Formaldehyde Epoxy Research Articles

Experimental and Theoretical Study of Gamma Radiolysis and Dose Rate Effect of o-Cresol Formaldehyde Epoxy Composites.

Gamma radiolysis behaviors and mechanisms of silica-filled o-cresol formaldehyde epoxy are studied at 2.20 × 10-5 to 1.95 × 10-1 Gy/s. The radiolysis-induced changes in chemical structures do not severely affect its thermostability. The slightly deteriorated mechanical strength at temperature exceeding 100 °C is accompanied by the declining glass transition temperature (from 185.9 to 172.2 °C) and enhanced damping ability. The gas yields of hydrogen, methane, and carbon dioxide manifest a remarkable dose rate effect. Based on the Schwarzschild law, their yields at an extremely low dose rate are accurately predicted by the established master curves. Besides, the latent radiolysis of gas products and postradiation effect are found with caution. The radiation-caused residual spin species are proved to be composed of silica defects and a phenoxy-type free radical with a tert-butyl group, according to the experimental results, theoretical calculations, and spectra simulations. The lower vertical ionization potential (7.6 eV) and adiabatic ionization potential (7.1 eV) are primarily due to the ionization of the benzene ring moiety with the tert-butyl group, which is likely to suffer from radiolysis. The calculated bond dissociation energy (260.8-563.5 kJ/mol) of the typical chemical bonds of epoxy is consistent with its radiolytic vulnerability and degradation mechanisms.

Fabrication of urea formaldehyde–epoxy resin microcapsules for the preparation of high self‐healing ability containing SBS modified asphalt

AbstractAsphalt exhibits self‐healing ability, though at a lower rate. In this study, urea formaldehyde–epoxy resin (UFE) microcapsules were prepared using polyurea formaldehyde as the wall and epoxy resin as the core material, which were in turn applied to fabricate UFE–styrene butadiene styrene modified asphalt (abbreviated as UBS asphalt). Scanning electron microscopy and transmission electron microscopy analyses revealed well‐coated microcapsules have globular geometry with obvious folds in the wall. Ductility test showed 90% higher healing rate of UBS asphalt than pure styrene butadiene styrene (SBS) modified asphalt. Dynamic shear rheometer and multi‐stress creep recovery tests indicated that UFE microcapsule incorporation can improve the viscoelasticity, high temperature stability, and permanent deformation resistance of pure SBS modified asphalt attributed to the even distribution of UFE microcapsules in asphalt and their better mutual compatibility, which was confirmed by fluorescence microscopy. At 100 and 3200 Pa, the recovery rate of 0.4% UBS asphalt was 32.1% and 71.7% higher than that of the original SBS modified asphalt, respectively. UFE microcapsule and asphalt only physically interacted as confirmed by Fourier infrared spectroscopy analysis. This study provides a feasible alternative approach for the preparation of UBS asphalt with enhanced mechanical properties and thermal stability for applications in construction and highway industries.

Fabrication and curing properties of o-cresol formaldehyde epoxy resin with reversible cross-links by dynamic boronic ester bonds

Conventional cured o-Cresol Formaldehyde Epoxy Resin (o-CFER) with permanent crosslink network is relatively stiff, brittle, and unrecyclable. In order to overcome these defects, herein 2,2′-(1,4-phenylene)-bis [4-mercaptan-1,3,2- dioxaborolane] (BDB) is employed as curing agent and a novel type of covalent adaptable network o-CFER is constructed by the reaction between thiols in BDB and epoxy groups in o-CFER. Obtained curing o-CFER vitrimers possess superior thermostability and good mechanical properties. Because of the transesterification of boronic ester bonds, o-CFER network topologies can be altered, contributing a self-healing ability and shape memory to the produced polymer. Besides, it is investigated the effects of the healing time and temperature on self-healing capability and achieved a healing efficiency of above 95% at 160 °C for 12 h. Moreover, through hot press, the pulverized samples of 8%C-o-CFER can be reshaped several times and mechanical properties of the recycled samples are well-restored even higher than those of pristine after being remolded at 200 °C for 60 min.

