Action of some organophosphonic compounds on a diglycidyl ether-bisphenol-A epoxy resin

The effect of three organophosphonic compounds on the thermooxidative degradation of the uncured diglycidyl ether-bisphenol-A epoxy resin was investigated, using infrared spectroscopy, thermogravimetry, differential thermogravimetry, static pyrolysis, pyrolysis-gas chromatography and elemental analysis. The results obtained indicate that additives with phosphorus and chlorine or nitrogen in molecules exercise an influence upon the degradative process of uncured resin by catalysing its decomposition in the lower temperature region. At the same time, the tested additives promote the formation of highly thermostable and non-flammable structures in the solid residue.     

Applicability of the turbidity test for castor oil to some other hydroxy and epoxy fatty compounds

A large number of hydroxy as well as nonhydroxy fatty compounds were employed to explore the applicability of the turbidity test for castor oil (1) and to understand the nature of the turbidity. The test was capable of detecting up to ca. 2% of hydroxy, hydroperoxy, and epoxy fatty acids and their esters, also the epoxy, acetoxy, and hydroxy fatty alcohols present in a petroleum ether solution of a nonpolar triglyceride oil. Monohydric primary alcohols, sterols, mono- and diglycerides were not detected. The turbidity developed, whether H₂SO₄ contained ammonium molybdate or not, because of the formation of a sulfate and its precipitation from the petroleum ether solution of oil.     

New epoxy resins. II. The preparation,characterization, and curing of epoxy resins and their copolymers

A polymer having high aromaticity and/or cyclic ring structures in the chain backbone usually gives high heat resistance and flame resistance. Five glycidyl ether-type epoxy resins are prepared from bisphenol A (DGEBA), 9,9-bis(4-hydroxyphenyl)fluorene (DGEBF), 3,6-dihydroxyspiro-[fluorene-9,9′-xanthane] (DGEFX), 10,10-bis(4-hydroxyphenyl) anthrone (DGEA), and 9,9,10,10-tetrakis(4-hydroxyphenyl)anthracene (TGETA) in order to study structure–thermal stability–flame resistance property relationships. In this study, trimethoxyboroxine (TMB) and diaminodiphenylsulfone (DDS) are employed as the curing agents. The char yield at 700°C under a nitrogen atmosphere and the glass transition temperature (T_g) for the uncured resins decrease according to the sequence TGETA > DGEFX > DGEA > DGEBF > DGEBA. The Tg values for these cured epoxy resins are DGEBA < DGEBF < DGEFX < DGEA. A T_g for the TGETA is not obtainable but would be expected to be the highest. The char yields at 700°C of these cured epoxy resins have the same trend as the uncured resins. DGEBF, DGEFX, DGEA, and TGETA added to the DGEBA system show increases in the char yield, T_g, and oxygen index with increasing concentration of these novel epoxy resins.     

Cure rates of some epoxy systems

The property changes of Epon 828 crosslinked by either diethylenetriamine or m-phenylenediamine at several temperatures have been studied by two in situ techniques. The mechanical property changes were followed by continuously monitoring the changes in the fundamental frequency of vibration during cure of a resin-coated substrate acting as a cantilever reed. The disappearance of the reactive epoxy group was followed in situ by continuously monitoring the absorbance of the infrared epoxide band at 915 cm.^?1. Correlation of the two techniques was accomplished by normalizing both the mechanical property and infrared data. The apparent energy of activation was calculated to be 10.4 and 11.4 kcal. /mole, respectively, for the m-phenylenediamine and diethylenetriamine systems by the mechanical technique, and 11.0 kcal./mole for the m-phenylenediamine crosslinked system by the infrared technique.     

Chemistry of thermal ageing in aerospace epoxy composites

The detailed chemical reactions involved in the thermal ageing (at 120°C) of a typical aerospace epoxy composite have been studied by the mid‐Fourier transform infrared spectroscopy (FTIR) spectral characterization of selected model compounds. The FTIR spectra indicate that at this particular temperature, the major reaction in the resin structure is probably an oxidation of a CH₂ group adjacent to the nitrogen atom of the tetraglycidyldiaminodiphenyl methane unit of the molecular structure, particularly where it is attached to one isomer of the diaminodiphenylsulfone hardener unit. The FTIR changes indicate that the major product is an amide group but other minor changes are also detailed and differences in the chemical changes seen at other ageing temperatures highlighted. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2210–2219, 2006     

