title: Bacterial poly(3-hydroxybutyrate): an optical microscopy and microfocus X-ray diffraction study.
abstract: Two-dimensional spatially resolved microfocus X-ray diffraction has been used to investigate spherulites of pure bacterial poly(3-hydroxybutyrate) (PHB) and of a blend of natural and synthetic atactic PHB (a-PHB) crystallized at a relatively high temperature (Tc = 140 degrees C). Both samples investigated contained practically two-dimensional spherulites, characterized by wide extinction bands (band spacing > 80 microns). The X-ray diffraction patterns confirmed that the unit cell alpha-axis is oriented along the spherulite radius in PHB and that the same is true for the a-PHB containing blend. Comparison of the matrix of diffraction patterns with the polarized optical micrograph of the scanned sample area indicated a very clear correlation between pattern changes and banding, yielding a straightforward picture of the structural variations within the spherulite.
authors.affiliation: Department of Chemistry G. Ciamician, Centro di Studio per la Fisica delle Macromolecole del CNR, University of Bologna, via Selmi 2, 40126 Bologna, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Gazzano
authors.forename: M L
authors.initials: ML
authors.lastname: Focarete
authors.forename: C
authors.initials: C
authors.lastname: Riekel
authors.forename: M
authors.initials: M
authors.lastname: Scandola
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D018360:Crystallography, X-Ray; D006885:Hydroxybutyrates / Q000737:chemistry*; D008859:Microscopy, Polarization; D011091:Polyesters / Q000737:chemistry*; D000094122:Polyhydroxybutyrates
chemical_list: D006885:Hydroxybutyrates; D011091:Polyesters; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates