Materials Literature
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Abstract The imidization of films of the polyamic acid obtained from reaction of pyromellitic dianhydride (PMDA) with oxydianiline (ODA) was studied by dynamic mechanical thermal analysis (with the Polymer Labs DMTA), Two process regions are observed. The first process is characterized by decomplexation of the NMP/pol…
A procedure is derived for proper refocusing of a dielectric-filled Rotman lens with beam port locations determined according to Snell's law. The theoretical performance of such a lens is compared with that of a conventional design at wide scan angle and the design equations for correct refocusing of the refracting le…
Binary mixtures of octyloxyphenyl-nitrobenzoyloxy benzoate (${\mathrm{DB}}_{8}$${\mathrm{ONO}}_{2}$) and decycloxyphenyl-nitrobenzoyloxy benzoate (${\mathrm{DB}}_{10}$${\mathrm{ONO}}_{2}$) exhibit a rich variety of smectic polymorphism. An ac calorimetric study has been carried out on six mixtures with mole percent X…
For pt.I see ibid., vol.37, no.3, p.534-41 (1989). Two analytical small-argument solution procedures for integral equations are presented. Explicit expressions for the elements of the coupling matrices in the small-aperture and small-obstacle ranges are derived for both TE and TM polarizations. Simple and useful equiv…
Abstract This paper is a continuation of a previous one on bifurcation of deep boreholes under uniform stress at infinity, 1 and it focuses on the effect of borehole radius on borehole stability. Rock is described by the equations of a deformation theory of plasticity for cohesive‐frictional, incompressible materials…
Abstract The growth rate dispersion (GRD) is reviewed from its start up to today. A definition is given followed by a summary of the facts and the first approaches for explanations. This all are surface reaction steps. The discussion of the consequences – no size dependent growth – is carried through. At the end the m…
Abstract Thermal behavior and degradation mechanisms of three polyester resins, namely bisphenol A based, isophthalic acid based, and general purpose were studied. These resins were cured with styrene in the presence of benzoyl peroxide (BPO) and methyl ethyl ketone peroxide (MEKP) as initiators. The cured resins were…
The thermal diffusivity of a well-characterized boron phosphide (BP) single-crystal wafer made by a chemical vapor deposition process was measured by a unique ring-flash light method. Thermal conductivity calculated from the products of thermal diffusivity, specific heat capacity, and density of the wafer yields a hig…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTResonance Raman spectra and normal-coordinate analysis of reduced porphyrins. 1. Zinc(II) tetraphenylporphyrin anionMichael Atamian, Robert J. Donohoe, Jonathan S. Lindsey, and David F. BocianCite this: J. Phys. Chem. 1989, 93, 6, 2236–2243Publication Date (Print):March 1, 1…
Mixtures of SF6 (100 kPa≤PSF6≤400 kPa) and water (concentrations ranging from 240 to 2000 vpm) have been submitted to point-plane 50-Hz ac corona discharges. The only stable gaseous by-products detected, either by gas-phase chromatography or gas chromatography–mass spectrometry techniques, were SOF2 and SO2F2. The var…
Abstract It is well known that during the sulfur curing of unsaturated rubbers, two competing reactions occur: (a) crosslinking or vulcanization, and (b) reversion or devulcanization. In the case of butyl rubber, these two competing reactions have been summarized in earlier reports. Tire curing bag (bladder) compounds…
Monodispersed ZrO 2 seed particles which were prepared by hydrolysis of zirconium alkoxide solutions were allowed to grow by further addition of zirconium alkoxide and water under conditions in which new particles do not nucleate and grow. The particle growth mechanism is presumed to be a surface reaction in which the…
Abstract An apparatus has been constructed that permits the measurement of time‐dependent changes in pressure near the point of vitrification. The same instrument is used for measuring steady‐state PVT properties, which are necessary for a proper analysis of the dynamic measurements. The former experiments are referre…
Abstract The organometallic oxide clusters [(MCp*)4V6O19] (M = Rh, Ir; Cp* = C5Me5) were prepared and characterized by elemental analyses, SIMS as well as IR and NMR (1H, 13C, 17O, 51V) spectroscopy. Single crystal X-ray analysis showed that [(RhCp*)4V6O19]·4CH3CN·H2O contains the vanadate hexamer core (V6O19). The rh…
An efficient and reliable method for characterizing the nature of stacking fault tetrahedra in f.c.c. metals using electron microscope diffraction image contrasts is presented. By using the 220 reflection, and thereby eliminating the contrast from overlapping stacking faults, one can differentiate between intrinsic-ty…
Abstract When chemical additives were found that could minimize the loss of chemical and physical properties of a thermally‐processable but heat‐sensitive polymer called poly(vinyl chloride) (PVC), an industry was born. And with it grew the world of plastics additives. Stabilizers for PVC became and industry itself, f…
The normal voltage failures in multilayer ceramic capacitors (MLC) using the temperature-humidity-bias test (THB) are described. The cumulative failure data showed that the MLC failures occurred in several stages during the THB test, with the extent of failures depending on the quality of the capacitor lot and the bia…
The essential oil of Bupleurum fruticosum was investigated qualitatively and quantitatively together with the anti-inflammatory activity of the whole essential oil and its major components. In addition, antispasmodic activity was determined in rat uterus preparations using acetylcholine and oxytocin as agonists. The a…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffect of nematic interaction in the orientational relaxation of polymer meltsMasao Doi, Dale Pearson, Julie Kornfield, and Gerry FullerCite this: Macromolecules 1989, 22, 3, 1488–1490Publication Date (Print):March 1, 1989Publication History Published online1 May 2002Publish…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics and mechanisms of thermal imidization of a polyamic acid studied by ultraviolet-visible spectroscopyEumi Pyun, Richard J. Mathisen, and Chong Sook Paik SungCite this: Macromolecules 1989, 22, 3, 1174–1183Publication Date (Print):March 1, 1989Publication History Publ…