Abstract: Expanded articles of biodegradable plastic material having a closed pore structure and a density of from 0.01 to less than 0.1 g/cm.sup.3 are produced by extrusion of a composition including starch and a synthetic polymer selected from ethylene-vinyl alcohol, ethylene-acrylic acid, and mixture thereof.

Abstract: A polymer composition usable for the production of articles of biodegradable plastics material includes an ethylene/vinyl alcohol copolymer and destructured starch. Preferably, the composition is obtainable by mixing the ethylene/vinyl alcohol copolymer, in a heated extruder, with a starch component constituted by a destructured starch composition produced beforehand by mixing starch with a high-boiling plasticizer, such as glycerine and a destructuring agent, preferably constituted by urea, in an extruder. Alternatively, the composition can be obtained by mixing the ethylene/vinyl alcohol copolymer with starch and a plasticizer in an extruder, with water added as appropriate and possibly with a suitable destructuring agent.The composition is particularly useful for the production of films with good resistance to perforation and tearing and molded articles with improved mechanical strength. The products made from this composition are also good oxygen and carbon dioxide barriers.

Abstract: Expanded articles of biodegradable plastics are produced by the extrusion of a composition including starch, a polymer compatible with starch, in particular, an ethylene-acrylic acid copolymer and/or ethylene-vinyl alcohol copolymer, and an expanding agent. Preferably use is made of sodium bicarbonate as expanding agent in the presence of a polymeric acid.

Abstract: Formed articles comprising destructurized starch, an ethylene-acrylic acid copolymer and a product of the interaction of starch and ethylene-acrylic acid copolymer wherein the starch not bound to the copolymer is in the form of particles having sizes below 1 micron. The water content of such articles is lower than the one usually present in the starch. Said formed articles can also contain urea in an amount no higher than 30% by weight and/or ammonia in an amount not higher than 0.5% by weight. The process for obtaining such articles comprises the steps of extruding starch, an ethylene-acrylic acid copolymer and optionally water, urea and/or ammonia at a temperature ranging from 90.degree. to 150.degree. C., reducing the water content to values lower than 6% by weight and injection molding or extrusion blowing the resulting composition.

Abstract: Polymer compositions useful for the production of articles of biodegradable plastics material with improved biodegradability include destructed starch and a polymer selected from the group consisting of ethylene-vinyl alcohol, polyvinyl alcohol and mixtures thereof wherein at least a portion of the said polymer is modified by the substitution of from 0.1 to 5 molar % of the functional alcohol groups in the polymer chain by X groups in which X is an oxo or an alkyl carbonyl group in which the alkyl group contains from 1 to 4 carbon atoms.

Abstract: The material, which is usable for the production of biodegradable articles in film, sheet or fiber form, can be produced by extrusion from a molten mass including a synthetic thermoplastic polymer and a destructured starch to which a boron containing compound, such as boric acid, metaboric acid, borax and derivatives thereof has been added. Articles made of this material have improved transparency, Young's modulus and tear strength.