1a.Objectives (from AD-416):
The objective of this cooperative research project is to increase the compatibility of starch and lignin. The long-term goal of the project is to produce starch-lignin plastic materials. A national bioproduct initiative aims to increase the use of biomass for plastics and other materials. Starch and lignin are abundant natural biopolymers. Both have been used separately to produce plastic materials. Past attempts to compatibilize starch and lignin sufficiently to produce functional materials have had limited success. We expect compatibilized starch-lignin materials to show increased water resistance relative to starch-only compositions. We also expect the following outcomes: (1) increased utilization of starch; (2) increased utilization of lignin, an abundant co-product of paper manufacturing; and (3) additional alternatives to petroleum-based plastics.
1b.Approach (from AD-416):
We will test the hypothesis that the compatibility of starch and lignin can be improved through extrusion. The hypothesis will be tested by preparing formulations of varying starch-lignin-additive compositions, measuring composition-property relationships in the resulting materials, identifying the relevant molecular interactions, and optimizing the physical and mechanical properties of the resulting materials.
Polystyrene foam as packaging material is a petroleum product and harmful to the environment. Starch foams produced from extrusion are well known as biodegradable alternatives, but starch foams have less water resistance than the polystyrene foams. The scientists at the State University of New York at Binghamton and ARS scientist, prepared extruded starch-lignin foams, which have not been reported before. The properties of the foams were characterized. ARS discovered that the starch-lignin foams containing 10% lignin prepared through extrusion had good water resistance without causing any deleterious effects on density, morphology, compressive strength, or resiliency compared with unmodified extruded starch foams. The extruded starch-lignin foams can be a good candidate as biodegradable packaging material to replace the polystyrene foams. A patent and a manuscript are in preparation.