聚合物驱含油污水的聚集特性研究

通过测定聚合物驱含油污水中油珠、絮体及Zeta电位的大小,研究了污水油含量、固体悬浮物含量、聚合物浓度对油珠及悬浮物的亚微观聚集形态、表面电荷及污水稳定性的影响。结果表明,随聚合物浓度或油含量的增加,污水中的油珠、絮体均有变大的趋势;随固体悬浮物浓度的增加,污水中的油珠、絮体不仅有变大的趋势,且大尺寸的絮体数量显著增加。聚合物浓度对带电颗粒的Zeta电位有显著的影响,聚合物浓度越高,带电颗粒的Zeta电位绝对值越高。表明聚合物是聚合物驱采油污水处理低效的原因。     

A glow discharge treatment to immobilize poly(ethylene oxide)/poly(propylene oxide) surfactants for wettable and non-fouling biomaterials

A non-fouling (protein resistant) polymer surface was achieved using an argon glow discharge treatment of a polyethylene surface which had been precoated with various poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) (PEO-PPO-PEO) tri-block copolymer surfactants. The surfactant is first deposited on the polymer surface via a solvent swelling and evaporation method. Then the coated surfactant is immobilized on the substrate surface by an inert gas discharge treatment. ESCA and water contact angle () measurements on treated and solvent washed surfaces show significant increases in both surface O/C ratios and surface water wettability (0 < 30°) compared to LDPE control surfaces, revealing the presence of PEO on the treated surfaces. A great reduction of fibrinogen adsorption on the modified surfaces is also observed for the highest PEO content surfactants. This simple surface modification process may have wide applicability to obtain wettable polymer surfaces in general, and non-fouling biomaterial surfaces in specific.     

Surface modification of ethylene copolymers moulded against different mould surfaces-1. Surface enrichment by functional groups

A polymer surface chemical composition can be changed by the influence of different environments. Results presented from this study show that the surface of the mould influences the outermost polymer surface by enriching it with specific functional groups. This was done by moulding random copolymers against polymer films with low and high surface energies. The values presented are interpreted in terms of differences in surface energy between the mould surface and the copolymer. The random copolymers used were poly(ethylene-co-vinylacetate) (EVA) and poly(ethylene-co-acrylic acid) (EAA), both with a different comonomer content. The copolymers were moulded in contact with mould surfaces made of polymer films which were perfluorinated ethylene propylene copolymer (FEP), poly(tetrafluoroethylene) (PTFE), and poly(ethylene terephthalate) (PET). The resultant surfaces were characterized by X-ray photoelectron spectroscopy (XPS or ESCA) and contact angle measurements The surface content of acrylic acid functional groups increased in the case of EAA copolymer moulded against PET, and decreased when moulded against FEP as compared to the bulk concentration. EVA copolymers were found to be enriched in acetate groups when moulded against FEP and deficient when moulded against PET. The contact angle measurements together with the XPS measurements showed significant differences between materials moulded in contact with low and high energy surfaces. A low molecular weight additive (an internal release agent), in an EVA copolymer, was found to be enriched at the moulded polymer surface when a PET film was used as mould surface. A material transfer was also found to occur from the solid polymer films to the moulded polymer surface.     

Poly(vinyl chloride) (PVC) hollow fibre membranes for gas separation

Poly(vinyl chloride) (PVC) gas separation hollow fibre membranes were produced from multicomponent dopes using dry/wet forced convection spinning. Membranes spun from a low polymer content solution exhibited disappointing gas separation properties. Their low selectivities were indicative of thick skins and high surface porosities. In contrast, high polymer content spun fibres showed good gas separation properties. Selectivities were high, active layers relatively thin and surface porosities moderate. Coating with poly(dimethylsiloxane) nullified the surface pores. The favourable performance of the high polymer content spun fibres was also related to shear rate and forced convection residence time during spinning. To the knowledge of the authors, this work represents the first reported success in producing PVC hollow fibre membranes with morphologies suitable for gas separation. The development of PVC hollow fibres relates to the ultimate quest to produce membranes capable of reliably separating oxygen and ozone gas mixtures.     

