The other theory is that the water present in the granuleat around 5–10% of the total content could act as a plasti-cizer, forming hydrogen bonds with the carbonyl groupsof P(3HB) [19]. The proposal is that this hydrogen bondingprevents strong dipole–dipole interactions from occurringbetween the C O and CH3groups in P(3HB) [19,158,159].Once this P(3HB)-bound water is removed, in situ crystal-lization can then occur due to increased hydrogen bonding,in a similar manner to the crystallization process on coolingfor pure P(3HB) [19,158].Once released from the granule structure, PHA crys-tallinity then develops and is core to the overall end-useproperties of PHA including their physical, chemical,mechanical and rheological characteristics [148].