ABSTRACT
The conversion of vinyl acetate polymers or copolymers to the corresponding polyvinylalcohol is an industrial process, applied mostly to (co)polymers containing a large amount of vinylacetate, at least 40%. This chapter discusses the reactivity of various alcohols in presence of two types of catalysts, respectively sodium methanolate and dibutyltin dilaurate. It analyses the kinetic data based on a homogeneous reaction showing that the high level of conversion is directly connected with an equilibrated reaction of transesterification. Chemical reactions carried on in molten polymers may be complicated by problems related to the limited solubility of reagents or catalysts and, as it is generally the case in polymer modification, by side reactions lowering the expected conversion level. The transesterification reaction of molten ethylene and vinyl acetate, in presence of paraffinic alcohols and basic catalysts, leads to high conversion of the ester groups to secondary alcohol in both discontinuous and continuous processing equipments.
