Non-isothermal melt- and cold-crystallization kinetics of poly(3-hydroxybutyrate)

Ziaee, Zainab; Supaphol, Pitt

doi:10.1016/j.polymertesting.2006.04.009

Cited by 48 publications

(30 citation statements)

References 23 publications

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“…An interesting feature of Ozawa model is the possibility to compare the results of crystallization during continuous cooling/heating with those obtained by means of the Avrami equation under isothermal conditions. Ozawa model requires a constant rate of temperature change, ϕ = |dT/dt|, and has been successfully used to study a number of nonisothermal crystallization processes 13,15 . Ozawa kinetic model is given by:…”

Section: Resultsmentioning

confidence: 99%

The Effect of Polystyrene on the Crystallization of Poly(3-hydroxybutyrate)

et al. 2015

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Mechanical properties, morphology and nonisothermal crystallization of poly(3-hydroxybutyrate) (PHB) and blends of PHB and polystyrene (PS) were studied by tensile tests, scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). A two-phase structure composed by a PHB matrix and nearly spherical particles of PS was clearly noticed in SEM images. The presence of small amounts (0.5% to 3%) of amorphous PS affected the crystallinity of PHB, being more evident when high cooling rates were applied. The kinetics of nonisothermal crystallization was modeled according to Ozawa equation. The dependence of Ozawa parameters on temperature followed the same trend for PHB and PHB/PS blends; model parameters were found to be lower for the blends than for the neat PHB.

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Section: Resultsmentioning

confidence: 99%

The Effect of Polystyrene on the Crystallization of Poly(3-hydroxybutyrate)

et al. 2015

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“…Double melting phenomena, because of melt-crystallization and consequent cold-crystallization, has been observed on the heating scans of some long-chained semicrystalline and semistiff polymers. 28,29 Upon cooling of melted semicrystalline polymers the so-called primary crystallites are formed; this process is defined as nonisothermal melt-crystallization. During consequent heating of the polymer beyond its glass transition temperature, secondary crystallites are formed within a portion of the amorphous region because of the increased molecular dynamics.…”

Section: Discussionmentioning

confidence: 99%

“…For example, poly(trimethylene terephthalate) and poly(3-hydroxybutyrate) demonstrate double endothermic peaks on the heating scan consequent to nonisothermal cooling. 29 The low-temperature endotherm is related to the melting of the primary crystallites, formed during the cooling, while high-temperature endotherm corresponds to the melting of the recrystallized crystallites formed during subsequent heating. 30 However, this type of double-peak melting was only observed at heating rates greater than or equal to 208C/min.…”

Section: Discussionmentioning

confidence: 99%

Effect of chirality on PVP/drug interaction within binary physical mixtures of ibuprofen, ketoprofen, and naproxen: A DSC study

Ivanov

Tsokeva

2008

Chirality

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We report on the thermal behavior of freshly prepared binary drug/polymer physical mixtures that contained ibuprofen, ketoprofen, or naproxen as a drug, and polyvinylpyrrolidone (PVP), hydroxyethylcellulose (HEC), or methylcellulose (MC) as excipient. At 6-10 degrees C/min heating rates the DSC detected a sharp, single endotherm that corresponds to the melting of drug. On heating physical mixtures of PVP and racemic ibuprofen or ketoprofen at lower heating rates, another endotherm was registered in front of the original one. To observe the additional endotherm, specific minimal values of the heating rate and of PVP weight fraction were needed; for ibuprofen and ketoprofen they were 1.5 and 2.0 degrees C/min, and 5 and 15% (w/w), respectively. At greater PVP weight fractions the top temperatures, T(mp), of both peaks were reduced almost linearly indicating strong solid-state interfacial reaction between the drug particles and PVP matrix. The additional endotherm was abolished at greater heating rates (2 degrees C/min for ibuprofen, 3 degrees C/min for ketoprofen), by replacing the racemate with respective S+-enantiomer and by replacing PVP with HEC and MC. Hence, the possible inclusion of enantioselective component within the PVP/drug interaction, responsible for the amorphization of physical mixture over storage, is assumed.

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“…Macroscopic crystallization in polymers starts at very low rates due to the first, slow nucleation step; crystallization rate increases during the main or bulk crystallization and then decreases as the material is depleted of crystallizable molecules and due to spherulitic impingement [20][21][22] . Most crystallization parameters are strongly dependent on the cooling/reheating rate, and the dependence is different for the melt and cold crystallization processes.…”

Section: Crystallization Analysismentioning

confidence: 99%

“…Material properties of semi-crystalline polymers are controlled by molecular and supra-molecular structures that are frequently determined by the crystallization mechanisms. Consequently, the study of crystallization and melting behavior is critical to understand and control material properties and the processing required to obtain them [8][9][10][11][12][13][14][15] . An experimental program was developed in order to understand the effect of thermal cycles on the phase transitions of the polymer.…”

Section: Introductionmentioning

confidence: 99%

Melting and crystallization of poly(3-hydroxybutyrate): effect of heating/cooling rates on phase transformation

et al. 2015

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SbstractWe studied the crystallization and melting phenomena of poly (3-hydroxybutyrate) (PHB), a biodegradable and biocompatible semi-crystalline thermoplastic, obtained from renewable resources. Its high crystallinity motivated several studies on crystallization and melting behavior, and also on ways to increase the amorphous polymer fraction. The effect of heating and cooling rates on the crystallization and melting of commercial PHB was investigated by differential scanning calorimetry. Several rates, ranging from 2.5 to 20 °C min -1 , were used to study the phase changes during heating/cooling/reheating cycles. The results showed that PHB partially crystallizes from the melt during the cooling cycle and partially cold crystallizes on reheating, and that the relative amount of polymer crystallizing in each stage strongly depends on the cooling rate. The melt and cold crystallization temperatures, as well as the rates of phase change, depend strongly on the cooling and heating rates.

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Non-isothermal melt- and cold-crystallization kinetics of poly(3-hydroxybutyrate)

Cited by 48 publications

References 23 publications

The Effect of Polystyrene on the Crystallization of Poly(3-hydroxybutyrate)

The Effect of Polystyrene on the Crystallization of Poly(3-hydroxybutyrate)

Effect of chirality on PVP/drug interaction within binary physical mixtures of ibuprofen, ketoprofen, and naproxen: A DSC study

Melting and crystallization of poly(3-hydroxybutyrate): effect of heating/cooling rates on phase transformation

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