Interest and durability of multilayers: from model films to complex films.

In a first part, this paper focuses on the interest of using a multilayer for vacuum insulation panels envelope. It is shown that piling up layers of metallized poly(ethylene terephthalate) does not seem to improve the initial barrier performance. In parallel, a permeation model to predict barrier properties of multilayer films was developed and validated with experimental results. In a second part, durability of a multilayer composite was investigated using accelerated hydrothermal ageing tests. It is shown that physical properties and in particular barrier properties decrease with ageing time. Polyurethane layer used as adhesive system in multilayer films is responsible for complete degradation of aluminum layer after 6 ageing months at 70°C - 90% relative humidity. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]