Preparation and surface properties of fluorine-containing diblock copolymers

Two series of semifluorinated fluorocarbon diblock copolymer poly(butyl methacrylate-co-perfluoroalkyl acrylate) have been synthesized by atom transfer radical polymerization (ATRP). The ¹H NMR, F-EA, GPC and FTIR were used to characterize copolymer structure. Contact angle measurements on the thin polymer films showed low critical surface tensions and low dispersion force contributions to the surface energy, which indicated the presence of the fluorinated block at the surface. The results showed that the water- and oil-repellency increased with the fluorine content in the diblock copolymers. After annealing at different temperatures or different times, the water- and oil-repellent properties of diblock copolymer were increased to approach maximum values. This phenomenon proves the propensity of polymer for fluorine enrichment at air-polymer surface.     

Chain Conformation and Surface Characteristics of Polymers

Films of styrene-butyl acrylate copolymers when pre-conditioned in polar or non-polar media, have been used for measurements of critical surface tension, for retention volume measurements by inverse gas chromatography, and as adhesives in joints with aluminium sheet. It has been shown that large variations in surface tension, and particularly in the non-dispersive force contribution, are generated by exposing the polymer to diverse media. Specific retention volumes indicate that the copolymer surface becomes enriched in polar groups when exposed to polar media including water and formamide. The peel strength of Al-polymer joints can be roughly doubled when the polymer surface is pre-conditioned in polar rather than in non-polar media. The magnitude of property variations diminishes with increasing content of the acrylic moiety in the polymer.

The results are interpreted as showing that the surface conformation of polymer chains is such as to diminish or enrich the surface concentration of polar moieties, depending on whether the polymer is in contact with polar or non-polar media. The proposed surface re-conformation appears to be reversible, and to proceed by diffusion-dependent rate processes. This evidence elaborates on the importance of attenuated responses in macromolecules to physico-chemical forces, and on the consequences of these responses to bulk as well as surface and interfacial properties of the polymer.     

Synthesis and Characterization of Hydroxyapatite/Poly(Vinyl Alcohol Phosphate) Nanocomposite Biomaterials

A hydroxyapatite (HAp)/poly(vinyl alcohol phosphate) (PVAP) nanocomposite has been prepared by a chemical method by varying the HAp content by 10–60% (w/w). The bonding between HAp and PVAP has been investigated through Fourier transform infrared absorption spectra, X-ray diffraction, and thermogravimetric analyses. Transmission electron microscopy study shows a homogeneous dispersion of nanoparticles in the polymer matrix. Scanning electron microscopy study shows enhancement of the surface roughness of the composite with an increase in the nanoparticle content. The mechanical properties of the composites improve significantly with an increase in the HAp content. The HAp/PVAP nanocomposite prepared may have bone–implant applications.     

Effect of imidazole based polymer blend electrolytes for dye-sensitized solar cells in energy harvesting window glass applications

The exploration of polymer electrolyte in the field of dye sensitized solar cell (DSSC) can contribute to increase the invention of renewable energy applications. In the present work, the influence of imidazole on the poly (vinylidene fluoride) (PVDF)-poly (methyl methacrylate) (PMMA)-Ethylene carbonate (EC)-KI-I₂ polymer blend electrolytes has been evaluated. The different weight percentages of imidazole added into polymer blend electrolytes have been prepared by solution casting. The prepared films were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV-visible spectra, photoluminescence spectra and impedance spectroscopy. The surface roughness texture of the film was analyzed by atomic force microscopy (AFM). The ionic conductivity of the optimized polymer blend electrolyte was determined by impedance measurement, which is 1.95×10^-3 S·cm^-1 at room temperature. The polymer electrolyte containing 40 wt% of imidazole content exhibits the highest photo-conversion efficiency of 3.04% under the illumination of 100 mW·cm^-2. Moreover, a considerable enhancement in the stability of the DSSC device was demonstrated.     

A rigid poly(amidehydrazide): Morphology and mechanical behavior

A wholly aromatic all-para oriented poly(amidehydrazide) has been prepared from N,N′-bis(4-aminobenzoyl)hydrazine and terephthaloyl dichloride by solution polycondensation. Films of the polymer were prepared by two processes, viz. a wet and a dry process, by using its solution in N,N-dimethylacetamide/LiCl. Optical anisotropy, surface morphology and tensile properties of the films were studied. Polarizing optical microscopic study reveals that the films prepared by the dry process have more pronounced birefringent characteristics and greater nematic order than the films prepared by the wet process. The birefringent characteristics in the films become more and more prominent with increase in polymer inherent viscosity. Scanning electron microscopic study reveals that when the LiCl content in the polymer solution used for the film casting is low (1 wt.-%), the corresponding films, prepared either by the wet or by the dry process, have smooth surfaces. But when the LiCl content is high (>1 wt.-%), only the wet process produces films with smooth surface, whereas there are microvoids on the surface of the films prepared by the dry process. Regarding the tensile study, in general, the films prepared by the dry process have higher strength and modulus, but lower elongation than the films prepared by the wet process due to a greater extent of retention of orientation in the films prepared by the dry process. The strength and modulus of the films are found to increase with increase in the polymer inherent viscosity.     

Effect of cobalt chloride on the physical and chemical properties of the solid residue from the pyrolysis of polymer tire cord

This work is focused on the effect of cobalt chloride on the physical and chemical properties of the pyrolysis residue of the polymer cord from scrap tires. It has been demonstrated by X-ray fluorescence analysis that the greater part (∼90%) of the catalyst used in polymer cord pyrolysis remains in the solid carbon residue, thus making possible catalyst regeneration. Use of cobalt chloride increases the specific surface area of the solid residue by 15% and reduces its zinc content by 70%. This is favorable for achieving a better quality of potential sorbents based on the polymer cord pyrolysis residue.     

Surface phase morphology and composition of the casting films of PVDF-PVP blend

Films of a binary polymer blend comprising of hydrophobic poly(vinylidene fluoride) (PVDF) and hydrophilic poly(vinylpyrrolidone) (PVP) have been prepared by solution-casting. The dependence of surface structure and composition of the films on the PVP content in the blend was investigated by using atomic force microscope (AFM), XRD, XPS, SEM and differential scanning calorimeter (DSC). It has been found that the interaction between the two homopolymers prevents PVDF from crystallization in the blend, the net result of which has a primary effect on the surface properties of the films. PVP has a greater concentration at the surface than in the bulk as long as PVDF crystallizes in the bulk during the film formation process, which leaves a thermodynamically non-equilibrium surface state. On the other hand, with an increase in the PVP content, the interaction between segmental PVDF and PVP in the beginning transforms the crystalline state of PVDF from α to γ phase, and finally results in the disappearance of crystalline PVDF phases. A meager crystallization of PVDF segments could still carry on at the surface of a film with a miscible (or an amorphous) bulk; this occurrence makes the surface more hydrophobic than its bulk phase.     

XPS studies of in situ plasma-modified polymer surfaces

X-ray photoelectron spectroscopy (XPS) has been used to study the chemical effects of both inert (argon) and reactive (oxygen, nitrogen, and mixed gas) plasma treatments done in situ on a variety of polymer surfaces. Inert gas plasma treatments introduce no new detectable chemical species onto the polymer surface but can induce degradation and rearrangement of the polymer surface. However, plasma treatments with reactive gases create new chemical species which drastically alter the chemical reactivity of the polymer surface. These studies have also shown that the surface population of chemical species formed after plasma treatment is dependent on both the chemical structure of the polymer and the plasma gas. The effects of direct and radiative energy-transfer processes in a plasma have also been studied. Polymers containing certain functional groups were found to be more susceptible to damage via radiative energy transfer. Ageing studies of plasma-modified polymer surfaces exposed to the atmosphere have shown that the ageing process consists of two distinct phases. The initial phase, which occurs rapidly, involves adsorption of atmospheric contaminants and, in some cases, specific chemical reactions. The second phase, which occurs slowly, is due to surface reorganization.     

甲基丙烯酸丁酯-PEG梳形共聚物的合成与表征

以偶氮双异丁腈(AIBN)为引发剂,四氢呋喃为溶剂,采用甲基丙烯酸正丁酯(BMA)与聚乙二醇单甲醚甲基丙烯酸酯(POEM)共聚制备了支链上含聚乙二醇(PEG)的梳形共聚物。采用1H-NMR、DSC和表面接触角等方法研究了梳形共聚物的结构与性能。结果表明,聚合物中两结构单元的含量与单体投料比中的含量基本一致;投料比对聚合物的结构和性能有较为显著的影响;梳形聚合物的熔点、焓值及静态接触角随着共聚物中BMA含量的升高而升高。     

聚醚与长链烷烃共改性硅油的研究及应用*

采用含氢硅油（PHMS）、烯丙基聚醚（FB1000）与不同质量的丙烯酸十八酯（SA）制备了系列具有侧链结构的高分子表面活性剂（PSA）。利用红外光谱（FT-IR）、核磁（NMR）、凝胶渗透色谱仪（GPC）、表面张力、动态激光光散射仪（DLS）、荧光光谱 (FLD)对产物的结构与溶液性质进行了表征和研究。结果表明随着SA含量的增加,聚合物越易聚集缔合形成胶束,粒径从71.40nm增加到141.07nm,粒度分散系数（PDI）增大至0.396,随着疏水基团的增加,溶液表面张力降低至24.20mN/m,临界胶束浓度(cmc)下降至0.49g/L。荧光光谱表明,聚合物溶液浓度增大到一定值时,溶液中会形成疏水微区,第一第三发射峰的比值（I1/I3）不断减小,达到临界缔合浓度（cac）后,芘分子会增溶到胶束中I1/I3趋于稳定。破乳实验结果表明,聚合物PSA的破乳脱水率达93%。     

The change of bead morphology formed on electrospun polystyrene fibers

Polystyrene (PS) dissolved in the mixture of tetrahydrofuran (THF) and N,N-dimethyl formamide (DMF) was electrospun to prepare fibers of sub-micron in diameters. Electropinning parameters such as polymer concentration, applied voltage and tip-to-collector distance were controlled. From these parameters it was determined that while the surface tension of polymer solution had linear correlation with the critical voltage, throughput was dependent on electric conductivity. The electrospun PS fibers produced contained irregular beads and electrospinning certainly was enhanced with increasing DMF content. The bead concentration was also controlled by DMF content. The aspect ratio of the formed beads and the diameter of fibers were increased with increasing solution concentration. When PS was dissolved in only THF, an unexpected half hollow spheres (HHS) structure appeared. Also, different shape forms of PS non-woven mats have been prepared by controlling electrospinning parameters.     

Weather-Induced Degradation of LLDPE: Calorimetric Analysis

Studies of polymer degradation over the past decade have increasingly been carried out using thermoanalytical methods. These methods involve the measurement of a convenient variable during a gradual, linear increase in temperature. The most widely used of these techniques are thermogravimetry (TG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC). The morphology of a polymer sample (i.e., the crystallinity, shape and size of the crystals, the structure of the surface of the crystals, and the strain of amorphous regions) influences the heat content and its dependence on temperature. The latter can be satisfactorily investigated by calorimetry measurement in a differential scanning calorimeter.     

Quantitative characterization of surface deformation in polymer composites using digital image analysis

The stress whitening of polymers and polymer composites during surface deformation (scratching) can represent a severe technological problem in certain applications. For example, scratch resistance is particularly important for poly(propylene) automobile interior components. Unfortunately, the addition of reinforcing agents such as talc or mica for improved dimensional stability and rigidity often results in an increased sensitivity to scratching. The ability to design new materials with reduced visible surface deformation requires more sophisticated information about the deformation mechanisms of polymers and polymer composites near surfaces and their relationship to the scattering of incident light. We have developed a technique to quantify the light scattered from polymer composite surfaces due to surface deformation. We first deform the material in a controlled manner using a scratch testing apparatus. We then analyze the region near the scratch with reflected polarized light in an optical microscope coupled to a digital image analysis system. By measuring the light scattering from the sample as a function of incident light polarization and sample orientation, it is possible to obtain information about the nature and extent of deformation at the sample surface. In this report, we describe our technique and demonstrate how it can be used to quantify the surface deformation of poly(propylene)-talc composites. By examining a series of materials as a function of talc content, we have been able to obtain information that can be related to specific micromechanisms of deformation near the scratch, such as the orientation of the polymer and the voiding near the talc particles. The technique should assist in the improved development of similar materials for applications in which surface appearance is a primary concern.     

