Modification of Rheological Properties Under Elongational Flow by Addition of Polymeric Fine Fibers

A new technique to provide melt elasticity using flexible fine fibers prepared from a polymer with high melting point is demonstrated. A polymer composite of poly(propylene) with a small amount of fine fibers of poly(butylene terephthalate) shows marked strain‐hardening behavior in elongational viscosity, i.e., a rapid increase in the transient elongational viscosity with time or strain. The blend also shows prominent normal stress difference at steady shear. These elastic properties have not been observed for polymer composites with rigid fibers and can be applicable to the modification of rheological properties and thus the improvement of processability.

     

Synthesis and chemical properties of polyethyleneimines crosslinked by penta-2,4-dienylideneammonium unit

The reaction of N-(2,4-dinitrophenyl)pyridinium anion ( salt(A) ; A = Cl⁻, FeCl₄⁻, and (CN)₂N⁻) with linear polyethyleneimine (LPEI; M_n = 20 380) and branched polyethyleneimines (BPEI1; M_n = 600, BPEI2; M_n = 10 000) at various molar feed ratios without using a catalyst resulted in pyridinium ring opening to yield ionic LPEI and BPEIs that were crosslinked by conjugated penta-2,4-dienylideneammonium (PDA) units, LPEI-PDA , BPEI1-PDA , and BPEI2-PDA , respectively. A model compound was synthesized by the reaction of salt(Cl) with diethylamine. The solubilities of BPEI1-PDA and BPEI2-PDA depended on the feed ratios between salt(Cl) and BPEI1 or BPEI2. Dipping LPEI-PDA into water and methanol yielded hydro- and organogels, respectively. UV–vis and reflection measurements revealed an expanded π-conjugation length between the polymer chains due to the through-space orbital interaction of the electrons on the two nitrogen atoms at the crosslinked positions in LPEI-PDA , BPEI1-PDA , and BPEI2-PDA . Cyclic voltammetry analysis suggested that the polymers underwent electrochemical oxidation. Measurement using a superconducting quantum interference device (SQUID) indicated that LPEI-PDA having FeCl₄⁻ anions was paramagnetic. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48712.     

采用MAMMOS技术的高密度光记录

MAMMOS(Magnetic Amplifying Magneto－ Optical System:磁畴扩大磁光系统 )是实现高密度磁光盘的有效方法。不仅能得到不依赖于磁畴长度的较大的读出信号振幅,而且还能实现超出光学系统衍射极限的分辨率。过去,为实现磁畴的复印与扩大,要对记录膜面施加垂直方向的外部磁场。而现在得知,同时施加垂直磁场和水平方向的磁场,可大幅度地提高微小磁畴的读出特性。确认采用施加水平磁场的方法,在λ =635 nm, NA=0.55的条件下, 0.15μ m的连续磁畴也能获得 BER=2× 10－ 4的读出效果。     

Synthesis and characterization of chitosan/poly(acrylic acid) polyelectrolyte complex

Polyelectrolyte complex based on chitosan and acrylic acid monomer by photoinitiated free‐radical polymerization in the absence of crosslinker showed a large transition in swelling in response to changes in pH of surrounding medium. Their ability to swell arises from polyelectrolyte interactions and molecular structure of the complex. The main properties of interest that related to the molecular structure, swelling volumes, glass transition temperature, and elastic modulus of the complex were investigated. The effect of water content, the only variable in the sample component, played an important role in molecular structure of the complex and as a consequence, the extent of intermolecular linkage, especially amide bonds which in turn governed the degree of swelling of the polyelectrolyte complex in this study. The decreased degree of swelling and higher temperature shift of glass transition temperature was found with increased water content, whereas increased modulus of elasticity of dry complex was found in lower water content of synthesis component. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1025–1035, 2002     

均相玻璃态高分子中溶剂扩散系数的数学模型

以自由体积理论为基础 ,提出改良的玻璃态高分子中溶剂扩散系数的数学模型 .模型推导过程中考虑了溶剂可塑化效应对高分子凝聚态的影响 ,并以明确的物理概念计算玻璃态聚合物的自由体积 .对橡胶态适用的自由体积参数在此模型中保持有效 ,所引入的表达溶剂可塑化效应的唯一参数 β可以通过计算玻璃化温度来确定 .所以 ,本模型中无可调节参数存在 ,具有完全可预测性 .以芳香族溶剂苯、甲苯、乙苯在玻璃态聚苯乙烯和聚甲基丙烯酸甲酯中的扩散系数为例对模型进行验证 ,理论计算结果和实验值取得良好一致     

Rh/γ-Al2O3 Catalytic Layer Integrated with Sol–Gel Synthesized Microporous Silica Membrane for Compact Membrane Reactor Applications

