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Modifikace izotaktického polypropylenu
Ličko, M. ; Jeníková, Z. ; Rybníček, J. ; Horník, J. ; Steidl, J. ; Raab, Miroslav
Injection moulded samples of polypropylene were used to study the effect of trigonal .beta.-phase and ethylene propylene rubber on mechanical-physical properties in respect to microstructure. The results were compared with pure isotactic polypropylene, .beta.phase induced by 0.33 weight percent of a nucleation reagent and 20 weight percent of EPM rubber increases the toughness of iPP. A substantial increase in toughness was observed by combining both additives resulting in spherolite refinement and reduction in amorphous content. However, the improvement in toughness was at the expense of the yield strength and modulus of elasticity.
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Optické a elektrické přepínání v organických polovodičích
Vala, M. ; Weiter, M. ; Nešpůrek, Stanislav ; Zmeškal, O.
The work deals with tuning of electro-optical properties of polymeric media using reversible light-driven switching of photochromic spiropyran guest molecules. The significant change of dipole moment during the photochromic conversion allows construction of simple switching units. Optical responses of such devices were studied using absorbance and photoluminescence, electrical responses, were detected by impedance measurements.
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Polymers and people
Raab, Miroslav
This lecture offers a chronological survey of the most important inventions in polymeric materials and their inventors. Special attention is devoted to the role of serendipity that seemingly assisted to some great discoveries.
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Vývoj fázové struktury při toku polymerních směsí
Fortelný, Ivan
State of art in description of the phase structure development in flowing polymer blends is discussed. It is shown that the rule satisfactorily predicting a type of the phase structure does not exist. Graphic solution of the equation describing dynamic equilibrium between the droplet breakup and coalescence provides satisfactorily prediction of the dependence of average droplet size on system parameters.
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