Abrasion studies of nylon 6/montmorillonite nanocomposites using scanning electron microscopy,fourier transform infrared spectroscopy,and X‐ray photoelectron spectroscopy

In this article, abrasion performance of commercial nylon 6 and nylon 6/montmorillonite (MMT) nanocomposites was studied. The polymer nanocomposites showed poor abrasion resistance compared to the neat polymer. The wear loss increased linearly with clay concentration. Changes in surface morphology, composition, and structure were investigated by scanning electron microscopy (SEM), Fourier transform infrared (FTIR)‐attenuated total reflection spectroscopy, and X‐ray photoelectron spectroscopy (XPS). SEM images showed that all the abraded surfaces contained fractured particles. However, the abraded nanocomposite surfaces had much deeper grooves compared to the homopolymer. FTIR results showed an increase in the amount of α crystals and a decrease in the amount of γ crystals on all the surfaces after abrasion. This was attributed to the strain‐induced γ to α crystal transformation. The largest amount of α crystals was formed in the abraded surface of pure nylon 6, and the amount of α crystals formed decreased with increasing MMT content. XPS results showed an increase in the [Si]/[N] elemental ratio for all nanocomposites after abrasion, indicating an increase in the clay content of the surface. Abrasive wear mechanism is as follows: (1) tensile tearing is the dominant wear mechanism for all the samples; (2) the cutting mechanism becomes more important when MMT content increases; (3) the polymer matrix is easier to be removed than clay during the abrasion process; (4) in nylon 6/MMT systems, the poor abrasion resistance is attributed to defects at the clay‐polymer interface, resulting in greater wear of the polymer matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The effect of surface properties on the adhesion of modified polychloroprene used as adhesive

The adhesion properties of polychloroprene can be improved by addition of such materials as piperylene–styrene co-polymer (PSC), VeoVa-10 polymer, VeoVa-11/methyl methacrylate/2ethylhexyl acrylate co-polymer (VeoVa-11/MMA/2EHA) and poly(vinyl acetate) waste (wPVAc). Here, the relationship between adhesion properties and surface tension of polychloroprene was investigated. Contact angle measurements have been used to study the effects of nature and content of polymeric additives on the adhesion and surface properties of polychloroprene. Low-surface-tension VeoVa-10 polymer has the tendency to migrate to the surface of polychloroprene; thus, adhesion is determined mainly by this additive property. Enrichment of polychloroprene film bottom layer by the additive was observed using high-surface-tension PSC and wPVAc. In this case, the adhesion properties of polychloroprene depend on the interactions at the interface. Adhesion properties of polychloroprene were found to depend not only on compatibility between adhesive components, but also on compatibility between the adherend and the adhesive.     

Composition-dependent properties of polyethylene/Kaolin composites. III. Thermoelastic behavior of injection-molded samples

Injection-molded samples of high-density polyethylene (HDPE) differing in the orientation pattern (with respect to the melt flow direction) and in filler content (untreated and surface-treated Kaolin, respectively) were characterized by wide-angle X-ray scattering, microhardness, and stretching calorimetry techniques. The crystallinity of the polymer matrix in filled samples shows the same value as that found for the neat polymer regardless, filler content, and/or filler surface treatment. The thermoelastic behavior of all samples in the strain interval below the apparent yield point ε* is quantitatively discussed in terms of classical equations for elastic solids. Analysis of thermoelastic parameters of the boundary interphase (BI) reveal an unusually stiff, highly oriented structure of the matrix polymer within BI. Discrepancies of experimental values for the internal energy increment in the inelastic strain interval above ε* between unfilled and filled samples is explained in terms of the filler debonding process. The latter process is discussed in light of the formation of a polymer-free filler surface and of the concomitant inelastic deformation (plastic flow) of a polymer matrix in the interstitial space between filler particles. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1041–1048, 1999