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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 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.

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.

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.

We present a simple methodology to develop nitrogen enriched polybenzoxazine thermosets by integrating polybenzoxazine network with polyethylenimine (PEI). Thermosets have been developed by polymerizing side-chain type resins, which have been prepared by introducing benzoxazine moieties on the amine terminated branches of nitrogen enriched PEI, using cardanol and eugenol as bio-based phenols. The aim of this study is to investigate the potential of benoxazines synthesized using different bio-based phenols and PEI, on the performance of nitrogen enriched thermosets, as well as to contribute in the array of side-chain type benzoxazine resins. The present work is a next leg of our previously reported article on the synthesis of side-chain type benzoxazine resins using guiacol and PEI (G-pei), where the reaction parameters such as reaction medium, time, and stoichiometry were optimized. It is to be noted that, due to relatively better performance of G-pei resins prepared at 8:1:16 and 10:1:20 (phenol: amine: paraformaldehyde) molar ratio, the same stoichiometry has been specifically adopted for the preparation of cardanol and eugenol-based analogous resins in the present work. The functionalization of PEI with benzoxazine as side-chains, has been confirmed using FTIR, 1H, 13C NMR spectroscopy techniques. Polar amine groups as well as alkyl chains of phenols, are expected to alter the polymerization behaviour of oxazine moieties and the same has been investigated using DSC studies, where the curing profiles display exotherms in the temperature range of 208–222 °C. Further, rheological studies suggest solvent-less processing for cardanol based resins. Polybenzoxazine network bonded with polyethyleneimine has been confirmed from FT-IR spectra of cured thermosets, and the nitrogen content has been evidenced from elemental analysis. Furthermore, the thermal stability of the crosslinked materials has been investigated using thermogravimetric analysis (TGA), while the glass transition temperature for the cured specimens has been obtained by dynamic mechanical analysis (DMA). Moreover, polarity associated with the polybenzoxazine network as well as nitrogen enriched amine, is expected to affect the surface property of the end materials, which has been investigated by performing contact angle measurements on the surface of cured thermosets. Lap shear adhesion experiments have been additionally performed using ASTM D1002 standard, and the results indicates relatively good wettability of cardanol based resins.

In this work, a sustainable approach was developed to melt-blend and enhance the compatibility of the immiscible blend of polylactide (PLA) and poly(acrylonitrile–butadiene–styrene) (ABS). Cardanol, a bio-based phenolic compound, was used as an interfacial (reactive) compatibilizer. The blending was conducted by a solvent-free reactive extrusion. The incorporation of cardanol resulted in an enhancement of the compatibility evidenced by the decrease of ABS nodules size within PLA from few micrometres to several tens of nanometres and the convergence of both polymers Tα around 68.5 °C. In-depth investigation evidenced that cardanol grafted onto ABS during the reactive extrusion via its phenolic ring, leading to a substantial plasticizing effect and a significant decrease of the surface energy of ABS, similar to those of PLA. This work paves the way to a multitude of new compatibilization strategies based on the reaction of phenolic compounds during the extrusion of PLA and ABS.

We present for the first time the aqueous emulsion radical polymerization of cardanol derived methacrylic monomer (CAMA) in order to pave the way for the replacement of styrene. This monomer was synthesized in two-step routes by epoxidation of cardanol prior to methacrylation. Polymerization of CAMA was studied both in toluene solution and in aqueous emulsion. Radical aqueous emulsion homo- and co-polymerization of CAMA with methyl methacrylate (MMA) were performed with sodium dodecyl sulfate as surfactant. Stable latexes were obtained with particle size between 25 and 75 nm. CAMA and MMA conversions were monitored versus time. Influence of radical initiator was studied on gel content, showing transfer to monomer in the case of persulfate as initiator. Glass transition temperature of homoPoly(CAMA) was determined and is suitable for coating application. Photo-crosslinking was performed by thiol-ene chemistry and allowed yielding cross-linked biobased aromatic coatings.

Main-chain benzoxazine oligomers can be phenol-capped now. In this article, cardanol, a renewable phenol extracted from agricultural byproduct, is designed as the capping agent for the oligomers. Benefiting from the long alkyl chain of cardanol, the oligomers possess good processability to satisfy resin transfer molding without adding any diluents. The structures of the oligomers are verified by Fourier transform infrared spectroscopy, 1 H and 13 C nuclear magnetic resonance spectroscopy. The molecular weight and distribution have been measured by size exclusion chromatography. The thermal properties, including glass transition temperature, coefficient of thermal expansion, thermal stability and char yield, are characterized and discussed in this study.

