In order to develop new eco-sustainable technologies to set up biodegradable films for agricultural activities, spray mulching coating have been planned, prepared and tested on experimental fields. The innovative approach of film forming consists on spraying aqueous solutions of natural polymers on the soil thus obtaining, after water evaporation, a continuous, protective, thin, waterproof coating, able to follow the unevenness of the soil surface. The suitable polymers used to this purpose were selected among biodegradable, biocompatible and non-toxic polymers, derived from available and renewable resources; therefore polysaccharides were chosen as the basic ingredients in the new-waterborne formulations developed. Due to their biodegradability, polysaccharides may be left on the soil or buried inside it and microorganisms degrade them transforming in carbon dioxide or methane, water and biomass. The mulching coating formed on the top soil must be water- resistant to assure both its durability and its covering function all over the crop growing period. The natural polymers selected in this study came from terrestrial origin, such as Arabic Gums and from marine origin, such as Agarose. To improve the mulching power and to increase the tensile strength of the film formed upon drying, in the new water-born formulations fillers like cellulose fibres were mixed to the polymeric matrices, together with natural plasticizer like glycerol and polyglycerol. The formulations experimented on the soil for the crop growing of lettuce consists of a water mixture of the galactomannans Locust bean gum and Guar gum at a concentration of about 1.5% of each component with the addition of a non-gelling concentration of agarose; to this blend, 1.5 % of glycerol and some fibres have been added. The water soluble blends were experimented on cultivations plots in open field and in greenhouse. In this work the attention is focused on the study and characterization of films peeled off from the soil at successive times. It was so possible to collect a sampling, that, throughout mechanical, morphological and water vapour transmission rate analysis, could give us information about the effect of the aging due to the permanence of the materials on the soil. Moreover it was possible to provide information about the influence of the different environment on the films performances. After about two months of aging and testing, we could assert that the different setting of natural aging influences the final properties of the films: the films aged in greenhouse showed better results as regarding their durability and permeability to water vapour. As regarding biodegradability, all the films showed, by morphological analysis, the same profile of decomposing.. At last, as concerning the agronomic point of view, the easy handling, the weeds suppression and the water resistance of the films evidence better performances mostly for the greenhouse films.
Characterizations of galactomannans and cellulose fibres based composites for new mulching spray technique
2008
Abstract
In order to develop new eco-sustainable technologies to set up biodegradable films for agricultural activities, spray mulching coating have been planned, prepared and tested on experimental fields. The innovative approach of film forming consists on spraying aqueous solutions of natural polymers on the soil thus obtaining, after water evaporation, a continuous, protective, thin, waterproof coating, able to follow the unevenness of the soil surface. The suitable polymers used to this purpose were selected among biodegradable, biocompatible and non-toxic polymers, derived from available and renewable resources; therefore polysaccharides were chosen as the basic ingredients in the new-waterborne formulations developed. Due to their biodegradability, polysaccharides may be left on the soil or buried inside it and microorganisms degrade them transforming in carbon dioxide or methane, water and biomass. The mulching coating formed on the top soil must be water- resistant to assure both its durability and its covering function all over the crop growing period. The natural polymers selected in this study came from terrestrial origin, such as Arabic Gums and from marine origin, such as Agarose. To improve the mulching power and to increase the tensile strength of the film formed upon drying, in the new water-born formulations fillers like cellulose fibres were mixed to the polymeric matrices, together with natural plasticizer like glycerol and polyglycerol. The formulations experimented on the soil for the crop growing of lettuce consists of a water mixture of the galactomannans Locust bean gum and Guar gum at a concentration of about 1.5% of each component with the addition of a non-gelling concentration of agarose; to this blend, 1.5 % of glycerol and some fibres have been added. The water soluble blends were experimented on cultivations plots in open field and in greenhouse. In this work the attention is focused on the study and characterization of films peeled off from the soil at successive times. It was so possible to collect a sampling, that, throughout mechanical, morphological and water vapour transmission rate analysis, could give us information about the effect of the aging due to the permanence of the materials on the soil. Moreover it was possible to provide information about the influence of the different environment on the films performances. After about two months of aging and testing, we could assert that the different setting of natural aging influences the final properties of the films: the films aged in greenhouse showed better results as regarding their durability and permeability to water vapour. As regarding biodegradability, all the films showed, by morphological analysis, the same profile of decomposing.. At last, as concerning the agronomic point of view, the easy handling, the weeds suppression and the water resistance of the films evidence better performances mostly for the greenhouse films.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
