Synthesis Of Epoxy Resins Research Articles

Fluorescent thiol-epoxy thermosets obtained from diglycidylether of bisphenol A and carbazole based diepoxy monomer

A new epoxy resin containing carbazole moieties was synthesized and added in several proportions to diglycidylether of bisphenol A (DGEBA) and trimethylolpropane tris(3-mercaptopropionate) (TTMP) formulations that were thermally cured by thiol-epoxy click reaction. The curing was catalyzed by a latent amine precursor, which after triggering at high temperature liberates the amine that enables the formation of thiolate groups. The curing process of the different formulations was monitored by calorimetric analysis, which allowed to observe that the increase of the proportion of the synthesized epoxy resin with carbazole groups in the formulation decreased the curing rate. However, all these formulations cured quickly after triggering, which make them adequate for the formation of layers in multilayer devices.Thermal characteristics of the obtained thermosets were determined by calorimetric, thermomechanical and thermogravimetric analysis. The obtained thermosets have good thermal stability. Their glass transition temperature increased when the proportion of the carbazole containing resin was increased in the formulation. The photophysical properties of the thermoset films were studied and it was proved that they exhibit fluorescence in the range of 352 to 369°C.

Thermal stability and thermal degradation kinetics of bio-based epoxy resins derived from cardanol by thermogravimetric analysis

Cardanol is a naturally occurring chemical compound consisting of meta substituted alkyl phenol. Two types of epoxy resins have been synthesized from cardanol. The synthesized epoxy resins have been characterized by FTIR and NMR spectroscopic analyses. The thermal stabilities and kinetics of the thermal degradation of cardanol-based resins were studied by thermogravimetric analysis under a nitrogen atmosphere with heating rates of 5, 10, 15 and 20 °C min−1. The molecular weights of the prepared novolac and epoxidized novolac resins were determined by gel permeation chromatography analysis. There is intense interest in understanding the degradation behavior and properties of cardanol-based epoxy resins. Three model-free methods, Kissinger, Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO), and the model-fitting Coats–Redfern method were employed to identify the kinetic triplet including activation energy, pre-exponential factor and reaction model. It was established that the Coats–Redfern model-fitting method is suitable for determining the kinetic reaction mechanism, but the most probable reaction functions R3 and D3 can be evaluated on the basis of the activation energy value which is nearest to the value of activation energy obtained by the FWO and KAS methods. A kinetic compensation effect was also observed for the above-mentioned bio-based epoxy resins.

Tannic acid based hyperbranched epoxy/reduced graphene oxide nanocomposites as surface coating materials

Abstract Hyperbranched epoxy resin (TAE) was synthesized by a simple polycondensation reaction using bio-based tannic acid as a branch generating moiety. The nanocomposites of TAE with different doses (0.25, 0.5, and 1 wt.%) of reduced graphene oxide (RGO) were prepared by solution technique. TAE was cured with poly (amido-amine) hardener at a temperature of 100 °C followed by post curing at 120 °C. FTIR, 1 H NMR, 13 C NMR etc. studies support the hyperbranched structure of the synthesized epoxy resin. Transmission electron microscopy (TEM), X-ray diffractometry (XRD), scanning electron microscopy (SEM) and UV–vis spectroscopic analysis confirmed the formation of polymer nanocomposites. The results of performance studies showed that polymer nanocomposites exhibited better performance than the pristine polymer. The tensile strength, scratch hardness, impact strength, initial degradation temperature and gloss were all improved by the formation of nanocomposite. Thus results indicate the studied nanocomposite has the potential for use as a surface coating material.

Biocatalytic Synthesis of Epoxy Resins from Fatty Acids as a Versatile Route for the Formation of Polymer Thermosets with Tunable Properties.

The work herein presented describes the synthesis and polymerization of series of bio-based epoxy resins prepared through lipase catalyzed transesterification. The epoxy-functional polyester resins with various architectures (linear, tri-branched, and tetra-branched) were synthesized through condensation of fatty acids derived from epoxidized soybean oil and linseed oil with three different hydroxyl cores under bulk conditions. The selectivity of the lipases toward esterification/transesterification reactions allowed the formation of macromers with up to 12 epoxides in the backbone. The high degree of functionality of the resins resulted in polymer thermosets with Tg values ranging from -25 to over 100 °C prepared through cationic polymerization. The determining parameters of the synthesis and the mechanism for the formation of the species were determined through kinetic studies by 1H NMR, SEC, and molecular modeling studies. The correlation between macromer structure and thermoset properties was studied through real-time FTIR measurements, DSC, and DMA.