On the Origin of Changes in the Adhesive Interaction between Veneer and Glue under Glue Polarization in Plywood Manufacture

The possibilities of using an electrostatic field in the technology for manufacturing plywood by the example of birch veneer with the use of carbamide–formaldehyde epoxy or polyvinyl acetate glues have been considered. It has been shown that preliminary treatment of the glue in an electric field results in a decrease of the glue viscosity and leads to an increase in the plywood strength under chipping, whereas the polarization of plywood samples in the course of the gluing procedure causes the ultimate strength under chipping to increase. The results can be explained as being due to the orientation of the glue macromolecules owing to an electric field, which leads to hardening of the material. This effect may be caused by a double electric layer occurring at the veneer–glue interface, increasing the adhesion of the glue to the veneer, by lowering glue viscosity and improving veneer surface wettability, as well as by an increase in the free surface energy of glues in the course of polarization thereof.

Preparation of water-based epoxy resin and its application as an automotive air filter paper binder

Water-based epoxy resin emulsion was prepared by emulsifying o-cresol formaldehyde epoxy resin with self-emulsified epoxy curing agent synthesized in this study and then used as an environmentally friendly binder for automotive air filter paper. The preparation process of the self-emulsified epoxy curing agent was confirmed by Fourier transform infrared spectroscopy (FTIR). The effects of neutralization degree (Neu) and amount of curing agent on the formation of epoxy resin emulsion were studied. The micro-morphology and size distribution of the epoxy resin latex were characterized by transmission electron microscopy (TEM) and dynamic and static light scattering, respectively. The micro-structure of the air filter paper surface was studied by scanning electron microscope (SEM). The mechanical strength and moisture-resistance properties of air filter strengthened by the prepared water-based epoxy resin emulsion was tested and compared to three commercial binders. The prepared epoxy resin emulsion greatly enhanced the mechanical properties and moisture-resistance properties of the air filter paper while maintaining its filtration properties. Therefore, the epoxy resin emulsion can be used as an environmentally friendly water-based binder for automotive air filter paper with excellent comprehensive properties.

Studying the corrosion mitigation behavior and chemical durability of FeTiO3/melamine formaldehyde epoxy composite coating for steel internal lining applications

Currently, construction of composite coating is considered a vital pattern for corrosion protection of steel petroleum internal lining applications. For supporting this concept, the potential of incorporating various loading levels of fabricated FeTiO3 (ilmenite)/melamine formaldehyde composite (IMFC) particles on the corrosion mitigation behavior and chemical resistance of the epoxy coating was investigated. Micro-sized FeTiO3 natural pigment particles were obtained by a direct solid-phase milling process as a bi-functional modifier. Characterizations for the micro-sized FeTiO3 grains were clarified using scanning electron microscope (SEM), x-ray diffraction (XRD) and dynamic light scattering (DLS) methods. The electrochemical behavior of epoxy coated films against blank carbon steel surface in high salinity formation water has been examined by using both potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques. Cure durability and water resistance tests were performed according to standard protocols to confirm the chemical resistance property of the modified coating. Scanning electron microscope (SEM) and energy dispersive analysis of X-rays (EDX) analysis were performed to investigate the corrosion protection performance of the surface modified IMFC epoxy coated film compared to the unmodified conventional coating on the C-steel substrate in high salinity formation water solution. The results of this study boosted the prominent corrosion mitigation behavior of the considered modified epoxy composite coating.

Influence of surface modified ilmenite/melamine formaldehyde composite on the anti-corrosion and mechanical properties of conventional polyamine cured epoxy for internal coating of gas and oil transmission pipelines

Abstract To support the corrosion protection behavior and mechanical performance properties of conventional epoxy utilized for internal coating of gas and oil transmission pipelines, the present approach was performed to prepare different high build epoxy coating formulations modified using various amounts of processed ilmenite/melamine formaldehyde composite (IMFC) cured by poly amine hardener. X-ray diffraction (XRD) analysis was implemented to assure the phase identification of the crystalline ilmenite particles. Dynamic light scattering measurements were accomplished to measure the particle size distribution of micro-sized ilmenite particles. The lamellar shape of the prepared ilmenite pigment particles (FeTiO 3 ) was illustrated by transmission electron microscope (TEM) investigation. Flaky-like nature and the arrangement in overlapping plates of ilmenite particles were confirmed by scanning electron microscope (SEM) technique. Energy dispersive analysis of X-rays (EDX) was performed to ensure the elemental composition of ilmenite pigment particles. FTIR characteristic spectra for melamine formaldehyde resin, ilmenite/melamine formaldehyde composite (IMFC), conventional polyamine cured epoxy and polyamine cured ilmenite/melamine formaldehyde epoxy composite were done. The anti-corrosion performance properties of the considered IMFC epoxy coating formulations against unmodified blank conventional epoxy were studied by accelerated corrosion experiment (salt spray chamber) after 500 h exposure in 5% NaCl solution. The obtained results revealed a significant improvement in the rust grade, blistering size, color tolerance and adhesion strength of IMFC modified epoxy coated steel films with increasing the loading level (%) by weight of the nanocomposite modifier in the coating film. To confirm the previous concept, mass loss method was performed. The mechanical performance properties of these films were investigated by adhesion pull-off, bend, impact and abrasion coating tests to confirm their application efficiency. From the recorded results, the adhesion properties, elongation character, resistance to rapid deformation and film stiffness of these coatings increased significantly with increasing the amount of IMFC modifier.

