scholarly journals Crystallization and Temperature Driven Morphological Evolution of Bio-based Polyethylene Glycol-acrylic Rosin Polymer

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1684 ◽  
Author(s):  
Yanzhi Zhao ◽  
Mengjun Zou ◽  
Huazhen Liao ◽  
Fangkai Du ◽  
Fuhou Lei ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Light Scattering ◽  
Morphological Evolution ◽  
Transformation Process ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Reversible Transformation ◽  
Heating And Cooling ◽  
Crystalline Core ◽  
Rayleigh Light

In this work, the morphological and conformational evolution of bio-based polyethylene glycol (PEG)-acrylic rosin polymer in water was studied by scanning electron microscopy (SEM), polarized optical microscopy (POM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Rayleigh light scattering (RLS) and dynamic light scattering (DLS) techniques during a heating and cooling cycle. When the concentration was higher than the critical micelle concentration (CMC), a reversible transformation process, i.e. from micelle to irregular lamella aggregations, was detected. As the concentration was equal to or below the CMC, individual unimers aggregated into needle-shaped crystals composed of acrylic rosin crystalline core in the heating run. The crystallization of acrylic rosin blocks acted as seeds and thus, in the subsequent cooling process, the PEG corona crystallized into the cube-shaped crystals. The cytotoxicity assay showed the biocompatibility of bio-based polyethylene glycol-acrylic rosin polymer. This has great potential in the application of drug delivery and release triggered by temperature.

scholarly journals EFFECT OF SELECTED POLYMERS ON DISSOLUTION AND STABILIZATION OF AMORPHOUS FORM OF MELOXICAM

2017 ◽  
Vol 9 (9) ◽  
pp. 33
Author(s):  
Rana Obaidat ◽  
Bashar Al-taani ◽  
Hanan Al-quraan
Keyword(s):  
Polyethylene Glycol ◽  
Solid Dispersions ◽  
Dissolution Profile ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Polyethylene Glycol 4000 ◽  
Amorphous Form ◽  
Molecular Weights ◽  
Low Solubility ◽  
Reproducible Manner

Objective: Meloxicam is classified as class II corresponding to its high permeability and low solubility (12μg/ml). This study aims to compare the effect of selected polymers on stabilization of amorphous form, and dissolution of meloxicam by preparation of different solid dispersions using selected polymers (chitosan oligomers, polyvinylpyrrolidone K30, and polyethylene glycols).Methods: These solid dispersions were prepared using two different methods; solvent evaporation method for the two molecular weights chitosan carriers (16 and 11KDa) and polyvinylpyrrolidone-K30 and melting method for the two different molecular weights polyethylene glycol (4000 and 6000). The physicochemical properties of solid dispersions were analyzed using differential scanning calorimetry, Fourier transform infra-red analysis, Powder X-ray diffraction, and scanning electron microscopy. Selected dispersions were then compared to two selected marketed drugs (Mobic® and Moven®).Results: Best dissolution rates were obtained for both polyvinylpyrrolidone-K30 and polyethylene glycol 6000, followed by chitosan 16 kDa, chitosan 11 kDa, and polyethylene glycol 4000. Increasing polymeric ratio increased dissolution rate except for chitosan. Precipitation of the drug as amorphous form occurred in chitosan and polyvinylpyrrolidone-K30 dispersions, while no change in crystallinity obtained for polyethylene glycol dispersions. Failure of polyvinylpyrrolidone-K30 in the maintenance of stability during storage time was observed while re-crystallization occurred in chitosan-based dispersions, which ends with preferences to polyethylene glycol dispersions. After comparing the release of selected dispersions with the two selected polymers; all dispersions got a higher release than that of the two marketed drugs release.Conclusion: The dissolution profile of meloxicam has been increased successfully in a reproducible manner.

