Crystallization kinetics in blends of isotactic and atactic poly(β-hydroxybutyrate)

Pearce, R.; Brown, G. R.; Marchessault, R. H.

doi:10.1016/0032-3861(94)90284-4

Cited by 71 publications

(65 citation statements)

References 43 publications

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“…PHB has a value of 37.2 erg Á cm À2 , which is in good agreement with the values reported in the literature. [53,61] As expected, for PHB/PCL 120k blends no significant changes were observed with respect to PHB in view of their immiscibility. Nevertheless, the presence of low molecular weight mPCL in the PHB-rich phase leads to a decrease in the energy barrier for secondary nucleation (K g ) since mPCL chains are causing a plasticizing effect on the PHB chains.…”

Section: Crystallization Of the Phb Fractionmentioning

confidence: 51%

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Crystallization, Morphology, and Enzymatic Degradation of Polyhydroxybutyrate/Polycaprolactone (PHB/PCL) Blends

Lovera

Márquez

Balsamo

et al. 2007

Macro Chemistry & Physics

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Two types of mixtures were prepared by solution blending: high molecular weight polyhydroxybutyrate (PHB)/poly(ε‐caprolactone) (PCL) and PHB/low molecular weight chemically modified PCLs (mPCL). The morphology, crystallization, and enzymatic degradation of the blends were studied by differential scanning calorimetry, polarized light optical microscopy, scanning electron microscopy, 1H NMR, and weight loss measurements. In addition, enzymatic degradation studies were performed by an exposure to Aspergillus flavus. High molecular weight PHB/PCL blends were found to be immiscible in the entire composition range. Phenomena such as PCL fractionated crystallization and a decrease in PHB nucleation density were detected. When PHB was blended with mPCLs, the blends were partially miscible; two phases were formed, but the PHB‐rich phase exhibited clear signs of miscibility through a depression of both the Tm and the Tg of the PHB component (which was stronger with lower molecular weight mPCL), and an increase in the growth rate of PHB spherulites in the blends as compared to neat PHB or to the PHB component in the PHB/PCL blends. The biodegradation by a exposure to A. flavus showed that the blends are synergistically attacked in comparison to the homopolymers. Two factors may influence the improved degradation rate of the blends: the dispersion of the components and their crystallinity that was reduced in view of the fractionated crystallization and impurities transfer. In the case of the PHB/mPCL blends, the increased miscibility between the components caused a reduction in the degradation rate.magnified image

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Section: Crystallization Of the Phb Fractionmentioning

confidence: 51%

“…Using a value of a ¼ 0.25, which is considered appropriate for high melting point polyesters, 61 and a o ¼ 6.6 Å and b o ¼ 5.8 Å , the values of s e were obtained and are listed in Table 3. PHB has a value of 37.2 erg Á cm À2 , which is in good agreement with the values reported in the literature.…”

Section: Crystallization Of the Phb Fractionmentioning

confidence: 99%

Crystallization, Morphology, and Enzymatic Degradation of Polyhydroxybutyrate/Polycaprolactone (PHB/PCL) Blends

Lovera

Márquez

Balsamo

et al. 2007

Macro Chemistry & Physics

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“…Pearce et al 139 have used the technique to study isotactic/atactic PHB blends and seen a reduction in the rate of spherulite growth in the isotactic polymer.…”

Section: Optical Microscopymentioning

confidence: 98%

A review of biodegradable polymers: uses, current developments in the synthesis and characterization of biodegradable polyesters, blends of biodegradable polymers and recent advances in biodegradation studies

Amass¹,

Amass²,

Tighe³

1998

Polym. Int.

920

488

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“…29 Table I shows that that the [a] 20 values of the samples increased with the L-lactide composition increasing.…”

Section: Resultsmentioning

confidence: 92%

Microstructure and mechanism study of polylactide obtained by the copolymerization of L‐lactide and D,L‐lactide

Zhao¹,

Wang²,

Zhong³

et al. 2009

J of Applied Polymer Sci

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The stereosequence of polylactide has been analyzed with 13 C-NMR spectroscopy, according to which syndiotactic addition is preferred. According to Markovian statistics, the reactivity ratio, which determines the extent of the syndiotactic stereosequence in the polymer chain, can be calculated by an analysis of the carbonyl and methine regions in the spectra. Moreover, the average lengths of segments SS and RR can be proposed and calculated with the distributing function of the sequence. On this basis, we have investigated the formation mechanism with respect to the preference for the syndiotactic addition of polylactide chains.

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Crystallization kinetics in blends of isotactic and atactic poly(β-hydroxybutyrate)

Cited by 71 publications

References 43 publications

Crystallization, Morphology, and Enzymatic Degradation of Polyhydroxybutyrate/Polycaprolactone (PHB/PCL) Blends

Crystallization, Morphology, and Enzymatic Degradation of Polyhydroxybutyrate/Polycaprolactone (PHB/PCL) Blends

A review of biodegradable polymers: uses, current developments in the synthesis and characterization of biodegradable polyesters, blends of biodegradable polymers and recent advances in biodegradation studies

Microstructure and mechanism study of polylactide obtained by the copolymerization of L‐lactide and D,L‐lactide

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