Phase Polymer System Research Articles

Thermodynamic Modeling and Validation of the Temperature Influence in Ternary Phase Polymer Systems.

The effect of the temperature, as a process variable in the fabrication of polymeric membranes by the non-solvent induced phase separation (NIPS) technique, has been scarcely studied. In the present work, we studied the influence of temperature, working at 293, 313 and 333 K, on the experimental binodal curves of four ternary systems composed of PVDF and PES as the polymers, DMAc and NMP as the solvents and water as the non-solvent. The increase of the temperature caused an increase on the solubility gap of the ternary system, as expected. The shift of the binodal curve with the temperature was more evident in PVDF systems than in PES systems indicating the influence of the rubbery or glassy state of the polymer on the thermodynamics of phase separation. As a novelty, the present work has introduced the temperature influence on the Flory–Huggins model to fit the experimental cloud points. Binary interaction parameters were calculated as a function of the temperature: (i) non-solvent/solvent (g12) expressions with UNIFAC-Dortmund methodology and (ii) non-solvent/polymer (χ13) and solvent/polymer (χ23) using Hansen solubility parameters. Additionally, the effect of the ternary interaction term was not negligible in the model. Estimated ternary interaction parameters (χ123) presented a linear relation with temperature and negative values, indicating that the solubility of the polymers in mixtures of solvent/non-solvent was higher than expected for single binary interaction. Finally, PES ternary systems exhibited higher influence of the ternary interaction parameter than PVDF systems.

Modelling of surface nanoparticle inclusions for nanomechanical measurements by an AFM or nanoindenter: spatial issues

Finite element analysis (FEA) is used to model nanoindentation by a rigid, spherically shaped indenter, axially indenting an elastic two phase polymer system comprised of a cylindrical nanoparticle of compliant polymer set in a semi-infinite matrix of stiffer polymer. The cylindrical nanoparticle is normal to the sample surface. An axisymmetric finite element model is used to determine the reduced modulus measured as a function of the indentation depth for various nanoparticle radii and extensions below the surface. We show how the previous simple analytical equations may be extended to describe these situations with accuracy. This gives excellent agreement with the FEA and provides a clear guide to the maximum indentation depth as a function of both the nanoparticle radius and its thickness consistent with a choice of either computation from the analytical equations or direct measurement with a maximum of 10% error in the measured reduced modulus.

ARTICHOKE PEROXIDASE TO PARTIAL REMOVAL OF PHENOLS FROM OLIVE MILL WASTE WATER

A very large amount of phenol-polluted waters is formed from the production of olive oil (olive mill waste water, OMWW) and their disposal represents a serious problem. The aim of this study was to investigate the use of peroxidase (POD) from artichoke (Cynara cardunculus L. subsp. scolymus (L.) Hayek) leaves to remove phenols present in OMWW. The POD catalyzes the polymerization and precipitation of aqueous phenols. This application could be useful, because in the Mediterranean region a large amount of OMWW as well as a lot of artichoke scraps resulting from artichoke processing industry, are produced. So, it is possible to consider this biomass (leaves and external bud bracts) as a useful and cheap source of peroxidase. The enzyme extraction was performed by homogenization and separation of pigments using an aqueous two phase polymer system (polyethylene glycol/(NH4)2SO4), that allowed the accumulation of POD in the salt phase. The optimal reaction conditions were evaluated. The phenolic concentration was assayed by Folin-Ciocalteu method. Preliminary results showed that the optimal conditions for enzyme activity were in a broad range of both pH (from 4 to 7) and temperature (from 5 to 50°C). In optimal enzymatic conditions, a reduction of more than 60% of initial phenolic concentration was observed.

Dielectric, dynamic mechanical and DSC evidence for a spatial and dynamic heterogeneity in a single phase polymer system

Of significant interest in the field of relaxation mechanisms in polymer systems is the possible existence of a spatial heterogeneity existing in an otherwise single phase homogenous polymer material. Here, frequency dependent dielectric and mechanical measurements along with DSC measurements show that as early as 5% conversion during cure of a styrene–dimethacrylate systems, two distinctly different α-relaxation regions exist along with two Tg is in the DSC spectra. The heterogeneity persists as the cure advances. The breadth of each relaxation increases and results in an extremely broad relaxation spectrum and Tg transition near cure completion. This result also provides an additional example demonstrating that the existence of two Tg is does not by itself indicate phase separation.