Commercially aqueous 2K-Polyurethane coatings are developed by reacting water based polyols with water based polyisocyanates in a stoichiometric amount for number of end applications such as coatings, adhesives and paints. These water based polyols are mainly derived from petroleum based raw materials. Due to growing environmental and health related concerns on the use of petroleum based feed stocks; the exploration of renewable resources can be the only obvious option. The worldwide demand on the use of renewable materials is mainly due to the fact that these materials are non-toxic, non-poisonous, abundantly available and eco-friendly as compared to fossil resources. In this regard, we have utilized one of the derivatives of cardanol, as a potential renewable resource to develop water based polyols for aqueous 2K-Polyurethane coatings. These polyols when cured with commercially available water based polyisocyanates resulted in crosslinked films. The developed polyols and cured coatings thereof were characterized by number of instrumental techniques like FTIR, NMR, DSC, TGA, EIS, and Tafel. The cured coatings were also characterized for general coatings properties to study the performance properties of cured coatings.

Polyepoxyurethane polymers were synthesized from PolyHydroxyUrethane (PHU) prepolymers terminated amine and epoxy multifunctional. In order to ensure this, PHU prepolymers was synthesized from the reaction between α, ω-bis-cyclic-carbonates (poly(propylene)oxide bis-carbonates) and different excess of diamines (ethylenediamine) to terminate these prepolymers by amine with differents chain length. Then, these aminotelechelic PHU oligomers were re-used in formulation with multifunctional epoxy compound (Bisphenol A Diglycidyl Ether, Di-epoxydized Cardanol or Phloroglucinol Tris Epoxy) to synthesize polyepoxyurethane polymers called also hybrid polymers. Firstly, the raw materials were analyzed in order to determine proportion stoichiometry for carbonate/amine and of hybrid materials formulations. Secondly, for the purpose to demonstrate that the reaction carbonate/amine form hydroxyurethane compound, a model study was realized. Then, syntheses and analyzes of prepolymers terminated amine by 1H, 13C NMR, TGA and DSC was conducted. Once these oligomers analyzed, the hybrid polymers were formulated from epoxy compounds at different temperatures to determine the best cross-linking proceed. Epoxyurethane polymers were characterized by ATG, DSC and measurement of their swelling index and gel content. These materials exhibited glass transition temperature between −5 °C and 42 °C and a thermal stability above 320 °C at 30% of weight loss.

Current epoxy industry still has a strong dependency on fossil-derived precursors as demonstrated in the use of bisphenol A-based resins. To improve the sustainability of the epoxy industry, bio-based chemicals have been explored for the synthesis of environmentally-friendly epoxy polymers. This paper reports the hydrophobization of fully bio-based epoxy coatings using only water as solvent. Three bio-based additives (hexanoic acid, resveratrol, and a cardanol-based epoxy resin) were studied aiming to enhance the hydrophobicity of the coatings. The curing reaction mechanisms have been extensively explored. The modified coatings showed better hydrophobicity, however, they tend to possess a lower crosslink density because these additives have, to some extent, disrupted the polymer network formation. The anticorrosion performance of the bio-based coatings was also evaluated and discussed based on the reported hydrophobicity and crosslink density. This study lays a foundation towards fully bio-based, environmentally-friendly polymers for hydrophobic applications in the future. Agency for Science, Technology and Research (A*STAR) We would like to express our gratitude to the Agency for Science, Technology and Research (A*STAR) of Singapore for the funds (SERC 1528000048) provided in this research.

In this study, two commercially available epoxidized cardanol resins, NC 514 with approximately two epoxies per molecule and LITE 2513HP with approximately one epoxy per molecule were methacrylated and the methacrylated NC-514 resin (NC514VE) was used as the cross-linker unit and the mono-functional methacrylated LITE monomer (LITEVE) was used as the reactive diluent in both conventional DGEBA vinyl ester resin (DGEBAVE) and in NC514VE resin at changing concentrations. Resin formulations of NC514VE using styrene as the reactive diluent were also prepared. The methacrylated products were characterized via spectroscopic techniques like FT-IR and 1H NMR spectroscopy. The viscosities of the liquid resin mixtures at 30 °C were examined and the curing behavior was analyzed via Differential Scanning Calorimetry (DSC). After the cure, the thermo-mechanical properties of the resins were determined via Dynamic Mechanical Analysis (DMA) and mechanical properties were determined via tensile tests. According to thermal gravimetric analysis (TGA) data, at 30 wt% co-monomer content, the temperature of 5% degradation were in 270–300 °C temperature region meaning that the samples were stable until this temperature range. The effect of the diluent content and the structures of the different monomers on both liquid resin and cured resin properties were also evaluated.

