Effect of UV radiation on dynamic-mechanical properties of ethylene-vinyl alcohol copolymer previously conditioned in water

Etilen/vinil-alkohol (EVOH) je kopolimer koji se sastoji od nepolarnog polietilena niske gustoće i polarnog poli(vinil-alkohola). Ovaj polimerni materijal se primjenjuje kada je postavljen zahtjev da proizvod bude nepropustan za plinove. Polimerni materijali podložni su raznim degradacijskim procesima uslijed izlaganja vanjskim uvjetima, što bitno utječe na njihova svojstva. Pomoću dinamičko-mehaničke analize ispitivani su uzorci EVOH folija s različitim udjelima etilena. Analiziran je utjecaj i UV zračenja na vodom zasićene folije i relaksacijske procese u njima. Uzorci folija su naizmjence držani u vodi pa ozračivani u kraćim ciklusima sve do ukupnog vremena zračenja od 45 minuta. Premda se uspoređivani kopolimeri jedva razlikuju po kemijskom sastavu, utjecaj vode i UV zračenja razlikuje se u ovisnosti o omjeru komponenata.Ethylene vinyl alcohol (EVOH) is a copolymer of a non-polar low density polyethylene and polar poly(vinyl alcohol). This type of polymer is used when low gas permeability is needed. Polymers are susceptible to different degradation processes when exposed to external conditions. Those degradation processes have a significant impact on their properties. Dynamic Mechanical Analysis was performed on samples of EVOH foils with different ethylene content. The influence of UV radiation on water saturated foils and relaxation processes within them were analyzed. Foil samples were alternately held in water then irradiated in short cycles in order to achive a total of 45 minutes of irradiation time. Although the compared copolymers have a slight difference in their chemical composition the water and UV irradiation effect differs depending on the component ratio