H. Abe et al., Crystallization behavior and thermal properties of melt-crystallized poly[(R)-3-hydroxybutyric acid-co-6-hydroxyhexanoic acid] films, INT J BIO M, 25(1-3), 1999, pp. 177-183
Citations number
17
Categorie Soggetti
Biochemistry & Biophysics
Journal title
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
Melt-crystallized films of poly[(R)-3-hydroxybutyric acid-co-10mol% 6-hydro
xyhexanoic acid] (P[(R)-3HB-co-6HH]) were prepared by isothermal crystalliz
ation at various temperatures for 3 days, and subsequently stored at room t
emperature after the films formed well-developed and volume-filled spheruli
tes. The lamellar morphologies and properties of melt-crystallized films we
re characterized by means of wide-angle X-ray diffraction, small-angle X-ra
y scattering, differential scanning calorimetry, transmission electron micr
oscopy, and atomic force microscopy. The melting endotherm of P[(R)-3HB-co-
6HH] films was composed of a broad peak starting around room temperature an
d of a sharper peak starting above the isothermal crystallization temperatu
re. The stacking of flat-on lamellae with lamellar periodicity of 8-10 nm w
as detected on the surface of P[(R)-3HB-co-6HH] films after the primary cry
stallization at 110 degrees C. On storage at room temperature above the T-g
(-5 degrees C) of copolyester, thin crystals of 1-4 nm thickness appeared
on the surface of P[(R)-3HB-co-6HH] films crystallized at 110 degrees C. Th
ese results suggest that long sequences of (R)-3HB units in a random copoly
ester form relatively thick P[(R)-3HB] crystalline lamellae during the prim
ary crystallization process at a given crystallization temperature, while s
horter sequences of (R)-3HB units, which are incapable of crystallizing at
a given crystallization temperature, form relatively thin crystalline lamel
lae during the subsequent crystallization process at room temperature. (C)
1999 Elsevier Science B.V. All rights reserved.