Effect of drag-reducing additives on free oscillatory flow

The damping rates of free oscillations in U-tube manometers were measured in water and aqueous solutions of Polyox WSR 301, Separan AP273 and a wetting agent (Aerosol OT). The manometers were made from flexible plastic (PVC) or glass tube. Small reductions of the linear damping constant by low concentrations of Polyox and Aerosol additives in the PVC tubes were attributed to a reduction in surface tension effects. All the additives increased the linear damping constants in both types of manometer, when used at larger concentrations. This was found to be due solely to increased solution viscosity. Large fractional reductions in damping due to Polyox in the PVC-tube systemwere associated with the nonlinear oscillations in the final period of the decay. This effect has not yet been explained.     

表面活性剂和水溶性聚合物对合成A型沸石的影响(续前)

图３可以看出 ,减少体系中水含量得到的晶体成长曲线与有添加剂的曲线相似。ＡＯＴ的加入出现的效果与其他添加剂出现的效果完全相反 ,它增加了诱导期和晶化期。图４显示了不同时期晶化产品的粒度分布 ,不含添加剂的图ａ和含ＡＯＴ的图ｃ是双峰分布 ,而在其他体系中则出现较窄的单峰分布 ,表１给出了每个实验的平均晶化体积、峰晶化体积和最大晶化体积。可以看出 ,含ＳＤＳ、ＣＡＢ、Ｐ４０、ＰＥＧ和无添加剂少水的体系均比无添加剂的体系获得了较小的晶粒 ,而添加了ＡＯＴ的体系获得了较大的晶粒。表１也给出了晶体成长的线性速率 ,可以看…     

Dielectric characterization of UICC asbestos samples

The frequency dispersion of the dielectric coefficient and of the dielectric loss measured on suspensions of asbestos fibers in paraffin oil as functions of fiber concentration and temperature showed for Canadian chrysotile relatively large energy dissipation maxima which can be explained in terms of relaxation of transverse and longitudinal polarization with slightly different energies of activation. Amosite fibers, in contrast, were found to be dielectrically inactive compared with the large-scale effects exhibited by chrysotile. Chrysotile suspensions were slightly thixotropic at volume concentations of the fibers as low as 0.5%, while the amosite suspensions did not show thixotropic behavior up to fiber concentrations of 1.0 vol.%.     

Electrospinning of aqueous lignin/poly(ethylene oxide) complexes

Microfibers of kraft lignin blended with poly(ethylene oxide) (PEO) were produced by electrospinning of the solution of lignin and high molecular weight poly(ethylene oxide) (PEO) in alkaline water. Interactions between lignin and PEO in alkaline aqueous solutions create association complexes, which increases the viscosity of the solution. The effect of polymer concentration, PEO molecular weight, and storage time of solution before spinning on the morphology of the fibers was studied. It showed that after one day the viscosity dropped and fiber diameter decreased. Results from the solutions in alkaline water and N,N‐dimethylformamide (DMF) with different polymer concentrations were compared. The 7 wt % of (Lignin/PEO: 95/5 wt/wt) in alkaline aqueous solution was successfully spun and the ratio of PEO in lignin/PEO mixture could be further reduced. In comparison, higher concentrations were needed to prepare a spinning solution in DMF and fiber diameters were in a much smaller range. The final target of spinning lignin is to produce carbonized fibers. Fibers spun from aqueous solutions had lower PEO content, which is a big advantage for the carbonization process as it reduces the challenges regarding melting of the fibers or void creation during carbonization. Furthermore, the larger diameter of these fibers inhibits disintegration of the carbonized fibers, which happens due to the mass loss during the process. © 2014 The Authors Journal of Applied Polymer Science Published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41260.     

Excess pressure losses in capillary flows

Accurate determinations of excess pressure losses at the entry and exit of capillary flows are essential for rheological characterization of fluids by capillary viscometry. A modification of Bagley's end correction method is presented which accounts for the effects of slight variations in the diameters of the tubes of varying length used in the evaluations. The method was applied to capillary flows of dilute aqueous Polyox solutions using the three homologues WSR 301, Coagulant and FRA of Polyox. The excess pressure losses were found to increase with increase in the apparent shear rate, polymer concentration and tube diameter.     

