to the merging of the relaxation temperatures of both polymers at 69.5 °C when 5 wt% CardE was used. In addition, it led to a substantial improvement of PLA/ABS impact strength and elongation at break. In a second approach, we used of a mixture of compatibilizers, containing raw and epoxidized cardanol, both of them reacting either with PLA or with ABS. Here, a clear synergistic effect was observed, as attested by the exceptional increases of both impact strength (+172% compared to neat PLA) and elongation at break (+1000% compared to neat PLA). We assumed modified chains of both PLA and ABS with cardanol derivatives during reactive extrusion would intersperse between PLA and ABS, reducing the interfacial tension and improving the interfacial adhesion, leading to the outstanding compatibilization of the blend.

In the evolving resin world, people are trying to develop the resins from bio-resources with the properties similar to or superior to the commercial resins. This research work presents an attempt to develop the flame-retardant coating from cardanol as a starting material. The two intermediates obtained using Phenylphosphonic dichloride (PPDC) and Dichlorodimethylsilane (DCDMS) are used in the development of polyurethane backbone in various proportions. Itaconic acid (IA) based polyol was used as a chain extender for curing. Characterization of the intermediates obtained was done using the Fourier transform infrared (FTIR) spectroscopy, Nuclear magnetic resonance (NMR) spectroscopy, acid value, hydroxyl value, epoxy value, etc. All the characterizations showed that the required products have been formed. The Coated films showed similar mechanical properties which were analyzed using flexibility, impact resistance and pencil hardness. The gel content and water absorption values obtained are inversely proportional to each other which can be correlated with the barrier properties of the films. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) showed that the FR50 produced the maximum amount of char and FR100 had the highest Tg with the value of 81.68 °C. Flame retardancy of the cured films was checked using the limiting oxygen index (LOI) and UL- 94 vertical burning test. All the coating films with the developed precursors were able to self-extinguish the fire within 10 s and FR50 obtained 29 as the highest value of LOI.

The present study deals with the development of five different brake friction composites to the standard of Indian scenario brake pads by varying the different cashew friction dusts namely furfural modified, boron modified, boron-graphite modified, cardanol and CNSL based without varying the other ingredients. The developed brake friction composites were tested for their physical, chemical, mechanical and thermal properties as per industrial standards. The thermal stability was found for varying ingredients and the developed composites using Thermo Gravimetric Analyser. Tribological properties were analysed using full-scale inertia brake dynamometer as per JASO-C-406 Schedule. The ranking of the dyno tested friction composites was done using VIKOR and ELECTRE methods. Scanning Electron Microscopy coupled with elemental mapping was used to elucidate back transfer and surface characteristics of the dyno tested brake pads. The results revealed that boron-graphite modified friction dust-based brake pads were beneficial with good fade, wear resistance and recovery characteristics due to its thermally stable and heat dissipating characteristics.

A series of copolymers (PSH#s, where # is the molar content (%) of (dimethylamino)ethylmethacrylate (DMAEMA) and sulfobetaine methacrylate (SBMA)) containing both plant-based cardanol and zwitterionic moieties was synthesized via free radical polymerization of 2-hydroxy-3-cardanylpropyl methacrylate (HCPM) and DMAEMA, followed by betainisation with 1,3-propanesultone. Transparent PSH# films could be prepared on the silicon wafers through spin-coating and UV-crosslinking processes. The bactericidal and antifouling properties of the polymer films were found to be closely related to the ratio of the HCPM and SBMA moieties in the copolymers. The films having a larger content of the bactericidal HCPM moiety show better bactericidal properties, while those having a larger content of the hydrophilic SBMA moiety show enhanced adhesion resistance to biofoulants. Moreover, all the films having both HCPM and SBMA moieties have sufficient biocompatibility, regardless of their ratio.

In recent years, natural fibers are replaced by synthetic fibers as reinforcing agents to fabricate biocomposites. The present study is aimed to blend an abundantly available natural fiber with biopolymer to fabricate green biocomposite material. Four sets of cardanol-based biocomposites were prepared by incorporating bagasse fibers cut length 10 mm (chemically treated and untreated) and 20 mm (chemically treated and untreated) with biopolymer. These cut fibers were blended in various wt% (viz., 0, 5, 10, 15, and 20 wt%) with cardanol. The tensile strength and impact test were performed to study the mechanical properties of the developed composites. The morphological study in tensile fractured specimens was carried out using scanning electron microscopy (SEM). In addition to this, differential scanning calorimeter (DSC) tests were also carried out. The result proved that the morphologies of the composites have an improved bonding between the fiber and resin, leading to enhanced mechanical properties. Among the four sets, 15 wt% of 20 mm NaOH-treated fiber length composite has better mechanical properties like higher tensile strength, impact strength, and thermal stability than other wt% composites. SEM photograph also supports for the same biocomposite.

International audience; Well‐defined linear alkyl benzene surfactants (COxn) were successfully synthesized using cardanol as a green phenolic alternative and initiator for polyoxazoline (POx), the hydrophilic block of nonionic surfactants. Various hydrophilic lipophilic balance values were investigated by varying the POx length according to the [monomer]/[initiator] ratio. The chemical structure of the surfactants, in particular the terminal groups, was well identified by matrix assisted laser desorption ionization time of flight mass spectrometry demonstrating the good progress of the cationic ring‐opening polymerization. The COxn surfactants spontaneously self‐assembled in water at a critical aggregation concentration of 1–2 µmol L−1 into nano‐objects characterized by a hydrodynamic diameter of 11–24 nm and a number of aggregations ranging from 30 to 60 according to the worm‐like micelle model.