Polyethylene Glycol/Expanded Vermiculite Shape-Stabilized Composite Phase Change Materials for Thermal Energy Storage

2016 ◽  
Vol 847 ◽  
pp. 39-45
Author(s):  
Yong Deng ◽  
Jin Hong Li ◽  
Ting Ting Qian ◽  
Wei Min Guan ◽  
Xiang Wang
Keyword(s):  
Polyethylene Glycol ◽  
Phase Change ◽  
Latent Heat ◽  
Phase Change Materials ◽  
Vacuum Impregnation ◽  
Impregnation Method ◽  
Scanning Calorimetry ◽  
Heating And Cooling ◽  
Expanded Vermiculite ◽  
Composite Phase Change Materials

Polyethylene glycol (PEG)/ expanded vermiculite (EVMT) shape-stabilized composite phase change material (ss-CPCM) was prepared by a facile vacuum impregnation method. The maximum mass percentage for PEG retained in ss-CPCM was 75.1 wt.% due to specific non-uniform flat layers pore structure of EVMT. The scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR) analysis results indicated that the melted PEG was adsorbed on the surface and completely dispersed into the pores of EVMT and no chemical changes took place during the heating and cooling processes. X-ray diffraction (XRD) results showed that the crystal structure of PEG was not destroyed after impregnation whereas the crystallization process of PEG was greatly restrained. Differential scanning calorimetry (DSC) results indicated that ss-CPCM melted at 57.61°C with a latent heat of 103.1 J/g and solidified at 33.19°C with a latent heat of 88.29 J/g. In addition, the thermal conductivity of ss-CPCM reached 0.418W/m K. The ss-CPCM can be considered as promising candidate materials for building applications due to their suitable phase change temperature, large latent heat and excellent chemical compatibility.

scholarly journals Kinetics of the Solution-Mediated Polymorphic Transformation of the Novel l-Carnitine Orotate Polymorph, Form-II

Pharmaceutics ◽  
2018 ◽  
Vol 10 (4) ◽  
pp. 171 ◽  
Author(s):  
Ji-Hun An ◽  
Wonno Youn ◽  
Alice Kiyonga ◽  
Changjin Lim ◽  
Minho Park ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Solid State ◽  
Polymorphic Transformation ◽  
Transformation Process ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Treatment And Prevention ◽  
Transfer Equations ◽  
Reactive Crystallization

Research studies related to the polymorphs of l-Carnitine orotate (CO), a medication used for the treatment and prevention of liver diseases, are insignificant or almost nonexistent. Accordingly, in the present study, l-Carnitine orotate (CO) was prepared for investigating CO polymorphs. Here, a reactive crystallization was induced by reacting 1g of l-Carn (1 equivalent) and 0.97 g of OA (1 equivalent) in methanol (MeOH); as a result, CO form-I and CO form-II polymorphs were obtained after 1 h and 16 h of stirring, respectively. The characterization of CO polymorphs was carried out utilizing Powder X-ray diffraction (PXRD), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and solid-state Nuclear Magnetic Resonance Spectroscopy (solid-state CP/MAS 13C-NMR). The solution-mediated polymorphic transformation (SMPT) of CO polymorphs was investigated in MeOH at controlled temperature and fixed rotational speed. The results revealed that CO form-I is a metastable polymorph while CO form-II is a stable polymorph. From the same results, it was confirmed that CO form-I was converted to CO form-II during the polymorphic phase transformation process. Moreover, it was assessed that the increase in temperature and supersaturation level significantly promotes the rate of nucleation, as well as the rate of mass transfer of CO form-II. In addition, nucleation and mass transfer equations were employed for the quantitative determination of SMPT experimental results. Lastly, it was suggested that CO form-II was more thermodynamically stable than CO form-I and that both polymorphs belong to the monotropic system.

Comparison of Solvent-Casting and Melt-Compounding Blended Biomedical (Polylactide)-(Polyethylene Glycol) Mixture as Drug Carrier

2014 ◽  
Vol 1002 ◽  
pp. 99-104
Author(s):  
Hong Jiang ◽  
Li Bo Wang ◽  
De Jun Xu ◽  
Xiao Yang Liu
Keyword(s):  
Polyethylene Glycol ◽  
Drug Carrier ◽  
Amorphous State ◽  
Solvent Casting ◽  
X Ray Diffraction ◽  
X Ray ◽  
Weight Percentage ◽  
Melt Compounding ◽  
Heating And Cooling ◽  
Degradation Time

For the purpose of drug carrier and delivery, the polylactide was modified by polyethylene glycol blending with the weight percentage of 80/20 by two methods: solvent-casting and melt-compounding. Characterizations of X-ray diffraction, Scanning Electron Microscope and degradation experiments have been done to study the crystallization, miscibility and degradation behavior. The melt-compounding provides a better miscibility associated with longer degradation time, however the heating procedure effects the polymers. Because of the heating and cooling cycle, the polymers had an opportunity to crystalize and the crystal peak can be seen in the XRD results. While the solvent-casting avoids the high temperature experience of blend with an amorphous state, and provides lower miscibility and short degradation time. These significant features will be considerable factors in drug carrier design.