A new approach based on monitoring of phase formation kinetics for examination of biological particles and cells, using aqueous two phase polymer systems

An original technique of use of two-phase polymer systems as an analytical research method is described. The technique is based on the absorbance change of two-phase systems in visible spectrum during formation of the phases. Dynamics of this process was demonstrated as the kinetic curves. Addition of studied objects (macromolecules or cells) to the two-phase system modified the shape of the kinetic curve, depending on their individual surface properties. The technique has the following advantages as compared with traditional procedures of the particle surface analysis with the help of two-phase polymer systems: examination of particles with partition coefficients approaching zero; multiple analyses of the same samples; use of interphase as a matrix for study of spontaneous formation of studied particle complexes. The opportunities of the technique were demonstrated in a series of previous authors' works.

Purification and stability of peroxidase of African oil palm Elaies guineensis.

In the previous work, after screening tropical plants (43 species) for peroxidase activity, high activity has been detected in leaves of some palms and especially African oil palm Elaeis guineensis. This palm is widely cultivated in Colombia and presents a promising source for the industrial production of peroxidase. The initial enzyme isolation included homogenization and extraction of pigments using aqueous two phase polymer system. Initially, traditional system, formed by polyethyleneglycol/K2HPO4, was used. The replacement of K2HPO4 with (NH4)2SO4 allowed direct application of the salt phase with accumulated peroxidase on a Phenyl-Sepharose column. The final purification was carried out by liquid chromatography on Sephacryl S200 and DEAE-Toyopearl columns. The specific activity of the purified peroxidase measured toward guaiacol was 4300 units per mg of protein. The molecular weight and isoelectric point for palm peroxidase were 57.000 and 3.8, respectively. Palm peroxidase possesses uniquely high thermostability and is more stable in organic solvents than horseradish peroxidase is.

Dielectric studies of heterogeneous phase polymer systems: poly(ethylene oxide) inclusions in polycarbonate - a model system

Dielectric measurements are reported on model sandwich structures which mimic heterophase polymer systems which have been studied in an attempt to explore the possible use of this technique for morphological characterization. The model consists of a polycarbonate sheet into which were introduced a large number of small diameter holes filled with air, poly(ethylene oxide) or triflate-doped PEO. The dielectric behavior of this model system is compared with that of a similar structure in which the same volume fraction of the conducting phase is incorporated interms of a single hole

Development of a general ligand for immunoaffinity partitioning in two phase aqueous polymer systems

The effect on the partition of erythrocytes in a two phase aqueous polymer system based on dextran T500 and polyethylene glycol (PEG) 8000 of a combination of immunoaffinity ligands, namely, rabbit immunoglobulin G (IgG) and PEG 1900-modified monoclonal IgG, was examined as a potential cell separation technique. Several hybridoma lines secreting mouse monoclonal IgG specific for the F c receptor of rabbit IgG were raised. The monoclonal IgG was modified by cyanuric chloride attachment of PEG 1900, causing the modified antibody to partition predominantly into the PEG-rich upper phase of the systems. The PEG-modified monoclonal IgG was used as an affinity ligand in the two phase polymer system to specifically increase the partition of rabbit anti-NN glycophorin IgG. The rabbit IgG was applied together with the PEG-modified monoclonal IgG to increase the partition of human erythrocytes. The same system had no effect on the partition of rabbit erythrocytes. These experiments demonstrate that a monoclonal antibody can be modified and used as a general reagent with which to alter cell partition in two phase aqueous polymer systems in an immunologically specific manner.

A phenomenological master curve for viscosity—structure data for two phase polymer systems in simple shear flow

AbstractA master curve hypothesis is established based on a mass balance and an assumption of continuous stress through interfaces for well dispersed two phase systems with “defined” zero shear viscosity. The master curve, which is in reasonable accordance with experimental data is represented in a double logarithmic plot of log (ηT/T,0) against log \documentclass{article}\pagestyle{empty}\begin{document}$ \left({\frac{{\eta _{T,0} M_C H\rho}}{{c^2 RT}}\dot \gamma _T} \right) $\end{document}. Mc is the molecular weight between entanglements, H = M̄w/M̄n, ρ is the density, c is the polymer concentration, all defined for the continuous phase. ηT and ηT,0 are the viscosity and zero shear viscosity of the blend, ηT is the apparent shear rate, R the gas constant, and T is absolute temperature.