Electrospinning of waterborne polyurethanes

Polyurethane (PU) fibers were obtained by electrospinning of waterborne PU dispersions. As dispersion cannot be electrospun, a water‐soluble polymer (poly (ethylene oxide) (PEO)) was dissolved in the PU dispersion and fibers were obtained from electrospinning the resulting mixture. Pure PU fibers were obtained after removing PEO with water extraction. Continuous PU fibers were obtained using a PU/PEO weight ratio higher than 2.5. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

The preparation of carbon nanotube/poly(ethylene oxide) composites using amphiphilic block copolymers

Polymer/multiwall carbon nanotube (MWCNT) composites were prepared by using amphiphilic block copolymers as dispersant. First, MWCNTs were wrapped with amphiphilic block copolymers in aqueous solution. Poly(ethylene oxide) was selected as the hydrophilic block because of its strong affinity with water while one of the following polymers: poly(ethylene), poly(butadiene), poly(styrene), poly(propylene oxide), or poly(thiophene) was used as the hydrophobic block of the copolymers. The dispersions were characterized by optical microscopy and transmission electron microscopy along with UV–Visible adsorption and dynamic light scattering. Based on the results, we could assess the effect on CNT dispersion quality of both, the molar mass of copolymers, the nature of the hydrophobic block and the length of hydrophilic block. The crystallization behavior of composites prepared from these dispersions was investigated. Results were related to the dispersion of the nanoparticles in the polymer matrix.     

海藻酸钠纤维的电纺性研究

通过与生物相容的合成高分子聚环氧乙烷(PEO)共混,天然高分子海藻酸钠被成功电纺成丝。扫描电镜等测试结果表明:海藻酸钠a/PEO比例为6∶4时得到无串珠的光滑纤维,并且纤维直径分布均匀。用乙醇/氯化钙(CaCl)2处理电纺纤维,其疏水性得到极大改善。     

A new dye‐modified poly(ethylene oxide)–poly(propylene oxide) polymer used as a dispersant for CI Disperse Red 60

A new dye‐modified poly(ethylene oxide)–poly(propylene oxide) polymer, in which the dye molecule (CI Disperse Red 60) is bonded onto polyether monoamine via a triazine ring, was synthesised for the preparation of dye aqueous dispersions and was characterised by Fourier Transform‐infrared spectroscopy, ¹H nuclear magnetic resonance spectroscopy and elemental analysis. This polymer exhibits unique dispersing performance for CI Disperse Red 60. The mechanism behind the improved performance is briefly discussed with the help of adsorption isotherms. The results indicated that the hydrophobic dye group of this polymer can strongly adsorb onto the dye particle surface through π–π interaction while its long hydrophilic poly(ethylene oxide) chains allow the formation of a thick layer around the dye particles. It was speculated that the adsorbed polymer molecule on the dye surface would form a brush‐like monolayer conformation. The dyeing performance of the prepared dye dispersions on polyester fabrics was also investigated. It was found that this polymer can effectively increase the apparent solubility of disperse dye. The dyed fabrics showed very good to excellent fastness to washing and rubbing, while the dyeing effluent was colourless.     

Polar–polar interaction between the reinforcement and matrix for kevlar fiber-reinforced composite: Effect of using the blend of polar polymers as matrix

For the purpose of investigating the polar–polar interaction between reinforcement and matrix in polymer composite, the mechanical dispersions were studied for the composite comprised of the Kevlar fiber and poly(hydroxy ether of bisphenol A) (I), with which poly(ethylene oxide) (II) or poly(ethylene adipate) (III) was blended as a part of matrix. It is shown by analyzing the storage modulus and loss modulus vs. temperature curves that the reinforcement–matrix interaction is increased relatively to the primary transition temperature of matrix by blending II or III with I, and II is more efficient for increase of the interaction than III. The results obtained from the mechanical dispersions do not contradict those from the Fourier transform infrared spectra on the matrix-polymer-coated Kevlar fiber and on the mixture of matrix polymers with benzanilide, which is used as a model compound for the Kevlar fiber.     

Study on a water‐swellable rubber compatibilized by amphiphilic block polymer based on poly(ethylene oxide) and poly(butyl acrylate)

A water‐swellable rubber (WSR), compatibilized by the amphiphilic block copolymer, has been prepared by blending a natural rubber (NR) matrix with crosslinked sodium polyacrylate (CSP), poly(ethylene oxide)‐b‐poly(butyl acrylate) (PEO‐b‐PBA), poly(ethylene glycol) (PEG), reinforced filler, and vulcanizing agents. The preparation process was described. The microphase structure of WSR was characterized by a scanning electron microscopy (SEM) photograph. The dependence of the degree of the water‐absorbing and the water‐swelling, the water‐absorbing and water‐swelling rates on CSP, PEG, and PEO‐b‐PBA contents were investigated. The compatibilizing mechanism of PEO‐b‐PBA on WSR was studied. And the optimum composition range was identified: CSP (30–60 phr), PEG (10–20 phr) PEO‐b‐PBA (PEO/PBA = 0.36, 5 phr). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3120–3125, 2002     

