Thermal degradation of vinylidene chloride/butyl acrylate copolymers

Vinylidene chloride/acrylate copolymers display a good barrier to the trans port of small molecules (oxygen, carbon dioxide, water, etc.) as well as to flavor and aroma constituents of food items. For this reason. they occupy a place of prominence in the barrier plastic packaging industry. However, a t process temperatures, these materials tend to undergo degradative dehydro chlorination. This is a typical radical chain process with distinct initiat ion, propagation, and termination phases and if unchecked can lead to the d evelopment of coloration which may be objectionable in some applications. T o examine the influence of an aliphatic side chain on this process, a serie s of vinylidene chloride/butyl acrylate (4, 8, 12, 18, 20 wt.%) copolymers have been sythesized and fully characterized by chromatographic, thermal, a nd spectroscopic methods and by thermogravimetry. Increasing levels of buty l acrylate in the copolymer have little impact on the rate of initiation of degradation but do modestly decrease the propagation rate for the degradat ion. (C) 2000 Elsevier Science B.V. All rights reserved.