Using Microcellular Starch Foam as an Environmentally Benign Filler in Paper Venditti and Pawlak, Paper Science and Engineering Introduction The objective of this project is to determine if starch can be substituted as a filler in the production of paper. An additional objective is to describe the effect this change has on the physical properties of the sheet. Research in the area of microcellular starch foams is important because there is potential to introduce sheet properties that will create a stronger, less dense sheet. Also, starch is a readily available, renewable, and biodegradable resource that could prove more cost effective and environmentally conscious that current filler technology. The proposed research will address the problem of determining an optimal method of incorporating the microcellular starch foam into the sheet. Once the foam is successfully added to the sheet, the effects of the starch foam on the mechanical properties of the sheet will be determined. Project Additional Information This project will be primarily experimental. A peer reviewed journal article will be prepared on the results. An experienced post doc will mentor the student. The project is currently being funded by the USDA so there is some support for supplies and equipment. The student should have basic undergraduate chemistry through organic chemistry. Any experience with polymers and chemical engineering principles is a plus. Background The worldwide availability and low cost of starch make it a desirable raw material to use in industrial processes. Approximately 4.5 billion pounds of starch were used in annually in the US for industrial applications in 1991, much of that being used in the paper industry. Currently, starch is used by the paper industry as a wet-end additive, surface coating, and as an adhesive. Starch, being a biodegradable resource derived from a renewable resource is highly attractive when compared to petroleum based resources or resources mined from the earth. Microcellular foams are low density, solid foams. They consist of a solid matrix with air-filled pores. Starch based foams can be made using methods originally developed for other polymeric materials. Microcellular foams can be made by gelatinizing starch then cooling the gel in a mold. Air-drying causes the porous structure to collapse, but freeze-drying preserves the structure and promotes low-density foam. Alternatively, the water can be replaced with a low surface tension liquid such as ethanol and liquid carbon dioxide and then extracted to preserve the matrix structure . The solvent-exchange process can be used with various types of starches, including high-amylose corn and wheat starches. The starch foams formed are white, opaque, and have densities ranging from 0.1 to 0.32 grams per cubic centimeter. Research Plan Microcellular foams from starch will be produced with varying amounts of sizing agents using solvent exchange methods. The foams optical properties and structure will be determined. An interpretation of the structure/properties relationship of the solid foams will be proposed. The foams will then be ground into particles for incorporation into paper. The paper samples with and without the starch foams incorporated will be produced, analyzed, and interpreted. Properties of the paper (optical and mechanical) will be determined versus type and concentration of the foam particles.