M. Ichikawa et al., MORPHOLOGICAL-STUDY OF BACTERIAL POLY(3-HYDROXYBUTYRATE-CO-3-HYDROXYPROPIONATE), Macromolecular chemistry and physics, 197(8), 1996, pp. 2467-2480
The solid-state structure of a bacterially synthesized copolyester, po
ly(3-hydroxybutyrate-co-3-hydroxypropionate), P(3HB-co-3HP), with the
'3HP content ranging from 0 to 37 mol-%, was analyzed by C-13 solid-st
ate high-resolution NMR, X-ray diffraction, differential scanning calo
rimetry and optical microscopy. For the copolymers containing up to ab
out 40 mol-% 3HP, it was confirmed from the X-ray diffraction measurem
ent that the crystallographic parameters are similar to those of P(3HB
) homopolymer and the degree of crystallinity decreases as the 3HP con
tent increases. From the measurement of C-13 spin-lattice relaxtion ti
me (T-1(c)) using solid-state high-resolution C-13 NMR, it was conclud
ed that the crystalline region is composed only of 3HB units, suggesti
ng that the cocrystallization of 3HB and 3HP units in the same crystal
lattice does not occur in P(3HB-co-3HP). This conclusion is supported
by the thermal properties and the rate of spherulite growth.