Liquid crystal (LC) alignment behaviors of poly(methyl methacrylate) derivative films containing different amounts of plant-based and renewable cardanol moieties were studied for the first time. The poly(methyl methacrylate) derivatives containing the cardanol moieties (HCP#) were prepared using 2-hydroxy-3-cardanylpropyl methacrylate (HCPM) and methacrylate (MMA) as monomers. These polymer films exhibited good optical transparency in the visible light region. The LC cells made from the polymer having 100 mol% of 2-hydroxy-3-cardanylpropyl methacrylate (HCP100) as the alignment layer showed vertical LC alignment having a pretilt angle of about 90°, while those made from HCP# films having smaller than 69 mol% of 2-hydroxy-3-cardanylpropyl methacrylate exhibited random planar LC alignment behavior. The vertical LC alignment behavior on the HCP100 film was ascribed to the hydrophobic HCP100 surface generated by the nonpolar cardanol groups in the polymers. The thermal stability of the LC cell made from UV irradiated HCP100 film (HCP100C) was enhanced compared with HCP100 due to the formation of the cross-linked structure of the unsaturated hydrocarbon in the cardanol group. Good electro-optical characteristics, such as voltage holding ratio (VHR) and residual DC voltage (R-DC), were observed for the LC cells fabricated using the HCP100 as a LC alignment layer. This can give the basic idea for the design of LC alignment layers based on renewable cardanol resource containing polymer films.

Acrylated cardanol diphenyl phosphate (ACP) was synthesized via epoxidation of unsaturation in long side chains of cardanol, followed by acrylation of epoxidized cardanol and, phosphorylation of acrylated cardanol. The chemical structure of synthesized products was confirmed using Fourier transform infrared spectroscopy (FTIR), Nuclear magnetic resonance spectroscopy (1H NMR, 13C NMR and, 31P NMR) and gel permeation chromatography technique (GPC) respectively. The effect of increasing content of ACP into UA oligomer on viscosity of coating formulations was studied using rheometer analysis. The properties of UV curable coatings were determined by differential scanning calorimetry (DSC), X-ray diffraction analysis (XRD) and, thermogravimetric analysis (TGA). The flammability of UV cured coatings were analyzed by limiting oxygen index (LOI) and UL-94 vertical burning test. TGA result shows that the introduction of ACP into UA oligomer promotes degradation of UA oligomer and enhances the char formation. The structure of obtained char residues was further investigated from scanning electron microscopy (SEM), FTIR and Raman spectroscopy analysis. These cardanol based reactive diluent is promising candidates for UV flame retardant UV curable coatings because of their unique structure contains rigid benzene rings, phosphate moiety, polar hydroxyl groups, and long aliphatic chains.

This paper deals with the synthesis and characterization of cardanol based pre-polymers, one containing epoxy group and the other with a benzoxazine unit, obtained from cashew nut shell liquid which is a by product of cashew industry. Using these monomers a new curing system has been developed by varying the proportion of the monomers in the copolymer mixture. Differential scanning calorimeter was used to study and monitor the cure process of monomers as well as their copolymers. Decrease of onset of reaction and the peak exothermic temperature with increase of epoxy content in the copolymers was observed due to the catalytic effect of free phenolic group in the cardanol epoxy. The tertiary amine formed during benzoxazine ring opening found to catalyze the cross linking reactions. The viscoelastic properties, evaluated by dynamic mechanical thermal analysis indicated an increase in storage modulus and tan δ values with incorporation of benzoxazine in the copolymers. Thermal stabilities of the cured polymers were studied by thermo gravimetric analysis. Two stage decomposition was observed for all the copolymers owing to cardanol side chain degradation at low temperature and main cross linked polymer structure at high temperature. The copolymers displayed lower char yields compared to the pure homopolymers because of less ordered structure due to copolymerization. The cardanol derived functional monomers can be used with epoxy and benzoxazine resins to impart flexibility to the cross linked networks.

Cardanol-based epoxidized novolac vinyl ester resin (CNEVER) was synthesized by reacting cardanol-based epoxidized novolac (CNE) resin and methacrylic acid (MA) (CNE:MA molar ratio 1:0.9) in presence of triphenylphosphine as catalyst at 90 °C. The CNE resin was prepared by the reaction of cardanol-based novolac-type phenolic (CFN) resin and epichlorohydrin, in basic medium, at 120 °C. The CFN resin was synthesized by reacting cardanol (C) and formaldehyde (F) (C/F ratio = 1:0.7) with p -toluene sulphonic acid (PTSA) as catalyst (0.5 wt.%) at 120 °C for 7 h. The resin products were analyzed by Fourier-transform infra-red (FTIR) and nuclear magnetic resonance (NMR) spectroscopic analysis. The number-average molecular weight of the prepared CNEVER was found to be 859 gmol −1 as determined by gel permeation chromatographic (GPC) analysis. The resin was cured by using the mixture of resin, benzoyl peroxide, and styrene at 120 °C. The CNEVER resin was found to be cured in 60 min at 120 °C. Differential scanning calorimetric (DSC) technique was used to investigate the curing behaviour. Single step mass loss in dynamic thermogravimetric (TG) trace of CNEVER was observed. Thermal stability of the vinyl ester sample containing 40 wt.% styrene was the highest amongst all other prepared systems.