Preparation, curing, and properties of boron-containing bisphenol-S formaldehyde resin/o-cresol formaldehyde epoxy resin/nano-SiO2 composites

Boron-containing bisphenol-S formaldehyde resin (BBPSFR) with different amounts of nano-SiO2 by in situ formation was used to cure o-cresol formaldehyde epoxy resin (o-CFER). The curing kinetics, dynamic mechanical properties, and thermal stability of BBPSFR/o-CFER/nano-SiO2 composites (BCS) were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetry (TG), and thermogravimetrymass spectrometry (TGMS). Morphology of nano-SiO2-containing BBPSFR and glass fiber laminates of the BCS were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The mechanical properties and electrical properties were also determined. The results showed that nano-SiO2 accelerated the curing process and decreased the curing temperature; the non-isothermal curing kinetics of the BCS can be described by the two-parameter (m, n) Sestak-Berggren kinetic model, and the average value of m was 0.32 and n was 1.00. The thermal stability was enhanced by the addition of nano-SiO2, especially at higher temperatures, and the residual weight increased with increasing nano-SiO2 content. Incorporation of 6 wt% of nano-SiO2 increased the impact strength from 105 to 149 kJ/m2 and storage modulus at ambient from 6.85 to 12.7 GPa, and the TEM photograph of which showed that nano-SiO2 particles (about 50 nm) were dispersed in the matrix more uniformly. The volume resistance, R v, and dielectric constant, e, slightly increased when the nano-SiO2 content was 3 wt%.

Mechanical and thermal properties of cationic ring-opening o-cresol formaldehyde epoxy/polyurethane acrylate composites enhanced by reducing graphene oxide

Polyurethane acrylate (PUA) and o-cresol formaldehyde epoxy resin (o-CFER) is synthesized. The PUA/o-CFER glass fiber-reinforced composites cured by free radical/cationic ring-opening reaction are modified by the reducing graphene oxide (r-GO). Effect of r-GO on the thermal and mechanical properties of PUA/o-CFER glass fiber-reinforced composites are characterized by FTIR, DMA and TGA. The result of FTIR shows that the system has cured completely. DMA analysis indicates that this system has better compatibility, and the glass transition temperature (T g) decreases with increasing r-GO content. TGA analysis shows that the initial thermal degradation temperature (T id) and activation energy (E a) enhance 13.1 °C and 3.12 kJ/mol, respectively. The tensile and impact strength of glass fiber-reinforced composites are approximately 50 and 60 % higher than those without r-GO. It is shown that the r-GO can enhance the mechanical properties and thermal stability of composites.

Preparation of phosphorous- and nitrogen-containing epoxy emulsion and its flame retardancy

In this study, phosphorous-containing epoxy resin was first prepared by modifying o-cresol formaldehyde epoxy resin with 9,10-dihydro-9-xa-10-phosphaphenanthrene-10-oxide. Self-emulsified nitrogen-containing epoxy curing agent was prepared by the reaction of bisphenol A epoxy resin E-44, triethylene tetramine and acrylonitrile. Phosphorous- and nitrogen-containing epoxy emulsion was obtained by emulsifying the phosphorous-containing epoxy resin with the self-emulsified epoxy curing agent. Effects of parameters to the formation of epoxy emulsion were studied. The microstructure and size distribution of the epoxy latex were characterized by transmitting electron microscopy and Malvern particle sizer, respectively. The flame retardancy of the phosphorous- and nitrogen-containing epoxy thermoset was tested by limiting oxygen index, UL-94 test method and thermal gravimetric analysis. Scanning electron microscopy was used to observe the micro-morphology of char residue of epoxy thermoset. The result shows that the prepared phosphorous- and nitrogen-containing epoxy emulsion presents excellent stability and the epoxy thermoset has excellent flame retardancy.

