Glass fiber-reinforced epoxy composites

Glass fiber-reinforced epoxy composites were prepared from the matrix resins tetraglycidyl diaminodiphenylmethane

1 Systematic name: N,N,N′,N′-Tetrakis(2,3-epoxypropyl)-4,4′-diaminodiphenylmethane.

(TGDDM) and tetraglycidyl bis(o-toluidino)-methane

2 Systematic name: N,N,N′,N′-Tetrakis(2,3-epoxypropyl)-4,4′-bis(o-toluidino)methane.

(TGMBT) using various amines like 4,4′-diaminodiphenylmethane (DDM), 4,4′-diaminodiphenylsulfone (DDS) and diethylene triamine (DETA) as curing agents. The fabricated laminates were evaluated for their mechanical and dielectrical properties and chemical resistance. The composites prepared using an epoxy fortifier (20 phr) showed significant improvement in the mechanical properties.     

Photochemical and thermal stability of amaranth (FD&C red no. 2) in aqueous media

The decomposition of the formerly

1 This dye was delisted by the U. S. Food and Drug Administration in 1976, and has not been legally used in the U. S. in foods, drugs, or cosmetics since that date.

used food and pharmaceutical dye amaranth (FD&C Red No. 2) in water was studied under a variety of conditions. A matter of some concern is that one of the decomposition products is α-naphthylamine, a known carcinogen.     

Dicyclopentadienoxidation. II 5. Katalysierte Flüssigphasenoxidation von Dicyclopentadien

Dicyclopentadiene Oxidation. II. Catalyzed Liquid-Phase Oxidation of Dicyclopentadiene The liquid-phase oxidation of dicyclopentadiene 1 by molecular oxygen was studied in the presence of MoO₂(acac)₂

1 Acac- Acetylacetonat

as a typical epoxidation catalyst. The yield of the mono-epoxides 2 and 3 is increased to 56,4% (uncatalyzed reaction: 43,6%). The ratio of the two mono-epoxides is decreased to 2/3 = 2,6 in relation to the uncatalyzed reaction ( 2/3 = 7,1). The influence of temperature, conversion and solvents is described. The bisepoxide 4 is formed at lower conversions than in the uncatalyzed reaction. But also at higher conversions of 1 not more than 10% of the bisepoxide 4 is formed     

Synthesis of phosphorus-containing polymers with potential bioactivity

Phosphorylation of poly(N-vinyl pyrrolidone-co-vinyl amine) and poly(N-vinyl pyrrolidone-co-glycidylcrotonate

1 Systematic name: (2,3-Epoxypropyl)crotonate.

) is realized by Atherton-Todd and Fields-Kabachnik reactions and by the means of direct interaction with phosphorus trichloride and phosphorus trichloride oxide. The composition and structure of the isolated final products was proved by NMR (¹H and ³¹P), IR spectroscopy and elemental analysis.     

Antioxidants and stabilizers, 107. Reaction of N-phenyl-1,4-benzoquinoneimine with the 1-cyano-1-methylethyl-radical

The reaction of N-phenyl-1,4-benzoquinoneimine (I)

1 Decoding of abbreviations see p. 103/104.

and 4-hydroxydiphenylamine (II) with the carbon centred 1-cyano-1-methylethyl radical (R^·) was studied in connection with an investigation of the action mechanism of industrial antidegradants, such as N-phenyl-N′-sec-alkyl-1,4-phenylenediamines. The mixture of I and II reacts very readily with R^·, giving rise to III , VI , and VIII . I alone reacts much slowlier, and the reaction mixture contains more products. IV and VII were identified along with III . Under the conditions used, II alone does not react at all. IV exists in two isomeric forms, syn and anti. VIII is very labile; XI was isolated from its transformation products. Reduction of IV gives V , which is labile, similarly to VIII .     

