Properties of baked starch foam with natural rubber latex

Petroleum-based synthetic plastics used for making consumer articles constitute the largest non-renewable source of municipal solid waste in the United States. Containers and packaging products represent the largest group within plastic waste in municipal landfills. Efforts are being made worldwide to search for renewable and biodegradable substitutes for non-biodegradable plastics. Starch from surplus commodity crops has been investigated as a possible replacement, but it does have some disadvantages such as its susceptibility to water owing to its highly hydrophilic nature. To improve the water resistance of starch-based products, we incorporated natural rubber latex into baked starch foams based on wheat, potato, and waxy corn starches. While latex increases the density of the foam, it also improves the flexibility of the product. Stabilization of the latex with non-ionic additives helped prevent irregularities in the foam product. The flexural properties of these foams are comparable with commercial products and can be ‘tuned’ by varying the starch type and adjusting the latex concentration. Latex also decreases the equilibrium moisture content and decreases the effect of higher humidity on the foam products.