MELTPROCESSIBLE STARCH COMPOSITION, A PROCESS FOR THE PREPARATION THEREOF AND THE USE OF THE COMPOSITION

摘要

The invention concerns a biodegradable starch composition, a process for the preparation thereof, the use of the composition and a process for increasing the degradation rate of intermediate products manufactured from starch derivatives and/or products made therefrom under conditions of biodegradation. According to the invention the composition contains 5 to 99 wt-% of a plastisized starch derivative and 1 to 95 wt-% of a biodegradable fibrous material. The microstructure of the composition is discontinuous and formed by a phase containing the starch derivate and a phase containing the fibrous material and any porosity, and its impact strength is at least 10 % better than the corresponding values of a plastisized starch derivative. The composition may further contain 0.01 to 30 wt.% of a biodegradable polyester, such as polylactide, polycaprolactone or a cellulose ester. According to the invention, the biodegradable starch composition is prepared by esterification of starch with glycerol in order to form a mixture containing starch acetate and acetic acid and then the mixture is blended with a biodegradable fibrous material for producing a composition which has a discontinuous microstructure. The invention provides a melt processible composition having good water resistance and mechanical properties which can be regulated by changing the relative amounts and the qualities of the components of the composition.