Biodegradable polymeric compositions comprising starch and a thermoplastic polymer

摘要

Polymeric compositions comprising thermoplastic starch and a thermoplastic polymer incompatible with starch, in which the starch constitutes the dispersed phase and the thermoplastic polymer constitutes the continuous phase, selected:
<UnorderedLists id="ula01" listStyle="none"><ListItem>A) from compositions comprising an agent with an interfacial effect selected from esters of polyols with mono- or polycarboxylic acids with dissociation constants within certain limits, the esters having specific values of the hydrophillic/lipophilic balance index HLB or being amongst the non-ionic surfactants which are soluble in water but cannot significantly be extracted by water from the compositions which contain them,</ListItem><ListItem>B) from compositions wherein the thermoplastic polymer is an aliphatic or aliphatic-aromatic copolyester wherein the ratio R between the average viscometric molecular weight and the melt index is greater than 25,000 and</ListItem><ListItem>C) from compositions wherein the thermoplastic polymer is selected from aliphatic-aromatic copolyesters, polyester-amides, polyester-ethers, polyester-ether-amides, polyester-urethanes and polyester-ureas and wherein the compositions are obtained by extrusion of the component maintaining a water content during the mixing stage from 1 to 5% by weight.</ListItem></UnorderedLists>