Crystallization and Morphology of Poly(β-hydroxybutyrate) and Its Copolymer

Mitomo, Hiroshi; Barham, Peter; Keller, A.

doi:10.1295/polymj.19.1241

Cited by 142 publications

(97 citation statements)

References 17 publications

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“…The relaxation temperatures of a-chitin and b-chitin have been investigated by Kim et al using dynamic mechanical thermal analysis instead of DSC measurement to observe the transition of the chain mobility 20) . The a-relaxation temperature of a-chitin was observed at 236 8C, which is much higher than that of PHB, i. e., about 0 8C, determined by DSC 27) . At the crystallization temperature (room temperature), which is much lower than the a-relaxation temperature of chitin, the amorphous region of chitin exists as 'glass'.…”

Section: Crystallinity Of Phb In the Blends Observed By Irmentioning

confidence: 62%

Thermal properties and crystallization behavior of poly(3-hydroxybutyric acid) in blends with chitin and chitosan

Ikejima

Yagi

Inoue³

1999

Macromol. Chem. Phys.

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SUMMARY: Films of blends of microbial poly(3-hydroxybutyric acid) (PHB) with a-chitin and chitosan were prepared as completely biodegradable polyester-polysaccharide composites. DSC revealed that the crystallization of PHB in these blends is suppressed when the proportion of the polysaccharide is increased. The same tendency was evident from the FT-IR band intensity of the carbonyl stretching absorption from PHB. Chitosan was found to have a stronger ability to suppress the crystallization of PHB than a-chitin. PHB in the blends was found by 13 C NMR spectroscopy to be trapped in the 'glassy' environment of the polysaccharide. Upon blending with PHB, the chitosan resonances are significantly broadend as compared to the chitin resonances. Hydrogen bonds are suggested to be formed between the carbonyl groups of PHB and the amide NH groups of chitin and chitosan.

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Section: Crystallinity Of Phb In the Blends Observed By Irmentioning

confidence: 62%

Thermal properties and crystallization behavior of poly(3-hydroxybutyric acid) in blends with chitin and chitosan

Ikejima

Yagi

Inoue³

1999

Macromol. Chem. Phys.

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“…However, there is no energy preference for a right-handed or left-handed helix. P(3HB) single crystals, up to this point, have been prepared from many kinds of solvents, chloroform/ethanol 24,25) , propylene carbonate [26][27][28][29][30][31] , poly(ethylene glycol) 32,33) , etc., and the surface morphology and crystal structure were investigated using transmission electron microscopy and atomic force microscopy. Typical electron micrograph and electron diffraction pattern of P(3HB) single crystal grown from dilute solution of chloroform/ethanol are shown in Fig.…”

Section: Poly([r]-3-hydroxybutyrate)mentioning

confidence: 99%

Crystal structure and biodegradation of aliphatic polyester crystals

Iwata¹,

Doi

1999

Macromol. Chem. Phys.

140

121

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SUMMARY: The biodegradability of aliphatic polyesters, which are produced by biosynthesis and chemosynthesis, strongly correlates to the polymer morphology such as crystallinity, molecular orientation, chain packing and crystal surface, in addition to the chemical structure. For elucidation of biodegradation mechanism of crystal regions on an atomic level, lamellar single crystals of poly([R]-3-hydroxybutyrate) (P(3HB)) and its copolymers, poly([R]-3-hydroxyvalerate) (P(3HV)), poly(4-hydroxybutyrate) (P(4HB)), poly(L-lactic acid) (PLLA) and poly(ethylene succinate) (PES) were prepared from dilute solution by isothermal crystallization, and the crystal structures and morphologies were investigated by means of mainly transmission electron microscopy and atomic force microscopy. All single crystals were intramolecular single crystals, with spiral growth in some cases, and these crystals gave well-resolved electron diffractograms. The enzymatic degradation of lamellar crystals of P(3HB) and its copolymers was carried out with extracellular PHB depolymerases, and it was revealed that enzymatic degradation of lamellar crystals progressed from crystal edges and ends rather than the chain-folding surfaces of crystals, in spite of the homogeneous adsorption of enzyme molecules on the crystal surfaces by substrate-binding domain. Furthermore, in the case of PLLA single crystals, single crystals were also degraded from the edges to yield a rounded shape without decreasing the molecular weights and lamellar thickness. These results suggest that the attack by the active site of enzyme takes place at disordered regions of the crystals, that is, disordered lateral sites with high mobility of molecular chains are preferentially degraded.

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“…16,17 For HV molar ratios higher than 30% the chains adopt the P(3HV) unit cell. 18 Although the crystallization behavior of these copolyesters has been extensively characterized 11,19,20 no attempt has been done so far to correlate microstructure with the dynamics of the amorphous phase during crystallization in real time.…”

Section: Introductionmentioning

confidence: 99%

Structure-dynamics relationships of the ?-relaxation in flexible copolyesters during crystallization as revealed by real-time methods

Nogales

Ezquerra

García

et al. 1999

J. Polym. Sci. B Polym. Phys.

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The evolution of the α‐relaxation during an isothermal crystallization process of a series of flexible copolyesters of hydroxybutyrate (HB) and hydroxyvalerate (HV) has been followed in real‐time by wide‐angle X‐ray scattering and dielectric complex permittivity measurements. The change of the dielectric parameters with crystallization time can be phenomenologically described in terms of the Havriliak‐Negami equation. The dielectric strength follows a sigmoidal‐shaped pattern similar to that shown by the crystallinity. A reduction of the overall mobility with crystallization time of the polymeric chains in the amorphous phase has been observed. This slowing down effect depends on the HV molar content. The influence of the chain flexibility on the crystalline‐induced restriction has been discussed in the light of similar studies carried out with more rigid polymers. Dielectric experiments suggest that the progressive immobilization of polymer segments as crystallization proceeds cannot be exclusively associated with the amount of crystalline material. Differences in microstructure, depending on the HV molar content, seem to be responsible for the observed behavior. The progressive broadening and symmetrization of the α‐relaxation with increasing crystallization time has been explained as due to a restriction of the large‐scale motions of the polymeric chains, as the material is being filled in with crystals. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 37–49, 1999

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Crystallization and Morphology of Poly(β-hydroxybutyrate) and Its Copolymer

Cited by 142 publications

References 17 publications

Thermal properties and crystallization behavior of poly(3-hydroxybutyric acid) in blends with chitin and chitosan

Thermal properties and crystallization behavior of poly(3-hydroxybutyric acid) in blends with chitin and chitosan

Crystal structure and biodegradation of aliphatic polyester crystals

Structure-dynamics relationships of the ?-relaxation in flexible copolyesters during crystallization as revealed by real-time methods

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