Strategies for synthesis of epoxy resins from oleic acid derived from food wastes

ABSTRACTThe use of biomass‐sourced chemical feedstocks creates a conflict over land use between food and fuel/chemical production. Such conflict could be reduced by making use of the annual 1.3 Pg food waste resource. Oleic acid is available from seed oils such as pumpkin, grape, avocado and mango. Its esterification with diols 1,3‐propanediol, resorcinol and orcinol was used to form diesters and the naturally occurring norspermidine was used to prepare a diamide, all under ambient conditions. These compounds were then epoxidized and polymerized. When esterification was followed by epoxidation and subsequent curing at elevated temperature with p‐phenylenediamine or diethylenetriamine, hard insoluble resins were formed. When the sequence was changed such that the epoxidized oleic acid was first reacted with cis‐1,2‐cyclohexanedicarboxylic anhydride and then esterified with orcinol and resorcinol, insoluble crosslinked polymers were also obtained. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 3159–3170

Curing and thermal behavior of epoxy resins of hexafluoro - bisphenol –A and bisphenol-A

This paper describes the synthesis and characterization of epoxy resins based on (hexafluoroisopropylidene)diphenol (EFN) and p,p’-isopropylidenebisphenol (EBN), respectively and 4, 4’- (hexafluoroisopropylidene)dipthalic-imideamine (IMAM), a curing agent. The synthesized epoxy resins and IMAM curing agent were characterized by Fourier Transform Infrared (FTIR) and 1H Nuclear Magnetic Resonance (NMR) spectroscopy.13C NMR technique was also used to characterize IMAM. Study of curing behavior of EFN and EBN with stoichiometric amount of aromatic 4,4’-diaminodiphenylmethane (DDM), 4,4’-diaminodiphenylsulfone (DDS) and IMAM by using Differential Scanning Calorimetery (DSC) indicated that IMAM was least reactive curing agent towards both epoxy resins as compared to DDS and DDM. The investigation of thermal decomposition of the cured compounds by thermogravimetric analyzer (TGA) indicated the higher thermal stability of EFN and EBN resins initially with DDS and at elevated temperatures with IMAM. It was also observed that EFN resins were thermally more stable than EBN resins cured with corresponding curing agents.

Synthesis of Epoxy Resin from Waste Ricebran Oil

Vegetable oil is triglyceride of higher molecular weight fatty acids and most of the vegetable oils have high content of unsaturated fatty acids, which can be converted into epoxy fatty acids. Epoxidized vegetable oils (EVO) are nowadays gaining importance because of their sustainable, renewable and environment friendly nature. EVOs are widely used as feedstock for the synthesis of plasticizers, lubricants, coating formulations, polyols etc. Due to the unsaturation present in Ricebran oil, it can be epoxidized to produce an eco-friendly and consumer-friendly product which can replace products produced from petroleum origin. In this study waste ricebran oil was successfully used to produce economically efficient epoxy resin. The waste ricebran oil (WRBO) used was obtained from refined ricebran oil, which was used as frying medium for 16 hours. 50 g waste ricebran oil (0.177 moles) having an iodine value 92 and acid value 1.2 was reacted with performic acid at 60°C for 7 hours. An excess of 30% hydrogen per oxide (60 ml, 1.76 moles) was taken for higher conversion in the reaction. This reaction was completed with formic acid (11.2 g, 0.243 moles) as oxygen carrier in presence of H2SO4 as catalyst in situ. The product was analyzed by Fourier Transform Infrared Spectroscopy (FTIR) and Proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR).

The unique activity of catalyst in the epoxidation of soybean oil and following reaction of epoxidized product with bisphenol A

Presented research shows the influence of different catalysts onto the selectivity and efficiency of soybean oil oxidation as well as their influence onto the progress of the further reaction of synthesized epoxidized oil with bisphenol A in the epoxy fusion process. Described experiments involved modification of vegetable oils and innovatory application of obtained products in a synthesis of new bio-based epoxy resins. Presented research respectively describes an epoxidation of soybean oil, in a presence of H2SO4, ion-exchange resins: Amberlyst 15 and Zerolit 325, as well as Zeolite Y and the immobilized enzyme lipase B, Novozym 435, as catalysts, leading to products, which were applied to partially replace petrochemical substrates used in a conventional process of synthesis of epoxy resins. Applied catalysts presented different activity, defined by various epoxy groups contents in the final product, due to which, they can be classify as follow (from the highest to lowest activity): Novozym 435 (EV=0.384mol/100g), H2SO4 (EV=0.323mol/100g), Zerolit 325 (EV=0.277mol/100g), Amberlyst 15 (EV=0.260mol/100g), Zeolite Y (EV=0.020mol/100g). For all catalysts before and after the epoxidation reactions, SEM images were taken and observed changes in the surface structure were analyzed. The products of epoxidation were characterized by epoxy, acidity, iodine and hydroxyl value (reflecting contents of reacted, unconverted and newly created functional groups), along with FT-IR and GPC for defining their chemical structure. The subsequent part of the performed research concentrates on the epoxy resins synthesis throughout the fusion process of epoxidized oil products, obtained in the presence of different catalysts, with bisphenol A, carried out in the presence of LiCl as a polyaddition catalyst. Various courses of that process, depending on the catalyst used in the epoxidation reaction, had been observed. It had been confirmed that even vestigial amount of catalyst, which has not been properly removed from epoxidized product, has significant influence on rapidity of the epoxy fusion process, that could possibly result in its impetuous progress (particularly seen in H2SO4 application) and gelation of synthesized epoxy resin.

