Synthesis,spectral, and thermal characterization of photoreactive epoxy resin containing cycloalkanone moiety in the main chain

Dual functional epoxy resins were synthesized by solution polycondensation of 2,6‐bis(4‐hydroxy‐3‐methoxy benzylidene)cyclohexanone and 2,5‐bis(4‐hydroxy‐3‐methoxy benzylidene)cyclopentanone with epichlorohydrin. The synthesized epoxy resins were characterized systematically for their structure by UV, Fourier transform infrared (FTIR), ¹H NMR, and ¹³C NMR spectroscopic techniques. Thermal characterization of synthesized epoxy resins was carried out by thermogravimetric analysis, and differential scanning calorimetry (DSC) under nitrogen atmosphere. The self extinguishing property of synthesized oligomers was studied by determining limiting oxygen index (LOI) values using Van Krevelen's equation. X‐ray analysis showed that the epoxy resins containing cyclopentanone have higher degree of crystallinity. The photoreactive property of the synthesized epoxy resins in solution and film states was investigated by UV–Vis spectroscopy. The photocross‐linking proceeds through the dimerization of olefinic chromophore present in the main chain of the oligomer via 2π + 2π cycloaddition reaction. The influence of photoacid generator on the rate of photocross‐linking of epoxy resin was studied by FTIR. UV irradiation of the epoxy resin in presence of photoacid generator produces aromatic sulfonium cation radicals and aromatic radicals which initiate the cationic ring‐opening polymerization of oxirane ring. The photoreactivity studies of the oligomers by FTIR and DSC indicated the presence of dual functionality in the synthesized epoxy resins. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis,characterization, and properties of silicone–epoxy resins

Silicone–epoxy (SiE) resins were synthesized through the hydrolytic condensation of 2‐(3,4‐epoxycyclohexylethyl) methyldiethoxysilane (EMDS) and the cohydrolytic condensation of EMDS with dimethyldiethoxysilane. Structural characterization was carried out by ¹H‐NMR, ²⁹Si‐NMR, and mass spectrometry analysis; the resins were linear oligomers bearing different numbers of pendant epoxy groups, and the average number of repeat Si O units ranged from 6 to 11. Methyhexahydrophthalic anhydride was used to cure the SiE resins to give glassy materials with high optical clarity. The cured SiE resins showed better thermal stability and higher thermal and UV resistances than a commercial light‐emitting diode package material (an epoxy resin named CEL‐2021P). The effect of the epoxy value on the thermal and mechanical properties and the thermal and UV aging performances of the cured SiE resins were investigated. The SiE resins became more flexible with decreasing epoxy value, and the resin with the moderate epoxy value had the highest thermal and UV resistances. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Dendritic carbosilane‐based macrophotoinitiator: synthesis,characterization, and photoinitiating behavior

A novel radical dendritic macrophotoinitiator, bearing alkyl pheone moieties linked to the surface of the dendrimer, was synthesized via alcoholysis of carbosilane dendrimer and the small‐molecule photoinitiator 2‐hydroxy‐2‐methyl‐1‐(4‐tert‐butyl)phenylpropane‐1‐one. The structure of the dendritic carbosilane‐based macrophotoinitiator (MPI) was characterized using Fourier transform infrared spectroscopy, ¹H NMR, ¹³C NMR, ²⁹Si NMR, elemental analysis, size exclusion chromatography/multi‐angle laser light scattering, UV‐visible spectroscopy, and differential photocalorimetry (DPC). UV‐visible analysis indicates that the absorption band of photosensitive moieties shifts towards high wavelength by introducing the carbosilane dendrimer core. The DPC results demonstrate that the initiating efficiency of MPI is effective when using epoxy acrylate (EA) as a model resin. Furthermore, thermogravimetric analysis of cured EA resin indicates that the thermal stability can be improved markedly by the incorporation of MPI in the curing formulation. Copyright © 2007 Society of Chemical Industry     

Nanocomposite coatings via simultaneous organic–inorganic photo‐induced polymerization: synthesis,structural investigation and mechanical characterization