Effects of carbon nanotubes on curing and properties of boron-containing bisphenol-S formaldehyde resin/o-cresol epoxy resin composites

Boron-containing bisphenol-S formaldehyde resin (BBPSFR) with different amounts of carbon nanotubes (CNTs) was used to cure o-cresol formaldehyde epoxy resin (o-CFER). The curing kinetics, dynamic mechanical properties, and thermal stability of BBPSFR/o-CFER/CNTs (BCC) composites were investigated by DSC, DMA, and TGA. The morphology of BCC composites was characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The mechanical properties and electric properties were also determined. The results showed that the glass transition temperature Tg, initial decomposition temperature Tid all increased with increasing CNTs content. The Tg and Td5 is about 20°C and 30°C higher than that of pure BBPSFR/o-CFER (BC), when content of CNTs is 1.5 wt%. The curing reaction active energy Ea can be calculated by Kissinger’s method. When the conversions α is between 0.15 and 0.95, Ea has a slight increase for the BBPSFR/o-CFER (BC) composite, but it exhibits slight decrease for the BCC composites. The non-isothermal curing kinetics of the BCC can be described by the two-parameter (m, n) Sestak-Berggren kinetic model. The BCC has the highest tensile and impact strength when contains of CNTs is 1.0 wt%, which is 34 MPa and 13 kJ/m2 higher than that of pure BC laminate, respectively. The electric properties of BCC laminates were improved by the addition of 1.0 wt% CNTs.

Preparation of phosphorus-containing epoxy emulsion and flame retardancy of its thermoset

In this study, the effects of the opening ratio and neutralization degree of diethanolamine to the formation of epoxy emulsion were examined. o-Cresol formaldehyde epoxy resin was modified with 9,10-dihydro-9-xa-10-phosphaphenanthrene-10-oxide and diethanolamine and was then neutralized by acetic acid to obtain a phosphorus-containing epoxy emulsion by the phase inversion method. The microstructure and size distribution of the epoxy latex were characterized using transmission electron microscopy and the Malvern particle sizer, respectively. The glass transition temperatures of epoxy resins and their thermosets were characterized using differential scanning calorimetry. The flame retardancy of the phosphorus-containing epoxy thermosets was tested by the UL-94 test method, limiting oxygen index (LOI), and thermogravimetric analysis (TGA). The result shows that when the diethanolamine opening ratio was 22.5% and neutralization degree was 100.0%, a stable epoxy emulsion was obtained. When the phosphorus content of the epoxy resin was 2.5 wt%, the LOI value of the epoxy thermoset can reach 36.8 and pass the V-0 rating of the UL-94 test. TGA and scanning electron microscopy images of char residue of epoxy thermosets show that the flame-retardant mechanism of the phosphorus-containing epoxy thermoset was mainly attributed to a condensed-phase mechanism.

Synthesis and Properties of Flame-Retardant Waterborne Emulsion Derived from O-Cresol Formaldehyde Epoxy Resin

By modifying O-cresol Formaldehyde epoxy resin with DOPO and Diethanolamine, and then neutralized by acetic acid, phosphorous-containing epoxy emulsion with excellent flame retardancy can be obtained under strong agitation. Diethanolamine opening rate and neutralized degree to the formation of epoxy emulsion were optimized. The flame-retardant property of the cured phosphorous-containing epoxy resin was test by UL-94, LOI and TGA method. The result shows that when the opening rate of Diethanolamine is 25.0% and the neutralized degree is 95.0%, stable epoxy emulsion can be obtained. When phosphorus content of the epoxy resin was 3.0wt%, the LOI value of the resin can be reach to 39.2 and pass the UL-94 test，the 700°C char remaining is 30.0wt%. The result shows that the flame retardant mechanism of the phosphorous-containing epoxy resin is mainly through a condensed- phase mechanism.

