Effect of UV radiation on dynamic-mechanical properties of ethylene-vinyl alcohol copolymer

Opisani su struktura i svojstva kopolimera etilen/vinil-alkohola (EVOH) te utjecaj UV zračenja na dinamičko-mehanička svojstva folija kopolimera etilen/vinil-alkohola (EVOH), i to s 32 mol% i s 44 mol% etilena. Kompleksni modul elastičnosti pri dinamičkom rasteznom opterećenju frekvencijom 1 Hz i faktor prigušivanja izmjereni su metodom dinamičko-mehaničke analize (DMA) u temperaturnom intervalu od -150 °C do 130 °C za različita vremena ozračivanja. Rezultati istraživanja pokazuju da EVOH s 32 mol% etilena ima veći udio kristalne faze te je i otpornija na UV zračenje u odnosu na EVOH s 44 mol% etilena. Krutost i faktor prigušivanja mijenjaju se nakon ozračivanja, a folije naposljetku postaju jako krhke i raspadaju se.SUMMARY A description of structure and properties of ethylene vinyl-alcohol copolymer (EVOH) with 32 mol% and with 44 mol% ethylene is given and the impact of UV irradiation2147483647 on dynamic mechanical properties of 15 m thin films was studied. Complex elastic moduli and damping factors of the films that were stressed by a dynamical force with the frequency of 1 Hz were measured by means of dynamical mechanical analysis (DMA) on a temperature interval form -150 °C to 130 °C for different irradiation times. The results prove that EVOH with 32 mol% ethylene has a higher amount of the crystalline phase and that improves its UV stability compared to that of the ethylene with 44 mol% ethylene. Stiffness and the damping factor change after irradiation and the films eventually become brittle and disintegrate