Curing characteristics of o-cresol novolac epoxy resin modified by bismaleimide

Curing characteristics of o-cresol novolac epoxy resin modified by 4,4-diaminodiphenylmethane bismaleimide (DDM-BMI) using FTIR were investigated and the glass transition temperature was measured. With the addition of DDM as hardener, the relative curing reaction conversion of DDM-BMI increased with equivalent weight ratio [R₁ = (equiv wt summation of epoxy and DDM-BMI)/equiv wt of DDM] and weight ratio of epoxy and DDM-BMI (R₂ = wt of epoxy resin/wt of DDM-BMI). Using phenol novolac resin (PN) as hardener, the curing reaction conversion of DDM-BMI was hardly changed, but the variation of that in the epoxy resin was observed with R₂ change. © 1996 John Wiley & Sons, Inc.     

Curing of liquid crystalline epoxy resins with a biguanide

This work extends the authors' investigations on liquid crystalline epoxy resins prepared from diglycidyl ether of 4,4′-dihydroxybiphenyl (DGE-DHBP) and aliphatic dicarboxylic compounds (ADC) or difunctional aromatic compounds. Syntheses and properties of these liquid crystalline epoxy resins are described elsewhere. In this paper a study on the curing reaction of the above mentioned liquid crystalline epoxy resins is presented. Ortho-tolylbiguanide was applied as the curing agent. The curing reactions were investigated by differential scanning calorimetry, microscopic observations and IR spectroscopy. Depending upon the temperature program of curing, it was possible to obtain polymeric networks with liquid crystalline order. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2739–2745, 1997     

Curing characteristics of carboxyl functionalized glucose resin and epoxy resin

The curing characteristics of carboxylic functionalized glucose resin (glucose maleic acid ester vinyl resin: GMAEV) and epoxy resin have been studied using DSC and FTIR methods. Exothermic reactions attributed to esterification and etherification reactions of the hydroxyl and carboxyl functionalities of GMAEV with the epoxy groups were identified. Exothermic reactions showed very different patterns according to the degree of carboxyl group substituent of GMAEV. The results showed that esterification reaction occurs in the early stage of cure and then etherification followed after completion of the esterification. A cured matrix containing epoxy resin and 50 wt.% of GMAEV was prepared and characterized. The cured matrix showed thermal stability up to 300 °C. The average glass transition temperature and storage modulus of the matrix were as high as 95 °C and 2700 MPa, respectively. The cured matrix of epoxy resin and GMAEV with higher degree of carboxyl group was found to have a lower density due to the formation of bulky groups in the crosslinks.     

Curing reaction of o-cresol novolac epoxy resin according to hardener change

The investigations of cure kinetics and glass transition temperature (T_g) versus reaction conversion (α) of o-cresol novolac epoxy resin with the change of hardener were performed. All kinetic parameters of the curing reaction such as the reaction rate order, activation energy, and frequency factor were calculated. The curing mechanisms were classified into two types. One was an autocatalytic mechanism and the other was a nth order kinetic mechanism. The constants related to the chain mobility of polymer segments were obtained by using the DiBenedetto equation. We have tried to correlate the relationships between curing mechanism and molecular structures of hardeners from these results. © 1993 John Wiley & Sons, Inc.     

Cure reaction and phase behavior of liquid crystalline epoxides-anhydride systems

A series of novel liquid crystalline epoxides with lateral substituents were cured with anhydrides and the cure kinetics was investigated by non-isothermal DSC technique. The results showed that the lengths of lateral substituents have great effect on the value of Ea. The curing reaction became less active, when the liquid crystalline epoxides have long lateral substituents and were controlled by diffusion at the late stage of cure. A nematic structure was observed by POM and XRD.     