Porous bead aliphatic-aromatic methacrylate copolymers,I. Effect of polymerization conditions on porous structure formation of methyl methacrylate — di(methacryloyloxymethyl)naphthalene copolymers

The influence of inert porogenic mixture and monomer mixture composition and concentration on specific surface areas, pore size distribution, volumes of pores capable of capillary condensation of nitrogen and true density of copolymers were investigated for a new type of methacrylate monomer system: methyl methacrylate and di(methacryloyloxymethyl)naphthalene. The obtained copolymers exhibit similar character as it is typical for PPS

1 PPS = Porous by Precipitant and Solvent.

styrene-divinylbenzene resins.     

The STOBBE Condensation with Dimethyl Homophthalate. Part I

The condensation of methyl 2-thienyl, methyl 2-furyl, and phenyl 2-thienyl ketone with dimethyl homophthalate in the presence of either potassium t-butoxide or sodium hydride as condensing agent, gave predominantly the (z)-half esters

1 The nomenclature of cis/trans isomers follows the IUPAC Tentative rules, Section E, Fundamental Stereochemistry, J. org. Chemistry 35 , 2849 (1970). See also N. R. El-Rayyes, J. prakt. Chem. 315 (2), 300 (1973). (E) = trans-(Heterocyclic ring/CO₂CH₃) (Z) = cis-(Heterocyclic ring/CO₂CH₃)

. The structure and configuration of the products were inferred by chemical and spectroscopic means.     

Mowrah (Madhuca latifolia) seed saponin. Toxicological studies

Mowrah seed (Madhuca latifolia) meal

1 Meal refers to solvent extracted material.

contains high levels of saponin (7%) making it unsuitable for incorporation in animal feedstuff formulations. The saponin from mowrah seed meal was isolated and purified by paper chromatography. This was used for in vitro tests as well as pharmacological and acute toxicity studies for a better understanding of its properties and toxicity. The oral, intraperitoneal and intravenous LD₅₀ of mowrah saponins in mice are 1 g, 15–20 mg and 15 mg/kg body weight respectively. Processing of the meal to remove or inactivate the saponin will be essential prior to its incorporation in animal feeds.     

Investigation of primers reducing the pink-ring formation in multilayer printed circuit boards

A rapid and easy screening test was applied to assess the capability of various formulated primers to reduce the defect of pink rings in multilayer printed circuit boards. The mixtures of silanes with multifunctional silanol groups (crosslinkers) and 3-glycidoxypropyl-trimethoxysilane

1 Systematic name: 3-(2,3-Epoxypropoxy)propyl-trimethoxysilane.

(referred to as silane C) or N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane

2 Systematic name: 3-[N-2-aminoethyl]aminopropyl-trimethoxysilane.

(silane B) were proved to be effective in reducing the pink rings. The performance of the mixed silanes using silane A and crosslinkers with aromatic groups were better than other formulated primers which was partly attributed to less amounts of hydrophilic groups and better integrity in the primer films. A developed primer consisting of siloxane compounds had the best performance. The online test confirmed the results from the screening test and demonstrated the feasibility of the designed screening test in assessing the performance of primers. The results of FTIR spectroscopy and thermogravimetric analyses confirmed that the effective primers coated on the copper oxides could improve the curing reaction and the thermal oxidative stability of the epoxy/CuO system.     

Fracture behavior of coated/uncoated graphite-epoxy composites

The static delamination behavior of graphite/epoxy composite specimens subjected to mode I tensile opening (using UDCB

1 Uniform double cantilever beam.

specimens), and pure mode II shear loading (using ENF

2 End-notched flexural.

specimens) were studied. The graphite epoxy composites for the study were made from commercially treated fibers, with and without an electropolymerized interlayer. The mode I fracture energy (G_IC) was found to be significantly higher (more than 50 percent) for the coated fibers. However, this improvement was accompanied by a high reduction (more than 3 times) in the mode II fracture energy (G_IIC). This effect is apparently related to poor adhesion between the interlayer and the epoxy resin, which may be corrected by use of a “top layer” of appropriate composition to form chemical bonds between the phases. The fracture toughness (K_IC) of composites made with commercially treated fibers was also evaluated, using double side-notched specimens.     

