SYSTEMATIC INVESTIGATIONS ON THE BIOLOGIC AL DEGRADABILITY OF PACKINGMATERIAL II - ON THE BIODEGRADABILITY OF POLYVINYLALCOHOL BASED FILMS

Earlier investigations have shown that polymers with a high density of functional groups along and/or in the molecular chain are more prone to good biodegradability than polymers with simple C-C-chains or block polymers with such ''biologically hard'' segments [1, 2]. In this cont ext, biodegradability supporting functional groups should not only be susceptible to simple removal (as e.g. the decarboxylation of COO- gro ups), but also be attractive to enzymatic attack leading to chain fiss ion by biochemical standard reactions or similar mechanisms. For the p roduction of packing films with good mechanical properties and good bi odegradablity, polymers like polyvinylalkohol and its derivatives seem to have the most encouraging properties among the water soluble films , ploy-epsilon-caprolactone and its derivatives being one of the most promising candidates for water insoluble films. Two mechanisms for the biodegradation of polyvinylalcohols-each dominating under different c onditions and for different product types-are proposed.