On Morphology of Polyhydroxybutyrate - Progress in Organic and Physical Chemistry: Structures and Mechanisms - page 238

FIGURE 2 Dependence of melting point PHB (Ɍ m ) from electrical dipole moment of
dissolvents (—).
18.4 CONCLUSION
Summarizing all told, it is possible to conclude that, with increase in polarity of dis-
solvent its ability to enter interacting with polar groups PHB increases. As a result of
this interacting there is a perfection of crystallites and consolidation of an amorphous
phase of polymer in the course of film formation.
Inprocess also it has been installed, that character change energy of Gibbs fusion
of crystal phase PHB and magnitude of cohesive energy density of molecules of dis-
solvent are practically identical in certain sequence, see Table 1.
It is known, that magnitude of cohesive energy density characterizes intermolecu-
lar interaction extent in substance [8].
From Table 1, it follows that with decrease of extent of intermolecular interaction
in dissolvent were increase the disorder in a crystal phase of ¿ lms PHB, characterized
by decrease of Gibbs energy of fusion.
In other words, the intermolecular interaction in dissolvent, the mobility of its mol-
ecules and, hence, speed of their transferring in a vaporous phase (transpiration) there
is less. Owing to various speed change the phase of molecules of observed dissolvents,
formation of ¿ lms PHB proceeds differently. It is expressed in extent of completeness
of process of crystallization and parametres of a crystal structure of polymer.
On the basis of the made researches, it is possible to formulate following leading-
outs: