Abstract: Biodegradable thermoplastic polymer blend compositions are presented in which a first polymer and a second polymer are intimately associated together in a uniform, substantially homogeneous blend. The second polymer of the composition acts to facilitate biodegradation of the composition, and of shaped articles manufactured therefrom, at a rate which is enhanced over that of the most slowly biodegrading individual polymer component of the composition. The composition may further comprise a polysaccharide component, such as a starch component like destructurized starch.

Abstract: Composite polymeric articles, which may be in layer or film form, comprise a larger portion of a polymer which is water soluble at 20.degree. C. against a smaller proportion of a polymer which is substantially water-insoluble at that temperature. For example, a layer product may have a thin layer (e.g. less than 5 microns) of insoluble polymer superimposed on a thicker layer (e.g. at least 20 microns) of soluble polymer. Both polymers are conveniently polyvinyl alcohol, which is non-toxic and useful in a number of domestic applications, e.g. as a diaper backing sheet. The insoluble portion gives water resistance but negligible mechanical strength; the soluble part gives the mechanical strength. On dissolution of the soluble portion, the insoluble portion disintegrates mechanically. Articles may be made by co-extrusion or by molding.