Improved cardanol derived epoxy coatings

Abstract Commercial epoxidized cardanol, from cashew nutshell liquid (CNSL), is a biobased reactant with interesting aromatic structure. Cured with two different diamines, isophorone diamine and Jeffamine T403, the synthesized materials exhibit good properties but they do not meet properties of bisphenol A diglycidyl ether (BADGE) epoxy resins. Therefore epoxidized cardanol cannot replace directly BADGE for the synthesis of epoxy resins. Three epoxy reactants, resorcinol, hBADGE and TMP, were used as reactive additives to enhance the properties of the cardanol derived materials. These epoxy networks with different ratios were characterized by thermogravimetric analysis, differential scanning calorimetry. Their hardness and gloss were measured as well as their resistance to chemical solvents.

Synthesis, thermal and mechanical behavior of a silicon/phosphorus containing epoxy resin

ABSTRACTA liquid silicon/phosphorus containing flame retardant (DOPO–TVS) was synthesized with 9,10‐dihydro‐9‐oxa‐10‐phosphapheanthrene‐10‐oxid (DOPO) and triethoxyvinylsilane (TVS). Meanwhile, a modified epoxy resin (IPTS–EP) was prepared by grafting isocyanate propyl triethoxysilane (IPTS) to the side chain of bisphenol A epoxy resin (EP) through radical polymerization. Finally, the flame retardant (DOPO–TVS) was incorporated into the modified epoxy resin (IPTS–EP) through sol–gel reaction between the ethyoxyl of the two intermediates to obtain the silicon/phosphorus containing epoxy resin. The molecular structures of DOPO–TVS, IPTS–EP and the final modified epoxy resin were confirmed by FTIR spectra and 1H‐NMR, 31P‐NMR. Thermogravimetric analysis (TGA), differential scanning calorimetry, and limiting oxygen index were conducted to explore the thermal properties and flame retardancy of the synthesized epoxy resin. The thermal behavior and flame retardancy were improved. After heating to 600°C in a tube furnace, the char residue of the modified resin containing 10 wt % DOPO–TVS displayed more stable feature compared to that of pure EP, which was observed both by visual inspection and scanning electron microscope (SEM). Moreover, the mechanical performance testing results exhibited the modified epoxy resins possessed elevated tensile properties and fracture toughness which is supported by SEM observation of the tensile fracture section. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42788.

Functionalization of the active ingredients of Japanese green tea (Camellia sinensis) for the synthesis of bio-based epoxy resin

The active ingredients of Japanese green tea (Camellia sinensis) were utilized to synthesize bio-based epoxy resin. The catechin compounds in the aqueous extract of green tea were functionalized with epichlorohydrin under alkaline conditions in the presence of tetramethylammonium chloride (TMAC), a water soluble phase transfer catalyst. A good yield of resin was synthesized, and curing was performed with methanol soluble lignin extracted from eucalyptus. The epoxy networks, so synthesized, were compared with bisphenol-A (BPA)-derived epoxy network. The thermal and mechanical properties of the bio-based resin were assessed through thermogravimetric, flexural strength, and glass transition (Tg) analyses. Catechin-based epoxy networks were found to exhibit good thermal and mechanical properties, rendering them potential BPA substitutes. The thermal decomposition temperature resulting in 5% weight loss (Td5) of synthesized epoxy resin was found to be above 300°C, which is slightly lower than that of BPA-derived epoxy resin. The synthesized bio-based resins meet the requirement for the dip-shoulder resistant temperature (250–280°C), with Tg values ranging from 155 to 178°C, highlighting their potential use as one of the most suitable BPA substituents as well as their use in electronic materials.

