14A-27

Packaging materials are typically made of polystyrene, vermiculite and other non-biodegradable plastics.  These materials are generally a problem for waste reduction.  More recently, starch based materials have come into the marketplace but also contain toxic or difficult to degrade substances and are nearly as expensive as Styrofoam beads.  Additionally, our Marine Pollution Act has forced us to develop biodegradable plastic materials so we can dispose of them at sea.

 

The objective of this work was to develop biodegradable packaging materials from rice flour for the military and private commercialization.  These materials need to be biodegradable in the marine environment but low in density and high enough in strength to support the shipped item.  In this work, we have developed both beads and a sheet material that can be made out of rice pieces or flour costing about 10 cents a lb. compared to polystyrene costing about 80 cents per lb.

 

These were made by extrusion in a single or twin-screw extruder.  To make the product, rice flour (or broken grains), water and glycerol were puffed through an extruder and dried. Textures ranging all the way from brittle to soft and spongy could be obtained through the correct addition of glycerol and water.  The addition of polyethylene glycol was less effective than the glycerol as a softening agent or plasticizer. Addition of monoglycerides made a stronger expanded product but it was much more brittle.  The cost of this process is much less than other plastic foam beads and boards on the market.  They are highly biodegradable, approximately 80% mineralization after several days, but have low resistance to water.  Appropriate inhibitors for insect, mold and fire resistance can also be formulated into this product. Unlike Styrofoam materials, this product has little static electricity charge.