Spherulite formation in poly(ethylene oxide) mixtures

Cheng, Stephen Z. D.; Barley, Jeffrey S.; Giusti, Paul A.

doi:10.1016/0032-3861(90)90045-z

Cited by 31 publications

(14 citation statements)

References 20 publications

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“…Generally, PEO crystallizes from the melt giving spherulites, which are spherical or disc‐shaped formations with chain‐folded lamellae radiating from a central point. Under polarized light, they can be recognized by the typical black Maltese cross 32. The size of crystals is dependent of crystallization temperature and cooling rate.…”

Section: Resultsmentioning

confidence: 99%

Preparation and thermal characterization of poly(ethylene oxide)/griseofulvin solid dispersions for biomedical applications

Stachurek

Pielichowski

2008

J of Applied Polymer Sci

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In this work, a series of poly(ethylene oxide)/griseofulvin (PEO/gris) solid dispersions has been prepared and characterized by PLM, FTIR, DSC, and MT-DSC. It has been found that the crystalline phase morphology depends strongly on the PEO molecular weight and, in the PEO/gris systems, griseofulvin molecules stay in amorphous phase of PEO, which enhances the solubility of a drug and increases its biological access. For PEO-drug systems containing 5, 10, and 15% gris, FTIR bands due to stretching vibrations of the OAH groups were found at 3436, 3436, and 3413 cm À1 , respectively, whereby for pure PEO 3400, they were located at 3513 cm À1-the observed shift proves the existence of hydrogen bonds between PEO and griseofulvin. The presence of griseofulvin caused lowering of the systems' melting temperature in the whole concentration range and, as evidenced by MT-DSC results, recrystallization of PEO in the PEO/griseofulvin systems during melting does occur.

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Section: Resultsmentioning

confidence: 99%

Preparation and thermal characterization of poly(ethylene oxide)/griseofulvin solid dispersions for biomedical applications

Stachurek

Pielichowski

2008

J of Applied Polymer Sci

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“…The PEO samples were crystallized by the same procedure as for SAXS and DSC, followed by surface replication using heavy metal (Au/ Pt, 40/60) and carbon. The detailed procedure has been described in ref 22. A JEOL JEM-120U transmission electron microscope with a 100-kV accelerating voltage was used in this study.…”

Section: Methodsmentioning

confidence: 99%

Isothermal thickening and thinning processes in low molecular-weight poly(ethylene oxide) fractions crystallized from the melt. 3. Molecular weight dependence

Cheng¹,

Chen²,

Barley³

et al. 1992

Macromolecules

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107

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“…We executed the etching procedure for the above crystallized PEOs according to Cheng et al 10 in a C 2 H 5 ONa/ C 2 H 5 OH (21/79 weight fraction) mixture at 25°C, and we washed them with C 2 H 5 OH at the same temperature. The etched specimens were obliquely shadowed with Pt-Pd by vacuum evaporation, followed by carbon coating, and then the carbon replicas were separated in water.…”

Section: Determination Of the Equilibrium Dissolution Temperaturementioning

confidence: 99%

Primary Nucleation Rate and Radial Growth Rate of Poly(ethylene oxide) Spherulite in Viscous Solutions

Sasaki

Yamamoto

Takahashi

2000

Polym J

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The primary nucleation rate I and radial growth rate G of the isothermal spherulitic growth ofpoly-(ethylene oxide) in tripropionin solutions of 5, 10, and 30 wt% polymer concentrations were studied by direct in situ observation using a CCD camera. I was found to decrease with pre-annealing at 200°C up to ca. 200 h, while G was almost constant. These results suggest that there exist micro-residuals of a crystalline-like structure that act as dominant seeds for primary nucleation and that they become dissolved with structural relaxation during pre-annealing, resulting in the solution approaching a homogeneous state. The supercooling dependencies of I and G were independently investigated, and it was found that the fold surface free energy and activation energy of the polymer diffusion increase with decreases in the polymer content of the solution. The frictional interaction between the polymer and solvent is also discussed on the basis of the reaction rate theory ofKramers.

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Spherulite formation in poly(ethylene oxide) mixtures

Cited by 31 publications

References 20 publications

Preparation and thermal characterization of poly(ethylene oxide)/griseofulvin solid dispersions for biomedical applications

Preparation and thermal characterization of poly(ethylene oxide)/griseofulvin solid dispersions for biomedical applications

Isothermal thickening and thinning processes in low molecular-weight poly(ethylene oxide) fractions crystallized from the melt. 3. Molecular weight dependence

Primary Nucleation Rate and Radial Growth Rate of Poly(ethylene oxide) Spherulite in Viscous Solutions

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