Synthesis of a novel epoxy resin containing naphthalene moiety and properties of its cured polymer with phenol novolac

A new epoxy resin (Bis-ENA) containing naphthalene structure linked with a 1,4-bis(isopropylidene)phenylene was synthesized and was confirmed by elemental analysis, infrared spectroscopy, and ¹H nuclear magnetic resonance spectroscopy. To estimate the effect of naphthalene moiety on the cured polymer, an epoxy resin (Bis-EP) having phenyl moiety was synthesized, and curing behaviors of Bis-ENA and Bis-EP with phenol novolac were evaluated by differential scanning calorimetry. The incorporation of naphthalene structure into the resin backbone increased the curing temperature and reduced the curing reactivity. Thermal properties of the cured polymers obtained from Bis-ENA and Bis-EP with phenol novolac were examined by thermomechanical analysis and dynamic mechanical analysis. Mechanical properties and moisture resistance were evaluated by flexural strength, flexural modulus, and moisture absorption measurements. The cured polymer obtained from Bis-ENA showed higher glass transition temperature, higher flexural modulus, lower thermal expansion, and lower moisture absorption than that from Bis-EP. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3063–3069, 1999     

Curing reaction of biphenyl epoxy resin with different phenolic functional hardeners

The investigation of cure kinetics and relationships between glass transition temperature and conversion of biphenyl epoxy resin (4,4′-diglycidyloxy-3,3′,5,5′-tetramethyl biphenyl) with different phenolic hardeners was performed by differential scanning calorimeter using an isothermal approach over the temperature range 120–150°C. All kinetic parameters of the curing reaction including the reaction order, activation energy, and rate constant were calculated and reported. The results indicate that the curing reaction of formulations using xylok and dicyclopentadiene type phenolic resins (DCPDP) as hardeners proceeds through a first-order kinetic mechanism, whereas the curing reaction of formulations using phenol novolac as a hardener goes through an autocatalytic kinetic mechanism. The differences of curing reaction with the change of hardener in biphenyl epoxy resin systems were explained with the relationships between T_g and reaction conversion using the DiBenedetto equation. A detailed cure mechanism in biphenyl-type epoxy resin with the different hardeners has been suggested. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 773–783, 1998     

胺固化环氧酚醛树脂对Hg~(2+)的吸附性能

螯合树脂能与金属离子形成稳定的配合物,在无机、冶金、分析药物、催化、海洋化学、放射化学、环境保护各领域都有非常重要的应用[1-3]。我们曾以酚醛树脂为大分子骨架与多胺反应制备了一系列螯合树脂并对其结构及对多种金属离子的吸附性能进行了探讨[4,5]。本文则以线型环氧酚醛树脂为大分子骨架、多乙烯多胺为固化剂,制备了五种不同氮含量的氨基环氧酚醛螯合树脂,并考察其对金属离子Ｈｇ2+的吸附性能。1　实验部分1.1　仪器与试剂ＮｉｃｏｌｅｔＭＡＧＮＡ ＩＲ550(ＳｅｒｉｅｓＩＩ)红外分光光度计,ＳＨＡ-Ｃ水浴恒温振荡器,ＰＥ2000…     

Phosphorus based epoxy terminated structural adhesive 2. Curing, adhesive strength and thermal stability

The curing behavior of phosphorus based epoxy terminated polymers was studied using diaminodiphenyl ether, diaminodiphenyl sulfone, benzophenone tetracarboxylic dianhydride and the commercial hardener of Ciba-Geigy's two-pack araldite, as curing agent. The adhesive strength of these adhesives was measured by various ASTM methods like lap-shear, peel, and cohesive tests on metal-metal, wood-wood and wood-metal interfaces. All these results were compared with the synthesized epoxy resins prepared from bisphenol-A and epichlorohydrin having the epoxy equivalent value of 0.519. The thermal stability of both the virgin resin and its cured form was also studied by thermogravimetric analysis.     

