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1.
Highly selective sulfonated poly(vinylidene fluoride‐co‐hexafluoropropylene)/poly(ether sulfone) blend proton exchange membranes for direct methanol fuel cells 下载免费PDF全文
Proton exchange membranes (PEMs) based on blends of poly(ether sulfone) (PES) and sulfonated poly(vinylidene fluoride‐co‐hexafluoropropylene) (sPVdF‐co‐HFP) were prepared successfully. Fabricated blend membranes showed favorable PEM characteristics such as reduced methanol permeability, high selectivity, and improved mechanical integrity. Additionally, these membranes afford comparable proton conductivity, good oxidative stability, moderate ion exchange capacity, and reasonable water uptake. To appraise PEM performance, blend membranes were characterized using techniques such as Fourier transform infrared spectroscopy, AC impedance spectroscopy; atomic force microscopy, and thermogravimetry. Addition of hydrophobic PES confines the swelling of the PEM and increases the ultimate tensile strength of the membrane. Proton conductivities of the blend membranes are about 10?3 S cm?1. Methanol permeability of 1.22 × 10?7cm2 s?1 exhibited by the sPVdF‐co‐HFP/PES10 blend membrane is much lower than that of Nafion‐117. AFM studies divulged that the sPVdF‐co‐HFP/PES blend membranes have nodule like structure, which confirms the presence of hydrophilic domain. The observed results demonstrated that the sPVdF‐co‐HFP/PES blend membranes have promise for possible usage as a PEM in direct methanol fuel cells. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43907. 相似文献
2.
Palsamy Kanagaraj Sivasubramaniyan Neelakandan Alagumalai Nagendran 《Korean Journal of Chemical Engineering》2014,31(6):1057-1064
A charged surface modifying macromolecule (cSMM) was synthesized, characterized by FT-IR spectroscopy and blended into the casting solution of cellulose acetate (CA) to prepare surface modified UF membranes by phase inversion technique. With an increasing cSMM additive content from 1 to 4 wt%, pure water flux (PWF) and water content (WC) were increases whereas the hydraulic resistance decreases. Surface characteristic study reveals that the surface hydrophilicity increased in cSMM modified CA membranes. The pore size and surface porosity of the 4 wt% cSMM blend CA membranes increases to 41.26 Å and 0.015%, respectively. Similarly, the molecular weight cut-off (MWCO) of the membranes ranged from 20 to 45 kDa, depending on the various compositions of the prepared membranes. Lower flux decline rate (47.2%) and higher flux recovery ratio (FRR) (89.0%), exhibited by 4 wt% cSMM blend membranes demonstrated its fouling resistant characteristic compared to pristine CA membrane. 相似文献
3.
Paulraj Kanmani Ramraj Satishkumar Neelakandan Yuvaraj Kupusamy Alagesan Paari Vellaiyan Pattukumar Venkatesan Arul 《Korean Journal of Chemical Engineering》2011,28(3):860-866
The aim of this study was to optimize medium composition for higher yield of total viable cells and bacteriocin by Enterococcus faecium MC13. The factors such as peptone, meat extract, yeast extract, lactose, glycerol, tween 80, triammonium citrate and K2HPO4 were selected based on the Lactobacillus MRS medium composition. Two level factorial designs (FD) and steepest ascent path were performed to identify vital factors among the variables. Through the 2?8 FD, peptone, yeast extract and lactose were found to be significant factors involved in the enhanced production of viable cells and bacteriocin. Therefore, these three foremost factors were further optimized by central composite design to achieve efficient yield. The optimum MRS composition was found to be peptone (40.0 g/L), meat extract (30.0 g/L), yeast extract (40.0 g/L), lactose (24.0 g/L), glycerol (5.8 g/L), Tween 80 (3.0 g/L), triammonium citrate (1.0 g/L), K2HPO4 (2.5 g/L), MgSO4·7H2O (0.10 g/L), MnSO4·7H2O (0.05 g/L) and dipotassium PO4 (2.0 g/L). The optimized growth medium allowed higher amount of bacteriocin activity (36,100 AUml?1) and total viable cells (14.22 LogCFUml?1) production which were two-times higher than the commercial MRS medium. 相似文献
4.
