Density and Crystallinity of Poly(3-Hydroxybutyrate 3-Hydroxyvalerate) Copolymers

PA Barker, FJ Mason, PJ Barham

Research output: Contribution to journalArticle (Academic Journal)peer-review

45 Citations (Scopus)


Bacteria can produce a range of optically active copolymers of (R)-3-hydroxybutyrate (HB) and (R)-3-hydroxyvalerate (HV). These copolymers have aroused much scientific interest because of their high crystallinity at all HB : HV compositions which suggests the possibility of inclusion of HB and HV in the same crystal. In this paper we look at the assessment of crystallinity by density measurements taking into account the possible changes in crystal and amorphous densities caused by the rejection or inclusion of HV from the crystallites. The approach developed is applicable to crystallization of copolymers and blends whatever the composition of the crystals and makes a distinction between mass fraction and mole fraction crystallinities for cases where the average molar mass of residues in the crystal and amorphous phases differs. While it is impossible to give values for crystallinity without knowing the degree of inclusion of HV into the crystals it is possible to say that the previous suggestions that the crystallinity remains constant independent of HV content and that there is equal concentration of HV in the crystal and amorphous phases are incompatible with the measured sample densities. We also show that the crystallization temperature is an important factor in the balance between the crystallinity and HV content of crystals.
Translated title of the contributionDensity and Crystallinity of Poly(3-Hydroxybutyrate 3-Hydroxyvalerate) Copolymers
Original languageEnglish
Pages (from-to)1952 - 1956
Number of pages5
JournalJournal of Materials Science
VolumeVolume 25, Number 4
Publication statusPublished - Apr 1990

Bibliographical note

Publisher: Springer Netherlands


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