The feasibility of boron removal from water by capacitive deionization

We report on the possibility of removing boron (in the form of boric acid) from water by electrochemical means. We explore capacitive de-ionization (CDI) processes in which local changes in pH near the surface of high-surface-area activated carbon fiber (ACF) electrodes during charging are utilized, in order to dissociate boric acid into borate ions which can be electro-adsorbed onto the positive electrode in the CDI cells. For this purpose, a special flow-through CDI cell was constructed in which the feed solution flows through the electrodes. Local pH changes near the carbon electrode surface were investigated using a MgCl₂ solution probe in three- (with reference) and two-electrode cells, and described qualitatively. We show that, to a certain extent, boron can indeed be removed from water by CDI.     

Yttrium barium copper oxide‐filled polystyrene as a dielectric material

Electrical impedance measurements are carried out on high temperature superconducting ceramic Yttrium Barium Copper Oxide (YBCO)–Polystyrene (PS) composite materials, in which superconducting particles are embedded in polystyrene matrix. The results of impedance versus frequency (100 Hz–13 MHz), phase angle versus temperature for volume percentage of superconductor (0–40%) are presented. No marked transition in phase angle is observed when the material goes through the superconducting transition temperature of the filler. The dielectric constant and losses increase with increasing YBCO content. However the increase in losses is modest and the excellent dielectric properties of the composites are not adversely affected. The system conforms to Clausius‐Mossotti equation. Dipole moment of YBCO particles and polarizability of the composites are calculated using the Clausius‐Mossotti approaches. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Fast and efficient synthesis of high molecular weight poly(epsilon‐caprolactone) diols by microwave‐assisted polymer synthesis

Because of advantageous features such as shorter reaction times, greater yields, limited generation of by‐products and relatively easy and straightforward scale‐up, microwave‐assisted synthesis has become a very appealing tool in organic synthesis. Conversely, its implementation in the context of the synthesis of biomaterials for biopharmaceutical applications has been more limited. The present work reports on the fast and efficient microwave‐assisted synthesis of poly(ethylene glycol) (PEG)‐initiated poly(ε‐caprolactone) diols (PCL) by the ring‐opening polymerization (ROP) of ε‐caprolactone using stannous octanoate as catalyst. Since the PEG content in the synthesized copolymers was extremely low (0.2–1.9%), products were highly hydrophobic and displayed the intrinsic thermal properties of pure PCL. As opposed to the more time‐consuming conventional thermally‐driven synthesis that usually demands 2–3 h, the microwave technique resulted in intermediate to high molecular weight PEG‐PCL derivatives within 10–15 min. The influence of different parameters affecting the synthetic process, namely monomer‐to‐initiator ratio, reaction time, catalyst concentration and the presence, type, and concentration of solvent were thoroughly investigated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

A simple model for the semicontinuous heterophase polymerization: Ethyl methacrylate as a case example

A simple but comprehensive model considering homogeneous and micellar nucleation, coagulation, entry of radicals to particles and to micelles and radicals' exit from particles, is presented. The model is validated, in a starved semicontinuous heterophase polymerization of ethyl methacrylate, at three monomer addition rates. The model accurately describes the overall and instantaneous conversion, the average particle density and diameter, and the number and weight average molar masses evolutions over time. It is found that even though the average number of radicals is much smaller than 0.5, the system is not 0-1. An empirical function was used to describe the gel effect. The homogeneous nucleation was the prevailing mechanism for particle formation and large exit rates of radicals were observed. POLYM. ENG. SCI., 60: 223–232, 2019. © 2019 Society of Plastics Engineers     

Transport and solvent sensing characteristics of styrene butadiene rubber nanocomposites containing imidazolium ionic liquid modified carbon nanotubes

Obtaining strong interfacial interaction between filler and polymer matrix is very crucial for the fabrication of polymer nanocomposites with superior performance. Present study is aimed to fabricate high performance styrene butadiene rubber (SBR) nanocomposites with imidazolium type ionic liquid modified multiwalled carbon nanotube (MWCNT). Ionic liquid facilitates the dispersion of MWCNT in rubber matrix and it is obvious from transmission electron microscopy images. Diffusion of toluene through SBR nanocomposite membranes has been investigated as a function of surface modified MWCNT (f-MWCNT) content to analyze the chain dynamics and filler-polymer interactions. O₂ gas barrier effect of nanocomposites with special reference to the filler loading is explored. The substantial improvement in the barrier effect in presence of filler interpreted on the grounds of a theoretical model describing permeability of heterogeneous systems. Finally solvent sensing characteristics of prepared nanocomposites are also analyzed and it is observed that prepared nanocomposites can be used as a flexible solvent sensor.     

Making Nonwoven Fibrous Poly(ε‐caprolactone) Constructs for Antimicrobial and Tissue Engineering Applications by Pressurized Melt Gyration

A pressurized melt gyration process has been used for the first time to generate poly(ε‐caprolactone) (PCL) fibers. Gyration speed, working pressure, and melt temperature are varied and these parameters influence the fiber diameter and the temperature enabled changing the surface morphology of the fibers. Two types of nonwoven PCL fiber constructs are prepared. First, Ag‐doped PCL is studied for antibacterial activity using Gram‐negative Escherichia coli and Pseudomonas aeruginosa microorganisms. The melt temperature used to make these constructs significantly influences antibacterial activity. Neat PCL nonwoven scaffolds are also prepared and their potential for application in muscular tissue engineering is studied with myoblast cells. Results show significant cell attachment, growth, and proliferation of cells on the scaffolds.

     

Development and performance analysis of a novel agitated vessel

The objective of the present study was to design, fabricate and evaluate the performance of a novel airi-nducing impeller system with a specially designed air-inducing tube-set. The novel air-inducing impeller system, when attached to a conventional baffled agitated vessel, could convert it into an air-inducing reactor. Water was used as the working fluid and the characteristics of the impeller system such as critical speed, power consumption and gas holdup were investigated by varying the gas free liquid level, orifice immersion depth, bottom clearance and impeller speed. Results showed that this novel air-inducing impeller system induced the air at speeds lower than the critical speeds reported by most of the investigators in the literature.     

Photopolymerizable multifunctional monomers and their evaluation as reactive Bis‐GMA eluents

Bis‐GMA {2,2‐bis[4‐(2′‐hydroxy‐3′‐methacryloyloxy‐propoxy)‐phenyl]‐propane}, TEGDMA <2‐{2‐[2‐(2‐methylprop‐2‐enoyloxy)ethoxy]ethoxy}ethyl‐2‐methylprop‐2‐enoate>, and methyl methacrylate (MMA) are some of the most commonly used monomers in the field of restorative dentistry. These compounds are characterized by having one or two terminal double bonds. Besides the effort to synthesize new monomers, several problems still affect the clinical behavior of contemporary dental materials. In this work, two monomers with three terminal double bonds, 5A13DA and 5A13DMA, were synthesized. Both monomers were used to completely replace TEGDMA as reactive diluent of photopolymerizable dental resin composites containing Bis‐GMA. The effects of 5A13DA and 5A13DMA on flexural properties, double bond conversion, water sorption, solubility, and polymerization shrinkage were evaluated. In addition, both monomers were evaluated as crosslinking agents for methylmethacrylate, resulting in copolymers with enhanced thermal stability. The results obtained suggest that newly synthesized monomers are potential substitutes for TEGDMA in the formulation of dental composites, providing 50% lower volumetric shrinkage than the composite resin used as control and adequate mechanical properties. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46240.