Preparation, physico-chemical characterization, and optical analysis of polyvinyl alcohol-based films suitable for protected cultivation

The use of biodegradable polymer films for mulching is a topic of great interest both from the environmental point of view and for the intrinsic properties that the above films, when appropriately designed, might have. In the present article we report on a synthetic approach that, starting from existing biodegradable polymers, leads to a new material characterized by a time-controlled biodegradation. The idea that subsides is to bridge polyvinyl alcohol (PVOH) chains through polycaprolactone (PCL) crosslinks. In such a way, PVOH looses its water sensitivity and can stand on the ground for the time needed for the mulching to occur, while the PCL crosslinks, being sensitive to (slow) fungal attack, will undergo cleavage, followed by the complete bio-assimilation of the residual PVOH chains. The number of crosslinks introduced can control time of biodegradation. The polymers are characterized in their intrinsic chemical-physical properties, while a preliminary evaluation of their efficiency as mulches is obtained through the analysis of their thermal behavior when deposited on an irrigated soil. The results are also compared with a model approach able to predict the thermal behavior of a film in specific environmental conditions. (C) 2002 Wiley Periodicals, Inc.