Hybrid sol–gel films were prepared via a simultaneous organic‐inorganic UV‐curing process using a diaryliodonium salt as a superacid photogenerator. In this single‐step procedure, an epoxy functionalized reactive resin mixed with a variable amount of either of two epoxy trialkoxysilane precursors was UV‐irradiated, causing both the initiation of epoxy ring‐opening copolymerization and the catalysis of trialkoxysilyl sol–gel reactions. The concomitant photo‐induced sol–gel process was found to have a significant effect on the two related propagation mechanisms in competition for the oxirane ring‐opening—the active chain‐end and the activated monomer mechanisms—as proved by a systematic examination of the hybrid material microstructure through ²⁹Si and ¹³C solid‐state NMR spectroscopy. The effect of the oxo‐silica network generation on the epoxy reaction kinetics was also evaluated using real‐time Fourier transform infrared spectroscopy upon varying the epoxysilane structure and its concentration. Thermal and dynamic mechanical analyses were systematically performed on these hybrids, by studying thoroughly their structure–property interdependence. Other mechanical characterizations through tribological and scratch tests suggested that the present photopolymer–silica hybrid material provides a powerful tool to tailor mechanical property profiles. Copyright © 2010 Society of Chemical Industry     

Synthesis,characterization, and mechanical properties of a novel terphenyl liquid crystalline epoxy resin

A novel terphenyl liquid crystalline (LC) epoxy resin was synthesized and characterized by ¹H‐NMR, Fourier transform infrared spectroscopy, differential scanning calorimetry (DSC), and polarizing optical microscopy. Depending on the curing temperature, the synthesized resin formed both smectic and nematic LC phases. A time‐temperature‐transformation diagram was constructed to optimize the curing process, which helped in the preparation of LC and isotropic system. The terphenyl epoxy resin obtained exhibited higher acid resistance than a comparable Schiff‐base epoxy resin, and also displayed excellent fracture toughness. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41296.     

Ultraviolet‐curing behavior of an epoxy acrylate resin system

Ultraviolet (UV)‐curing behavior of an epoxy acrylate resin system comprising an epoxy acrylate oligomer, a reactive diluent, and a photoinitiator was investigated by Fourier transform infrared (FTIR) spectroscopy. The conversion changes of the resin system containing 20 phr of 1,6‐hexanediol diacrylate as a reactive diluent and 2‐hydroxy‐2‐methyl‐1‐phenyl‐propan‐1‐one as a photoinitiator were measured under different UV‐curing conditions. The fractional conversion was calculated from the area of the absorption peak for the vinyl group vibration occurring at 810 cm^?1. The effects of photoinitiator concentration, total UV dosage, one‐step or stepwise UV irradiation, UV intensity, atmosphere, and temperature on the curing behavior of the resin system were investigated. The conversion of the resin system increased rapidly at the initial stage of the UV‐curing process but increased very slowly after that. The final conversion of the resin system was mainly affected by total UV dosage. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1180–1185, 2005     

Anticorrosive properties of epoxy resin coatings cured by aniline/p‐phenylenediamine copolymer

Aniline/p‐phenylenediamine copolymer [poly(ANI‐co‐p‐PDA)] was prepared by chemical oxidative polymerization. FTIR and ¹H‐NMR analysis indicate that the poly(ANI‐co‐p‐PDA) is oligomer with end‐capped amino groups, which can cure epoxy resin. The anticorrosion performance of carbon steel (CS) samples coated by epoxy resin coating cured with poly(ANI‐co‐p‐PDA) and epoxy resin coating cured with triethylenetetramine exposed to 5 wt % NaCl and 0.1 mol/L HCl aqueous solution is studied by the potentiodynamic polarization and electrochemical impedance spectroscopy. The results show that the CS coated by epoxy resin coating cured with poly (ANI‐co‐p‐PDA) has more excellent corrosion protection than that of epoxy resin coating cured with triethylenetetramine. Raman spectroscopy analysis indicates that the surface of CS coated by epoxy resin coating cured with poly(ANI‐co‐p‐PDA) forms passive layer, which is composed of α‐Fe₂O₃. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

In situ growth of multilayered crystals in amorphous matrix: Thermal,dynamic mechanical,and morphological analysis of nylon‐6/epoxy composites

A new procedure for processing of epoxy/polyamide blend was explored via solution polymerization of ε‐caprolactam in N‐methylpyrollidone (NMP), which resulted in a suspension of nylon‐6 in solvent at room temperature. The suspension was blended with water based epoxy resin using mechanical stirring at room temperature. Several films were prepared from blend by varying the amount of nylon‐6 without curing agent. All films were fully characterized for thermal and dynamic mechanical properties using differential scanning calorimetry and dynamic mechanical analysis. The addition of nylon‐6 had a plasticizing effect on epoxy evident by decrease in glass transition temperature (T_g). The reaction between nylon‐6 and epoxy was studied using Fourier transform infrared spectroscopy by following the characteristic epoxy peak (914 cm^?1). The growth of nylon‐6 crystals in epoxy matrix lead to spherulitic multiphase morphology, which was observed under scanning electron microscope. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3319–3327, 2013     

