Current mass production bioplastics are based on starch and have been refined over the last two decades. Starch is a polymeric glucose used by plants to store energy, it is composed of two types of polysaccharides: amylose and amylopectin. Amylose is an unbranched form polysaccharide and of interest for bioplastic production due to its compact configuration that has higher crystallinity. Amylose is present in 20-30% of plant derived starch but high amylose starches are available commercially, known as hylon VII.
Open source projects
Hobbyists have demonstrated a high amylose starch bioplastic that has high strength and good optical properties as a film. The process involves mixing 25:25:1 amylose starch:water:plasticizer and heating in a modified pressure cooker at 154 C and 55 psi.
Publically available information
High amylose starch
Composites of starch bioplastics with cellulose have increased strength, durability, and water resistance (see Cellulose acetate). Composites with clay or metals may be effective at increasing strength and altering other properties of the plastic, such as heat resistance.
The properties of starch bioplastics may be improved by substituting other functional groups for the glucose hydroxyl groups, such as acetate. This is an area of active research and has been found to improve product characteristics for injection molding.