Novel macromolecular epoxy resin curing agent containing biphenyl and maleimide moieties: Preparation, curing kinetics, and thermal properties of its cured polymer

A new curing agent containing maleimide and biphenyl moieties (MIBP) was synthesized by the condensation polymerization of 4,4′-bismethoxymethylbiphenyl and N-(4-hydroxyphenyl)maleimide (HPM). The chemical structure was characterized with Fourier transform infrared (FTIR) spectroscopy, and the molecular weight of the new curing agent was determined by gel permeation chromatography. Curing reactions of O-cresol formaldehyde epoxy (CNE) resin with MIBP were investigated under nonisothermal differential scanning calorimetry, and the exotherm exhibited two overlapping exothermic peaks during the curing process; this was demonstrated by FTIR traces. The Flynn–Wall–Ozawa and Friedman methods were used to examine the kinetic parameters and the kinetic models of the curing processes of the CNE/MIBP mixtures. Both reactions turned out to be nth-order curing mechanisms. Values of the reaction order (n) = 1.42 and activation energy (Ea) = 91.2 kJ/mol were obtained for the first reaction of the curing of the CNE/MIBP system, and values of n = 1.11 and Ea = 78.7 kJ/mol were obtained for the second reaction. The thermal properties of the cured resin were measured with thermogravimetric analysis, and the results show a high glass-transition temperature (Tg = 155°C), good thermal stability (temperature at 10% weight loss, under nitrogen and in air, ≈ 400 and 408°C, respectively), and high char yield (temperature = 800°C, char residue = 44.5% under nitrogen). These excellent thermal properties were due to the introduction of the maleimide and biphenyl groups of MIBP into the polymer structure. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Curing kinetics, thermal, mechanical, and dielectric properties based on o‐cresol formaldehyde epoxy resin with polyhedral oligomeric (N‐aminoethyl‐γ‐amino propyl)silsesquioxane

The curing reaction and kinetics of o‐cresol formaldehyde epoxy resin (o‐CFER) with polyhedral oligomeric silsesquioxane of N‐aminoethyl‐γ‐amino propyl group (AEAP‐POSS) were investigated by differential scanning calorimetry (DSC). The thermal, mechanical, and dielectric properties of o‐CFER/AEAP‐POSS nanocomposites were investigated with thermogravimetric analysis (TGA), torsional braid analysis (TBA), tensile tester, impact tester, and electric analyzer, respectively. The results show that the activation energy (E) of curing reaction is 58.08 kJ/mol, and the curing reaction well followed the Šesták‐Berggren (S‐B) autocatalytic model. The glass transition temperature (Tg) increases with the increase in AEAP‐POSS content, and reaches the maximum, 107°C, when the molar ratio (Ns) of amino group to epoxy group is 0.5. The nanocomposites containing a higher percentage of AEAP‐POSS exhibited a higher thermostability. The AEAP‐POSS can effectively increase the mechanical properties of epoxy resin, and the tensile and impact strengths are 2.84 MPa and 143.25 kJ m−2, respectively, when Ns is 0.5. The dielectric constant (ε), dielectric loss factor (tan δ), volume resistivity (ρv), and surface resistivity (ρs) are 4.98, 3.11 × 10−4, 3.17 × 1012 Ω cm3, and 1.41 × 1012 Ω cm2, respectively, similarly at Ns 0.5. Copyright © 2009 John Wiley & Sons, Ltd.

Preparation, characterization, and polymerization of novel maleimidobenzoxazine containing carboxylic moiety and its cocuring behaviors with epoxy resin

AbstractA novel benzoxazine containing maleimide and carboxylic moieties, 1‐[3‐(4‐carboxylphenyl)‐3,4‐dihydro‐2H‐benzo[e][1,3]‐oxazin‐6‐yl]maleimide (Mal‐Bz‐Co), was synthesized and the structure was identified by 1H‐NMR and FTIR. Mal‐Bz‐Co exhibited good solubility in common organic solvents. The cure behavior of Mal‐Bz‐Co and cocure behavior of Mal‐Bz‐Co with o‐cresol formaldehyde epoxy resin were investigated by differential scanning calorimetry. Results indicated that Mal‐Bz‐Co showed a single curing exothermic peak at about 238.3°C. However, the maximum curing temperature (Tp) decreased to 146.1°C when Mal‐Bz‐Co cocured with o‐cresol formaldehyde epoxy resin in the molar ratio of 1 : 1. The Tp was about 92°C lower than that of Mal‐Bz‐Co. Thermogravimetric analysis showed that high‐decomposition temperature and char yield were observed for the cured resins of Mal‐Bz‐Co and Mal‐Bz‐Co/o‐CFER. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Curing Behavior, Kinetics and Thermal Properties of o-Cresol Formaldehyde Epoxy Resin Modified by Liquid Crystalline Epoxy Resin

