The stability of vinylidene chloride copolymers in the presence of selected multifunctional amines

Vinylidene chloride copolymers, particularly acrylate copolymers, occupy a position of position of prominence in the barrier plastic packaging industry. They display excellent barrier to the transport of oxygen (to prevent spoilage of packaged food items) and flavor and aroma agents (to prevent ‘scalping’ during transport and storage). However, these polymers undergo thermally-induced degradative dehydrochlorination at process temperatures, 150–170°C. To scavenge evolved hydrogen chloride and thus prevent the formation of metal halides (Lewis acids) by interaction with the extruder walls, these materials are usually blended with a small amount of passive base prior to processing. To determine the suitability of selected commercially available multifunctional amines for this purpose, blends containing 1–10% of various amines with a standard vinylidene chloride/methyl acrylate (5 mol%) copolymer have been examined by thermogravimetry. In general, the amines studied are sufficiently basic so as to promote dehydrochlorination.