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Poly(3-hydroxybutyrate) (PHB) was plasticized with dioctyl (o-)phthalate, dioctyl sebacate, and acetyl tributyl citrate (ATBC). The thermal properties, mechanical properties, and melt flow ability were studied with differential scanning calorimetry, thermogravimetric analysis, a universal material testing machine, and a melt flow indexer. ATBC was revealed to be an efficient plasticizer, reducing the glass-transition temperature and increasing the thermoplasticization ability of PHB. We also blended poly(3-hydroxybutyrate-co-hydroxyhexanoate) (PHBHHx) and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3/4HB)] with PHB, ATBC, and antioxidant 1010 to overcome the brittleness of PHB and improve the melt flow stability of the materials. PHBHHx did little to improve the thermal processing but increased the fluidity of PHB, and P(3/4HB) toned the toughness of PHB. The addition of antioxidant 1010 enhanced the thermal stabilization of PHB.

Boron nitride (BN), talc, hydroxyapatite (HA), and zinc stearate (ZnSt) were investigated as nucleation agents (NA) for nonfossil-based poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) plastics. Nonisothermal crystallization behaviors of the P3/4HB/NA blends were examined by DSC. It revealed that BN is the most efficient nucleation agent to promote the crystallization rate, however, but not the crystallization degree. The lasting crystallization of P3/4HB was also removed. The nucleation effect was strengthened with increase of BN content up to 1% and then slackened deeply when further BN was added. Isothermal crystallization analysis revealed that the addition of nucleation agent BN does not alter the crystal growth mode of P3/ 4HB, with maintaining the Avrami parameter n value around 2.40. Talc did enhance the crystallization of P3/4HB with however milder crystal growth rate. HA and ZnSt did not promote, but depressed the crystallization of P3/4HB plastics.

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Naturally amorphous biopolyester poly (3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) containing 21 mol % of 4HB was blended with semi-crystal poly(butylene succinate) (PBS) with an aim to improve the properties of aliphatic polyesters. The effect of PBS contents on miscibility, thermal properties, crystallization kinetics, and mechanical property of the blends was evaluated by DSC, TGA, FTIR, wide-angle X-ray diffractometer (WAXD), Scanning Electron Microscope (SEM), and universal material testing machine. The thermal stability of P3/4HB was enhanced by blending with PBS. When PBS content is less than 30 wt %, the two polymers show better miscibility and their crystallization trend was enhanced by each other. The optimum mechanical properties were observed at the 5-10 wt % PBS blends. However, when the PBS content is more than 30 wt %, phase inversion happened. And the two polymers give lower miscibility and poor mechanical properties.