Search results for "Hildebrand"

Structure-properties relationships of polyhedral oligomeric silsesquioxane (POSS) filled PS nanocomposites

2012

The polyhedral oligomeric silsesquioxane (POSS) additivated polystyrene (PS) based nanocomposites were pre- pared by melt processing and the structure-properties relationships of the POSS-PS systems were compared to those of the neat PS. In order to investigate the effect of these structural parameters on the final properties of the polymer nanocompos- ites, five different kinds of POSS samples were used, in particular, POSS with different inorganic cage and with different organic pendent groups. The rheological investigation suggests clearly that the POSS acts as a plasticizer and that the processability of the PS was positively modified. The affinity between the POSS samples and the PS ma…

Między metafizyką wspólnoty a praktyką życia wspólnotowego. O wspólnocie widzianej przez Dietricha von Hildebranda i Jeana Vaniera

2019

W filozofii politycznej i społecznej opis relacji pomiędzy jednostką a wspólnotą należy do dwóch przeciwstawnych nurtów: indywidualizmu i kolektywizmu a skrajnych postaciach między libertynizmem a komunitaryzmem. Powyższy temat wpisuje się w dyskusję na temat tego, w jaki sposób wspólno- ta wpływa na konkretnego człowieka i odwrotnie. Zostało to uczynione jednak z innej perspektywy. Autor rozdziału wykorzystał myśl dwóch personalistów: Dietricha von Hildebranda i Jeana Vaniera. Hildebrand, korzystając z dorobku personalizmu oraz fenomenologii w dziele „Metafizyka wspólnoty” wskazuje, że wspólnota nie jest dodatkiem do życia społecznego. Vanier, będąc założycielem wspólno- ty L’Arche (skupia…

A New Simple Static Method for the Determination of Solubilities of Condensed Compounds in Supercritical Fluids

2002

Abstract A simple static method based on gravimetric measurements has been adopted to measure the solubility of benzenecarboxylic acid, 2-hydroxy-benzenecarboxylic acid, 4-hydroxy-benzenecarboxylic acid and 1,8-dihydroxyanthraquinone along several isotherms in the temperature range 318–357 K and the pressure interval 7–23 MPa. Solubility data have been correlated with the Zieger–Eckert approach, using the Fedor atomic and group contribution method to estimate the solubility parameter and the molar volume of the solutes. A good agreement was obtained between data reported in the literature and those determined using the proposed method which allows one to measure solubility mole fraction as …

Solubility of Polymers

2011

Detailed knowledge concerning the phase state (homogeneous or coexistence of two or more condensed phases) of polymer containing mixtures is indispensible in virtually any area related to the production or application of macromolecules. In addition to this qualitative information it is for many purposes highly desirable to dispose of quantitative data regarding solvent quality or, more generally, with respect to the thermodynamic interaction between the components of the mixtures. This contribution starts with a brief presentation of the thermodynamic criteria deciding on the phase state and presents the experimental methods used in this area. The next section gives an overview on typical b…

Experimental P-T-ro Measurements of Supercritical Mixtures of Carbon Dioxide, Carbon Monoxide, and Hydrogen and Semiquantitative Estimation of Their …

2007

The P-T-ρ behavior of the CO2-CO-H2 system was studied in the supercritical region under operative conditions close to those adopted to perform hydrogenation and hydroformylation reactions in dense CO 2, thus providing new interesting information on this fluid mixture. Experiments were performed in a fixed volume reactor in the temperature range from 298 K to 343 K changing the density and the composition of the fluid phase. The one-component (Hildebrand) solubility parameter of the mixture was estimated from experimentally measured P vs T profiles, and its dependence on the density and composition of the system was analyzed to study the antisolvent effect of the permanent gases. We have fo…

1977

Advancements in Sustainable PVDF Copolymer Membrane Preparation Using Rhodiasolv® PolarClean As an Alternative Eco-Friendly Solvent

2021

In this work, Rhodiasolv® PolarClean was employed as a more sustainable solvent for the preparation of poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) flat sheet membranes via phase inversion technique by coupling vapour induced phase separation (VIPS) and non-solvent induced phase separation (NIPS) processes. Preliminary calculations based on Hansen solubility parameters well predicted the solubilization of the polymer in the selected solvent. The effect of exposure time on humidity and the influence of polyethylene glycol (PEG), polyvinyl pyrrolidone (PVP) and sulfonated polyether sulfone (S-PES) on membrane properties and performance, were evaluated. Three different coagulation …

Equilibrium swelling and solvation studies on crosslinked polyacrylamides

2004

Polyacrylamide (PA) crosslinked with four different crosslinking agents, triethyleneglycol dimethacrylate (TEGDMA), N,N′-methylene bisacrylamide (NNMBA), hexanediol dimethacrylate (HDDMA) and divinylbenzene (DVB), with mole percents ranging from 5 to 20, was prepared by solution polymerization and subjected to swelling and solvation studies. Solubility parameters and cohesive energy density were determined from swelling studies. Molecular weight between crosslinks for these systems were determined by Flory–Rehner analysis. There is a discontinuous volume change for 10% NNMBA and HDDMA crosslinked PA, 15% TEGDMA crosslinked PA and 10 and 15% DVB crosslinked PA in solvent mixtures of acetic a…

Pressure dependence of the demixing of polymer solutions determined by viscometry

1981

From the break-down in the viscosity of a polymer solution, associated with the entrance into the two phase region, the pressure dependence of the demixing temperatures of solutions of polystyrene (M = 600.000) in cyclohexane, cyclopentane, diethylmalonate and 1-phenyldecane was measured up to 1000 bar. The application of pressure increases the solubility of polystyrene in cyclopentane and diethylmalonate, but decreases that in 1-phenyldecane; in the case of cyclohexane, a pressure of optimum miscibility is observed at ca. 120 bar.

1985

From the break-down in the viscosity and from the increase of the intensity of the scattered light, associated with the entrance into the two-phase region, the pressure dependence of the demixing temperature of solutions of PVC 37 000, PVC 75 000 and PVC 100 000 in phenetole and PVC 75 000 in o-xylene was measured up to 1 000 bar. (The numbers in the codes of the PVC specimens are their approximate molecular weights.) The application of pressure increases the demixing temperatures of PVC in both solvents by about 1 K/100 bar. For a qualitative forecast of the pressure effects, the solubility parameter theory in combination with the corresponding states principle, and an empirical correlatio…