Molecular dynamics of chiral semi-crystalline poly(R)-(3-hydroxyalkanoates)

Cheung, Man Ken; Gao, Ping; Li, Si Wan

doi:10.1016/s0032-3861(03)00222-2

Cited by 5 publications

(4 citation statements)

References 42 publications

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“…A possible reason is that, due to 3HHx units, the amorphous phase of P(3HB‐3HHx) increases and dilutes the concentration of 3HB crystallizable segments and decreases the viscosity, which favours the mobility of 3HB crystallizable segments. This result is in agreement with our previous result 10. Here, the K g value obtained from the Avrami equation is determined to be (2.87 ± 0.21)× 10 5 K 2 by using the empirical ‘universal’ value of U * = 1500 cal mol −1 .…”

Section: Resultssupporting

confidence: 92%

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Crystallization kinetics and melting behaviour of microbial poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)

Chen

Cheung

2005

Polymer International

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Isothermal and non-isothermal crystallization kinetics of microbial poly(3-hydroxybutyrateco-3-hydroxyhexanoate) [P(3HB-3HHx)] was investigated by differential scanning calorimetry (DSC) and 13 C solid-state nuclear magnetic resonance (NMR). Avrami analysis was performed to obtain the kinetic parameters of primary crystallization. The results showed that the Avrami equation was suitable for describing the isothermal and non-isothermal crystallization processes of P(3HB-3HHx). The equilibrium melting temperature of P(3HB-3HHx) and its nucleation constant of crystal growth kinetics, which were obtained by using the Hoffman-Weeks equation and the Lauritzen-Hoffmann model, were, respectively, 121.8 • C and 2.87 × 10 5 K 2 when using the empirical 'universal' values of U * = 1500 cal mol −1 . During the heating process, the melting behaviour of P(3HB-3HHx) for both isothermal and non-isothermal crystallization showed multiple melting peaks, which was the result of melting recrystallization. The lower melting peak resulted from the melting of crystals formed during the corresponding crystallization process, while the higher melting peak resulted from the recrystallization that took place during the heating process.

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Section: Resultssupporting

confidence: 92%

“…In our previous work,10 P(3HB‐3HHx) was found to be more mobile than PHB in the crystalline regions. The molecular‐level evidence from solid‐state nuclear magnetic resonance (NMR) that the P(3HB‐3HHx) chain was more flexible than PHB is echoed by the dynamic frequency sweep measurements of the biopolymer melts.…”

Section: Introductionmentioning

confidence: 87%

Crystallization kinetics and melting behaviour of microbial poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)

Chen

Cheung

2005

Polymer International

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“…Proton spin-lattice relaxation time in the rotating frame T 1ρ (H) measured via polarisation transfer from proton to carbon spins were found to be much shorter for amorphous regions of PHB (3-7 ms) than those of crystalline regions (77-98 ms) [1]. On the other hand, only single exponential T 1ρ (H) relaxation curves were observed for PHB and its blends in [8] by the same measuring method. It was also found that signals of PHB in 13 C NMR spectra changed their shape when PHB was mixed in miscible blends [9,10] and almost the same values of the spin-lattice relaxation times in the rotating frame T 1ρ (H) were observed for both blend components [9].…”

Section: Introductionmentioning

confidence: 85%

“…PHB and its blends mostly with other PHAs were studied employing solid-state NMR techniques including 13 C direct polarization (DP) and cross polarization (CP) magic angle spinning (MAS) methods, measuring of relaxation times T 1 (C), T 1ρ (C), indirect measuring of relaxation times T 1 (H), T 1ρ (H) via polarisation transfer to carbon spin system and wide-line 1 H NMR and T 1 (H) experiments [1,3,4,[7][8][9][10][11][12]. It was shown that PHB was composed of crystalline and amorphous regions with distinct molecular dynamics.…”

Section: Introductionmentioning

confidence: 99%

Solid-State NMR Study of Poly(3-Hydroxybutyrate) and Ecoflex reser Blends

Hutníková

Fričová

2016

Acta Phys. Pol. A

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Biodegradable blends of poly(3-hydroxybutyrate) and aromatic-aliphatic co-polyester Ecoflex ® were studied by means of basic solid-state NMR techniques.13 C NMR spectra pointed at existence of individual components in blends, however, existence of regions in which components affect each other was also deduced from changes of shape of some spectral lines. Analysis of proton spin-lattice relaxation process in laboratory frame running in blends with different fractions of components revealed poor miscibility of these polymers. The domain size of components was calculated based on the values of spin-lattice relaxation times in laboratory frame. Spin-lattice relaxation process in the rotating frame of Ecoflex ® proton spin system was only slightly influenced by the blending. Incompatibility of these polymers was confirmed by all realized experiments.

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Chain Mobility in Different Polymers

Wypych¹

2020

Chain Mobility and Progress in Medicine, Pharmaceutical, and Polymer Science and Technology

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Molecular dynamics of chiral semi-crystalline poly(R)-(3-hydroxyalkanoates)

Cited by 5 publications

References 42 publications

Crystallization kinetics and melting behaviour of microbial poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)

Crystallization kinetics and melting behaviour of microbial poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)

Solid-State NMR Study of Poly(3-Hydroxybutyrate) and Ecoflex reser Blends

Chain Mobility in Different Polymers

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