Extruded starch-lignin foams
AssigneeThe Research Foundation for The State University of New York
InventorEugene S. Stevens
Life of this patent
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Abstract
Extruded starch foams are well known as biodegradable alternatives to foamed polystyrene packaging materials. Extruded foams of unmodified starch replacing 1% to 20% of the starch with kraft lignin were prepared. At 10% lignin, there are no deleterious effects on foam density, morphology, compressive strength, or resiliency as compared to a starch extruded foam, yet the foam retains its integrity after immersion for 24 hours in water. At 20% lignin there is a decrease in compressive strength and resiliency. Addition of cellulose fibers restore the mechanical properties but with an increase in density.
Claims17
An expanded cellular structure, comprising:
- a mixture of:
- chemically unmodified starch consisting essentially of unmodified amylose and unmodified amylopectin;
- about 9-18% by weight lignin;
- and
- about 5-10% by weight cellulose fibers,
- wherein a uniform cell structure is distributed throughout the expanded cellular structure, and the expanded cellular structure has a unit density of about 36-61 kg/m3, a resiliency of about 56% to 72%, a compressive strength of at least 0.16 MPa, and retains structural integrity after 1 hour of aqueous immersion.
An expanded cellular structure formed by a process comprising:
- mixing chemically unmodified starch consisting essentially of chemically unmodified amylose and chemically unmodified amylopectin, about 5-10% by weight cellulose fibers, and about 9-18% by weight lignin in an aqueous medium, and
- extruding the mixture under sufficient heat and pressure to yield an expanded cellular structure,
- wherein a uniform cell structure is distributed throughout the expanded cellular structure, having a density of about 36-61 kg/m3, a resiliency of about 56% to 72%, a compressive strength of at least 0.16 MPa, and sufficient water resistance to retain structural integrity after 1 hour of aqueous immersion.
Dependencies are inferred from the claim text.