Performance of an acrylic-acid-grafted poly(3-hydroxybutyric acid)/starch bio-blend: characterization and physical properties

In this study, a fully biodegradable poly(3-hydroxybutyric acid) (PHB) and starch blend (PHB/starch) was prepared by means of a melt-blending method. In addition, the acrylic-acid-grafted PHB (PHB-g-AA) was studied as an alternative to PHB. It was found that the dispersion of starch in the polymer matrix and the water resistance of PHB-g-AA/starch were better those of PHB/starch, due to the formation of ester carbonyl function group via reaction between the –OH group of starch and the anhydride carbonyl group of PHB-g-AA. As the result of mechanical test, the PHB-g-AA/starch blends not only gave larger values of tensile strength than those of the PHB/starch blends, but also provided a plateau value of tensile strength when the starch content was up to 50 wt%. Furthermore, the PHB-g-AA/starch was more easily processed than the PHB/starch because the former had lower melt viscosity than the latter. Biodegradation tests of blends were also studied under the enzymatic environment, and the result showed that the mass of blends reduced by about the starch content within 6 weeks.