Biodegradable polymers for agriculture
One of the principal problems encountered in hot climatic environments is the supply of good quality water. When this is combined with the loss of water in irrigation systems through drainage, heat and wind, it became necessary to use polymers for storing water close to crops. However, with the recent introduction of landfill taxes (in certain countries) and the general increase in polymer disposal costs, an Italian institute saw the need for biodegradable alternatives. The research institute investigated two known polymers with a view to fusing them into strong water resistant films that will breakdown when composted. It was noted that Polyvinlalcohol (PVOH) was a classic example of a biodegradable polymer and when melt processed it could be manufactured into a clear durable film. Of all the polymers investigated, it was shown to degrade far faster due to its greater sensitivity to water. The second polymer to be chosen was functionalised Polycaprolactone (PCL). The investigation proved that the cross linking of the biodegradable bridges between PVOH and PCL provided a blended film that exhibited long lasting water resistance. But the most interesting aspect was when the blended film was buried in soil. It was shown that microorganisms attacked the PCL bridges, and the PVOH would then degrade quite easily due to its water sensitivity. Additional benefits for this new material will no doubt find their way into the household horticultural industry, in the form of grow bags, and water retention devices used for hanging baskets. Yet there is one other polymer that currently inflicts substantial damage to the environment; and that is the humble supermarket carrier bag. This blended polymer (PVOH-x-PCL) could therefore render this, the world’s biggest environmental eyesore into the environmental history books - for all time.
