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structure and properties of macromolecules

elasticity of macromolecular networks

-- The theory of elasticity of Gaussian networks has been developed on a more general basis and the equations of state relating variables of pressure, volume, temperature, stress and strain have been precisely formulated.

Simple elongation has been treated in detail.

The various stress-temperature coefficients for constancy of volume and strain, constancy of pressure and strain, and constancy of pressure and length have been interrelated.

The dilation accompanying elongation and the simultaneously developed anisotropy of compressibility have been related to the elongation.

In continuation of these theoretical studies, a more precise elucidation of the effects of imperfections in network structure is sought.

( P. J. Flory, C. A. J. Hoeve ) chain conformations of polymeric chains

-- Recent theoretical work to calculate the dimensions of polymeric chains by Volkenstein and Lifson has been extended to include more general types of chains.

The mean-square end-to-end distance of the polyisobutylene chain has been calculated in reasonable agreement with values deduced from viscosity data.

These studies are being extended to different polymers to increase our knowledge about the hindrances to rotation around chain bonds.

( C. A. J. Hoeve, A. A. Blumberg ) crystallization in polymers and copolymers

-- The crystallization of copolymers comprising Af units interspersed with a minor percentage of Af is limited by the inability of the crystal lattice characteristic of the former to accommodate the bulky side group of the latter.

Only uninterrupted sequences of the former are eligible for formation of crystallites.

Limitations on the lengths of these sequences diminish the stability of the comparatively short crystallites which can be formed, and this is reflected in a broadening of the melting range.

( Robert Chiang, J. B. Jackson, P. J. Flory ) Carefully executed melting studies on this system ( M. J. Richardson ) permit quantitative estimation of the instability engendered by reduced crystallite length.

The complex morphology of polycrystalline homopolymers is necessarily dependent on the same factor.

Hence, the present studies offer a possible basis for interpretations in the latter field.

Contraction of muscle

-- Glycerinated muscle, in the presence of the physiological agent ( ATP ) responsible for delivering energy to the mechanochemically active proteins of muscle, has been shown to undergo a contraction which is highly sensitive both to temperature and to solvent composition in mixtures of alcohols and water.

Experiments carried out over long periods of time in order to allow establishment of a steady state have shown that the onset of contraction and its completion are confined to an interval of several degrees Centigrade and to a concentration range of only several per cent.

The contraction therefore partakes of the character of a phase transition.

While ATP appears to be necessary for the occurrence of contraction, its presence and enzymatic hydrolysis of it by the muscle protein myosin are not the only criteria for contraction.

( C. A. J. Hoeve, P. J. Flory ) anionic Polymerization

-- One of the principal aims of anionic polymerization techniques is the synthesis of polymers of extremely narrow molecular weight distribution.