Ground State Complexes between 5-(4-Carboxyphenyl)-10,15,20-Tritolyl Porphyrin and Benzoquinones

The interactions of 5-(4-carboxyphenyl)-10,15,20-tritolyl porphyrin (TTPa)

1 Abbreviations: TTPa: 5-(4-carboxyphenyl)-10,15,20-tritolyl porphyrin; BQ: 1,4-benzoquinone; DQ: 2,3,5,6-tetramethyl 1,4-benzoquinone; CHLQ: 2,3,5,6-tetrachloro 1,4-benzoquinone; DMSO: dimethyl sulfoxide

with benzoquinones have been studied by spectrophotometry and steady state and transient fluorescent methods. TTPa forms a 1:1 molecular complex with 1,4-benzoquinone, 2,3,5,6-tetramethyl 1,4-benzoquinone and 2,3,5,6-tetrachloro 1,4-benzoquinone in dimethyl sulfoxide at room temperature. The equilibrium constants for the interaction of TTPa with the different quinones were evaluated.     

The STOBBE Condensation with Pyrrolyl Aldehydes – a synthesis of indole derivatives

The condensation of pyrrolyl-2-aldehyde or 1-methyl-pyrrolyl-2-aldehyde with dimethyl succinate, using sodium hydride as condensing agent, gave predominantly the halfesters 1a and 1c respectively. Their structure and (E)-configuration

1 i. e., pyrrol ring and COOCH₃ group are in trans position. This nomenclature follows the IUPAC 1968 Tentative Rules, Section E, Fundamental Stereochemistry, J. org. Chemistry 35 , 2849 (1970).

were confirmed by their cyclisation to the corresponding indole derivatives 2a–h .     

Dicyclopentadienoxidation. I,Unkatalysierte Flüssigphasenoxidation von Dicyclopentadien

Dicyclopentadiene Oxidation I. Uncatalyzed Liquid-Phase Oxidation of Dicyclopentadiene Dicyclopentadiene is oxidized by molecular oxygen to a mixture of the monoepoxides 2 and 3 . The identification of the epoxides 2 , 3 and 4 was executed with authentic samples prepared by epoxidation with peracetic acid or with tert-butylhydroperoxide in the presence of MoO₂(acac)₂

1 acac — Acetylacetonat

The main product is the substituted norbornene oxide 2 . Allylic oxidation is also observed. Remarkable amounts of hydroperoxides can be determined iodometrically. The formation of allylic oxidation products 7 , 8 , 9 and 10 was proved by GC-MS-analysis. It is shown that in the uncatalyzed liquid phase oxidation of dicyclopentadiene no more than 50% of epoxides are formed. The bisepoxide 4 was found in small amounts only at higher conversions of the dicyclopentadiene.     

Magnetic field processing of polymers. I. Hydroxypropyl cellulose

Hydroxypropyl cellulose (HPC) of degree of substitution three and average molecular weight of 100,000 was processed in a magnetic field of 1.2T. Films of HPC were cast from water, methanol, ethyl methyl ketone, and 1,1,2,2-tetrachloroethane solutions in a magnetic field using static and dynamic casting techniques. The processed films were evaluated for tensile strength, elastic modulus, microhardness, and molecular chain alignment by wide angle x-ray diffraction and polarized infrared. The best alignment and hence the greatest improvement in properties was obtained using a combined magnetic field and flow alignment procedure. These samples showed no increase in the elastic modulus, a 106% increase in the tensile strength, a 21% increase in the microhardness, and were dichroic. © 1994 John Wiley & Sons, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Grafting of methyl methacrylate on isoprene rubber

Methyl methacrylate has been grafted on artificial isoprene rubber (IR) latex, with use of redox initiation. The properties of latices containing up to 40 phr