Synthesis of reactive soybean oils for use as a biobased thermoset resins in structural natural fiber composites

Biobased thermosets resins were synthesized by functionalizing the triglycerides of epoxidized soybean oil with methacrylic acid, acetyl anhydride, and methacrylic anhydride. The obtained resins were characterized with FTIR, ¹H‐NMR, and ¹³C‐NMR spectroscopy to confirm the functionalization reactions and the extent of epoxy conversion. The viscosities of the methacrylated soybean oil resins were also measured for the purpose of being used as a matrix in composite applications. The cross‐linking capability was estimated by UV and thermally initiated curing experiments, and by DSC analysis regarding the degree of crosslinking. The modifications were successful because up to 97% conversion of epoxy group were achieved leaving only 2.2% of unreacted epoxy groups, which was confirmed by ¹H‐NMR. The ¹³C‐NMR confirms the ratio of acetate to methacrylate methyl group to be 1 : 1. The viscosities of the methacrylated soybean oil (MSO) and methacrylic anhydride modified soybean oil (MMSO) were 0.2 and 0.48 Pas, respectively, which indicates that they can be used in resin transfer molding process. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of a novel quaternary ammonium tetraphenylborate salt and its use for photo‐induced thermal curing of epoxides and radical polymerization of acrylates

A novel photoinitiator, quaternary ammonium tetraphenylborate salt bearing 4‐(4^′‐benzoylphenyl)‐acetophenone (BPPAPG), has been synthesized and characterized by elemental analysis ¹H NMR and IR. The photochemistry and photophysics of BPPAPG were investigated by UV spectroscopy. The formation of 1,4‐diazabicyclo[2.2.2]octane in the photolysis of BPPAPG was ascertained by mass spectrometry. The photoinitiation reactivity of BPPAPG was studied and the results showed that it possessed two sorts of initiation properties, ie thermal curing of the epoxy resin EPON827 and free radical polymerization of acrylates such as trimethylolpropane triacrylate. Copyright © 2005 Society of Chemical Industry     

Synthesis,formulation, and characterization of siloxane‐modified epoxy‐based anticorrosive paints

Diglycidyl ether of bisphenol A epoxy (E) was modified with hydroxyl‐terminated polydimethylsiloxane through a ring‐opening addition polymerization reaction. The structural elucidation of the siloxane‐modified epoxy resin (ES) was carried out with Fourier transform infrared, ¹H‐NMR, and ¹³C‐NMR spectroscopy techniques. The physicochemical characterization of the synthesized resin (ES) was performed with standard methods. E and ES were subjected to paint formulation with the help of a rutile (TiO₂) pigment. The formulated paint systems were cured at room temperature with 1,6‐diaminohexane (AH) and 1,3‐diaminopropane (AP), which were used as curatives. The E–AH, E–AP, ES–AH, and ES–AP paint systems were applied to mild steel strips. The physicomechanical and anticorrosive performance of the coated panels was evaluated with standard methods. The thermal analysis of these E–amine and ES–amine systems was carried out via thermogravimetric analysis. The effects of siloxane incorporation and amine curatives on the coating properties of the paint systems were also investigated. The ES–AP system exhibited good thermal and corrosion stability performance among all the E and ES paint systems. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4981–4991, 2006     

Synthesis,characterization, and curing of {2,6–bis‐[2‐(bis‐oxiranylmethyl‐amino)‐methylbenzyl]‐phenyl}‐bis‐oxiranylmethylamine (BPBOMA)

The curing behavior of epoxy resin prepared by reacting epichlorohydrin with amine functional aniline acetaldehyde condensate (AFAAC) was investigated using AFAAC as a curing agent. The epoxy resin, {2,6‐bis‐[2‐(bis‐oxiranylmethyl‐amino)‐methylbenzyl]‐phenyl}‐bis‐oxiranylmethylamine (BPBOMA), was characterized by FTIR and ¹H‐NMR spectroscopy, viscosity measurement, and determination of epoxy content. Analysis of the curing reaction was followed by differential scanning calorimetry (DSC) analysis. To investigate the curing kinetic with AFAAC, dynamic DSC scans were made at heating rates of 5, 10, 15, and 20°C/min. The activation energy and frequency factor of the AFAAC formulation were evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3168–3174, 2006     