Crystallization behavior of polypropylene/silver nanocomposites using polyethylene glycol as reducing agent and interface modifier

2015 ◽  
Vol 30 (5) ◽  
pp. 662-677 ◽  
Author(s):  
Pablo H Camacho ◽  
Ana B Morales-Cepeda ◽  
Homero Salas-Papayanopolos ◽  
Jesús E Bautista ◽  
Carlos Castro ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Reducing Agent ◽  
Infrared Spectrometry ◽  
X Ray Diffraction ◽  
Ag Nps ◽  
Scanning Calorimetry ◽  
Easy Method ◽  
Β Phase ◽  
Single Screw Extruder ◽  
Diffraction Patterns

In this work, isotactic polypropylene (iPP) nanocomposites were prepared containing silver nanoparticles (Ag-NPs) with a novel and easy method, using polyethylene glycol (PEG) as reducing agent and surface modifier. Ag-NPs were prepared using different amounts in weight of silver nitrate into PEG to induce the formation of Ag-NPs. PP/Ag nano compounds were prepared by melt blend method: single-screw extruder and internal Brabender mixer. The effects of Ag-NPs and PEG on the crystallization, morphology, thermal, and mechanical properties were evaluated. Ag-NPs with a particle size of 80 nm and typical growth of the β-form in iPP were observed. The presence of PEG in samples of PP/Ag-NPs was detected by infrared spectrometry and the peak characteristic of Ag-NPs by ultraviolet–visible analysis. X-Ray diffraction patterns and differential scanning calorimetry thermograms showed the β-phase formation in both of the dispersion methods, but Brabender mixer showed higher percentages of crystallinity (31% of β-phase). The elongation at break was increased and it was directly dependent on the relative amount of crystalline β-phase. PEG is an excellent precursor to get Ag-NPs and a good interface modifier of iPP.

Phase Transformation in Ni-Ti Shape Memory and Superelastic Alloys Subjected to High Pressure Torsion

2010 ◽  
Vol 123-125 ◽  
pp. 1007-1010 ◽  
Author(s):  
Karimbi Koosappa Mahesh ◽  
Francisco M. Braz Fernandes ◽  
Gheorghe Gurau
Keyword(s):  
High Pressure ◽  
Phase Transformation ◽  
Shape Memory ◽  
High Pressure Torsion ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
One Stage ◽  
Heating And Cooling ◽  
Ti Alloys ◽  
M Phase

A systematic study on the phase transformation of Ni-Ti shape memory and superelastic alloys subjected to Severe Plastic Deformation (SPD) – High Pressure Torsion (HPT) technique has been carried out. Ni-Ti alloys of three compositions were chosen for the study. Specimens of these alloys in as-received (AR) condition and after HPT have been subjected to Differential Scanning Calorimetry (DSC) and X-ray Diffraction (XRD) analyses. In this study, while comparing the results of DSC thermograms and XRD spectra for the same sample conditions, some differences were observed. In the case of NiTi-H alloy after HPT, there appeared one stage phase transformation with DSC both while heating and cooling suggesting Martensite↔Austenite transformation but, with respect to XRD spectra while cooling, at the intermediate temperature of 55°C, the R-phase peaks corresponding to (1 1 2)R and (3 0 0)R planes appeared. In the thermogram obtained for the NiTi-B alloy subjected to HPT, it is observed that, while cooling, the Austenite to R-phase transformation is merged with R-phase to Martensite transformation. The results of the XRD obtained at -180°C show the presence of R-phase along with M-phase. The DSC curve of the NiTi-S alloy subjected to HPT corresponds to one stage phase transformation both while heating and cooling but, the diffractogram of the sample obtained at -180°C corresponds to the presence of both R-phase and M-phase.