Synthesis of a novel epoxy resin containing diphenylether moiety and thermal properties of its cured polymer with phenol novolac

A new type of epoxy resin containing 4,4′-diphenylether moiety in the backbone (2) was synthesized, and was confirmed by gel permeation chromatography, infrared spectroscopy, and ¹H nuclear magnetic resonance spectroscopy. In addition, in order to evaluate the influence of 4,4′-diphenylether moiety in the structure, epoxy resins having 4,4′-biphenylene moiety (4) and having 1,4-phenylene moiety (6) in place of 4,4′-diphenylether moiety were synthesized. The cured polymer obtained through the curing reaction between the new diphenylether-containing epoxy resin and phenol novolac was used for making a comparison of its thermal and physical properties with those obtained from 4, 6, and bisphenol-A (4,4′-isopropylidenediphenol) type epoxy resin. The cured polymer obtained from 2 showed markedly higher anaerobic char yield at 700°C of 44.0 wt %, higher fracture toughness, and higher mechanical strength and modulus. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3687–3693, 1999     

Cure kinetics of biphenyl epoxy‐phenol novolac resin system using triphenylphosphine as catalyst

The effects of the concentration of triphenylphosphine as a catalyst on the cure reaction of the biphenyl epoxy/phenol novolac resin system were studied. The kinetic study was carried out by means of the analysis of isothermal experiments using a differential scanning calorimeter. All kinetic parameters including the reaction orders, activation energy and kinetic rate constants were evaluated. To describe the cure reaction with the catalyst concentration, the normalized kinetic model was developed. The suggested kinetic model with a diffusion term was successfully able to describe and predict the cure reaction of epoxy resin compositions as functions of the catalyst content and temperature. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 713–720, 1999     

Rheological behaviors and structural transitions in a polyethersulfone-modified epoxy system during phase separation

The rheological behaviors and gelation transitions in a polyethersulfone (PES)-modified epoxy system during phase separation were studied by rheometry, time-resolved light scattering, and differential scanning calorimetry. Two separate structural transitions in the curing process of the blend were identified as the first one because of phase separation and the second one related to cross-linking reaction of epoxy resin. Both the times of the two structural transition at different temperatures could be described well by the Arrhenius type equation. The complex viscosity exhibits an exponential growing process during phase separation at various temperatures, correlating to the light-scattering results. The exponential behavior of complex viscosity could be attributed to the viscoelastic flow of epoxy-rich escaping from PES-rich during phase separation process.     

Effect of structure on thermal behaviour of epoxy resins

The paper deals with the curing behaviour of diglycidyl ether of bisphenol-A (DGEBA) using three novel multifunctional aromatic amines having phosphine oxide and amide-acid linkages. The amines were prepared by reacting tris(3-aminophenyl)phosphine oxide (TAP) with 1,2,4,5-benzenetetracarboxylic acid anhydride (P)/4,4^′-(hexafluoroisopropylidene)diphthalic acid anhydride (F)/3,3^′,4,4^′-benzophenonetetracarboxylic acid dianhydride (B). Amide-acid linkage in these amines is converted to thermally stable imide linkage during curing reaction. Curing temperatures of DGEBA were higher with phosphorylated amines than the conventional amine 4,4^′-diamino diphenyl sulphone (D). A decrease in initial decomposition temperature and higher char yields were observed when phosphorus containing amide-acid amines were used as curing agents for DGEBA.     

Mechanical properties and curing kinetics of epoxy resins cured by various amino-terminated polyethers

<正>A high performance thermosetting epoxy resin crosslinkable at room temperature was obtained via directly moulding diglycidyl ether of bisphenol A(DGEBA) and flexibleα,ω-bisamino(n-alkylene)phenyl terminated poly(ethylene glycol).The influences of the n-alkylene inserted in aminophenyl of flexible amino-terminated polythers(ATPE) on the mechanical properties,fractographs and curing kinetics of the ATPE-DGEBA cured products were studied.The results show that the insertion of n-alkylene group into the aminophenyl group of the ATPE,on one hand,can significantly increase the strain relaxation rate and decrease glass transition temperature of the ATPE-DGEBA cured products,resulting in slight decrease of the Young's modulus and tensile strength,and significant increase of the toughness and elongation of the ATPE-DGEBA cured products.On the other hand,it can remarkably enhance the reactivity of amine with epoxy,much accelerating the curing rate of the ATPE-DGEBA systems.The activation energy of DGEBA cured by BAPTPE,BAMPTPE and BAEPTPE was 53.1,28.5 and 25.4 kJ·mol~(-1),respectively.The as-obtained ATPE-DGEBA cured products are homogeneous, transparent,and show excellent mechanical properties including tensile strength and toughness.Thus they are promising to have important applications in structure adhesives,casting bulk materials,functional coatings,cryogenic engineering, damping and sound absorbing materials.     

