Effects of water content on the properties of starch/poly(ethylene–vinyl alcohol) blends

The physical properties of unmodified starch, poly(ethylene vinyl alcohol), glycerol, and water mixtures are reported. Thermal and melt-flow properties of the preprocessed, physically mixed materials were determined along with the tensile properties and morphology of injection-molded microtensile samples. Melt-flow properties were measured by a capillary rheometer, and the water content was varied from 4 to 18%. The morphology, rheology, and tensile properties are all highly related to the percentage of water present. A transition in the tensile properties and morphology of the blends was observed at approximately 11% moisture content. © 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.

     

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.     

Functional polyamides. 3. Synthesis and chelating properties of a new poly(amide thioether)

Polymerization of β,β′-(ethylenedithio)dipropionitrile

1 IUPAC name: 4,7-dithiadecane dinitrile.

with formaldehyde in the presence of sulfuric acid was carried out in order to permit the synthesis of polymides containing thioether groups. The obtained poly(amide thioether)s were characterized; they coordinate mercury (II) with a high degree of selectivity.     

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 .     

Properties of standard materials for reflection

This article gives a short survey of some literature on the calibration, suitability, properties, and use of various materials which are used as standards of reflectance. The classical ultimate reference standard, smoked magnesium oxide, is discussed briefly, and information is given on the properties of materials presently used: BaSO₄, Russian opal glasses, ceramic tiles, and Halon.

1 Halon is a registered trade name of the Allied Chemical Corporation.

The suitability of these materials for use as transfer standards or working standards is discussed.     

Alumina trihydrate as a flame retardant filler for flexible vinyl compounds

In those flexible vinyl compounds which can accept fillers, alumina trihydrate can significantly improve flame resistance as measured by oxygen index

1 It should be appreciated that degrees of flammability as measured by small-scale tests such as oxygen index may in no way reflect the relative hazard of these same materials when involved in a fully developed fire.

. Over a range of plasticizer concentrations, the lower the concentration of burnable plasticizer, the greater the contribution of hydrate to flame retardancy. Combinations of alumina trihydrate with antimony oxide are especially effective for improving the flame resistance of flexible vinyl compounds.     

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.     

The synthesis and properties of a cation-exchange resin prepared by the pyrolysis of starch in the presence of phytic acid

A black charcoal-like material having cation exchange and adsorption properties was prepared by the controlled pyrolysis of starch in the presence of a commercial phytic acid solution. Resins with binding capacities of 0.7–5.7 meq/g of calcium were prepared by varying the phytic acid to starch ratio, the temperature, or the duration of heating of the reaction mixture. SEM photomicrographs of some of these new materials showed that they are composed of particles similar in size and shape to the starting starch granules. These resins also removed atrazine from aqueous solutions. © 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.

     

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     

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.     

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.     

Effect of gas diffusion on creep behavior of polycarbonate

Biaxial tension-tension creep experiments were performed to study the effect of gas diffusion on creep behavior of polycarbonate. Experiments were conducted on a thin-walled tubular specimen by applying both gas pressure and axial tension at room temperature, and measuring axial strain and gas absorption. Experiments were performed with helium, nitrogen, air, carbon dioxide and Freon-22

1 Registered trademark, E. I. duPont de Nemours Co., Inc.

. It was found that the creep deformation was highly affected by the solubility controlled gases, carbon dioxide and Freon. The absorption measurements showed that the gas absorption behavior was clearly affected by the creep deformation of the material. Also an anomalous diffusion-type behavior appeared even in permanent gas-polymer systems under creep conditions. The modified superposition principle satisfactorily predicted the recovery following creep. The axial creep for the biaxial tension-tension experiments was also computed from data previously reported for creep under combined tension and torsion of a different sample of polycarbonate.     

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.

     

A simple dilatometer for thermoset cure shrinkage and thermal expansion measurements

A simple capillary and bulb mercury dilatometer designed for specific volume measurements on thermoset resin systems during the curing reaction and as a function of temperature is described. The design, calibration, operation, data treatment, and error analysis are presented in detail, with data on the bisphenol A dicyanate resin system used as an example. Particular attention is directed at experimental difficulties such as monomer/prepolymer degassing, filling the dilatometer under vacuum, adhesive distortion of the curing resin on the dilatometer bulb, and the dilatometer bulb to capillary connection problem. © 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.

     

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.     

The hierarchical structure and flexure behavior of woven carbon fiber epoxy composite

The hierarchical structure and flexure behavior of woven carbon fibers epoxy composite were investigated in this work. First, the hierarchical structure of the composite is characterized on three levels: composite, ply, and yarn. Structura imperfections,

1 In this paper, “structural imperfections” is used to describe the inherent structural characteristics of the actual composite, which deviate from the theoretically ideal and perfect composites, control, that are used in composite theories.

such as, ply‐ply misalignment, ply‐ply offset, and resin pockets, are identified and described. Second, a four‐point bending arrangement is used to study the flexure properties of the composite. Additionally, in‐situ traveling microscope and acoustic emission (AE) techniques are utilized to gain insight to the failure proceses during flexure test. AE showed early stages of matrix cracking before visual observation, which makes it a valuable tool for early failure detection.     

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.     

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.