The Experts below are selected from a list of 90093 Experts worldwide ranked by ideXlab platform

Abu T M Serajuddin - One of the best experts on this subject based on the ideXlab platform.

  • investigation of polymer surfactant and polymer drug surfactant Miscibility for solid dispersion
    Aaps Journal, 2016
    Co-Authors: Suhas G Gumaste, Simerdeep Singh Gupta, Abu T M Serajuddin
    Abstract:

    In a solid dispersion (SD), the drug is generally dispersed either molecularly or in the amorphous state in polymeric carriers, and the addition of a surfactant is often important to ensure drug release from such a system. The objective of this investigation was to screen systematically polymer-surfactant and polymer-drug-surfactant Miscibility by using the film casting method. Miscibility of the crystalline solid surfactant, poloxamer 188, with two commonly used amorphous polymeric carriers, Soluplus® and HPMCAS, was first studied. Then, polymer-drug-surfactant Miscibility was determined using itraconazole as the model drug, and ternary phase diagrams were constructed. The casted films were examined by DSC, PXRD and polarized light microscopy for any crystallization or phase separation of surfactant, drug or both in freshly prepared films and after exposure to 40°C/75% RH for 7, 14, and 30 days. The Miscibility of poloxamer 188 with Soluplus® was <10% w/w, while its Miscibility with HPMCAS was at least 30% w/w. Although itraconazole by itself was miscible with Soluplus® up to 40% w/w, the presence of poloxamer drastically reduced its Miscibility to <10%. In contrast, poloxamer 188 had minimal impact on HPMCAS-itraconazole Miscibility. For example, the phase diagram showed amorphous Miscibility of HPMCAS, itraconazole, and poloxamer 188 at 54, 23, and 23% w/w, respectively, even after exposure to 40°C/75% RH for 1 month. Thus, a relatively simple and practical method of screening Miscibility of different components and ultimately physical stability of SD is provided. The results also identify the HPMCAS-poloxamer 188 mixture as an optimal surface-active carrier system for SD.

  • application of film casting technique to investigate drug polymer Miscibility in solid dispersion and hot melt extrudate
    Journal of Pharmaceutical Sciences, 2015
    Co-Authors: Tapan Parikh, Simerdeep Singh Gupta, Anuprabha Meena, Imre Vitez, Nidhi Mahajan, Abu T M Serajuddin
    Abstract:

    ABSTRACT Determination of drug-polymer Miscibility is critical for successful development of solid dispersions. This report details a practical method to predict Miscibility and physical stability of drug with various polymers in solid dispersion and, especially, in melt extrudates by applying a film-casting technique. Mixtures of itraconazole (ITZ) with hydroxypropylmethylcellulose phthalate (HPMCP), Kollidon® VA 64, Eudragit® E PO, and Soluplus® were film-casted, exposed to 40°C/75% RH for 1 month and then analyzed using differential scanning calorimetry (DSC), powder X-ray diffractometry, and polarized light microscopy (PLM). ITZ had the highest Miscibility with HPMCP, being miscible at drug to polymer ratio of 6:4 (w/w). There was a downward trend of lower Miscibility with Soluplus® (miscible at 3:7, w/w, and a few microcrystals present at 4:6, w/w), Kollidon® VA 64 (2:8, w/w) and Eudragit® E PO (

John Agren - One of the best experts on this subject based on the ideXlab platform.

  • influence of nitrogen gas pressure on the Miscibility gap in the ti zr carbonitride system
    International Journal of Refractory Metals & Hard Materials, 2012
    Co-Authors: Ida Borgh, Susanne Norgren, Annika Borgenstam, John Agren
    Abstract:

    Abstract The microstructure of cemented carbides with a gradient structure at the surface consists of WC, cubic carbonitrides and a binder phase. The carbonitrides can, for example, consist of Ti(C,N)–Zr(C,N) where it is reasonable to believe that there is a Miscibility gap with Ti-rich and Zr-rich carbonitrides. In the present work, the effect of the N2-gas pressure on the equilibrium composition of the Miscibility gap in the (Ti,Zr)(C,N) system has been investigated. In the study, the carbonitride system is in equilibrium with: WC, liquid binder, graphite and, N2-gas of different pressures. Both Fe and Co are used as binder phase to study the effect of the binder phase. The results verify that there is a Miscibility gap in the carbonitride system and that the region of the Miscibility gap will change when N is introduced. There is a critical N2-gas pressure lower than 0.1 bar and above that pressure the compositions of the carbonitride are rather constant as a result of the formation of a surface rim.