Polymer functional group mobility. 2—Partition of ion pairs between hydrophobic and hydrophilic phases of plasma oxidized polyethylene

AbstractPlasma modification of polyethylene is modeled most simply as a process generating a two phase polymer system: a thin hydrophilic surface phase and a relatively unperturbed hydrophobic bulk phase. The oxidized surface of polyethylene exposed to a N (PEN) or to an Ar (PEAr) glow discharge plasma contains functional groups of N (i.e., amines) and of O (i.e., alcohols, carbonyls and carboxylic acids) and constitutes an interesting, chemically unique phase of the polymer. Lipophillic protonated alkyl ammonium nitrates, perchlorates and iodides are more soluble in the internal, hydrocarbon phase of the modified polymer and consequently show negligible electron spectroscopy for chemical analysis intensities. On the other hand, the hydrophilic protonated alkyl ammonium phosphates, sulfates and chlorides concentrate in the more polar surface phase and are readily detected by electron spectroscopy for chemical analysis. Electron spectroscopy for chemical analysis of protonated alkyl ammonium chlorides and iodides is complicated by the evolution of HCl and HI, respectively, into the vacuum. Complete protonation of the N functional groups of PEN with H2SO4 is prevented by prior intra polymer reactions of amines with carbonyl and carboxylic acid groups to form less basic imines and amides, respectively. Sodium carboxylate salts are more soluble in the surface hydrophilic phase, whereas tetrabutylammonium carboxylate salts readily partition into the internal hydrophobic phase. The partition of functional groups between the hydrophilic surface phase and the hydrophobic bulk phase will exert a profound influence on their availability for reaction at the polymer surface.

Isolation of neuronal plasma membranes from the crayfish Procamburus clarkii, with an aqueous two phase polymer system followed by sucrose density gradient centrifugation

An aqueous two phase polymer system (Dextran-polyethyleneglycol system was developed for isolation of plasma membrane fraction from nerves of the crayfish, Procamburus clarkii. The polymer system effectively reduced both mitochondrial and endoplasmic reticulum marker enzyme activity from a crude membrane fraction. The similar enrichment of (Na+ + K+)-ATPase (ATP phosphohydrolase, EC 3.6.1.3) was shown by the polymer system as well as by the sucrose density gradient centrifugation. The purified plasma membrane fraction (PM) was obtained using the polymer system followed by sucrose density gradient centrifugation. The PM fraction had a high specific activity of (Na + K+)-ATPase of up to 17 times that in the homogenate, with smaller contamination by mitochondria and endoplasmic reticulum enzyme activities than any other membrane fraction. Electron micrographs of the PM fraction also supported the above evidences. The protein recovered from the PM fraction amounted to 1.1% of the total protein in the homogenate. The specific activity of acetylcholinesterase (acetylcholine hydrolase, EC 3.1.1.7) in the membrane fractions was less increased than that of (Na+ + K+)-ATPase. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis suggested that polypeptide chains of estimated molecular weight 115,000 and 31,000 were enriched in the plasma membranes of the crayfish nerves.

Fine structures and fracture processes in plastic/rubber two phase polymer systems, 1 — observation of fine structures under the electron microscope: Matsuo, M., Nozaki, C. and Jyo, Y. Polymer Engineering and Science, 9, No 3, p 197 (May 1969)

Fine structures and fracture processes in plastic/rubber two phase polymer systems, 1 — observation of fine structures under the electron microscope: Matsuo, M., Nozaki, C. and Jyo, Y. Polymer Engineering and Science, 9, No 3, p 197 (May 1969)

Fine structures and fracture processes in plastic/rubber two ‐phase polymer systems. I. Observation of fine structures under the electron microscope

AbstractFine structures of several plastic/rubber two ‐phase polymer systems were studied by means of direct observations of ultrathin sections under the electron microscope using osmium tetroxide staining and a hardening procedure developed recently by Kato. Samples used are several types of both ABS polymers and high ‐impact polystyrenes, and several PVC/rubber blends and the results were discussed in relation to their dynamic viscoelastic properties. It is suggested that these studies may fruitfully be extended to clarify the structure ‐to property relationships by use of this method.

Fine structures and fracture processes in plastic/rubber two ‐phase polymer systems. II. Observation of crazing behaviors under the electron microscope

AbstractDetailed crazing behavior in several plastic/rubber twophase polymer systems was studied by means of direct observation of ultrathin sections under the electron microscope by employing osmium tetroxide staining and hardening procedure. Samples used are ABS polymer, high ‐impact polystyrene and several PVC/rubber blends. All of the systems investigated showed evidence of stress ‐crazing when under flexural stress. Relationships between the dispersed rubber particles and the crazing behaviors were studied, and the role of rubber particles in the toughening mechanism of plastics was discussed based on these observations.