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Poly (3-hydroxybutyrate) (PHB) is a valuable bio-based and biodegradable polymer that may substitute common polymers in packaging and biomedical applications provided that the production cost is reduced and some properties improved. Blending PHB with other biodegradable polymers is the most simple and accessible route to reduce costs and to improve properties. This review provides a comprehensive overview on the preparation, properties and application of the PHB blends with other biodegradable polyesters such as medium-chain-length polyhydroxyalkanoates, poly(ε-caprolactone), poly(lactic acid), poly(butylene succinate), poly(propylene carbonate) and poly (butylene adipate- co -terephthalate) or polysaccharides and their derivatives. A special attention has been paid to the miscibility of PHB with these polymers and the compatibilizing methods used to improve the dispersion and interface. The changes in the PHB morphology, thermal, mechanical and barrier properties induced by the second polymer have been critically analyzed in view of industrial application. The biodegradability and recyclability strategies of the PHB blends were summarized along with the processing techniques adapted to the intended application. This review provides the tools for a better understanding of the relation between the micro/nanostructure of PHB blends and their properties for the further development of PHB blends as solutions for biodegradable packaging. [ABSTRACT FROM AUTHOR]

Poly(3-hydroxybutyrate) (PHB) is a promising substitute to petroleum-based polymers in packaging and biomedical applications provided that its melt processability and degradability are improved. A new method to control the properties of PHB by using cheap calcium stearate (CS) as a lubricant and decomposition catalyst in melt-mixed PHB-CS compounds was first used. CS is composed of a metallic cation, which promotes PHB degradation, and a hydrophobic anion that improves the compatibility with PHB and processability. An environmentally friendly melt mixing technique was employed to obtain the PHB-CS compounds. Incorporation of 0.5 or 5 wt% CS reduced the melt viscosity and molecular weight of PHB, decreased the melting temperature with up to 5 °C, the crystallization temperature with more than 25 °C, and the degradation temperature with 15 and 40 °C, respectively. In small amounts (0.05 wt%), CS improved the processability and mechanical properties of PHB. In higher amount (0.5 wt%), CS slightly improved the Young's modulus, reduced the tensile strength and enhanced degradation. A better control of thermal and mechanical properties of PHB is, thus, possible by using different CS amount and processing conditions. These results are relevant for PHB application in the context of the global transition to biodegradable packaging. [ABSTRACT FROM AUTHOR]