Materials Literature
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Abstract There are wide discrepancies in the literature values for the heat of fusion (Δ H u ) of isotactic polypropylene. A study was therefore made of the variables affecting Δ H u as determined by differential thermal analysis. The results of this study show Δ H u for 100% “crystalline” polypropylene to be 2400 cal…
It is shown that a dc electric field can generate continuous oscillations of current in a CdS crystal provided a region of higher resistivity exists near the positive electrode of the sample. Frequency measurement reveals the existence of two kinds of periods. One corresponds to a round-trip of sound waves in the samp…
Abstract The reaction rates for the uncatalyzed as well as the dibutyltin dilaurate‐catalyzed reactions between polyether polyols and tolylene diisocyanate (80/20 mixture of 2,4 and 2,6 isomers) are reported. Titration and infrared absorption methods were used for the determination of the residual isocyanate content,…
The hea t of combustion of a luminum carbi de (Al, 0 3) in oxyge n was m eas ured by mea ns of bomb calorimetry. The solid produ ct of t he co mbust ion cons ist ed of alpha a luminum oxi de a nd a nother crystalline form of a lumina, whi ch was characterized as delta alumi na . The h eats of combustion wer e correcte…
Torque and susceptibility measurements with well annealed and chemically polished crystals of CoO were made down to 90°K. When cooled through the Néel point of 20°C with a temperature gradient along one of the cubic principal axes, the crystals yielded torque and susceptibility curves that are attributable to nearly u…
Birefringence patterns in antiferromagnetic NiO crystals were investigated with the orthoscope and conoscope methods using a polarizing microscope. A new birefringence pattern (p-domain pattern), which differs from usual twin domain patterns in NiO crystals, was found within a crystallographically single domain in rat…
The transformation from one resistance state to another by glasses in the system As‐Te‐I is discussed and a model is postulated. The anomalous behavior of the electrical properties of glasses in this system is shown to result from thermal breakdown of the dielectric during which reversible glass‐to‐crystal phase trans…
A study has been made of the morphology of fractionated linear polyethylene crystallized from solution in n-alkanes. Crystals have been found whose habits, though markedly different from any described in this polymer, are similar to, and provide useful models for, the radial crystalline units in melt-grown spherulites…
Monatomic and alternating diatomic chains, with nearest neighbour harmonic interactions, are considered; in each case the force constants are governed by a probability distribution function which is continuous and bounded in a well-defined region and zero elsewhere. It is shown that the lattice modes are, in general,…
The ranges of electrons in evaporated films of aluminium, copper, silver and gold have been measured for incident energies E 0 between 5 and 20 keV. From electron transmission measurements the maximum range and the extrapolated range were determined. Energy loss measurements gave the mean range and the Thomson-Whiddin…
Abstract X‐ray diagrams of different samples of nylon passed over a hot‐plate held at different temperatures show that the observed effect depends on the type of nylon used. Clear evidence consistent with the melting of the core of the nylon is obtained for monofilament.
This article describes work carried out in UKAEA laboratories to examine the possibility of using protective coatings on cadmium plate—such as that used to protect mild steel—in order to prevent or minimise corrosion due to hostile organic vapours. The degree of attack by vapours of acetic, formic, butyric and propion…
In FeTiO 3 , CoTiO 3 and NiTiO 3 the dominant magnetic exchange interactions are held to be of super-superexchange type, using two oxygens or one oxygen and one diamagnetic Ti 4+ ion between the pairs of paramagnetic cations. In order to explain the antiferromagnetic ordering of manganese spins in the same layer in Mn…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAnalysis of Mixtures of Hydroxyl Compounds Using Differential Reaction Rates.Friso. Willeboordse and F. E. CritchfieldCite this: Anal. Chem. 1964, 36, 12, 2270–2274Publication Date (Print):November 1, 1964Publication History Published online1 May 2002Published inissue 1 Nove…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPyrolytic Conversion of 7,7-Dichloronorcarane to CycloheptatrieneG. C. RobinsonCite this: J. Org. Chem. 1964, 29, 11, 3433–3434Publication Date (Print):November 1, 1964Publication History Published online1 May 2002Published inissue 1 November 1964https://pubs.acs.org/doi/10.…
Abstract The thermal degradation in oxygen of a number of fluorine‐containing polymers has been studied by using a weight loss technique. The relative thermal stabilities of the different polymers have been determined and, where possible, the overall activation energy and frequency factors for their breakdown. The res…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Crystal Structure of Strontium Bromide MonohydrateMaurice Dyke and Ronald L. SassCite this: J. Phys. Chem. 1964, 68, 11, 3259–3262Publication Date (Print):November 1, 1964Publication History Published online1 May 2002Published inissue 1 November 1964https://pubs.acs.org/…
Abstract Further studies on the thermal degradation of POPG‐TDI polymer have been carried out. It has been shown that at temperatures of ∼200°C., the predominant degradation process involves random scission of the urethane linkages to give substantial amounts of isocyanate and hydroxyl. Kinetic data suggests that the…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHexachlorotungstate(V) CompoundsR. N. Dickinson, Susan E. Feil, F. N. Collier, W. W. Horner, Sally M. Horner, and S. Y. TyreeCite this: Inorg. Chem. 1964, 3, 11, 1600–1603Publication Date (Print):November 1, 1964Publication History Published online1 May 2002Published inissue…
Lithium ferrite, an inverse spinel with an order-disorder transition at about 800°C, has been grown in the ordered state. The narrowest ferromagnetic resonance linewidth yet observed in a spinel has resulted from the growth of single crystals of lithium ferrite in the ordered state. Details of the growth conditions, m…