Preparation and evaluation of some water‐soluble polyester surfactants

A novel series of water‐soluble polyester surfactants were prepared by the polymerization of bis‐1,4‐(dicarboxymethoxy) benzene, maleic anhydride, and oxypropylated 1,4‐butane diol (IP₁–IP₅) or oxypropylated 1,6‐hexane diol (IIP₁–IIP₅). The unique structural features of these surfactants were confirmed by IR and ¹H‐NMR spectra. These water‐soluble polyester surfactants exhibited excellent surface tension, interfacial tension, low foaming, good emulsifier capability, and good biodegradability in river water, solubilization, wetting, and dispersant properties for applied dyes. The antimicrobial and antifungal properties of the prepared polyester surfactants were measured and found to be highly active. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3413–3424, 2001     

A QUASI NEWTONIAN MODEL FOR SIMULATING THE FLOW OF DILUTE POLYMER SOLUTIONS THROUGH A SUDDEN CONTRACTION

The flow of a quasi Newtonian model fluid, which allows shear thinning as well as extension thickening, through a sudden planar 4:1 contraction is studied numerically. Comparing with numerical results for a purely shear thinning fluid differences show up which follow the trend of experimental data.     

New Semi-Interpenetrating Polymeric Networks from Linear Polysulfone and Thermosetting Bismaleimide and Polyaminobismaleimide Resins

New semi-interpenetrating (semi-IPN) polymeric networks from commercial polysulfone (UDEL RP-1700) and thermosetting bismaleimide (4, 4'-bismaleimidodiphenylmethane) (BMDM) and maleimide terminated polyaminobismaleimide prepolymer based upon BMDM and 4, 4'-diaminodiphenylmethane were prepared. The chemistry, processing, physical and mechanical properties, phase morphology, thermal stability and solvent resistance of the neat resins are presented. The interrelationships among structure, processing, propcrties, and morphology are also discussed.     

Hydroxyl end-functionalized poly(2-isopropyl oxazoline)s used as nano-sized colloidal templates for preparation of hollow polymeric nanocapsules

Hollow polymeric nanocapsules with a thermosensitive membrane are prepared and characterized. They reversibly change their dimensions during temperature variations below and above the transition of the membrane. The nanocapsules were prepared by three steps: (i) well-defined mesoglobules prepared from an LCST polymer (hydroxyl end functionalized poly(2-isopropyl-2-oxazoline), PiPOZ-OH) were coated with a thermo-sensitive cross-linked shell formed via seeded radical copolymerization of N-isopropylacrylamide (NIPAM) and N,N′-bis-methylene acrylamide to produce core–shell nanoparticles (ii), which were subjected to extensive dialysis below the LCSTs of both the core-forming PiPOZ-OH and shell-forming PNIPAM to remove the core (iii). The use of a core-forming polymer of low molecular weight (<8900 g mol⁻¹), narrow dispersity (<1.15) and relatively low T_g (52–68 °C) is beneficial as far as the effectiveness of the removal of the cores is concerned. The inherent immiscibility between PiPOZ-OH and PNIPAM as well as the specific raspberry-like structure of the core–shell particles also contributed for enhancement of the core removal effectiveness.     

A novel copolymer of N-[(tert-butylperoxy)methyl]acrylamide and maleic anhydride for use as a reactive surfactant in emulsion polymerization

A new copolymer of N-[(tert-butylperoxy)methyl]acrylamide (tBPMAAm), containing a primary–tertiary peroxide group and maleic anhydride (MA), was synthesized and employed as a reactive surfactant (inisurf) for the emulsion polymerization of styrene to yield surface-functionalized (peroxidized) reactive latex particles. The copolymerization characteristics were analyzed to determine the monomer reactivity ratios and to provide a way to control the copolymer composition. The ability of tBPMAAm–MA to act as a reactive surfactant during emulsion polymerization was confirmed by the synthesis of monodisperse polystyrene latexes of varying particle size. In addition, peroxide groups were localized on the surface of the particles in a controllable amount (depending on the copolymer concentration), thus, providing the opportunity for further modification of the surface of the particles. This novel copolymer is expected to be a promising and efficient material in the synthesis of functional polymer nanoparticles with well-defined core–shell morphologies.     