Alfonso Maffezzoli - One of the best experts on this subject based on the ideXlab platform.

  • plasticizer for poly vinyl chloride from cardanol as a renewable resource material
    Polymer Degradation and Stability, 2010
    Co-Authors: Antonio Greco, D Brunetti, G Renna, Giuseppe Mele, Alfonso Maffezzoli
    Abstract:

    The present work is aimed to the preliminary analysis of the applicability of cardanol derivatives as renewable plasticizers for soft PVC. Two different plasticizers were studied, obtained by esterification of the cardanol hydroxyl group (cardanol acetate) and further epoxidation of the side chain double bonds (epoxidated cardanol acetate). Differential Scanning Calorimetry (DSC) was used to study the Miscibility between PVC and cardanol derived plasticizers. The Miscibility was correlated to the chemical structure of plasticizer by means of the Hansen solubility parameter analysis. Results obtained indicated that esterification of cardanol yields a partial Miscibility with PVC, whereas esterification and subsequent epoxidation yield a complete Miscibility with PVC. Therefore cardanol acetate, obtained by solvent-free esterification of cardanol, was used as a secondary plasticizer of PVC. Mechanical and rheological analysis showed that the cardanol acetate can partially replace DEHP in PVC formulation.

Naima Belhanechebensemra - One of the best experts on this subject based on the ideXlab platform.

  • Miscibility of pvc pmma blends by vicat softening temperature viscometry dsc and ftir analysis
    Polymer Testing, 2006
    Co-Authors: Kamira Aouachria, Naima Belhanechebensemra
    Abstract:

    Abstract  This paper deals with the Miscibility of polyvinyl chloride (PVC) with polymethyl methacrylate (PMMA). Blends of variable compositions from 0 to 100 wt% were prepared in the presence (15, 30 and 50 wt%) and in the absence of di ethyl- 2 hexyl phtalate as plasticizer. Their Miscibility was investigated by using various analytical methods: determination of the Vicat softening temperature, a viscometry method based on the α criterion of polymer–polymer Miscibility, differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). The results show that the plot of Vicat temperature against composition is a continuous curve, indicating the Miscibility of the blend. The viscometry method and DSC find that the two polymers are miscible up to about 60 wt% of PMMA. This Miscibility is due to a specific interaction of hydrogen bonding type between carbonyl groups (C=O) of PMMA and hydrogen from (CHCl) groups of PVC, as evidenced by FTIR spectroscopy. The two-band deconvolution shows an increase in associated groups percentage in the domain of Miscibility.

Rachel Orenstein - One of the best experts on this subject based on the ideXlab platform.

  • solid solution formation in mg2 si sn and shape of the Miscibility gap
    Acta Materialia, 2020
    Co-Authors: Mohammad Yasseri, Aryan Sankhla, Hasbuna Kamila, Rachel Orenstein, D Nhi Y Truong, Nader Farahi, Johannes De Boor
    Abstract:

    Abstract Investigation of the thermochemical stability of Mg2(Si,Sn) thermoelectric materials is crucial for further development of thermoelectric modules. There is a Miscibility gap reported for the quasibinary Mg2Si–Mg2Sn series, though the exact compositions of its limits are disputed. Gaining a better understanding of intersolubility limits in Mg2(Si,Sn) is important for further optimization of material performance by exploiting the gap-induced phase segregation. For a better understanding on the boundaries of the Miscibility gap below 700°C, two approaches were taken to provide evidence of thermodynamic stable phases and, hereby, monitor the borders of the Miscibility gap. The approaches cover the homogenization of Mg2SixSn1-x at 700°C and diffusion couple experiments at 600°C, 525°C, and 450°C. For 600°C we find two ranges where Mg2Si and Mg2Sn are not miscible, namely x = 0.35 ± 0.05 and x = 0.75 ± 0.05 for Miscibility gap I and 0.85 ± 0.05