Biolignin™ based epoxy resins

Wheat straw Biolignin? was used as a substitute of bisphenol‐A in epoxy resin. Synthesis was carried out in alkaline aqueous media using polyethyleneglycol diglycidyl ether (PEGDGE) as epoxide agent. Structural study of Biolignin? and PEGDGE was performed by solid‐state ¹³C NMR and gel permeation chromatography, respectively, before epoxy resin synthesis. Biolignin? based epoxy resins were obtained with different ratios of Biolignin? : PEGDGE and their structures were analyzed by solid‐state ¹³C NMR. The crosslinking of PEGDGE with Biolignin? was highlighted in this study. Properties of Biolignin? based epoxy resins were analyzed by differential scanning calorimetry and dynamic load thermomechanical analysis as well as compared with those of a bisphenol‐A epoxy‐amine resin. Depending on the epoxy resin formulation, results confirmed the high potential of Biolignin? as a biosourced polyphenol used in epoxy resin applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Design,synthesis and characterization of a novel self‐doped polyaniline derivative

A type of self‐doped polyaniline derivative was successfully synthesized using an oxidative coupling polymerization approach. The structure of the electroactive polymer was investigated using Fourier transform infrared and ¹H NMR spectroscopy and gel permeation chromatography. Its thermal and spectral properties were characterized using thermogravimetric analysis and UV‐visible spectroscopy. The electrochemical activity of the polymer was studied using cyclic voltammetry (CV) in 1.0 mol L^?1 H₂SO₄ solution with various scan rates. The peak current increases linearly with scan rate from 10 to 120 mV s^?1, which indicates that the electrode reaction is controlled by a surface process. In addition, the self‐doped characteristic was investigated using CV in 1.0 mol L^?1 KCl solution with pH value changing from 1 to 12, and the results indicate that the polymer has excellent electrochemical activity even in neutral and alkaline environments. Copyright © 2010 Society of Chemical Industry     

Synthesis and thermal stability of a novel cycloaliphatic epoxy resin system

A novel cycloaliphatic epoxy resin was synthesized from dicyclopentadiene, ethylene glycol, and nadic anhydride. The chemical structures of the resultant epoxy resin and its precursor were characterized with Fourier transform infrared spectroscopy, ¹H‐NMR, and mass spectrographic analyses. The thermal stability of the cured polymer was investigated with differential scanning calorimetry and thermogravimetric analysis. Compared with the thermal stability of the commercial cycloaliphatic epoxy resin 3,4‐epoxy cyclohexyl methyl‐3′,4′‐epoxy cyclohexyl carboxylate, a higher thermal stability for the cured polymer of the novel epoxy resin was observed. The results imply that the novel cycloaliphatic epoxy resin has good potential applications in electronic encapsulation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Cationic electron‐beam curing of a high‐functionality epoxy: effect of post‐curing on glass transition and conversion

This paper reports on the cationic electron‐beam curing of a high‐functionality SU8 epoxy resin, which is extensively used as a UV‐curing negative photoresist for micro‐electronics machine systems (MEMS) applications. Results show that elevated post‐curing treatment significantly increased both the conversion and the glass transition. The degree of conversion and the glass transition temperature were measured by using Fourier‐transform infrared (FTIR) spectroscopy and modulated differential scanning calorimetry (MDSC^®), respectively. The glass transition temperature (T_g), which has been observed to be dependent on the degree of conversion, reaches a maximum of 162 °C at 50 Mrad and post‐curing at 90 °C. The degradation pattern of the cured resin does not show much variation for exposure at 5 Mrad, but does show significant variation for 50 Mrad exposure at various post‐curing temperatures. A degree of conversion of more than 0.8 was achieved at a dosage of 30 Mrad with post curing at 80 °C, for the epoxy resin with an average functionality of 8 a feature simply not achievable when using UV‐curing. Copyright © 2004 Society of Chemical Industry     

Synthesis and characterization of emulsion‐type curing agent of water‐borne epoxy resin

Self‐emulsified water‐borne epoxy curing agent of nonionic type was prepared using triethylene tetramine (TETA) and derivative of epoxy resin as a capping agent, which was synthesized by liquid epoxy resin (E51) and polyethylene glycol (PEG), and the curing agent possessed emulsification and curing properties at the same time. The curing agent with good property of emulsifying liquid epoxy resin could be obtained under the condition of the molar ratio of PEG : E51 : TETA as 0.8 : 1 : 3.5 at 80°C for 5 h. The mean particle size of the emulsion liquid was about 220 nm with the prepared curing agent and epoxy resin at the mass ratio of 1 : 3. The structure of the emulsion‐type curing agent was confirmed by FTIR and ¹H NMR spectra, and the mechanism of cured film formation was also analyzed by SEM photographs. The cured film prepared by the emulsion‐type curing agent and epoxy resin under ambient cure conditions showed good properties even at high staving temperature. This study provides useful suggestions for the application of the water‐borne epoxy resins in coating industry. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2652–2659, 2013     

