Authors:J. Suñol, J. Farjas, R. Berlanga, and J. Saurina
A modified isoconversional method is applied to perform the kinetic analysis of non-isothermal processes. The solidification
process of a polyethylene glycol with a mean molecular of 4000 (PEG 4000) was here analyzed. It was stated that the Avrami
model provides a good description of the solidification process.
Temperature-cooling rate-transformation diagrams were constructed and there was a good agreement between experimental data
and the calculated T-CR-T curves. Moreover, morphological qualitative analysis has been performed by means of scanning electron
Polyurethanes based on biopitch and PEG of distinct molecular masses (Mw 1500, 4000 and 6000) were synthesized using polymeric MDI. Different materials were obtained through syntheses using various
biopitch content and NCO/OH ratio. Thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) were used to
determine their thermal properties. Variations of thermal stability were observed with amorphous and semicrystalline structures
depending on the biopitch content and the NCO/OH ratio.
Five poorly soluble drugs namely hydrochlorothiazide, menadione, propylthiouracil, quinine sulfate and sulfamerazine were
used to evaluate the ability of an index (Ic) based on the van't Hoff equation to predict the eutectic composition at a higher heating rate than previously published.
The term Ic is a dimensionless index which has been defined in the literature and is used to predict eutectic composition. This current
work uses this study to determine if the correlation holds true at the higher heating rate of 10C min-1. The maximum deviation was observed for quinine sulfate, for which the predicted eutectic composition was 10% lower than
what was observed with the DSC. It can be concluded that the Index developed here has a good correlation with the experimentally
determined eutectic composition.
Authors:C. G. Mothé, A. D. Azevedo, W. S. Drumond, S. H. Wang, and R. D. Sinisterra
excellent mechanical properties, they might be widely used in pharmaceutical and other medical applications. Poly(ethylene glycol) (PEG) presents remarkable biological and physico-chemical properties, including hydrophilicity, solubility in water and organic
A radiometric method, for the determination of PEG-1000 based on the extraction of an associate Ba2+-PEG-chlorinated dicarbolide anion /[/C2B9H8Cl3/2Co]–, further abbreviated BCl–/ into a mixture nitrobenzene + chloroform /41/, has been alaborated. The activity of133Ba which is used as a radioactive indicator, is proportional to the PEG-1000 concentration in the sample. The optimum conditions for the determination of PEG-1000 /e.g. the acidity of the solution, the barium concentration, the concentration of the extraction agent etc./ have been studied in detail.
Authors:Pranay Sinha, Shekhar Kumar, U. Kamachi Mudali, and R. Natarajan
Phenyl trifluoromethyl sulfone (FS-13) is an inert diluent used in HCCD/PEG process for isolation and recovery of cesium and
strontium from highly radioactive raffinate waste. There is no experimental data available in open literature describing pressurization
due to the thermal decomposition of FS-13 at elevated temperatures. Experiments were conducted for determination of flash
point and heating of FS-13 under pressurized closed-vent conditions in an adiabatic calorimeter. During adiabatic experiments,
negligible pressurization was observed.
Authors:J. M. Ginés, M. J. Arias, J. R. Moyano, Cs. Novak, G. Pokol, and P. J. Sánchez-Soto
A thermal study using DSC and Hot Stage Microscopy (HSM) was carried out to investigate the interaction in solid state of the binary system PEG 4000 — oxazepam, and to establish their phase diagram. The eutectic composition, which melting occurs at lower temperature as compared with the pure components, has been determined. The results obtained by DSC and HSM have indicated that PEG 4000 — oxazepam mixtures displays no obvious incompatibilities, and that the system shows a typical eutectic behaviour. However because of the closeness of the melting of PEG 4000 to the eutectic temperature, it was difficult to determine precisely the eutectic composition and temperature on the basis of DSC measurements alone. The use of heats of fusion corresponding to physical mixtures allowed an estimation of the eutectic composition at 6% w/w oxazepam. Additional information of temperature (57.6‡C) and composition (5–10% w/w oxazepam) of the eutectic was obtained by HSM using the contact method. This low melting temperature in this range of compositions offers advantages in terms of drug stability and easy manufacture.
The solubility and rate of dissolution of a poorly-soluble active principle are of importance when substances are destined
for oral administration. Physical blends in wich drug and carrier are able to form particular compositions, such as a eutectic,
may exibit an increased rate of dissolution. In this work the interactions lorazepam and PEG 6000, were examined, the particular
thermal behaviour of lorazepam being taken into account. An eutectic was obtained and its composition was studied by means
of differential scanning calorimetry, thermomicroscopy, infrared spectroscopy and X-ray methods.