Commercially available methacrylates often contain derivates of bisphenol A (BPA), a known human endocrine disruptor and petrochemical derived compound; therefore, alternatives are being investigated to increase sustainability and reduce toxicity. An asymmetric, bio-based bisphenol, VAC, was synthesized via an electrophilic aromatic condensation of vanillyl alcohol and cardanol. The alkyl side chain of VAC was subsequently hydrogenated to yield VAHC to determine the effects of side chain unsaturation on material properties. These bisphenols were methacrylated to prepare VACDM and VAHCDM, blended with a reactive diluent, cured, and compared to BPA dimethacrylate (BPADM), bio-based bisguaiacol dimethacrylate (BGDM), and a commercial BPA based vinyl ester (VE828). Resins containing VACDM and VAHCDM have reduced viscosities relative to BGDM and both BPA-based dimethacrylates, and the unsaturation on the side chain was shown to provide further reduced viscosities. Cured resins with VACDM and VAHCDM exhibit directly comparable thermal stability in both inert and oxidative environments, and decreased glass-transition temperatures due to increased aliphatic character relative to BPA-based resins. The toughness of the thermosets comprised of the bio-based bisphenols were greater than that of BPADM, where the alkyl substituent was shown to impart toughness into the network, yet the level of side chain saturation shows minimal effect on fracture toughness.

In the present work, we developed a green and more efficient method to prepare biobased polyurethane (PU) foams under catalyst-free condition. Firstly, novel organosilicon grafting cardanol-based autocatalytic polyols (SCAPs) with low viscosity were synthesized through the ring opening of cardanol glycidyl ether (CGE) and the hydrosilation of unsaturated alkyl chain with heptamethyltrisiloxane (HMTS). Subsequently, PU foams were synthesized by SCAPs in absence of catalyst. The structure and properties of the PU foams were evaluated and discussed. In addition, the thermal degradation mechanism of PU foams was investigated by using a thermogravimetric analysis instrument coupled with fourier transform infrared and mass spectrometer (TG-FTIR-MS). The results showed that the PU foams had high compression strength and thermo-stability.

In this study, a new type of bio-based azobenzene-containing benzoxazine (Bza) was synthesized using p-aminoazobenzene, paraformaldehyde, and cardanol the raw materials, and the resulting Bza was mixed with bio-based epoxy soybean oil (ESO) in different composition ratios in the presence of adipic acid as a reaction curing agent, affording a bio-based thermosetting composite thermosets. The chemical structure of the synthesized Bza was characterized by Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance spectroscopy. The thermal curing behavior in the absence of any catalyst was investigated by differential scanning calorimetry, indicating that the synthesized Bza exhibits certain liquid crystalline characteristics during heating. The existence of liquid crystal state was further confirmed by the polarizing microscope studies. The mechanical and thermal properties of the composite thermosets with different proportions of Bza were studied. The results show that the addition of increasing amount of Bza to ESO improved its performance to a certain extent; however, further addition beyond a certain range deteriorated the performance. Attributing to excellent processability and high performance of soybean oil-based thermosetting materials and photochromism of azobenzene compounds, the resulting composite materials endowing the characteristics of their components will have a wide range of applications in many fields.

International audience; Hydrophobically modified chitooligosaccharides (COSs) were tested for suitability as an emulsifier in cationic bituminous emulsions. COSs with polymerization degrees (DPs) of 5, 10, 15, and 20 were obtained by nitrous acid deamination. A complete study on depolymerization and precise product and side product characterization was undergone. Chemical modification of COSs was performed to achieve amphiphilic structures using three fatty epoxides with a growing chain length butyl (C4), octadecyl (C9), and hexadecyl glycidyl ether (C16)). The grafting efficiency according to reaction conditions was established. Different substitution degrees (DSs) were obtained by modulating the ratio of fatty epoxy to NH2. It was shown that after a certain DS, the oligomers thus formed were not water-soluble anymore. At the end, cardanol glycidyl ether was grafted on DP 5, 10, and 15 COSs, cardanol being a biobased compound extracted from cashew nut shell; this reaction led to a potentially fully biobased structure. Water-soluble candidates with a higher DS were used as surfactants to emulsify motor oil as a simulation of bitumen. Cardanol–chitosan-based surfactants led to direct oil-in-water emulsion (60/40 w/w) composed of particles of 15 μm average size that were stable at least for 24 h.

Polybenzoxazine is an interesting class of high-performance polymers with potential applications in both the scientific and industrial fields. Due to its remarkable properties along with environmental concerns, different benzoxazine monomers are being synthesized in order to afford more sustainable alternatives for polymeric materials development. Here, we report a microwave-assisted and formaldehyde-free methodology for the synthesis of a cardanol-based benzoxazine. The reaction use cardanol and HMTA as starting materials with the efficient microwave-assisted heating, affording the desired product in a matter of minutes and high yields, in a reaction system completely absent of organic solvents. Monomer characterization was performed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance Spectroscopy (1H and 13C NMR) and differential scanning calorimetry (DSC). The obtained thermoset was studied by thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA), showing good thermal and mechanical properties. The results indicate the successful protocol for the development of highly bio-based monomer under solvent- and formaldehyde-free conditions, starting form cardanol, an agro-industrial residue.