Materials Literature
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An opti cal and electron microsco pi cal study is PJese nte d of th e habits exhibited by chainfolded polyoxymethylene crys tals grow n from hot 0.02 percent solutions of th e polymer in orthodi chlorobe nzene when th ese solutions are cooled to temperatures (Te) between 140 and 80 C inclus ive . In co ntras t with th…
A transmission and scanning electron microscope study was made of cell wall development in the root velamen of Ansellia gigantea. The pattern of fibrillar deposition in the primary walls was established by means of shadowed surface preparations. The helical wall thickenings were shown to originate by the localised app…
Summary Experimental procedures giving complete unimolecular surface coverage of montmorillonite by ethylene glycol (EG) are described. The EG sorption data, excluding rate effects, are independent of the nature of the exchangeable cations associated with the clay surfaces. The amount of EG sorbed (0.357±0.007 g EG/g…
Abstract The adsorption of Cl by Andepts from Mexico, Colombia, and Hawaii was measured in solutions of HCl, HCl + NaCl, and AlCl 3 . Chloride adsorption varied from 0‐8 meq/100 g at pH 6 to as much as 32 meq/100 g at pH 3.8. At given pH, adsorption was concentration‐dependent in a manner consistent with the Langmuir…
Abstract Soil carbohydrate in thirteen different profiles was investigated using gas‐liquid chromatography to identify and determine quantities of monosaccharides released by acid hydrolysis. Total quantities of monosaccharides extracted by sulfuric acid were positively correlated with organic carbon for the soils stu…
Abstract The magnetic susceptibilities of manganese(II) phthalocyanine (PcMn) have been measured in the paramagnetic region between 13.8 and 280 K. The deviation from the Curie-Weiss law was found at a moderately high temperature (about 70 K), and the Weiss constant was obtained as 23 K. Comparing the ratio of Tc to θ…
Abstract Erucamide has, to a great extent, replaced the use of oleamide because of its higher mp and higher heat resistance. These properties are desirable because of the higher operating temperatures of newer polymers. Various derivatives are discussed, such as N‐stearyl erucamide, which has a still higher mp and gre…
Samples of low-density polyethylene, free from additives, were kept at temperatures between 284° and 355°C under nitrogen containing 1.16% oxygen or less. Changes in molecular weight distribution (MWD) and degree of long-chain branching (LCB) were followed by gel chromatography (GPC) and viscosity measurements. Other…
We have measured energy loss cross sections for 2000-keV 4He ions in a number of elements and in their solid compounds. Observed compound values were compared with those predicted by linear combination of elemental values by using Bragg's rule. Within an experimental uncertainty of ∼2%, we report agreement in each cas…
Summary The arsenopalladinite concentrates from Itabira, Minas Gerais, Brazil, have been found to contain three arsenide-antimonides of palladium, namely arsenopalladinite, atheneïte, and isomertieite. The second and third of these are new minerals. Arsenopalladinite, redefined, is Pd 5 (As,Sb) 2 and triclinic with a…
Abstract Fatigue is defined as decay caused by cyclic deformations at an amplitude less than necessary for fracture in one cycle. Such failures are initiated by flaws which act as stress concentrators. These flaws occur in the material either through mechanical or chemical action during service or through agglomeratio…
Previous studies of gas diffusion in glass have suggested that the activation energy is a continuous function of temperature. Several models have been offered to explain this departure from the Arrhenius behavior commonly observed in diffusion studies. These models are compared with each other and with a new model whi…
Abstract A polymer, poly(2,5‐trimethylene benzimidazole), the first of a new family of nonsymmetrical polymers, was synthesized via an eight‐step synthetic route. The polymer, obtained by melt polymerization, is amorphous and in its neutral form behaves as a moderate insulator. It forms 1 : 1 HCl adducts. When cast fr…
ADVERTISEMENT RETURN TO ISSUEPREVArticleHydrogen-Transfer Polymerization of Acrylic Acid to Poly(β-propiolactone)Takeo Saegusa, Shiro Kobayashi, and Yoshiharu KimuraCite this: Macromolecules 1974, 7, 2, 256–258Publication Date (Print):March 1, 1974Publication History Published online1 May 2002Published inissue 1 March…
Abstract The four pasture species alfalfa ( Medicago sativa L.), subterranean clover ( Trifolium subterraneum L.), Harding grass ( Phalaris tuberosa L.), and perennial ryegrass ( Lolium perenne L.) were grown in pots on an acid sandy loam soil treated with CaCO 3 and H 2 SO 4 to give a pH (0.01 M CaCl 2 ) range from 4…
Abstract 1,3‐Bis( p ‐phenoxybenzenesulfonyl)benzene and 4,4′‐bis( p ‐phenoxybenzenesulfonyl)‐diphenyl ether were polymerized with isophthaloyl and terephthaloyl chloride in Friedel‐Crafts type polymerizations. These polymers had 5‐cyanoisophthaloyl units in the backbone, obtained by using 5‐cyanoisophthaloyl chloride…
Observations on a glass tube filled with the liquid crystal N-P-cyano-benzylidene-p-n-octyloxyaniline (CBOOA) and which has been treated so that the CBOOA lies radially at the innerwall are presented. We have cooled the CBOOA tube through the nematic-smectic A transition temperature, Tc . Our results may be summarized…
The phase diagram of the system Ga-Se has been determined by the differential thermal analysis (DTA). The main features of the diagram are as follows: (1) the melting point of GaSe is 938±3°C and Ga 2 Se 3 is 1005±3°C. (2) the monotectic transition occurs at 915°C in the lower composition region than 50 at.%Se. (3) th…
Abstract The crystal structure of polyisobutylene was determined by x‐ray analysis. The orthorhombic cell, with a = 6.88 Å, b = 11.91 Å, c (fiber axis) = 18.60 Å (space group: P 2 1 2 1 2 1 − D ), contains two molecular chains each consisting of eight monomeric units in the fiber identity period. The chain conformatio…
The factors which determine the resolution and sensitivity of electron spectrometers are discussed. Various types of instruments commonly used in X-ray or ultraviolet photoelectron spectroscopy are reviewed, mainly from an electron-optical point of view. The influence of fringing fields and preretardation on resolutio…