Polyester nanocomposite fibers: comparison of their properties with poly(ethylene terephthalate) and poly(trimethylene terephthalate) (II)

Summary Two polyester nanocomposites were synthesized, one with poly(ethylene terephthalate) (PET) and the other with poly(trimethylene terephthalate) (PTT), by using organoclay. The in-situ interlayer polymerization method was used to disperse the organoclay in polyesters at different organoclay contents and at different draw ratios to produce monofilaments. The thermal stability and tensile mechanical properties increased with increasing organoclay content at a DR=1 . However, the values of the tensile mechanical properties of the hybrid fibers decreased with increasing DR. The reinforcing effects of the organoclay of the PET hybrid fibers were higher than those of the PTT hybrid fibers.     

Surface modification of kaolin. 2. Enhanced steric stabilisation of polymer-modified kaolin

The polymer-modified surface of kaolin was studied to determine the effect of changing the molecular weight of the polymer chain grafted on the surface. The particle was modified by attaching poly(ethylene oxide) to the surface using a urethane linkage. Upper critical flocculation temperature and contact angle measurements were conducted to quantify the changes in surface characteristics and stability in an aqueous dispersion. The effect of pH on stability and grafted density of polymer chains showed the mechanism of stabilisation to be that of enhanced steric stabilisation. The kaolin particle was also modified with the more hydrophobic poly(propylene oxide). The behaviour was characterised as for poly(ethylene oxide) and interesting differences in extent and mechanism for stabilisation were observed.     

The drag reduction of dilute polymer solutions as a function of solvent power,viscosity, and temperature

The frictional drag reduction of high molecular weight poly(ethylene oxide) and polystyrene solutions under turbulent flow conditions has been studied as a function of temperature, solvent power, and solvent viscosity. A rotating-disc apparatus was used to make the drag reduction measurements. For aqueous poly(ethylene oxide) solutions, at concentrations well above that needed to produce maximum drag reduction, all drag reduction data reduced to a common curve when per cent drag reduction was plotted against the Reynolds number for the flow. However, for poly(ethylene oxide) solutions below this optimum concentration, the drag reduction-versus-Reynolds number curves showed decreasing drag reduction with increasing temperature. The data are explained primarily in terms of the inverse temperature solubility characteristics of poly(ethylene oxide) in water. The per cent drag reduction of polystyrene in nonaqueous liquids was found to be greater in good solvents than in poor ones. It was also found that increases in solvent viscosity and decreases in temperature increased the per cent drag reduction. The results are discussed in relation to the current drag reduction theories and are shown to be in opposition to Virk's theory. It is concluded from the data that drag reduction is very likely a function of a relaxation time phenomenon involving the polymer molecules and the flow system. The results also emphasize the importance of considering solvent power, viscosity, and temperature in the design of an efficient drag reduction system.     

Properties of Poly(vinyl chloride)/poly(ethylene oxide)/polyaniline Conductive Films: The Effect of Poly(ethylene glycol) Diglycidyl Ether

The effect of polyaniline and poly(ethylene glycol) diglycidyl ether on tensile properties, morphology, thermal degradation, and electrical conductivity of poly(vinyl chloride)/poly(ethylene oxide)/polyaniline conductive films was studied. The poly(vinyl chloride)/poly(ethylene oxide)/polyaniline conductive films were prepared using a solution casting technique at room temperature until a homogeneous solution was produced. Poly(vinyl chloride)/poly(ethylene oxide)/polyaniline/poly(ethylene glycol) diglycidyl ether conductive films exhibit higher electrical properties, tensile strength, modulus of elasticity but lower final decomposition temperature than poly(vinyl chloride)/poly(ethylene oxide)/polyaniline conductive films. Scanning electron microscopy morphology showed that the polyaniline more widely dispersed in the poly(vinyl chloride)/poly(ethylene oxide) blends with the addition of poly(ethylene glycol) diglycidyl ether as surface modifier.     