Liquid crystalline epoxides with long lateral substituents: Synthesis and curing

A series of liquid crystalline epoxides with long lateral substituent from 4 to 12 carbon atoms was synthesized and characterized by ¹H NMR, FTIR spectroscopy, differential scanning calorimetry (DSC), polarized light optical microscopy (POM). The curing products of the LCE with DDM, was analyzed by POM and WAXS. The cure kinetics of epoxides and aromatic amine was investigated. The curing activation energy about 43.3-53.2 kJ mol⁻¹ was determined and compared for all the LC epoxides through Ozawa method. The change of activation energy suggests that the reaction active depends upon the lateral substituents, because the lateral substituents parallel to the rod-like core and can act as bound solvent.     

热致性液晶聚合物的种类对液晶/环氧树脂共混物固化反应动力学的影响

采用等温DSC固化动力学研究方法,用自催化动力学模型对反应型热致性液晶聚合物/环氧树脂共混体系进行研究.结果表明,EP/DDS未改性体系,在α＜40%范围遵循自催化反应机理;EP/DDS/LCPU共混改性体系,在α＜60%范围遵循自催化动力学反应机理,而且自催化反应速率和非催化反应速率均大于未改性体系,表明反应型热致性液晶聚合物的活性基团对固化反应起到了催化促进作用;EP/DDS/PHBHT共混改性体系能够较好符合n级反应机理,固化反应的活化能较大,说明没有反应基团的液晶聚合物(PHBHT)对固化反应无明显促进作用.     

固化剂对双介晶基元液晶环氧树脂相结构和热性能的影响

以芳香二胺（SAA）、酸酐（THPA）和叔胺（DMAP）为固化剂,固化偶氮类双介晶基元液晶环氧树脂,采用偏光显微镜和X射线衍射研究了固化剂对液晶热固体相结构产生的影响。DMAP催化环氧自聚固化,有利于液晶分子的有序排列,易于形成梯形结构,可以得到近晶相的固化产物。SAA在较低温度下固化时也得到近晶相结构,但在较高温度固...     

Fracture toughness and fracture mechanism of liquid‐crystalline epoxy resins with different polydomain structures

Liquid‐crystalline (LC) epoxy resins were cured at different temperatures to obtain polydomain LC phase–cured resins. The cured resins had polydomain structures with a nematic LC phase and their domain diameters differed depending on the curing temperatures. The relationship between the domain diameter and fracture toughness of the diglycidyl ether of terephthalylidene‐bis‐(4‐amino‐3‐methylphenol) (DGETAM)/m‐phenylenediamine (m‐PDA) systems with the nematic phase and the previously reported smectic LC phase structures was investigated. It was clarified that the highly ordered LC structure (smectic phase) in each domain could improve the fracture toughness. In addition, the changes in the network orientation of the DGETAM/m‐PDA systems were evaluated by a mapping of the microscopic infrared dichroism in the fracture process and their toughening mechanism was suggested. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010     

Anisotropic thermosets from liquid‐crystalline azomethynic epoxy resins and primary aromatic diamines

Novel epoxy‐terminated monomers based on imine groups were synthesized and their mesogenic properties studied. Aliphatic spacers of different lengths were introduced between the rigid unit and the glycidylic group, and their liquid‐crystalline behavior was examined. They were reacted with primary aromatic diamines inside a magnetic field so that the formation of anisotropic networks could be investigated. The influence of curing conditions and the structure of monomers and amines on the formation of liquid‐crystal thermosets were investigated. Thermosets with locked nematic textures were obtained in all cases. The influence of a 7.1 T magnetic field on the macroscopic orientation of these materials was studied, and mechanical properties of the resulting networks were evaluated by dynamic mechanical analysis. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1–12, 2003