Compatibilization of blends of polyethylene with a semirigid liquid crystalline polymer by PE-g-LCP copolymers

The blends of thermoplastics with liquid crystalline polymers show, in general, poor properties because of the lack of adherence between the two phases. The use of ad hoc synthesized copolymers containing the monomer units of the two polymers has been recently considered by some of us for blend compatibilization, and the results appear promising. In this work, new PE-g-LCP copolymers, prepared either by the synthesis of the LCP in the presence of a functionalized PE, or by reactive blending of the latter polymer with preformed LCP, have been employed as compatibilizing additives for blends of PE with a semirigid LCP. The morphology and the rheological and mechanical properties of the ternary blends, compared with those of samples without compatibilizers, or containing conventional maleic anhydride grafted PE, indicate that the PE-g-LCP copolymers do in fact lead to an improvement of interfacial adhesion, both in the melt and in the solid state, as well as to a modest enhancement of the mechanical properties. The results may be rationalized considering that the PE-g-LCP copolymers used by us consist of fairly short PE backbones with LCP grafts of various length. The molecules with longer LCP branches are thought to become mixed at the surface of the LCP particles and to give rise to fairly weak interaction with the PE matrix. It is argued that new PE-g-LCP copolymers synthesized from higher molar mass functionalized PE samples might show much better compatibilizing performance.     

Actual nutrition and health of several groups of rural and urban population of the Republic of Georgia]

The results of the study have shown that the nutrition of rural population is characterized by excessive consumption of bread and baked products, by high content of phosphorus, magnesium and iron, low content of animal proteins, vegetable oils, calcium, vitamins A, ascorbic acid and riboflavin. The incidence of cardiovascular, respiratory and alimentary diseases in this group of population was rather high. The nutrition of students is characterized by excessive consumption of polysaccharides, vegetable oils, thiamine, niacin, ascorbic acid (in winter-spring period), and calcium. Diseases associated with nutrition disorders (obesity, hepatitis, cholecystitis, colitis) are most often recorded in this group of population.     

Study of submicron deposits in polycrystalline materials using the internal-friction method

An internal friction method is proposed for investigating the kinetics of impurity deposits on grain surfaces in polycrystalline samples. The possibilities of the method have been tested on polycrystalline, gas-sensitive, tellurium-doped layers of tin dioxide. Fiz. Tekh. Poluprovodn. 31, 841–843 (July 1997)     

On the form of the elastic potential relative to different reference states

Summary Using the method of wavefront analysis the paper presents an analysis of shock wave formation in a two-dimensional steady supersonic flow of a radiating gas past plane and axisymmetric bodies such as a beak and sharp edged ring. Transport equations are derived which lead to the determination of the shock formation distance and also to conditions which insure that no shock will ever evolve on the wavefront. It is assessed as to how the shock formation distance is influenced by the presence of thermal radiation, the initial body curvature and upstream flow Mach numberM ₀>1.With 1 Figure     

Redistribution of alloy elements in aging of austenitic chrome-manganese steel containing nitrogen

Conclusions In interrupted decomposition of the austenite of chrome-manganese steel containing nitrogen in the 600–900°C range the alloy element content in the nitride phase formed changes. The quantity of chromium increases while that of iron decreases significantly. The manganese content in the nitride is low and remains approximately constant.The residual austenite in the grains which have undergone interrupted decomposition is gradually depleted of chromium and nitrogen.The growth of pearlitelike colonies consisting of transformed austenite and type M₂N nitride is controlled simultaneously by the mechanisms of grain-boundary and three-dimensional diffusion.Institute of Metallurgy and Metals Technology, Sofiya, Peoples Republic of Bulgaria. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 60–61, November, 1988.     

Phase transitions occurring in glassy chalcogenide semiconductors induced by electric field or laser pulses

Order-disorder phase transitions in thin films of glassy chalcogenide semiconductors of the system Ge-As-Te, which take place during times on the order of microseconds in micron-sized volumes, have been studied and analyzed. The relationship between the reversible structural transitions induced by laser light pulses and the reversible semiconductor-metal transition taking place in a strong electric field is discussed. It is shown that the film can be taken repeatedly through a reversible phase transition in the conductivity at ∼500–600 K, as previously established. It has been shown that repeated transition from the crystalline to the glassy state is possible without destruction of the material for a wide range of power levels for durations of the laser light pulse less than a few microseconds, and that this fact plays a decisive role in the reversible structural transformations. It is shown that the existence of such a range of power levels is attributable to overheating. Fiz. Tekh. Poluprovodn. 32, 939–943 (August 1998)