Polymer blends of biodegradable or bio-based and synthetic polymers and foams thereof

A process for making a foam structure, comprising:

• providing at least one alkenyl aromatic polymer in the amount between about 10 to 90 percent by weight of a blend;
• providing at least one bio-based or biodegradable polymer selected from polylactic acid and copolymers thereof or polyglycolie acid and copolymers thereof in the amount between about 10 to 90 percent by weight of the blend;
• providing at least two blend compatibilizers comprising a first blend compatibilizer selected from the group consisting of styrene-ethylene-butene-styrene and maleated styrene-ethylene-butene-styrene and a second blend compatibilizer selected from the group consisting of styrene-maleic anhydride copolymer and styrene-methyl methacrylate copolymer;
• forming the blend by blending the at least one alkenyl aromatic polymer, at least one bio-based or biodegradable polymer, and at least two blend compatibilizers;
• extruding the blend to form an extrudate;
• and
• expanding the extrudate to produce the foam structure, wherein the foam structure comprises at least about 0.2 percent by weight of the first blend compatibilizer and at least about 0.5 percent by weight of the second blend compatibilizer, and up to about 10 weight percent of the at least two blend compatibilizers, collectively.

A bio-based or partially biodegradable thermoplastic foam composition comprising:

• a foamed polymer blend of:
• at least one alkenyl aromatic polymer in the amount between about 10 to 90 percent by weight of the blend;
• at least one bio-based or biodegradable polymer selected from polylactic acid and copolymers thereof or polyglycolic acid and copolymers thereof in the amount between about 10 to 90 percent by weight of the blend;
• and
• at least two blend compatibilizers comprising a first blend compatibilizer selected from the group consisting of styrene-ethylene-butene-styrene and maleated styrene-ethylene-butene-styrene and a second blend compatibilizer selected from the group consisting of styrene-maleic anhydride copolymer and styrene-methyl methacrylate copolymer,
• wherein the foamed polymer blend comprises at least about 0.2 percent by weight of the first blend compatibilizer and at least about 0.5 percent by weight of the second blend compatibilizer, and up to about 10 weight percent of the at least two blend compatibilizers, collectively.

A bio-based or partially biodegradable thermoplastic foam article comprising:

• a foamed polymer blend of:
• at least one alkenyl aromatic polymer in the amount between about 10 to 90 percent by weight of the blend;
• at least one bio-based or biodegradable polymer selected from polylactic acid and copolymers thereof or polyglycolic acid and copolymers thereof in the amount between about 10 to 90 percent by weight of the blend;
• and
• at least two blend compatibilizers comprising a first blend compatibilizer selected from the group consisting of styrene-ethylene-butene-styrene and maleated styrene-ethylene-butene-styrene and a second blend compatibilizer selected from the group consisting of styrene-maleic anhydride copolymer and styrene-methyl methacrylate copolymer,
• wherein the foamed polymer blend comprises at least about 0.2 percent by weight of the first blend compatibilizer and at least about 0.5 percent by weight of the second blend compatibilizer, and up to about 10 weight percent of the at least two blend compatibilizers, collectively.