Relationship Between Crystallization, Mechanical Properties, and Disintegration in Compost of Polyhydroxybutyrate Containing Different Nucleating Agents

Polyhydroxybutyrate (PHB) is one of the most promising bio-based and biodegradable polymers because of its highly interesting properties. In this paper, we report an in-depth study on the crystallization kinetics induced by different nucleating agents and how the obtained morphology can be related to the mechanical behavior and capacity of disintegrating in a composting environment. The different nucleating agents are added at a fixed content to PHB by melt compounding. The crystallization process is studied by DSC and the crystalline morphology by polarized optical microscopy. Mechanical performance is studied both by tensile and impact tests. Disintegration in compost, which represents the first step of the biodegradation process, is also performed. As a result, the nucleating efficiency of the different additives is evaluated, demonstrating how a more effective nucleating process is related to better mechanical properties. Finally, although PHB shows a good disintegration in compost in all cases, the presence of the nucleating agents, and thus a different crystalline morphology, leads to a slower compost disintegration process.