Aerobic Biodegradation of Extruded Polymer Blends with Native Starch as Major Component

The aerobic biodegradation of extruded blends containing native starch and an acetylated compound (starch or cellulose) was studied with the Bacillus amyloliquefaciens strain and also with the Biolen mixture known for its amylolytic activity. In the presented experiments, the rate of biodegradation is related to the percentage of acetylated compound in the blend. In fact, if the blend hydrolysis is facilitated by the amorphous state of the substrate, the inhibitory action of the acetyl group content is the major factor responsible of the weak hydrolysis. For instance, the conversion of the carbon material into CO₂ decreases strongly from 39% (native starch alone) to 7% (equimolar blend of starch and acetylated compound). All the other parameters used to estimate the hydrolysis extent (as the production of reducing sugars or acetic acid release) lead to the same conclusion.