1 Parts per hundred parts of rubber.

methyl methacrylate (MMA) as well as solid products containing up to 80 phr of this compound were studied. Compared with ungrafted IR latex with the same solids content, the grafted IR latices had a lower viscosity, owing to their particle size being larger. Vulcanised films obtained from the grafted latices showed a considerably higher modulus, particularly at large deformations, than those based on IR or blends of IR with polymethyl methacrylate. by incorporation of certain reinforcing white fillers in the MMA-grafted IR latices, a further increase in the modulus of the latex films was effected.     

The STOBBE condensation with substituted succinic esters,part I. A Synthesis of Benzothiophene Derivatives

The condensation of some thienyl carbonyl compounds with dimethyl methylsuccinate in presence of potassium t-butoxide or sodium hydride gave predominantly the (E)-half-esters

1 i. e., CO₂CH₃ group and thiophene ring in trans-position. The nomenclature of cis/trans isomers used herein follows the IUPAC 1968 Tentative Rules, Section E, Fundamental Stereo-chemistry, J. Org. Chem. 35 , 2849 (1970). See also: J. E. Blackwood, C. J. Gladys, K. L. Loening, A. E. Petrarca, and J. E. Rush, J. Amer. chem. Soc. 90 , 510 (1968); Introduction to Subject Index of Chem. Abstr. 66 (1963).

1a – d , which were cyclised to benzothiophene derivatives 2a – d . The (E)-dibasic acids 6a – d were converted to the corresponding anhydrides 7a – d , which upon methanolysis produced the isomeric half-esters 8a – d . Treatment of 6d with concentrated sulphuric acid gave the cyclic ketonic lactone 9 together with the fluorenone derivative 10 .     

Oxidative aging of thermoplastic polyimide films

Two linear polyimides were subjected to accelerated isothermal aging at temperatures between 300 and 400°C. Losses in toughness correlated well with changes in glass transition temperature (T_g) of the films, but not with weight loss. Both materials have extrapolated lifetimes of 100,000 h near their T_g's. © 1995 John Wiley & Sons, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Synthesis and characterization of melt-polymerizable aminophthalocyanine monomers

The strategy, synthesis, and characterization of a soluble amine-functionalized phthalocyanine monomer and two examples of its polymerization into optically transparent glasses are reported. A simple, fast, and versatile method for incorporating metal ions into the metal-free phthalocyanine is demonstrated. Measurements of the nonlinear optical properties associated with a lead-substituted phthalocyanine/urethane copolymer are also reported. © 1995 John Wiley & Sons, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Solid-state polymerization in poly(butylene terephthalate): The Equilibrium constant

Poly(butylene terephthalate)

1 PBT or Poly-1, 4-butanediyl 1, 4-diearboxylate.

polycondenses readily in the presence of small amounts of organo-titanium compounds to form progressively higher molecular weight polymers, The reaction is reversible in the presence of the condensation byproduct, 1,4-butanediol. Usually this reaction is carried out in the melt phase, but the viscosity is soon limiting. In the current work the polymerization is carried out in the solid phase just below the melting point of 227°C. The equilibrium constant for this reaction is measured by subjecting the polymer to a nitrogen stream saturated with a controlled quantity of butanediol. The reaction is followed by measuring the change in the number of alcoholic end-groups by infrared spectroscopy. At about 220°C the equilibrium constant is 0.31 (σ = 0.08).     

Styrene emulsion polymerization in the presence of a maleate-functional surfactant

Dodecylhemiester of maleic anhydride is a very good anionic stabilizer for the emulsion polymerization of styrene. Rather high solid contents may be produced. Up to about 70% of the surfactant can be grafted onto the surface of the particles. Upon floculation with calcium salt, only 3% of the surfactant is left in the washing water. © 1997 John Wiley & Sons, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

J Appl Polym Sci 65: 2289–2296, 1997