Robert E. Wrisley

Improvements in flex oxygen barrier properties of polymeric films by microlayer coextrusion

This study describes a process technology to maintain or improve the gas barrier property of ethylene vinyl alcohol (EVOH) barrier films after flexing. EVOH and polyethylene-grafted maleic anhydride (PE-g-MA) multi- and microlayer samples with 5, 19, and 35 layers were produced in a coextrusion line. Flexing was performed using a Gelbo flex tester (400 flexes). After flexing, pin hole tests were performed on the film and only those with fewer than two pin holes were re-tested for oxygen transmission rate (OTR). Pin holes decreased after 400 Gelbo flexes as the number of layers increased. The OTR on these films demonstrated that thin EVOH barrier layers can improve film flex crack resistance. This proves that for a given barrier resin total thickness the flex barrier property can be increased dramatically by microlayering.