Preparation of epoxy resin/silica hybrid composites for epoxy molding compounds

Phenolic novolac/silica and cresol novolac epoxy/silica hybrids were prepared through in situ sol‐gel reaction of tetraethoxysilane (TEOS). The formed hybrids were utilized as a curing agent and an epoxy resin in epoxy curing compositions, respectively. Via the two‐step preparation route, the resulting epoxy resin/silica hybrid nanocomposites exhibited good thermal stability, high glass transition temperatures, and low coefficients of thermal expansion. High condensation degree of the condensed silica was observed with a high content of siloxane bridges, p > 85%, measured by ²⁹Si NMR. The two‐step route also provides feasibility of preparation of epoxy resin/silica hybrid nanocomposites compatible with the current processes of manufacturing of epoxy molding compounds. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4047–4053, 2003     

Heterocyclic compounds. X. Synthesis of some oxazoloquinoline derivatives

A series of 2-aryl-oxazolo[4,5-h]quinoline-5-arylidines (II) was prepared through the reaction of 5,7-diamino-8-hydroxy quinoline with aromatic aldehydes in the presence of a basic catalyst such as piperidine. The reaction also proceeded with aliphatic aldehydes but under slightly different conditions. On the other hand, 2-stilbyl-5-diacetyl-amino-oxazolo[4,5-h]quinolines (V) were prepared by interaction of 2-methyl-5-diacetylamino-oxazolo[4,5-h]quinoline (IV) with aromatic aldehydes. Such compounds possessed structural relationships to some known antibiotics and their chemical constitution was confirmed by spectral studies.     

Hydrolytic stability of some uncured epoxy resins

The hydrolytic stability of triglycidyl(4-aminophenol) (ERL 0500), tetraglycidyl(methylenedianiline) (MY720), and a number of model compounds has been investigated. It has been shown that at 60°C and 96% relative humidity undiluted N-glycidyl aromatic amine-based epoxy resins readily undergo hydrolysis followed by homopolymerization. Impurities in the resin may significantly accelerate the rate of reaction. The effect of the consequent loss of epoxide on the performance of an adhesive based on ERL 0500 has been studied. The high-temperature tensile-shear strength of Joints was markedly reduced when the adhesive was aged, before cure, for 24 hr at 60°C and 96% relative humidity. Some implications of these findings for aerospace applications of epoxy compounds are discussed.     

木质素基环氧树脂固化剂的制备

环氧-胺化两步反应法制备生成了含有活性胺基基团的胺化木质素衍生物。采用精制后的木质素与环氧氯丙烷生成反应性较高的环氧木质素,对环氧木质素进行胺化改性,并探讨了反应条件比对最终产物胺化木质素中活性胺基含量的影响。应用红外光谱测试、X射线光电子能谱测试以及热重测试对产物的结构与性质进行了表征,结果表明,当环氧木质素与二胺化合物物料比为1∶8,反应温度80℃,反应时间4 h,得到的胺化木质素产物总胺基含量达到184.8%。最终产物胺化木质素改性物中含有较多反应性较高的伯胺(81.21%)以及仲胺基团(99.82%),产物有较好的热降解稳定性,可以用作环氧树脂的固化剂。     

Advantages of modification of epoxy adhesives and compounds

The feasibility of controlled changes in the characteristics of epoxy adhesives via modification with inert and reactive plasticizing agents, oligomers, and hardeners is considered with account for their chemical structure and hardening schedule.     

Dynamic mechanical properties of some epoxy matrix composites

Dynamic mechanical properties of some epoxy matrix composites have been studied, comparing experimental data with theoretical models. The matrix in all composite samples was Shell Epon 828, a diglycidyl ether of bisphenol A, cured with meta-phenylenediamine. Fibrous composite samples were made with glass and graphite fibers. Particulate composite samples were made with glass microspheres, atomized aluminum, powdered silica, alumina, asbestos, mica, carbon black, and graphite. The dynamic elastic modulus and damping of these samples were measured at temperatures between 85° and 345°K by a free-free flexural resonance technique. The dynamic modulus of parallel fiber composites follows the linear rule of mixtures for low fiber volume fractions; deviations from linearity at higher volume fractions appear to be due to defects caused by the sample fabrication technique. Dynamic moduli of the particulate composites conform, within experimental error, to the static modulus theory of Wu up to filler volume fractions of 0.35 to 0.40. Deviations from Wu's theory at higher volume fractions may be due to agglomeration of filler particles. The damping of particulate composites with quasi-spherical filler particles appears to follow the rule of mixtures. In particulate composites with needle- and flake-type fillers, and in fibrous composites, the fillers are more highly stressed; with more of the strain energy in the low-damping fillers, overall damping is reduced. Damping greater than that attributable to the matrix and filler may be due to slippage at the interface between them. In addition to supporting Wu's theory of the elastic modulus of a particulate composite, this study demonstrates the utility of the nondestructive free-free flexural resonance techniques for obtaining a large body of reliable data in a short time from relatively few small samples. This greatly facilitates the experimental testing of theoretical models and the evaluation of fillers, matrix materials, and fabrication techniques.     

