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Polymer surface tension and properties of state
Jůza, Josef
This contribution presents transformation of some well-known equations expressing surface tension using state properties and other parameters to express the ratio of the surface tension to the drop density, which is more reliable and available even if density is unknown.
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Impact of weathering on chemical and morphological changes in stabilized polymers
Pospíšil, Jan ; Pilař, Jan ; Billingham, N. C. ; Marek, Antonín ; Kruliš, Zdeněk ; Nešpůrek, Stanislav ; Habicher, W. D.
Photooxidation, considered as the principal component of natural and accelerated weathering, affects together with oxygen,oxidizing and acid atmospheric pollutants durability of stabilized polymers by changing their chemical and supramolecular structure and influencing efficiency of stabilizers. Effects of the harshness of accelerated photooxidation, negative influences of atmospheric pollutants, heterogeneity in polymer oxidation together with formation of concentration gradients in stabilizer consumption and spatial distribution of stabilizer sacrificial transformation products are outlined. The data give more information on processes accompanying testing of stabilizer polymers and help to minimize misleading influences from over-accelerated tests.
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Thermoanalytical evaluation of the oxidative stability of liquid polybutadienes
Kovářová, Jana ; Podešva, Jiří
Hydroxy-terminated liquid polybutadienes, as commercially available polymeric diols, are used in teh production of special types of elastomeric polyurethanes. A comparison of the oxidation susceptibility in a series of hydroxy-terminated polybutadiene rubbers in relation to the degree of hydrogenation shows that the oxidative stability of liquid rubbers gradually increases with the decreasing content of double bonds in the 1-PB chains.
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Molecular current switch
Nešpůrek, Stanislav ; Sworakowski, J.
Scheme of an optically controlled current switch is put forward, based on properties of a conducting polymer containing photochromic moieties chemically attached to the main chain. The idea is supported with results of calculations of local states for charge carriers formed in the vicinity of dipolar species in molecular materials, and with measurements of the drift mobilities in polysilane copolymers containing polar benzaldehyde 2,4-dinitrophenyl-hydrazone groups.
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