Interlayer delamination and adhesion of coextruded films

摘要

Efforts to evaluate interlayer adhesion of coextruded films are often hampered by the inability to initiate delamination. On the other hand, interlayer delamination was often noticed at cut or trimmed edges of coextruded films. In this study, a test method was developed by first initiating delamination by uniaxial stretching and then measuring interlayer adhesion by peel test. Delamination was initiated by uniaxial stretching under controlled conditions for samples with double-neck geometry. The double-neck geometry was designed to create a specimen for the subsequent 180degrees peel test. Peel force was used to quantify interlayer adhesion of coextruded films based on polycarbonate and its copolymers. With this two-step technique, coextruded films with peel force as high as 5300 N/m or 30 lb./in. were quantified. In addition, effects of copolymer composition and coextrusion processing condition on interlayer adhesion of these coextruded films were clearly demonstrated. A great deal of variation of interlayer adhesion across film surface was also revealed. (C) 2004 Wiley Periodicals, Inc.