Sulfonated branched polymer membranes have been gaining immense attention as the separator in energy‐related applications especially in fuel cells and flow batteries. Utilization of this branched polymer membranes in direct methanol fuel cell (DMFC) is limited because of large free volume and high methanol permeation. In the present work, sulfonated fullerene is used to improve the methanol barrier property of the highly branched sulfonated poly(ether ether ketone sulfone)s membrane without sacrificing its high proton conductivity. The existence of sulfonated fullerene with larger size and the usage of small quantity in the branched polymer matrix effectively prevent the methanol transportation channel across the membrane. The composite membrane with an optimized loading of sulfonated fullerene displays the highest proton conductivity of 0.332 S cm?1 at 80°C. Radical scavenging property of the fullerene improves the oxidative stability of the composite membrane. Composite membrane exhibits the peak power density of 74.38 mW cm?2 at 60°C, which is 30% larger than the commercial Nafion 212 membrane (51.78 mW cm?2) at the same condition. From these results, it clearly depicts that sulfonated fullerene‐incorporated branched polymer electrolyte membrane emerges as a promising candidate for DMFC applications. 相似文献
5.
Kumar M Islam MN Terry FL Freeman MJ Chan A Neelakandan M Manzur T 《Applied optics》2012,51(15):2794-2807
We measure the diffuse reflection spectrum of solid samples such as explosives (TNT, RDX, PETN), fertilizers (ammonium nitrate, urea), and paints (automotive and military grade) at a stand-off distance of 5 m using a mid-infrared supercontinuum light source with 3.9 W average output power. The output spectrum extends from 750-4300 nm, and it is generated by nonlinear spectral broadening in a 9 m long fluoride fiber pumped by high peak power pulses from a dual-stage erbium-ytterbium fiber amplifier operating at 1543 nm. The samples are distinguished using unique spectral signatures that are attributed to the molecular vibrations of the constituents. Signal-to-noise ratio (SNR) calculations demonstrate the feasibility of increasing the stand-off distance from 5 to ~150 m, with a corresponding drop in SNR from 28 to 10 dB. 相似文献
6.
Teng Chang Chandrasekaran Neelakandan Thein Kyu Yu-Tsan Tseng Linda DeFine Thomas Alexander 《Polymer》2014
Development of asymmetric channel morphology driven by coagulation-induced phase separation of genistein (G) modified poly(ether sulfone)/poly(vinyl pyrrolidone) (PES/PVP) blends has been examined in relation to their miscibility phase diagram. PES/G pairs turned out to be miscible in the amorphous state, whereas solid–liquid phase separation occurred at high genistein compositions. The solid–liquid phase diagram involving the liquidus and solidus lines were computed self-consistently in the framework of the combined free energy of Flory-Huggins for liquid–liquid phase separation and phase field free energy for crystal solidification. The ternary phase diagram of PES/PVP/G blends was subsequently established that consisted of various coexistence regions. The actual amounts of genistein incorporated in the PES/PVP membranes were determined as a function of weight percent of genistein in feed. On the basis of UV-vis spectroscopy, the extent of genistein leaching during incubation in human blood was evaluated in conjunction with the PVP leaching from the blend membrane. 相似文献
7.
