Abstract: Blends of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) ［P(3,4HB)］ and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were prepared by using a solvent mixing method, and their mechanical properties were investigated. Moreover, the blends were also characterized by differential scanning calorimetry and thermogravimetry analysis. Microbiological degradation behaviors of blend was studied by using a Pseudomonas mendocina DS04-T bacterium, and then scanning electron microscopy was conducted to characterize the microstructure of the test sheets after biodegradation. The results indicated that the blends exhibited optimal mechanical properties in tensile strength and elongation at break when the weight ratio of P(3,4HB) and PHBV was set at 80/20. A stable crystal structure was observed in the blends due to good interaction and miscibility between two phases when the loading of PHBV was less than 60 wt %. The degradation time of the blends was much shorter than that of pure P(3,4HB) with the aid of Pseudomonas mendocina DS04-T bacterium.

Key words: poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), modification, microbiological degradation