Reducing the risk of particulate matter containing asbestos using a high-efficiency,low-differential pressure system

The purpose of this study was to improve the efficiency of filters used in asbestos control systems, such as those used at asbestos removal sites. We evaluated the melt-blown (MB) filter media for their asbestos removal efficiencies. The filter grades were based on the ISO and European standards (EN 1822) of E12 (≥99.5% collection efficiency) and H13 (≥99.95% collection efficiency) with a size of <0.2?μm asbestos diameter. Based on test chamber experiments, the asbestos removal efficiency of the grade H13?MB filter (99.974%) was higher than that of the E12 grade MB filter (97.120%). In addition, the lowest level of pressure drop was observed in the case with a 3.8?mm pitch interval. The concentrations of airborne asbestos based on phase contrast microscopy in the sites with asbestos concentrations presenting high risks before turning on the asbestos control system was 0.038 fiber cm^?3 at demolition site A and 0.027 fiber cm^?3 at demolition site B. Chrysotile asbestos was detected at both demolition sites A and B before turning on the system, but were not detected after using the system. Therefore, MB filters present an efficient alternative to current commercial filters and should be considered for use in asbestos removal applications.

© 2018 American Association for Aerosol Research     

Smart secondary polyurethane dispersions

Secondary dispersions of cationic segmented polyurethanes (PUs) with thermoresponsivity (upper critical solution temperature (UCST) in water), high solid contents and antibacterial properties are highlighted in this paper. PUs were prepared by polyaddition reactions and subsequent quaternization with methyl iodide. No additional stabilizers, organic solvents or special procedures were required to obtain stable aqueous dispersions containing up to 10 wt% PU; in contrast, stable dispersions were straightforwardly accessed by a combination of UCST behavior and repulsive electrostatic forces among the positively charged segments, which meets the requirements of a green chemistry process. Particle size and UCST strongly depended on the solid content of the dispersions and the content of poly(ethylene glycol) segments in the copolymers. The dispersions exhibited fast‐acting antibacterial properties against Escherichia coli. © 2013 Society of Chemical Industry     

Development of waterborne UV-A curable clear coat for car refinishes

The development of a waterborne UV-A curable clear coat for car refinish application is described. The clear coat formulations are based on specially developed acryloyl or maleimide functional polyurethane dispersions. The functional PUR dispersions are characterized by a relatively low molecular weight, a high CC functionality and an optimized amount of poly(ethylene oxide). These characteristics are necessary for obtaining optimal film formation which results in good appearance and other film properties. It was found that poly(ethylene oxide) had a positive effect on surface cure when irradiated with UV-A light (less influence of oxygen inhibition). The synthesis of PUR dispersions and their performance in clear coats are described, including several aspects on film formation (conversion of CC, AFM measurements) and film properties (durability, physical and chemical properties).     

Esterification of hydroxylated polymers with 2-sulfobenzoic acid cyclic anhydride: A facile approach for the synthesis of near-monodisperse strong acid homopolymers and diblock copolymers

A convenient two-step route was developed to prepare a range of low polydispersity strong acid homopolymers and several examples of well-defined diblock copolymers. Atom transfer radical polymerization (ATRP) of either 2-hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate or glycerol monomethacrylate afforded the corresponding near-monodisperse hydroxylated homopolymers, while several diblock copolymer precursors were prepared by either (1) the one-pot ATRP of 2-hydroxypropyl methacrylate and 2-(diethylamino)ethyl methacrylate using sequential monomer addition or (2) the ATRP of either 2-hydroxypropyl methacrylate or glycerol monomethacrylate using a poly(ethylene oxide)-based macro-initiator. Excess 2-sulfobenzoic acid cyclic anhydride was used to fully esterify the hydroxy groups of these homopolymers and diblock copolymers under mild conditions. The resulting zwitterionic diblock copolymers undergo micellar self-assembly on adjusting the pH of the solution, while one of the anionic poly(ethylene oxide)-based diblock copolymers formed colloidal polyelectrolyte complexes in aqueous solution when mixed with a cationic poly(ethylene oxide)-based diblock copolymer.     

Development of a gel spinning process for high‐strength poly(ethylene oxide) fibers

This article describes a new gel‐spinning process for making high‐strength poly(ethylene oxide) (PEO) fibers. The PEO gel‐spinning process was enabled through an oligomer/polymer blend in place of conventional organic solvents, and the gelation and solvent‐like properties were investigated. A 92/8 wt% poly(ethylene glycol)/PEO gel exhibited a melting temperature around 45°C and was highly stretchable at room temperature. Some salient features of a gel‐spun PEO fiber with a draw ratio of 60 are tensile strength at break = 0.66 ± 0.04 GPa, Young's modulus = 4.3 ± 0.1 GPa, and a toughness corresponding to 117 MJ/m³. These numbers are significantly higher than those previously reported. Wide‐angle x‐ray diffraction of the high‐strength fibers showed good molecular orientation along the fiber direction. The results also demonstrate the potential of further improvement of mechanical properties. POLYM. ENG. SCI., 54:2839–2847, 2014. © 2014 Society of Plastics Engineers