Dielectric relaxations investigation of a synthesized epoxy resin polymer

A diglycidylether of bisphenol A (DGEBA) epoxy resin was synthesized, and cured with 3,3′-diaminodiphenyl sulfone (DDS) at a curing temperature of 120 °C. The relaxation properties of the realized polymers were studied by two complementary techniques: dielectric relaxation spectroscopy (DRS), in the temperature range 173–393K and in the frequency interval 10−1–106 Hz, and thermally stimulated depolarization current (TSDC) with a windowing polarization process. Current-voltage (I–V) measurements were also carried out to study interfacial relaxations. Dielectric data were analyzed in terms of permittivity and electric modulus variations. Three relaxation processes (γ, β and α) have been identified. They were found to be frequency and temperature dependent and were interpreted in terms of the Havriliak-Negami approach. Relaxation parameters were determined by fitting the experimental data. The temperature dependence of the relaxation time was well fitted by the Arrhenius law for secondary relaxations, while the Vogel-Fulcher-Tamann model was found to better fit the τ(T) variations for α relaxation. We found τ 0 = 4.9 10−12 s, 9.6 10−13 s and 1.98 10−7 s for γ, β and α relaxations, respectively. The obtained results were found to be consistent with those reported in the literature. Due to the calculation of the low-frequency data of dielectric loss by the Hamon approximation, the Maxwell-Wagner-Sillars (MWS) relaxation was highlighted.

植物由来のクルクミンを原料としたエポキシ樹脂の合成

植物由来のクルクミンを原料としたエポキシ樹脂の合成

Preparation of Epoxy-Novolac Resin Binder Using Phenolic Rich Fractions of Biomass Pyrolytic Oil as Partial Substitute of Phenol

Epoxy resins are among the basic components for coatings manufacture but because of their cost and environment effects, some environmental protection regulations have restricted the use of chemicals considered toxic. The potential of using phenolic rich fractions of bio-oil derived from the pyrolysis of a sustainable agricultural waste for epoxy resin synthesis was investigated. Epoxy resins with different concentration of water-insoluble heavy fraction were synthesized. The bio-oil, heavy fraction and prepared resins were later characterized using Fourier Transform Infra-Red (FTIR), Gas Chromatography Mass Spectrometry (GC-MS) and Differential Scanning Calorimetry (DSC). FTIR and GC-MS results confirmed the presence of phenols on both the bio-oil and heavy fraction with heavy fraction having a higher concentration. DSC analysis showed a corresponding increase on curing time of the resins with increased quantity of phenolic rich components. FTIR analysis of the resin indicated high-ortho structure. Utilization of bio-oil as a source of phenol for epoxy resins manufacture would significantly reduce the cost and negative environmental effects of the current resins.

Study on Synthesis of Epoxy Resin Modified with Polysiloxane

With allyl glycidyl ether and terminal hydrogen silicone oil, in certain conditions, the silicone-modified epoxy resin synthesized by the hydrosilylation reaction. This study discuss the effect of the structure and properties on the synthesized product, such as the catalyst, reaction time, reaction temperature and the C = C/Si-H molar ratio of allyl glycidyl ether and terminal hydrogen silicone oil. Infrared spectroscopy, gel permeation chromatography (GPC), epoxy value and hydrolysis chlorine of the polysiloxane-modified epoxy resin were characterized and analysized. The results show that the terminal hydrogen silicone oil-modified epoxy resin has balanced epoxy value, molecular weight and molecular weight distribution, the conversion of reactive hydrogen is the highest when the dosage of H2PtCl66H2O is 0.01% to 0.02% of reactant in weight, the molar ratio of C=C /Si-H in AGE (allyl glycidyl ether) and the terminal of hydrogen silicone oil is 4.28:1, the reaction temperature is 80°C to 85°C, reaction time is controlled in 6 hours.

Studies on the effect of concentration of formaldehyde on the synthesis of resole-type epoxidized phenolic resin from renewable resource material

Epoxidized cardanol/formaldehyde resins (ERCF) were synthesized by reacting resole type cardanol/formaldehyde resin and epichlorohydrin in basic medium at 120 °C. Resole-type phenolic resins were synthesized by reacting cardanol and formaldehyde (molar ratios 1:1.3, 1:1.5, 1:1.7, 1:1.9,and 1:2.1) in the presence of sodium hydroxide, as catalyst, at five different temperatures ranging between 60 and 80 °C with an interval of 5°C for a maximum period of 6 h. A set of samples were characterized by Fourier transform infrared and nuclear magnetic resonance spectroscopic analysis. The molecular size distribution of resole phenolics was studied by high-resolution gel permeation chromatography. Differential scanning calorimetry technique was used to investigate the curing behavior of the synthesized epoxy resins. Single-step mass loss in dynamic thermo gravimetric traces for the ERCF was observed.

