A novel approach to design chitosan-polyester materials is reported. The method is based on mechanical activation and effective intermixing of the substrates under high pressure and shear deformation in the course of solid-state reactive blending. The marked departure of this approach from previous practice resides on exploitation of a variety of chemical transformations of the solid polymers that become feasible under conditions of plastic flow. Low temperatures (aboveTgbut below the melting points of the crystalline polymers) are maintained throughout the process, minimizing mechanical and oxidative degradation of the polymers. Morphology as well as structural, mechanical, and relaxation properties of those prepared blends of chitosan with semicrystalline poly(L,L-lactide) and amorphous poly(D,L-lactide-co-glycolide) has been studied. Grafting of polyester moieties onto chitosan chains was found to occur under employed pressures and shear stresses. The prepared polymer blends have demonstrated an amphiphilic behavior with a propensity to disperse in organic solvents that widens possibilities to transform them into promising materials for various biomedical applications.

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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In this work, for the first time, we described the possibility of eliminating the brittle fracture of filled polymer nanocomposites in orientation stretching by preliminary compression deformation and small uni form shear deformation before stretching. After such a treatment, the polymer composite material becomes capable of experiencing larger deformation elonga tions in stretching.Orientation stretching is known to be an efficient way to improve the mechanical properties of polymer materials [1]. However, such stretching of polymer composite materials filled with various dispersed fillers is often accompanied by their brittle fracture even early in the deformation [2].We studied specimens of a polymer composite (PC) based on polypropylene (commercial polymer of HC101BF grade (Borealis, Vienna, Austria) with a melt flow rate of 3.2 g/10 min) containing 5 wt % of a standard nanodiamond blend produced by detonation synthesis (ZAO Almaznyi Tsentr, St. Petersburg, Rus sia). The nanodiamond soot is a finely dispersed filler of a new type, which is promising for using in polymer composites [3,4]. The mixing of the components (polymer and soot powders) and the homogenization of a polymer composite melt were performed in a dou ble screw micro mixer at 200°C. Polymer composite specimens shaped as 0.5 mm thick plates were pre pared by compacting the material at 200°C with sub sequent fast cooling (quenching) in water with ice. This ensured the formation of a "structureless" amor phous-crystalline polymer matrix, which itself is gen erally well deformable in stretching [5]. The reference specimens (RS) were made from the initial polypropy lene without nanodiamond soot, which was prepared by slowly cooling the melt. According to polarized light optical microscopy data, this propylene had a developed large spherolite supermolecular structure incapable of experiencing large deformation elonga tions in stretching [5].The pretreatment of test specimens was performed in a special setup (Fig. 1). It produced a combination of compression and uniform shear of a specimen placed between plates made of a plastic Pb-Sn alloy while extruding through a conical die of a certain diameter, which determined the preliminary strain in treated specimens (specimens PC tr and RS tr ).The subsequent orientation stretching and record ing of the stress-strain curves of the specimens PC, PC tr , RS, and RS tr were performed at room tempera ture in a Shimadzu AGS 10 universal testing machine in uniaxial stretching mode at a relative deformation rate of 1 min -1 .The large and small angle X ray scattering studies and also the determination of the change in the speci men thickness in the necking region by X ray nanog raphy in the nanography mode were carried out on a Bruker NANOSTAR system (CuK α radiation) equipped with an area detector. Isotropic specimen Pb-Sh alloyOriented specimen Fig. 1. Setup for uniform shear of a material.