Occurrence Of Polymer Research Articles

The Effect of Surfactant on Performance of Polymer Systems Used During Enhanced Oil Recovery Operations

The combined occurrence of polymers and surfactants has been an intense area of study for many years and has long been recognized to be important in influencing the properties of mixed systems. This article presents the results of an extensive study aimed at describing the effect of surfactant on rheological properties of polymer solutions containing polyacrylamide polymers (FP and AN113) for enhanced oil recovery. Using a homogeneous micro-model and polymer/surfactant solutions with different concentrations, the floods were performed to examine the influence of a surfactant (Hostarex ABSD) on some properties of polymer solutions, such as viscosity and interfacial tension. From the experimental results, it appears that the solutions of FP polymer have obtained better performance on keeping their rheological properties even after being contacted with various concentrations of surfactant.

Thermodynamic and Structural Investigations on the Different Forms of Syndiotactic Polystyrene Intercalates

The occurrence of polymer−solvent intercalates of syndiotactic polystyrene (sPS) in biphenyl, benzophenone, and diphenylmethane has been observed from thermodynamic, structural, and morphological investigations. For each system the temperature−concentration phase diagram has been established by DSC and has allowed one to determine the number of sPS/solvent compounds. Experiments by X-ray diffraction and neutron diffraction bear out the outcomes of T−C phase diagrams of these systems. In addition, these diffraction experiments have shown that the highly solvated form, discovered in sPS/benzene systems [Daniel et al. Polymer 1996, 37, 1273], is more common than expected. We suggest to designate the usual chlathrate form as δc-form while the more solvated form could be named δi-form. Also, another form has been observed in these systems, which possesses a nematic-like order. As this form is also a sPS/solvent compound, we suggest to designate it as δN-form The morphology of each system significantly varies w...

Use of pyrolysis-gas chromatography/mass spectrometry to study environmental pollution caused by synthetic polymers: a case study: the Ravenna Lagoon

Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) has been applied to study the composition of synthetic polymers in sediments and nepheloid layers of Pialassa Baiona, a coastal lagoon located north-east the city of Ravenna (Italy), in the proximity of an industrial area. To this purpose sample pyrograms are compared with pyrograms of standard synthetic polymers, namely poly(vinyl chloride) (PVC), poly(vinyl acetate) (PVA), polystyrene (PS), polybutadiene (PB), poly(acrylonitrile- co-styrene- co-butadiene)(ABS), styrene–butadiene random (SBR) and block (SBS) copolymers. The presence of synthetic polymers in environmental samples is indicated by anomalous high levels of styrene and benzene in the pyrograms, and by the detection of selected markers (e.g. chlorobenzene for PVC, acetic acid for PVA, benzenebutanenitrile for ABS, cyclohexenylbenzene for styrene–butadiene rubbers), which are useful for a better identification of individual polymers. The occurrence of polymers in the solid phase collected in surface and bottom waters is discussed in connection with the presence of mercury, another major pollutant of the lagoon.

Energy Criterion for Fatigue Strength of Wood Structural Members

This report describes a mathematical model for fatigue strength of cellulosic materials under sinusoidal loading. The model is based on the Reiner-Weissenberg thermodynamic theory of strength in conjunction with a nonlinear Eyring’s three-element model. This theory states that failure depends on a maximum value of the intrinsic free energy that can be stored elastically in a volume element of the material. The three-element mechanical model, which consists of a linear spring in series with a parallel array of another linear spring and an Eyring dashpot, provides a good description of rheological material properties. The strength model system was able to predict rupture occurrence of polymers and wood structural members under constant and ramp loading with satisfactory results. For sinusoidal loading, the present study shows that the strength model system can predict time at fracture as a function of applied mean stress, amplitude of cyclic stress, and stress frequency. Numerical examples with model parameters evaluated for small Douglas-fir beams are presented.

Ocuurrence of polymers containing N-acetylglucosamine-1-phosphate in bacterial walls.

WALLS of Staphylococcus lactis I3 contain substantial proportions of a novel teichoic acid in which N-acetyl-glucosamine l-phosphate residues form an integral part of the polymer chain1,2. A similar teichoic acid is believed3 to be present in walls of Micrococcus hyicus ATCC 11249 and we now report the occurrence of N-acetylglucosamine l-phosphate residues in polymers present in the walls of two further species of bacteria. Sugar l-phosphate linkages are found in yeast phosphomannans4 and phospho-galactans5; the suggestion6 that pneumococcal C-substance is a simple polymer of N-acetylgalactosamine l-phosphate has been shown to be unlikely7, although such a linkage is believed to form the point of attachment between the polysaccharide and peptidoglycan components of the wall of Lactobacillus casei8. Polymers containing such linkages have a characteristically high liability to acid and, in some cases, to alkali; consequently, their distribution may be more widespread than present reports suggest, for the conditions employed for the isolation of polysaccharides would in many cases cause considerable degradation of such comparatively labile linkages.