The curing kinetics of a bi-component system of o-cresol-formaldehyde epoxy resin (o-CFER) modified by liquid crystalline p-phenylene di[4-(2,3-epoxypropyl) benzoate] (p-PEPB), with 4,4-diamino-diphenyl ether (DDE) as a curing agent, was investigated by nonisothermal differential scanning calorimetry (DSC) method. The relationship between apparent activation energy, Ea, and the conversion α was obtained by the isoconversional method of Ozawa. A molecular reaction mechanism is proposed. The results show that the values of Ea in the initial stage are higher and tend to decrease slightly with the reaction progress. The primary amines have a higher Ea than secondary amines. The average curing Ea of o-CFER/p-PEPB/DDE system is 61.64 KJ/mol. These curing reactions can be described by a model proposed by Šesták and Berggren, which includes two parameters of m and n. Parameters such as reaction orders were evaluated using the Šesták-Berggren (S-B) equation and the following kinetic equation: dα/dt = Aexp(−Ea/RT)α m (1 − a) n . The curing behavior of the system was studied by polarized optical microscopy (POM) and torsional braid analysis (TBA). The compatibility of the p-PEPB and o-CFER system is very good. Temperature of mechanical loss peak is higher by 63°C than the common o-CFER epoxy resin, when the weight ratio of p-PEPB with o-CFER is 4:100.

Curing Kinetics of o-Cresol Formaldehyde Epoxy Resin and Succinic Anhydride System Catalyzed by Tertiary Amine

The kinetics of the cure reaction for system of o-cresol formaldehyde epoxy resin (o-CFER)/succinic anhydride (SA) and tertiary amine as a catalyst was investigated with a differential scanning calorimeter (DSC). Autocatalytic behavior was shown in the first stages of the cure for the system, which was well described by the model proposed by Kamal that includes two rate constants, k1 and k2, and two reaction orders, m and n. The overall reaction order, m + n, is in the range 2.1-2.6, and the activation energy for k1 and k2 was 109 and 72.0 kJ/mol, respectively. In the later stages, a cross-linked network was formed and the cure reaction is mainly controlled by diffusion. Diffusion factor, f(alpha), was introduced into Kamal's equation, then the calculated values agree very well with the experimental data. The molecular mechanism of this curing reaction was discussed.

Blends of thermotropic liquid crystalline polymer and O‐cresol formaldehyde epoxy resin. II. Curing kinetics

AbstractCuring kinetics of O‐cresol formaldehyde epoxy resin and its blends with a liquid crystalline block copolymer (PDBH) cured with linear phenol–formaldehyde resin were studied by the nonisothermal differential scanning calorimetry (DSC) and isothermal DSC methods. The parameters of nonisothemal curing kinetics were obtained according to the Kissinger method, and those of isothermal curing kinetics were deduced on the basis of the n‐order mechanism proposed by Kamal. The curing reaction is considered 1‐order reaction as shown by the nonisothermal and isothermal results. The model gave a good description of curing kinetics up to the onset of vitrification. A diffusion factor has been introduced in the latter stage of reaction to describe the degree of conversion over the whole range. The obtained n‐order model modified by diffusion‐controlled factor is consistent with the experimental data almost over the whole range of conversion. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1269–1276, 2006

Modification of an o‐cresol formaldehyde epoxy resin by the thermotropic liquid crystalline polymer

AbstractTwo novel liquid crystalline polymers, polydiethyleneglycol bis(4‐hydroxybenzoate) terephthaloyl and block copolymer (PDBH), were synthesized by condensation reaction. The blends of the two liquid crystalline polymers and o‐cresol formaldehyde epoxy resin were prepared by linear phenol‐formaldehyde resin as curing reagent. Both mechanical and thermal properties of the blends containing liquid crystalline polymer were improved to a certain extent. By adding 5 wt % PDBH, the impact strength, bending strength, and the glass transition temperature were enhanced by 128%, 23.84%, and 28°C, respectively, compared with the unmodified version. The results of curing kinetics showed that the curing reaction active energy of the modified system by PDBH decreased from 79.70 to 70.26 kJ/mol. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1626–1631, 2005