Simultaneous Thermal and Structural Measurements of Oriented Polymers by DSC/XRD Using an Area Detector

1988 ◽  
Vol 32 ◽  
pp. 617-623
Author(s):  
Steven T. Correale ◽  
N. Sanjeeva Murthy
Keyword(s):  
Structural Information ◽  
Variable Temperature ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Oriented Polymers ◽  
X Ray ◽  
Precise Control ◽  
Area Detector ◽  
Heating And Cooling ◽  
Complementary Techniques

Differential scanning calorimetry (DSC) and variable temperature x-ray diffraction (XRD) are two complementary techniques which provide thermal and structural information. By using DSC and XRD simultaneously, one can directly correlate the results from the two techniques. The simultaneous measurements eliminate problems which might arise due to sample inhomogeneity and instrumental differences. In addition, the DSC provides precise control over temperature, and heating and cooling rates.

scholarly journals Application of Nanosilicon to the Sintering of Mg-Mg2Si Interpenetrating Phases Composite

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7114
Author(s):  
Anita Olszówka-Myalska ◽  
Hanna Myalska ◽  
Patryk Wrześniowski ◽  
Jacek Chrapoński ◽  
Grzegorz Cios
Keyword(s):  
Volume Fraction ◽  
Sintering Temperature ◽  
Intermetallic Phases ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Heating And Cooling ◽  
In Situ Fabrication ◽  
Composite Formation ◽  
Porosity Measurements

The new in situ fabrication process for Mg-Mg2Si composites composed of interpenetrating metal/intermetallic phases via powder metallurgy was characterized. To obtain the designed composite microstructure, variable nanosilicon ((n)Si) (i.e., 2, 4, and 6 vol.% (n)Si) concentrations were mixed with magnesium powders. The mixture was ordered using a sonic method. The powder mixture morphologies were characterized using scanning electron microscopy (SEM), and heating and cooling-induced thermal effects were characterized using differential scanning calorimetry (DSC). Composite sinters were fabricated by hot-pressing the powders under a vacuum of 2.8 Pa. Shifts in the sintering temperature resulted in two observable microstructures: (1) the presence of Mg2Si and MgO intermetallic phases in α-Mg (580 °C); and (2) Mg2Si intermetallic phases in the α-Mg matrix enriched with bands of refined MgO (640 °C). Materials were characterized by light microscopy (LM) with quantitative metallography, X-ray diffraction (XRD), open porosity measurements, hardness testing, microhardness testing, and nanoindentation. The results revealed that (n)Si in applied sintering conditions ensured the formation of globular and very fine Mg2Si particles. The particles bonded with each other to form an intermetallic network. The volume fraction of this network increased with (n)Si concentration but was dependent on sintering temperature. Increasing sintering temperature intensified magnesium vaporization, affecting the composite formation mechanism and increasing the volume fraction of silicide.

Microstructure of Mg-Ti-Al Composite Hot Pressed at Different Temperature

2012 ◽  
Vol 191 ◽  
pp. 199-207 ◽  
Author(s):  
Anita Olszówka-Myalska ◽  
Roman Przeliorz ◽  
Tomasz Rzychoń ◽  
Monika Misiowiec
Keyword(s):  
Powder Mixture ◽  
Thermal Effects ◽  
Sintering Temperature ◽  
Weight Ratio ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Magnesium Matrix ◽  
X Ray ◽  
Heating And Cooling ◽  
Al Composite

Metal matrix composite comprising a multiphase magnesium matrix and titanium particles fabricated by hot pressing was characterized. Powder mixture of the Mg:Ti:Al at weight ratio equal to 10.5:6.1:3.4 was sintered at 640, 650 and 660°C whereas other parameters were held constant. Thermal effects during heating and cooling of powder mixture were measured by differential scanning calorimetry (DSC). Microstructure of composite was characterized by scanning electron microscopy (SEM) with a use of X-ray energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). For all conditions of components consolidation α-Mg, α-Ti, Mg17Al12 and Al3Ti were identified. It was revealed that dispersion and location of Mg17Al12 and Al3Ti compounds depended on sintering temperature. Measurements of hardness and density of obtained non-porous composite gave approximate results of 130 HV and 2.7 g/cm3 respectively

Collision induced hyper-Rayleigh light scattering in CCl4

1996 ◽  
Vol 88 (3) ◽  
pp. 683-691 ◽  
Author(s):  
P. KAATZ ◽  
D.P. SHELTON
Keyword(s):  
Light Scattering ◽  
Rayleigh Light Scattering ◽  
Rayleigh Light
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