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Multiple cracking of a thin platinum film deposited on polyethylene terephtalate, isoprene rubber, and natural rubber substrates under tensile deformation was studied by light and scanning electron microscopy. The cover fractures on several fragments elongated in the direction perpendicular to the loading direction. The width of the fractured platinum fragments depends on the thickness of the deposited layer and applied tensile stress. A semiempirical equation describing the average width of the cover fragments was obtained. Appearance of a wavy pattern on an originally smooth surface of composites with rubberlike polymer substrate was observed. The mechanism of the appearance of the surface wave is a mechanical buckling instability of the cover under compressive force.

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Self-diffusion of three high generations (the fifth, sixth, and seventh) of poly(allylcarbosilane) dendrimer in solutions with deuterated chloroform has been studied over a wide range of macromolecular concentrations (φ). Diffusivity has been measured by NMR with a pulsed gradient of the magnetic field. It is shown that concentration dependences of the dendrimer self-diffusion coefficients (D) can be reduced to the generalized concentration dependence. Over the range of volume concentrations from 0.01 up to 0.55, the curve of the generalized dependence of D for dendrimers coincides with the analogous dependence for globular protein in aqueous solutions. Analogous to the universal concentration dependence of D for linear polymers in solvent, the generalized concentration dependence of dendrimers tends to the asymptote D′(φ)/D 0 ∝ φ 0 ) 1 in the limit of extremely dilute solutions and to the asymptote D′(φ)/D0 ∝ φ -3 in the range of concentrated solutions 0.3 < φ < 0.55. Here, D0 ) limφf0 D(φ) and D(φ) are the self-diffusion coefficients of dendrimer in an extremely dilute solution and in a solution with macromolecular concentration φ, respectively. D′(φ) ) D(φ)/L(φ), where L(φ) is a normalizing function, taking into account the change of the local mobility of dendritic branches as the macromolecular concentration increases; the L(φ) functions have been experimentally extracted from the concentration dependence of the longitudinal relaxation times for the dendrimers in solutions studied.

Molecular forms of silica based on polyethoxysiloxane, silicasol, and tetraethoxysilane, being prospective fillers for polymer nanocomposites were prepared and studied thoroughly by gel permeation chromatography (GPC), viscometry, dynamic light scattering (DLS), thermomechanics, and wide angle X-ray scattering (WAXS). All synthesized objects were shown to possess the structure of ''core -shell'' type. Particle radius varies in a range of 0.5-10 nm. The core structure depends on a method of preparation, while a particle morphology (share of core and shell) may be regulated within every of three methods. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: [4310][4311][4312][4313][4314][4315][4316][4317][4318][4319][4320][4321][4322] 2010

Based on the results of Part 1 of this work, we have chosen acrylonitrile copolymers for preparing dopes in dimethyl sulfoxide (DMSO). Modeling the spinning process in static conditions was carried out by following the evolution of the interaction between a drop of solution and precipitant. In addition, the diffusion zone was controlled by the laser-interference method. Fibers were spun on a laboratory stand. It was found that the optimal ratio of DMSO to water in a coagulation bath was 85/15. The analysis of the structure of different fibers (including fibers with carbon nanotubes) demonstrated the superposition of crystalline phase and orientation-disordered mesophase. The evolution of this structure could provide the answer to the question of which structure of "white" fibers is best for obtaining high-quality "black" fibers. Measurement of the structure and mechanical properties of fibers allowed us to optimize the technology of thermal treatment of fibers including the intensity of heat output in the stages of thermal-oxidative stabilization and carbonization as well as the strain characteristics and applied tension. Model carbon fibers have a satisfactory complex of mechanical properties. We aimed to choose a set of experimental approaches as a proper way to produce high-strength carbon fibers.

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