Epoxy Resin and Polyurethane Compositions from Glycolized Poly (ethylene terephthalate) Wastes

The possibility to use poly(ethylene terephthalate) (PET) bottles production waste as raw material for compositions with high adhesion ability has been investigated. PET waste was glycolyzed with polypropylene glycol and three kinds of oligoesters were formed after depolymerization reaction. The polydispersity of product formed was 1.05. The possibilities to use PET glycolysis products – oligoesters for epoxy resin and polyurethanes were studied. Two-step reaction of oligoesters with epichlorohydrin was chosen for epoxy resin synthesis, while glycolyzed PET reaction with aliphatic isocyanate was used for polyurethane synthesis. The structure and properties of the obtained polymers were investigated. DOI: http://dx.doi.org/10.5755/j01.ms.19.3.5237

Ultrasonic-assisted synthesis of nano-BaSO4 and its effect on thermal and cross-linking density of epoxy nanocomposites

Thermal and morphological behavior of epoxy nanocomposite system was investigated under the influence of barium sulfate nanoparticles. Initially, epoxy resin and nano-BaSO4 were synthesized under controlled ultrasound cavitation technique. At the time of epoxy resin synthesis, nano-BaSO4 (2–10 mass% loading) was added under controlled ultrasound. The intense collapse effect was arising due to cavitation, which enhances the polymerization process with uniform mixing of nano-BaSO4. The effect of nano-BaSO4 on thermal and functional group linkage was studied using differential scanning calorimetry, thermogravimetric analysis, and Fourier transform infrared spectroscopy, respectively. Addition of nBaSO4 accelerates the rate of epoxy resin curing during composite formation with uniform dispersion of nano-BaSO4 under controlled ultrasonic waves (50 kHz), which shows remarkable change in cross-linking density. The thermal stability of epoxy resin nanocomposite was found to be improved as compared to neat epoxy resin. The increasing amount of loading of nano-BaSO4 shows enhancement in thermal properties of epoxy nanocomposite. It was demonstrated that ultrasonic synthesis is a unique and ultimate way for preparation of epoxy resin with nanoaddition. Due to controlled ultrasonic waves, formation of long-term stable polymerization occurs, which consists of polymer/inorganic nanoparticles composite.

Synthesis of Epoxy Resin Based on Biphenyl Structure for Application in Carbon Fiber-Reinforced Composites

A series of epoxy resins based on biphenyl structure were prepared to produce heat-resistant carbon fiber-reinforced composites. The molecular weight of the epoxy resin was characterized by gel permeation chromatograph (GPC). The thermal properties of the cured polymers were evaluated with dynamic thermal mechanical analysis (DTMA) and thermo gravimetric analysis (TGA). Results showed that the cured polymer exhibited a higher glass transition temperature (Tg) of 192.9°C and a better thermal stability by introducing biphenyl structure. Moreover, the carbon fiber-reinforced composites containing biphenyl structure showed high tensile and shear properties at 120°C. Such properties make the resin highly promising for heat-resistant aluminum conductor composite core (ACCC) applications.

Novel high performance tough hyperbranched epoxy by an A2+ B3polycondensation reaction

High performance tough epoxy thermoset with excellent adhesive strength is one of the most in demand materials for advanced engineering applications. In the present investigation three hyperbranched epoxy resins with varying compositions were synthesized by a single step controlled polycondensation reaction using an A2 + B3 approach for the first time. The physical properties like epoxy equivalent, hydroxyl value, viscosity, etc. of the synthesized epoxy resins were determined by different analytical techniques. The hyperbranched structure of the resins was characterized by spectroscopic techniques. The degrees of branching were found to be 0.60, 0.79 and 0.51 for the resins with 10, 20 and 30 wt% of the B3 moiety respectively, as obtained from the 13C NMR study. The poly(amidoamine) cured hyperbranched epoxy thermosets exhibited high thermostability (up to 293, 298 and 296 °C), tensile strength (38, 47 and 26 MPa), elongation at break (43, 21 and 52%), strain energy or toughness (1277, 758 and 1056 MPa), exceptionally high adhesive strength (1987, 2662, 1638 MPa), impact resistance (>100 cm) and scratch hardness (8.5, 9.0, 8.0 kg). The results showed the prominent role of the amount of the B3 moiety in the performance of the thermosets. The study, therefore, revealed that the unison of the aliphatic–aromatic moiety in the hyperbranched structure can offer a high performance tough epoxy thermoset without any processing difficulty.