Starch based Bioplastics
One of the most abundant renewable resource biodegradable polymers found in nature is starch. These natural polymers can be derived from various agricultural resources including corn, wheat, and potatoes. Starch polymers are usually found as micron sized granules, and are made of amylose and amylopectin.
As shown in above figure, amylose is a linear polymer with 200 – 2000 of anhydroglucose units. Amylopectic is is a brached polymer and contains 20- 30 anhydroglucose units. The relative ratio of amylase and amylopectim in starch granules could vary with the source. The highly ordered structure causes the starch granules to be highly crystalline.
Depending on the performance properties of the target product, starch can be blended with other renewable resource or conventional polymers. For example, Mater Bi biodegradable bioplastics are made by blending starch with Polyesters. Over the years, research was devoted to get starch based thermoplastics with better properties. Errec et al has reported improved mechanical properties of starch thermoplastics that were blended with castor-oil-based polyurethanes.
Applications of Starch based bioplastics include disposable products such as shopping bags, bread bags and bait bags.
Yongshang Lua, Lan Tighzerta, , , Patrice Doleb and Damien Errec. Polymer, 46, (23, 14), 2005, 9863-9870