Blends of polymers with similar glass transition temperatures: A DMTA and DSC study

Bikiaris, Dimitrios N.; Prinos, J.; Botev, M.; Betchev, C.; Panayiotou, Costas

doi:10.1002/app.20531

Cited by 70 publications

(44 citation statements)

References 32 publications

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“…Additionally, a correlation between the interactions' intensity and the hydrophilicity of the systems is investigated. It is well established that the presence of strong heteromolecular forces, especially hydrogen bonds, may differentiate the physicochemical characteristics of the initial molecules [13]. Due to this behaviour the dissolution rate and the bioavailability of these systems cannot be predicted as they are not proportionally relative to the drug:polymer ratio.…”

Section: Introductionmentioning

confidence: 99%

Effect of hydrogen bonding interactions on the release mechanism of felodipine from nanodispersions with polyvinylpyrrolidone

Karavas

Ktistis

Xenakis

et al. 2006

European Journal of Pharmaceutics and Biopharmaceutics

138

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Solid dispersion systems are widely investigated for the dissolution enhancement of poorly water soluble drugs. Nevertheless, very limited commercial use has been achieved due to the poor predictability of such systems caused by the lack of a basic understanding of the dissolution optimization mechanism. In the present study an investigation of the release mechanism is performed for solid dispersion systems composed by polyvinylpyrrolidone (PVP) and felodipine (FEL), based on a correlation of their hydrophilicity with the intensity of interactions. The existing interactions were evaluated by using NMR and UV spectroscopy while molecular simulation techniques were also enabled. It was found that the interactions that take place correspond to the creation of hydrogen bonds. The correlation between the intensity of interactions and the concentration of PVP in the matrix showed a sigmoid function. The interactions are impressively increased for polymer concentration exceeding 75% (w/w). This phenomenon was well explained by using the molecular simulation technique. A similar sigmoid pattern was found for the function between dissolution profiles and polymer concentration in the matrix, indicating that the intensity of interactions promotes the dissolution enhancement. Investigation of the solubility and the particle size distribution of FEL in the binary system appeared to have similar behaviour indicating that the interactions affect the release profile through these two factors. The hydrophilicity of PVP does not significantly affect this enhancement as the contact angle was found to be linear to PVP concentration. Microscopic observation of the dissolution behaviour showed that FEL remains in fine dispersion in aqueous solution, verifying the release mechanism.

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Section: Introductionmentioning

confidence: 99%

Effect of hydrogen bonding interactions on the release mechanism of felodipine from nanodispersions with polyvinylpyrrolidone

Karavas

Ktistis

Xenakis

et al. 2006

European Journal of Pharmaceutics and Biopharmaceutics

138

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“…Therefore, this technique has been used in conjunction with DSC to study the miscibility of different polymer blends (Pomposo et al, 1996;Cascone et al 1997;Bikiaris et al, 2004).…”

Section: Characterization Of Melt Extrudatesmentioning

confidence: 99%

Section: Characterization Of Melt Extrudatesmentioning

confidence: 99%

“…The difference between the Tg values determined by DSC and DMTA methods is common. In DMTA, the exact position of Tg depends mainly on the studied frequency, whereas in DSC Tg depends on the used heating rate (Bikiaris et al, 2004).In our study, DMTA was used to provide more detailed and accurate information about the Tg of formulations and hence the miscibility within the binary and ternary systems. The DSC and DMTA thermograms of CX, PEO, Eudragit ® S100 and the melt extrudates are shown in Figures 1 and 2, respectively.…”

mentioning

confidence: 95%

“…In general, the temperature at which the mechanical damping factor, tan delta or loss tangent, exhibits a maximum at Tg of the material. It has been demonstrated that DMTA is more sensitive than DSC by 1000 times in detecting the Tg of polymers (Bikiaris et al, 2004). The ability of DMTA to accurately detect changes in the moduli of polymeric systems forms the basis of the experimental determination of Tg temperature (Ferry, 1980).…”

mentioning

confidence: 99%

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The Use of Binary Polymeric Networks in Stabilizing Polyethylene Oxide Solid Dispersions

