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The structural changes after ageing of polyurethane by UV irradiation has been studied by comparative spectroscopic measurements. The polyurethane was prepared from diphenylmethane-4,4'-diisocyanate, (MDI) and polyester from adipic acid and ethylene glycol. The experimental results show that various oxidized structures are formed in UV degraded samples with simultaneous decomposition of polyurethane. This leads to the formation of new structures such as carbonyl, azo, carbodiimide, quinoid as well as polyene sequences. According to the experimental results and the data taken from the literature, the mechanism of the process was discussed.

Swelling measurements in six organic solvents were carried out on samples of dicumyl peroxide crosslinked ethylene-propylene-diene (EPDM) having various crosslink densities. The Flory-Huggins interaction parameter x was determined for EPDM vulcanizates 312 and 812 as well as their mixture 312/812 using the FloryRehner equation. The results show that the x parameter for the crosslinked polymer is greater than for the uncrosslinked one and is a linear function of the crosslink density. The swelling behavior of the networks were also interpreted by the FloryErman theory using the structural factor F 4 to characterize the network and its behavior during the swelling. The obtained x values indicate that broadening of the molecular mass distribution, in the Gaussian region of distribution, mixture 312/812, increases interactions with solvents.

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Eight samples of poly(ethy1ene-co-propylene-co-diene) (EPDM, were vulcanized with 0.5-8.0 phr dicumyl peroxide. The influence of molar volumes V of cyclohexane, hexane, heptane, iso-octane, tetrachloromethane, carbon disulfide, xylene, benzene, toluene, tetrahydrofuran, trichloromethane and chlorobenzene on the swelling intensity of the EPDM vulcanizates was studied, and it was found that regardless of the solubility parameters, polarity, dielectric constants, acidity or basicity of solvents, a linear relationship exists between Vl and number of moles of solvent in the gels, n,. With increase of V,, n1 decreases. ZUSAMMENFASSUNG:Acht Proben von Poly(ethy1en-co-propylen-co-dien) (EPDM, 55 Gew.-% Ethylen) wurden mit 0,5-8,0 phr Dicumylperoxid vernetzt. Der EinfluB der Molvolumina (V,) von Cyclohexan, Hexan, Heptan, iso-Octan, Tetrachlormethan, Schwefelkohlenstoff, Xylol, Benzol, Toluol, Tetrahydrofuran, Trichlormethan und Chlorbenzol auf das Quellungsvermogen der vulkanisierten EPDM-Proben wurde untersucht. Es wurde gefunden, daR unabhangig von den Loslichkeitsparametern, Polaritaten, Dielektrizitatskonstanten, Aciditat und Basizitat der Losungsmittel eine lineare Beziehung zwischen V, und der Anzahl der Mole Losungsmittel im Gel (n,) besteht. Mit zunehmendem Vl nimmt nl ab.