Mass spectral studies of some epoxy resin precursors

The mass spectra were determined of three epoxy resin precursors: N,N-bis-(2,3-epoxypropyl)-N′,N′-dimethyl-4,4′-diaminodiphenylenemethane (G2A); N,N′-bis-(2,3-epoxypropyl)-N,N′-dimethyl-4,4′-diaminodiphenylene methane (G2S); and N′,N′,N′,N′-tetrakis-(2,3-epoxypropyl)-4,4′-diaminodiphenylene methane (TGDDM); and of three related model compounds: N,N-dimethylaniline (DMA); N-methyl-N-glycidylaniline (MGA) and N,N-digrycidylaniline (DGA). The results helped to confirm the structure of the resin precursors and are intended to pave the way for subsequent thermal degradation studies of cured resin samples. Despite the similarity in chemical structure of the compounds studied there are quite large differences in the mass spectral results obtained.     

Study on preparation and tribological properties of epoxy resin/SiO2 hybrid thin film

A series of organic–inorganic hybrid thin films are prepared by means of the sol–gel process in curing epoxy and hydrolyzing tetraethoxysilane. The epoxy group of γ‐glycidyloxipropyltrimethoxysilane can be incorporated into the sol–gel network to form the interaction between the inorganic and organic phases. Inorganic and organic components can be mixed on the nanometer scales, thereby leading to the formation of so‐called hybrid materials. Transmission electron microscopy examinations and atomic force microscopy are employed to study the morphology and roughness of the samples, respectively. In addition, the tribological behavior of dip‐coating thin films is evaluated by the use of a dynamic/static friction precision measurement apparatus (unidirectional sliding tester). The influences of the contents of both the filler and the coupling agent on the tribological properties of the nanocomposite thin films are systematically studied. These results indicate that the films sliding against a GCr15 steel ball display excellent antiwear and friction reduction performance. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 38–43, 2005     

环氧树脂基纳米复合材料制备的研究进展

综述了目前环氧树脂纳米复合材料的制备方法．包括插层复合、共混分散、纳米复合膜法等,介绍了环氧树脂纳米复合材料的优异性能,并对其增韧改性机理作了探讨,最后展望了环氧树脂纳米复合材料的应用前景。     

环氧大豆油制备工艺研究

介绍了在硫酸、７３２阳离子交换树脂的催化作用下，制备环氧大豆油的工艺，得出了最佳工艺条件。     

Effects of moisture on properties of epoxy molding compounds

In this article the effects of moisture on a novel epoxy molding compound, including the mechanical properties, temperature transition, and thermal degradation behavior, are studied. The experimental results reveal that the absorbed water acts predominantly as a crazing agent, continuously decreasing the mechanical strength with the time in water. The glass-transition temperature decreases at the early stage and is finally equilibrated. The thermal degradation behavior of the materials is not greatly influenced by the hydrothermal age. The decomposition of samples in oxygen is composed of two independent steps: the thermal degradation and oxidation at high temperature. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2253–2259, 2001     

Reaction of methyltrans-2,3-epoxyhexadecanoate with urea: Synthesis of long chain fatty 2-oxazolidones

Methyltrans-2,3-epoxyhexadecanoate on refluxing with urea in dimethylformamide (DMF) afforded isomeric 4(5)-tridecyl-5(4)-carbomethoxy-cis-2-oxazolidone (II), 5-tridecylmethylene hydantoin (II) and 2-hydroxy-3-carbamidohexadecanoic acid (III). Presented at the 4th Convention of the Indian Council of Chemists at Uttar Pradesh, India, December 1984.