Sivasubramaniyan Neelakandan Arunachalam Muthumeenal Dipak Rana Noel Jacob Kaleekkal Alagumalai Nagendran 《应用聚合物科学杂志》2019,136(16):47344
Poly(diallyldimethylammonium chloride) (PDDA) and phosphotungstic acid (PTA) were used as cationic and anionic polyelectrolyte layers, respectively, in an alternating fashion to enhance the methanol barrier property and oxidative stability of sulfonated poly (phenylene ether ether sulfone) (SPEES) proton exchange membranes (PEMs). The multilayer PEMs were characterized by AFM, FTIR, and AC impedance spectroscopy. Methanol permeability of the multilayered membranes was found to be much lower than the bare SPEES membrane. The multilayered membranes displayed significantly improved oxidative stability and dimensional stability compared to pristine SPEES membrane. Conversely, the water uptake (%) and proton conductivity (S cm−1) of the prepared membranes decrease to some extent with increasing the PDDA/PTA bilayers in comparison to the pristine SPEES membrane. The maximum relative selectivity (2.23 × 104 S cm−3 s) and retained weight (88.9%) were observed for SPEES-[PDDA/PTA]5 multilayered membrane. The obtained results exposed the possibility of SPEES-[PDDA/PTA]5 multilayered membrane to serve as high-performance PEMs in direct methanol fuel cells. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47344. 相似文献
8.
Manton Matthews Walter Pharr Gautam Biswas Harish Neelakandan 《Artificial Intelligence Review》2000,14(1-2):121-141
This paper describes the knowledge sources and methods of knowledge acquisition for USCSH (University of South Carolina SHell). USCSH is an active intelligent assistance system for Unix. The system operates in two modes, the active mode and the intelligent mode. In the active mode USCSH monitors the user's interactions with the system, and at appropriate times makes suggestions on how the user may better utilize the system to perform tasks. In the intelligent mode the system accepts questions in natural language and responds to them, taking into consideration the ability of the user and the context of the question. 相似文献
9.
Performances of poly(vinylidene fluoride‐co‐hexafluoropropylene) ultrafiltration membranes modified with poly(vinyl pyrrolidone) 下载免费PDF全文
Palsamy Kanagaraj Alagumalai Nagendran Dipak Rana Takeshi Matsuura Sivasubramaniyan Neelakandan Rajendran Revathi Nambirajan Pandiyarajan 《Polymer Engineering and Science》2015,55(11):2482-2492
The structure and performance of modified poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVdF‐co‐HFP) ultra‐filtration membranes prepared from casting solutions with different concentrations of poly(vinyl pyrrolidone) (PVP) were investigated in this study. Membrane properties were studied in terms of membrane compaction, pure water flux (PWF), water content (WC), membrane hydraulic resistance ( R m), protein rejection, molecular weight cut‐off (MWCO), average pore size, and porosity. PWF, WC, and thermal stability of the blend membranes increased whereas the crystalline nature and mechanical strength of the blend membranes decreased when PVP additive concentration was increased. The contact angle (CA) decreased as the PVP concentration increased in the casting solution, which indicates that the hydro‐philicity of the surface increased upon addition of PVP. The average pore size and porosity of the PVdF‐co‐HFP membrane increased to 42.82 Å and 25.12%, respectively, when 7.5 wt% PVP was blended in the casting solution. The MWCO increased from 20 to 45 kDa with an increase in PVP concentration from 0 to 7.5 wt%. The protein separation study revealed that the rejection increased as the protein molecular weight increased. The PVdF‐co‐HFP/PVP blended membrane prepared from a 7.5 wt% PVP solution had a maximum flux recovery ratio of 74.3%, which explains its better antifouling properties as compared to the neat PVdF‐co‐HFP membrane. POLYM. ENG. SCI., 55:2482–2492, 2015. © 2015 Society of Plastics Engineers 相似文献
10.
Oil palm wood (OPW) from different portions of the trunk was tested on edge to evaluate its fatigue life, a criterion necessary for furniture application. It was found that as the stress levels increased, as a percentage of its MOR, a reduction in fatigue life was observed. Further, the phenol–formaldehyde resin impregnated OPW from the middle and center portion of the oil palm trunk showed comparable fatigue life with those untreated samples from the periphery of the trunk, and hence, the allowable design stress for the OPW for furniture applications could be set at 40 % of its MOR. The results show oil palm wood of acceptable density can be successfully used for furniture applications. 相似文献