An efficient and compact catalytic membrane reactor for reforming of CH₄ was developed by integrating a hydrogen perm-selective silica membrane with an Rh/-Al₂O₃ catalyst layer. The catalytic layer was sandwiched between the outer surface of the -Al₂O₃ support tube and the silica membrane with an aim of improving the heat and mass transfer rates through the system and to simplify the reactor geometry. The system showed improved efficiency for reforming of CH₄ at comparatively lower operating temperatures and steam to C molar ratios than the conventional fixed-bed steam reforming systems. Under optimized conditions, a nearly 25-30% improvement from the equilibrium conversion level was achieved as a result of abstraction of hydrogen from the product stream by the silica membrane integrated with the catalyst layer. The performance of the system was evaluated as a function of various process parameters. Because of the compactness and efficiency, the present system emerges as a promising alternative to the conventional membrane reactors, which possess separate catalytic and membrane units.     

Preferential mineralization of CaCO3 layers on polymer surfaces from CaCl2 and water‐soluble carbonate salt solutions supersaturated by poly(acrylic acid)

CaCO₃ was mineralized from solutions supersaturated only by poly(acrylic acid) (PAA), without bubbling any CO₂ gas in the solution. For example, a layer of CaCO₃ was built up on the surface of a chitosan membrane from a supersaturated aqueous solution containing CaCl₂, Na₂CO₃, and PAA. In this newly developed method, the PAA alone suppresses the precipitation of CaCO₃ from the bulk solution, and therefore, increases the supersaturated concentration. This concentration is estimated to be the same order as that attained in the method in which both CO₂ gas and PAA were used. At the same time, PAA supplies nucleation fields by forming a polymer complex with chitosan. The crystal system obtained was different from those obtained when using CO₂ gas. Self‐organization of aragonite crystallites led to the formation of uniform, concentric, or branching patterns in the surface‐domain structure. These patterns had morphologies similar to those discovered by other researchers, typically in the crystallization of ascorbic acid. Thicker layers of CaCO₃ could be formed on chitosan membranes, the surfaces of which had been converted to a polyelectrolyte complex (PEC) by exposure to PAA solution before the onset of mineralization. Under certain conditions, the CaCO₃ layer had a small spherical curvature, similar to a half‐lens, and generated Newton's ring pattern from the interference fringes of visible light. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91:3627–3634, 2004     

Interfacial charge-transfer resistance at ionizable thiol monolayer-modified gold electrodes as studied by impedance spectroscopy

This paper examines the influences of ionizable thiol monolayers on the interfacial charge-transfer rates for redox-active ions by electrochemical impedance spectroscopy. Whereas short-chain thiols such as 4-aminothiophenol hardly affected the charge-transfer resistance for Ru(NH₃)₆³⁺ having a high standard heterogeneous rate constant, the 11-mercaptoundecanoic acid monolayer raised this resistance to 3×10⁴ times that observed at a bare electrode in acidic solutions. As the terminal carboxyl group ionized, the charge-transfer resistance decreased by a factor of 300 because of a double-layer effect. When 3-mercaptopropionic acid was mixed with 1-hexadecanethiol, the charge-transfer resistance varied over four orders of magnitude with the composition of the two-component monolayer. The apparent rate constant for indigotetrasulfonate at 4-aminothiophenol-modified electrodes decreased by a factor of 25-30 as the solution pH varied from 4 to 2. This decrease was opposite to the change expected from protonation of the terminal amino group. It can be ascribed to a strong binding interaction between the redox anion and the positively charged monolayer.     

Flow instability in capillary extrusion of plasticized poly(vinyl chloride)

Flow instability in a capillary extrusion is studied for a high molecular weight, plasticized poly(vinyl chloride) (PVC). The onset of melt fracture correlates with the long time relaxation ascribed to the generation and/or growth of PVC crystallites. An increase in the residence time in the cylinder leads to this long time relaxation and results in the melt fracture, although the apparent shear stress remains constant, irrespective of the residence time. The extrudate temperature and the species of the plasticizer also have a significant influence on the apparatus of the extruded products. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1277–1283, 2001     

Emission of Particulate Matter 2.5 (PM2.5) from Sewage Sludge Incinerators in Japan

Because fine particulate matter ≤2.5 µm in diameter (PM2.5) causes health problems, PM2.5 emissions are of concern. However, little research on stationary sources has been conducted. To determine the concentration and filtration behavior of PM2.5, dust was collected from five fluid-bed sewage sludge incinerators (SSIs) sorted by particle size using cascade impactors. The average PM2.5 concentration was 0.00014–4.8 mg/Nm³. The total estimated amount of PM2.5 emissions from the SSIs for all plants in Japan was 0.96–8.9 tons/year. Since the SSIs with dry Electrostatic Precipitators (EP) contributed 75–99% of the total emissions, replacing dry EPs with bag filters would significantly reduce the PM2.5 emissions from SSI.