Materials Literature
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A new copolyester of 3-hydroxybutyrate (3HB) and 3-hydroxypropionate (3HP) was produced by Alcaligenes eutrophus in a nitrogen-free culture solution of 3-hydroxypropionic acid, 1,5-pentanediol, or 1,7-heptanediol. The copolymer composition varied from 0 to 7 mol% 3HP, depending on the type of carbon substrates supplie…
Abstract A new polymer‐forming monomer, 3,4‐bis(4‐aminophenyl)‐2,5‐diphenylpyrrole, was synthesized in three steps starting from 4′‐nitrodeoxybenzoin. Tetraphenylpyrrole‐containing aromatic polyamides and copolyamides were prepared from the diamine with various aromatic diacid chlorides and from a mixture of the diami…
The gas‐solid isotope exchange method using with the continuously recording gravimetric technique was employed for the measurement of the oxygen tracer diffusion coefficient in single‐crystal zirconia. In the temperature range investigated (1300–1600°C) the tetragonal form of the oxide is stable. Both helium and hydro…
A theory has been constructed for the ${\mathrm{CH}}_{3}$F molecule's nuclear-spin conversion induced by the intramolecular magnetic dipole-dipole nuclei interaction. It is shown that for $^{13}\mathrm{CH}_{3}$F molecules this mechanism leads to the rate of spin conversion (0.71\ifmmode\pm\else\textpm\fi{}0.2)\ifmmode…
Abstract Polyurethanes based on methylene bis ( p ‐phenyl isocyanate), bis (hydroxymethyl) propanoic acid, and poly (tetramethylene oxide) were synthesized, and their morphology and physical properties investigated. The acid polyurethanes exhibited very poor phase separation and mechanical properties, but upon neutral…
Ferroelectric thin film compositions in the PLZT system were prepared from water-soluble acetate precursors. Dip coated, multilayer thin films were applied to various substrates, pyrolyzed at 700°C and characterized in regard to dielectric and ferroelectric properties.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructure and conformation of poly(ethylene oxide), PEO, in the trigonal form of the PEO-urea complex at 173 KAbdellatif Chenite and Francois BrisseCite this: Macromolecules 1991, 24, 9, 2221–2225Publication Date (Print):April 29, 1991Publication History Published online1 Ma…
The advantage of certain amounts of MgO addition in alumina sintering has been realized, and it is common practice. In an attempt to understand the role of MgO in the presence of CaO in commercial‐grade alumina, grain‐boundary segregation of Ca was investigated by scanning Auger electron microprobe (SAM) using an ultr…
Measurements of the scattering of thermal neutrons from natural samples of molten ZnCl2, ZnBr2, and ZnI2 are reported. The experiments were undertaken on the liquids and amorphous materials diffractometer of the ISIS spallation source at the Rutherford–Appleton laboratory. The data reveal some shortcomings in earlier…
Transient currents induced by the polarity reversal of a dc voltage applied to a liquid-crystal cell have been experimentally studied. For voltages less than a characteristic value, the time occurrence of the peak current decreases with decreasing applied voltage, which is contrary to behavior expected for a normal ca…
Abstract Polymerization of epichlorohydrin (ECH) in the presence of diols, catalyzed by Lewis or protic acids, proceeds by activated monomer mechanism (AMM), i.e., by subsequent additions of protonated monomer molecules to the terminal hydroxyl groups of the growing chain. As opposed to the typical active chain end me…
Low kinetic energy particle bombardment of a growing film surface has been employed to grow high‐quality copper thin films on silicon and with ideal metal/substrate interface characteristics. It is shown that the energy of Ar ions concurrently bombarding a growing film surface determines the crystal structure of the f…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSegment density distribution of symmetric diblock copolymers at the interface between two homopolymers as revealed by neutron reflectivityThomas P. Russell, Spiros H. Anastasiadis, Alain Menelle, Gian P. Felcher, and S. K. SatijaCite this: Macromolecules 1991, 24, 7, 1575–15…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHigh oxygen-evolving activity of rigidly linked manganese(III) porphyrin dimers. A functional model of manganese catalaseYosinori Naruta and Kazuhiro MaruyamaCite this: J. Am. Chem. Soc. 1991, 113, 9, 3595–3596Publication Date (Print):April 1, 1991Publication History Publish…
An indirect method to determine the oxygen dissolved in AIN is devised for AIN(Y 2 O 3 ) ceramics and then related to thermal conductivity. Dissolved oxygen is determined by first constructing the AIN‐rich corner of the AIN—Y 2 O 3 —Al 2 O 3 phase diagram (isothermal section). This is achieved by (1) measuring the tot…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and characterization of novel quasiaromatic zinc-sulfur aggregates and related zinc-oxygen complexesMarilyn M. Olmstead, Philip P. Power, and Steven C. ShonerCite this: J. Am. Chem. Soc. 1991, 113, 9, 3379–3385Publication Date (Print):April 1, 1991Publication Histo…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolymeric organosilicon systems. 10. Synthesis and conducting properties of poly[2,5-(disilanylene)thienylenes]Joji Ohshita, Daisuke Kanaya, Mitsuo Ishikawa, Tsuneaki Koike, and Toru YamanakaCite this: Macromolecules 1991, 24, 8, 2106–2107Publication Date (Print):April 1, 19…
Abstract In the presence of a catalytic amount of a nickel(II) complex coordinated with 1,3-diketone, various cyclic or acyclic ketones are converted into the corresponding lactones or esters by the Baeyer–Villiger oxidation on treatment with an atmospheric pressure of molecular oxygen (oxidant) and an aldehyde (reduc…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTUltrastructure of poly(p-phenylenebenzobisoxazole) fibersDavid C. Martin and Edwin L. ThomasCite this: Macromolecules 1991, 24, 9, 2450–2460Publication Date (Print):April 29, 1991Publication History Published online1 May 2002Published inissue 29 April 1991https://pubs.acs.or…
Abstract Five different analytical schemes for examining isothermal and nonisothermal degradation of polymers were reviewed and found inadequate for describing multistage decomposition. The different schemes were experimentally tested using thermogravimetric analysis data for an ethylene‐vinyl acetate (EVA) copolymer,…