Showing papers by "Ministry of Supply published in 1960"

Solvent effects on infra-red group frequencies

Abstract: In previous publications we have shown that solvent effects on group frequencies can be studied conveniently by plotting the relative frequency shifts ∆ ν/ν of one solute in a series of solvents, directly against the corresponding values for some other (Bellamy, Hallam & Williams 1958). Thus, ∆ ν/ν the values for the NH stretching frequency of pyrrole yield a linear plot against the ∆ ν/ν values for any other X —H stretching absorption such as the O—H of methanol or the B—H of decaborane. These relations hold over a wide range of different solvents, and each X H compound has a characteristic slope when plotted in this way against a common standard. The slopes measure the relative proton donating powers of the solutes. Similar plots have been obtained for a large number of carbonyl compounds (Bellamy & Williams 1958). Here the pattern of solvent effects is altogether different from that given by X —H links as the dipole available for solvent association is reversed. The sensitivity of individual carbonyl compounds to solvent effects varies widely and seems to depend upon a number of different factors.

Atmospheric salinity and metal corrosion at various places in great britain

Abstract: An account is given of the distribution of chloride, sulphate and ammonia in airborne particles at many sites in Great Britain. The distribution of chloride, subject to many local anomalies, has the same general relation to distance from the sea as was found in West Africa.1 The atmospheric corrosion of steel and zinc varies comparatively little between sites and bears no relation to salinity. Movement of exposed surfaces increases salt deposition and the corrosion of metals.

Solvent Effects on the Infra-Red Spectra of Hindered Phenols

Abstract: The effects of variation in the shapes of the solvent and solute molecules have been studied in the hindered phenol series. When a solvent/solute complex is broken by thermal agitation it seems that reassociation of the phenolic OH with another solvent molecule occurs very rapidly. However, the introduction of bulky substituents in the immediate neighbourhood of the OH group lengthens the time between collisions suitably oriented for association. It then becomes possible to detect free OH absorptions corresponding to solute molecules in transit from one molecular association to another. These occur even in such strongly bonding solvents as ethers, and the proportions increase with the complexity of the hindering groups. Similar effects are found when a hindered phenol is examined in a series of solvents of increasing complexity, confirming that there is a dynamic equilibrium between free and associated OH groups. The OH group in the hindered phenols is largely coplanar and only in the 2,6-di- tert. -butyl derivative is there any direct steric hindrance to the approach of the solvent molecule.

Methods op burnins rate control in solid propellants

Abstract: The experimental methods used for determining the burning rates of solid propellants at rocket pressures are briefly described The two main classes of solid propellant, namely double base and composite are then discussed The relationships between burning rate and chemical composition for both classes are considered, and the effects of operating pressure, temperature, and erosion on propellant burning are reviewed In the composite propellant field, particular mention is made of pressed charges based on ammonium nitrate as the oxidizer, and on plastic propellants based on ammonium perchlorate as the oxidizer Present limitations on burning rates are discussed, and the modification of burning rate by the addition of lower energy materials, such as dinitrotoluene or ammonium picrate, is mentioned The stabilization of burning at low pressures by the addition of potassium cryolite, or other refractory materials, is considered Recent published papers on solid propellant burning rates and on the mechanisms proposed for the combustion of the various types of solid propellants are reviewed