A new aromatic diacid monomer viz., 4-(4′-carboxyphenoxy)-2-pentadecylbenzoic acid was synthesized starting from cardanol and was characterized by FTIR, 1H- and 13C NMR spectroscopy. A series of new aromatic polyamides containing ether linkages and pendant pentadecyl chains was prepared by phosphorylation polycondensation of 4-(4′-carboxyphenoxy)-2-pentadecylbenzoic acid with five commercially available aromatic diamines viz., 1,4-phenylenediamine, 4,4′-oxydianiline, 4,4′-methylenedianiline, 1,3-phenylenediamine, and 4,4′-(hexafluoroisopropylidene)dianiline. Inherent viscosities of the polyamides were in the range 0.45–0.66 dL/g in N,N-dimethylacetamide at 30 ± 0.1 °C. The introduction of ether linkages and pendant pentadecyl chains into polyamides led to an enhanced solubility in N,N-dimethylacetamide and 1-methyl-2-pyrrolidinone at room temperature or upon heating. The polyamides could be solution-cast into tough, flexible and transparent films from their N,N-dimethylacetamide solution. Wide angle X-ray diffraction patterns exhibited broad halo indicating that the polymers were essentially amorphous in nature. X-Ray diffractograms also displayed a diffuse to sharp reflection in the small-angle region (2θ = ∼2–5°) for the polyamides characteristics of formation of loosely to well-developed layered structure arising from packing of flexible pentadecyl chains. The glass transition temperature observed for the polyamides was in range 139–189 °C. The temperature at 10% weight loss (T10), determined by TGA in nitrogen atmosphere, of the polyamides was in the range 425–453 °C indicating their good thermal stability.

Different types of cardanol-based novolac-type phenolic resins are produced under a wide range of operating conditions for the application in the resin producing industries. Different operating conditions employed for the production of such resins result in different extent of conversion. In order to understand the system behavior, mathematical relationship between the process variables and the extent of conversion was established by employing the ‘Response surface methodology’. Geometrical representation of the mathematical models in three-dimensional surface plots served as a good aid in understanding the behaviour of reaction under different operating conditions. The maximum extent of conversion of the condensation reaction of cardanol and formaldehyde was found to be 93.0 percent at optimum sets of condition of reaction temperature, time, catalyst concentration and pH of the reaction mixture. All the predicted values for optimum process conditions were in good agreement with experimental data.

Models capable of predicting the maximum extent of conversion (p) of cardanol-based novolac-type phenolic resin, have been developed using response surface methodology to determine the optimum reaction conditions. Three-dimensional response surface and their contour plot were drawn. The maximum extent of conversion (98.93%) was predicted when the cardanol was condensed with formaldehyde (molar ratio 1:0.652) at 119.84 °C for a time period of 3 h with the catalyst (e.g., citric acid) concentration of 1.988% of total volume of cardanol and formaldehyde. The pH of the reaction mixture was maintained at 3.0. These predicted values for optimum process conditions were in good agreement with experimental data.

A novel copolyester was synthesized by solution polycondensation of terephthaloyl chloride with 4-[(4-hydroxy-2-pentadecenylphenyl)diazenyl] phenol (HPPDP) and 1,4-butane diol. The monomer (HPPDP) has been synthesized from 3-pentadecenyl phenol, a renewable resource and a by-product of the cashew industry characterized earlier [1] . The copolyester was characterized through elemental analysis, 1 H -NMR, IR, and UV spectroscopy. Dilute solution viscosity of its solution was also determined by viscometry. The intrinsic viscosity [η] was 0.98 dl/gm. The melting temperatures of the copolyester were 63 and 127°C as observed from Differential Scanning Calorimetric (DSC) studies. Thermogravimetric analysis show that degradation commences at 290°C in nitrogen atmosphere. Wide-angle X-ray diffraction study of the copolyester indicates absence of any crystallinity, whereas DSC studies indicate the presence of two melting peaks. Thus, it is presumed that the copolyester has short range crystallinity.

Hydrosilylation of cardanol with methyldichlorosilane followed by hydrolysis leads to the grafting of polysiloxanes by thermally and chemically stable Si-C linkages. This strategy permits the preparation of new formo-phenolic resins which are expected to possess improved mechanical properties as well as increased resistance to chemical and climatic factors.