Mechanics of the indentation test and its use to assess the adhesion of polymeric coatings

The indentation test provides a simple means by which the adhesion of coatings can be qualitatively assessed. On the way to establishing a quantitative measurement of the adhesion strength of coatings and films, it is important that the mechanics of this test are clearly understood. To investigate the influence of factors such as the coating thickness, the indenter radius, and friction during the test, numerical simulations of the indentation of a typical polymeric coating, polymethylmethacrylate (PMMA), bonded to a rigid substrate were conducted by using the finite element method. The stress generated during the indentation test were obtained by employing an accurate constitutive model of the elastic-viscoplastic behaviour of the polymeric coating under consideration. The results of this analysis illustrate the effects of the factors mentioned above on the deformation of the coating during indentation, its confinement, and interfacial shear, and the normal, shear, and hoop stress distributions occurring during indentation. These results provide insight into the possible failure mechanisms operative during the indentation of thin coatings and the important effects of the coating thickness during such tests.     

Influence of surface characteristics on the adhesion of Alcaligenes denitrificans to polymeric substrates

The adhesion of Alcaligenes denitrificans to several polymeric materials was investigated. As the nature of the surfaces of the micro-organisms and the substrate materials is an important factor in the adhesion process, characteristics such as the electrokinetic potential and hydrophobicity were also determined and correlated with the capacity of bacterial cells to adhere to solid surfaces. The substrates used were high-density polyethylene (HDPE), polypropylene (PP), poly(vinyl chloride) (PVC), and poly(methyl methacrylate) (PMMA). The electrokinetic potential of the cells and the substrates was determined by measurements of electrophoretic mobility and the hydrophobicity was determined by contact angle measurements. All the substrates studied as well as the bacterial strain have a negative zeta potential, which means that adhesion is not mediated by electrostatic interactions. As far as hydrophobicity is concerned, PP is the most hydrophobic material, PMMA is the least hydrophobic, whereas HDPE and PVC present an intermediate behavior. As bacteria cells are hydrophilic, adhesion is favored to PP; therefore, this substrate material seems to be the one that promotes a stronger adhesion and the development of the most stable biofilm for use as a biomass carrier in denitrifying inverse fluidized bed reactors. This was confirmed by the results of adhesion tests. In this way, adhesion seems to be dominated by hydrophobic interactions.     

Influence of plasticizer contents on the properties of HEC-based solid polymeric electrolytes

Solid polymeric electrolytes were obtained by the plasticization process of hydroxyethylcellulose (HEC) with different quantities of glycerol and addition of lithium trifluoromethane sulfonate (LiCF₃SO₃) salt. The samples were prepared in the form of transparent films with very good adhesion properties. These films were characterized by X-ray diffraction, thermal analysis (DSC) and UV-NIR spectroscopy. The ionic conductivity measurements were obtained by impedance complex spectroscopy as a function of both salt contents and temperature. The best conductivity values of 1.07 × 10⁻⁵ S/cm at 30 °C and 1.06 × 10⁻⁴ S/cm at 83 °C were obtained for the samples of HEC plasticized with 48% of glycerol and containing [O]/[Li] = 6. These results show that plasticized HEC is a very good material to be used for the preparation of new solid polymeric electrolytes.     

Investigation of polymerization parameters affecting dopamine selectivity of a polymeric membrane

Summary By means of electrochemical oxidative polymerization, poly (1,3-phenylenediamine) films on a gold electrode were prepared at a potential of 0.8 V. The permeation properties of polymeric films at the different thickness were investigated by cyclic and differential pulse voltammetry techniques. Voltammetric studies showed that polymeric film at the 1.2 mC thickness exhibited selective permeation for dopamine while rejecting ascorbic acid. Then, all the polymerization parameters affecting the permselective characteristics were systematically investigated and the optimal values were determined. Moreover, stability of polymeric membrane was examined. The results showed that polymeric membrane, owing to permselective character, could be used as a dopamine selective membrane. Received: 10 December 1999/Revised version: 12 March 2000/Accepted: 27 March 2000     

Membrane processing of used frying oils

Studies were conducted with used frying oils in a flat membrane batch cell using five different types of polymeric membranes to decrease the soluble degradation products. During membrane processing, triglycerides permeated preferentially compared to the majority of the polar compounds including oxidation products, polymers, and color compounds. Two of the composite membranes, NTGS-AX and NTGS-2200, selectively rejected polar compounds and oxidation products to the extent of 25–48% and 24–44% respectively. The reduction in Lovibond color values (5R+Y) was in the range of 83–93%. The viscosity of the used frying oil was reduced to the extent of 22%. The composite membranes were effective in reducing the soluble impurities, as well as insoluble particulates, without causing any undesirable changes to the oil. The membrane process appears to improve the life of used frying oils and does not have the disadvantages associated with the active filtration systems, however, for commercial application the permeate flux needs to be improved considerably.