The synthesis and properties of new epoxy resin containing phosphorus and nitrogen groups for flame retardancy

A new type of epoxy resin, which contained phosphorus oxide and nitrogen groups in the main chain, was synthesized. The structure of the new type of epoxy resin was confirmed by infrared (IR) spectroscopy, ¹H nuclear magnetic resonance (¹H‐NMR), and ¹³C‐NMR spectroscopic techniques. In addition, compositions of the new synthesized epoxy resin (TGDMO) with three curing agents, for example, bis(3‐aminophenyl) methylphosphine oxide (BAMP), 4,4′‐diaminodiphenylmethane (DDM), and 4,4′‐diaminodiphenylsulfone (DDS), were used for making a comparison of its curing reactivity, heat, and flame retardancy with that of Epon 828 and DEN 438. The reactivities were measured by differential scanning calorimetry (DSC). Through the evaluation of thermal gravimetric analysis (TGA), those polymers which were obtained through the curing reactions between the new epoxy resin and three curing agents (BAMP, DDM, and DDS) also demonstrated excellent thermal properties as well as a high char yield. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 413–421, 1999     

Solution‐state NMR analysis of hydroxymethylated resorcinol cured in the presence of crude milled‐wood lignin from Acer saccharum

Resorcinol‐formaldehyde adhesives can reinforce stress fractures that appear from wood surface preparation. Researchers have found that applying the resorcinol‐formaldehyde prepolymer, hydroxymethylated resorcinol, to the surface of wood improves the bond strength of epoxy and polyurethane adhesives to wood. Hydroxymethylated resorcinol is thought to plasticize lignin components and stabilize stress fractures through reactions with lignin subunits and hemicelluloses in wood. In this study, a dilute solution of hydroxymethylated resorcinol (HMR) is cured in the presence of a crude milled‐wood lignin (cMWL) from Acer saccharum and subsequently dissolved in dimethylsulfoxide‐d₆ to delineate reactivity with lignin and O‐acetyl‐(4‐O‐methylglucurono)xylan using solution‐state NMR spectroscopy. ¹H–¹³C single‐bond correlation NMR experiments revealed that the HMR only formed 4,4′‐diarylmethane structures with itself in the presence of the cMWL; the 2‐methylols that formed remained free and did not crosslink with resorcinol. Cured HMR resin formed both 4,4′‐ and 2,4‐diarylmethane structures, confirming that the presence of lignin and O‐acetyl‐(4‐O‐methylglucurono)xylan hinders crosslinking at the C‐2 position. No evidence of reactivity between HMR and lignin subunits was found. New peaks consistent with ester linkages were observed in ¹³C‐NMR spectra of the cMWL sample treated with HMR that may be attributable to HMR moieties condensing with glucuronic acid substituents. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45398.     

Synthesis of rosin‐based flexible anhydride‐type curing agents and properties of the cured epoxy

BACKGROUND: Although rosin acid derivatives have received attention in polymer synthesis in recent years, to the best of our knowledge, they have rarely been employed as epoxy curing agents. The objective of the study reported here was to synthesize rosin‐based flexible anhydride‐type curing agents and demonstrate that the flexibility of a cured epoxy resin can be manipulated by selection of rosin‐based anhydride‐type curing agents with appropriate molecular rigidity/flexibility. RESULTS: Maleopimarate‐terminated low molecular weight polycaprolactones (PCLs) were synthesized and studied as anhydride‐type curing agents for epoxy curing. The chemical structures of the products were confirmed using ¹H NMR spectroscopy and Fourier transform infrared spectroscopy. Mechanical and thermal properties of the cured epoxy resins were studied. The results indicate that both the epoxy/anhydride equivalent ratio and the molecular weight of PCL diol play important roles in the properties of cured resins. CONCLUSION: Rosin‐based anhydride‐terminated polyesters could be used as bio‐based epoxy curing agents. A broad spectrum of mechanical and thermal properties of the cured epoxy resins can be obtained by varying the molecular length of the polyester segment and the epoxy/curing agent ratio. Copyright © 2009 Society of Chemical Industry