Water resistance,mechanical properties,and biodegradability of poly(3‐hydroxybutyrate)/starch composites

Composites of poly(3‐hydroxybutyrate), P(3HB), and starch were prepared by solution casting technique. To improve adhesion of starch to P(3HB), stearic acid was added as a compatibilizer and glycerol as a plasticizer. The water resistance, mechanical, and biodegradable properties of the P(3HB)/starch composites were studied. Diffusion and penetration coefficients of water increased with increasing starch content in the composites. The results showed that the elastic modulus and strain at rupture of the P(3HB)/starch composites were enhanced by increasing starch content upto 10 wt % and the tensile strength increased from 21.2 to 93.9 MPa. The presence of starch content higher than 10 wt % had an adverse effect on the mechanical properties of the investigated composites. The biodegradation rate using Actinomycetes increased proportionally to the starch content in the composite and accelerated in a culture medium of pH ≈ 7.0 at 30°C. Enzymatic degradation experiments showed that lipase produced by Streptomyces albidoflavus didnot degrade P(3HB)/starch composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010