The infra-red spectra of gaseous and liquid acrylonitrile have been studied from 2.5 μ to 25 μ with a spectrometer using LiF, CaF2, NaCl, and KBr prisms. The Raman spectrum of the liquid has been obtained, including intensity and polarization data. A normal coordinate calculation of the non-planar frequencies has been made, using force constants from related molecules. This information permits a complete assignment of the fifteen fundamental frequencies and a calculation of the thermodynamic quantities for the molecule.
This paper outlines the design and construction of a fast, highresolution, moderate-dispersion grating spectrograph suitable for use in an industrial laboratory. The experimental techniques found satisfactory for the obtaining of Raman spectra in a routine manner are described along with the special appurtenances necessary for such work. Many structural problems which are soluble by the
By means of initiation with ionizing radiation, styrene and 2,4‐dimethylstyrene have been polymerized in the crystalline solid state, in the pure liquid state, and in solution at different temperatures (−80°C. to 25°C.). In solution polymerization, it has been found that for the same type of initiation, other conditions being constant, the mechanism by which these monomers polymerize is temperature‐dependent. At lower temperatures a cationic mechanism predominates; at higher temperatures a free‐radical mechanism is in the ascendency. At intermediate temperatures, both cationic and freeradical polymerizations take place. Furthermore, these intermediate temperatures are different for different monomers, being higher in a monomer whose electronic structure is more favorable for cationic polymerization. The difference in mechanism at different temperatures has been proved by: (1) the dose rate dependencies, both of the polymerization rates and of the molecular weights of the resulting polymers; (2) the activation energies for the polymerization; and (3) the relative reactivities in the polymerizations of styrene and substituted styrenes.
Chloromethylstyrene monomer was grafted to 3 denier (preformed) polypropylene fibers by using ionizing radiation. At elevated temperatures, microscopical investigations of changes in diameter and in birefringence demonstrated that this monomer swells the fibers without dissolving them. Thus, it is comparatively simple to achieve grafting all the way to the center. Such grafted fibers can be dyed by direct or acid dyes in non‐aqueous baths (e.g., dimethylformamide at 210°C.) using levels of graft of ∼25% by weight. This leads to covalent bonding arising from reaction between the dye and the benzyl chloride group of the graft. Dyeing in standard aqueous baths can also be achieved at even lower levels of graft (less than 10% by weight) if the grafted material is treated with a nucleophilic reagent such as pyridine. Using thin cross sections of treated fibers, photomicrographs were taken with monochromatic UV radiation, and with visible light on color film. These, combined with electron micrographs of much thinner cross sections provide pictorial proof of the complete penetration of the graft and of the dyes as well as showing the opening up of the structure effected by grafting. By the means employed, it was possible to achieve marked improvements in dyeability, sticking temperature, moisture regain, and antistatic behavior without diminishing the excellent mechanical properties of the polypropylene fibers.
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