Jones

Tian

Shu

et al. 2016

Journal of Pharmaceutical Sciences

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The objective of this study was to investigate the role of amorphous domain of polyethylene oxide (PEO), a semicrystalline polymer, on the stability of drug/PEO solid dispersion. Molecular dispersion of drugs within hydrophilic low molecular weights PEOs (solid solution) has been demonstrated as a viable approach to enhance the dissolution properties and hence the oral bioavailability of poorly soluble drugs. In this system, the drug molecules are dissolved within the amorphous domain of the polymer and a miscible amorphous drug/polymer combination can result in a decrease of the polymer crystallinity, and hence increasing its amorphous fraction. This may result in increasing the drug solubility in the polymer hence affecting the stability of drug/polymer solid dispersion system. PEO is a highly crystallisable semi-crystalline polymer in natural and a rapid decrease in the amorphous fraction of the polymer may occur immediately after hot-melt extrusion resulting a forced migration of amorphous drug into nearby amorphous region. Thus, the actual concentrations of the drug within PEO solid dispersion were much higher than the concentration that we intended. Therefore, we are proposing a novel method of stabilising the amorphous drug/PEO solid dispersion by stabilising the amorphous region of PEO using another amorphous polymer. Inclusion of a miscible polymer that can increase the glass transition (Tg) of PEO (antiplasticization) or/and form strong inter-polymer interactions was used to enhance the stability of the amorphous PEO. In this study, the effects of inter-polymer interactions and miscibility between PEO and an amorphous polymer of high Tg, Eudragit ® S100, on the stability of the amorphous PEO and consequently the PEO/drug celecoxib (CX) solid dispersion was studied. Hot-melt extrusion (HME) was used to prepare different ratios of binary polymer blends of PEO/S100 (70/30, 50/50 and 30/70 w/w) and ternary solid dispersion systems containing pre-defined drug loading within the PEO/S100 polymer blends. Results from differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) suggested a great miscibility between PEO and S100 polymer blends particularly in the 50/50 ratio. After immediately HME, single Tg was observed in all ternary systems that increase with increasing S100 amount (antiplasticization). The completely absence of PXRD crystalline Bragg's peaks also suggested the full amorphous CX/polymer solid dispersion has been produced. Upon storage, CX crystallized rapidly from the CX/PEO (30/70) system within 3 days at 40°C and 75% RH, whereas it remained stable without crystallization up to 4 weeks within CX/(PEO/S100) 30/(50/50) system. Interestingly, both the stability of the amorphous PEO and CX were greater in the ternary system containing the polymer blend at 50/50 ratio than other systems. Despite of the lower Tg of 30/(50/50) system than 30/(30/70) one, the former was more stable. This indicates that the antiplasticization effects by Eudragit ® S100 were not the ...

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Characterization of epoxidized natural rubber/ethylene vinyl acetate (ENR‐50/EVA) blend: Effect of blend ratio

Mohamad¹,

Ismail²,

Thevy

2005

J of Applied Polymer Sci

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Epoxidized natural rubber/Ethylene vinyl acetate copolymer (ENR-50/EVA) blends with different ratios were prepared by using a Haake internal mixer. The effect of the blend ratio on the processing, tensile properties (such as tensile strength, elongation at break, Young's modulus and stress-strain behavior), morphology, dynamic mechanical properties, and thermal properties has been investigated. The tensile properties increase with the increase of EVA content, whereas the stabilization torque increases with the increase of ENR-50 content in the blend. In 40:60 and 50:50 blend of ENR-50/EVA, both the phases exist as continuous phases, producing a co-continuous morphology. At these blend ratio, the drastic change in properties were noted, indicating that the phase inversion occurs. The results on dynamic mechanical properties revealed that the blends are compatible. Blending of ENR-50 and EVA lead to the improvement in thermal stability and 50:50 blend ratios is the most stable blend.

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Blends of polymers with similar glass transition temperatures: A DMTA and DSC study

Cited by 70 publications

References 32 publications

Effect of hydrogen bonding interactions on the release mechanism of felodipine from nanodispersions with polyvinylpyrrolidone

Effect of hydrogen bonding interactions on the release mechanism of felodipine from nanodispersions with polyvinylpyrrolidone

The Use of Binary Polymeric Networks in Stabilizing Polyethylene Oxide Solid Dispersions

Characterization of epoxidized natural rubber/ethylene vinyl acetate (ENR‐50/EVA) blend: Effect of blend ratio

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