Experimental Investigation of Emulsion AGET ATRP of MMA in a Stirred Tank Reactor

10.32920/ryerson.14649087.v1 ◽

2021 ◽

Author(s):

Kishor Regmi

Keyword(s):

Monomer Conversion ◽

Single Step ◽

Reducing Agent ◽

Influential Factor ◽

Aget Atrp ◽

Molecular Weights ◽

Step Procedure ◽

Catalyst Complex ◽

Main Effects ◽

Factor Interaction

This study investigates the emulsion AGET ATRP of MMA in a 2-L reactor using the reactants: surfactant (Brij 98), catalyst complex (CuBr2/dNbpy), initiator (EBiB) and reducing agent (ascorbic acid). Preliminary trials demonstrate that the two-step procedure preserves the ATRP living features much better than the single-step procedure. An experimental design and statistical analysis were performed to investigate the main effects and two-factor interaction effects of temperature, surfactant, catalyst complex, initiator and reducing agent on the monomer conversion, average molecular weights and polydispersity index of the polymer. The input-output model predictions agree with experimental data. The results revealed that the temperature was the most influential factor for all three-process responses with 71.34%, 32.78% and 27.76 % contribution. However, the initiator was the least influential factor for both conversion and PDI with 0.035% and 0.13% contribution, whereas the surfactant was the least influential factor for molecular weight with 0.068% contribution

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Experimental Investigation of AGET ATRP Polymerization of Butyl Methacrylate in an Emulsion Stirred Tank Reactor

10.32920/16814722.v1 ◽

2021 ◽

Author(s):

John Tam

Keyword(s):

Ascorbic Acid ◽

Catalyst Activity ◽

Stirred Tank ◽

Butyl Methacrylate ◽

Aget Atrp ◽

Stirred Tank Reactor ◽

Tank Reactor ◽

Step Procedure ◽

Catalyst Complex ◽

Key Variables

This study investigates ATRP emulsion polymerization of butyl methacrylate (BMA) in a 2-L stirred tank reactor using AGET as the initiation technique with ascorbic acid. The polymerization is performed in two step procedure using surfactant (Brij 98) in distilled water. The reaction is initiated by the catalyst CuBr2/dNbpy and initiator EBiB under a blanket of nitrogen to minimize air presence. An experimental design is performed to investigate the effects of the key variables: temperature, catalyst complex, surfactant and reducing agent. For reaction temperatures of 50°C, 60°C and 70°C, BMA conversion obtained is 63.9%, 70.2% and 85.8%, respectively. All other nine tests are done at 70°C for appropriate amounts of reactants. The results concluded that BMA conversion improves to 90% and the PDI increases slightly from 1.15 to 1.29 for more ascorbic acid. BMA conversion and PDI improve with less surfactant, but more ligand narrows MWD and reduces the catalyst activity.

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Experimental Investigation of AGET ATRP Polymerization of Butyl Methacrylate in an Emulsion Stirred Tank Reactor

10.32920/16814722 ◽

2021 ◽

Author(s):

John Tam

Keyword(s):

Ascorbic Acid ◽

Catalyst Activity ◽

Stirred Tank ◽

Butyl Methacrylate ◽

Aget Atrp ◽

Stirred Tank Reactor ◽

Tank Reactor ◽

Step Procedure ◽

Catalyst Complex ◽

Key Variables

This study investigates ATRP emulsion polymerization of butyl methacrylate (BMA) in a 2-L stirred tank reactor using AGET as the initiation technique with ascorbic acid. The polymerization is performed in two step procedure using surfactant (Brij 98) in distilled water. The reaction is initiated by the catalyst CuBr2/dNbpy and initiator EBiB under a blanket of nitrogen to minimize air presence. An experimental design is performed to investigate the effects of the key variables: temperature, catalyst complex, surfactant and reducing agent. For reaction temperatures of 50°C, 60°C and 70°C, BMA conversion obtained is 63.9%, 70.2% and 85.8%, respectively. All other nine tests are done at 70°C for appropriate amounts of reactants. The results concluded that BMA conversion improves to 90% and the PDI increases slightly from 1.15 to 1.29 for more ascorbic acid. BMA conversion and PDI improve with less surfactant, but more ligand narrows MWD and reduces the catalyst activity.

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Multiple Boris solvers for particle-in-cell (PIC) simulation

10.5194/egusphere-egu21-9368 ◽

2021 ◽

Author(s):

Seiji Zenitani ◽

Tsunehiko Kato

Keyword(s):

Plasma Physics ◽

Particle Motion ◽

Charged Particles ◽

Single Step ◽

Pic Simulation ◽

Particle In Cell ◽

Step Procedure ◽

Cell Simulation ◽

Continuous Demand

<div> <div> <div> <p>&#160;Particle-in-cell (PIC) simulation has long been used in theoretical plasma physics. In PIC simulation, the Boris solver is the de-facto standard for solving particle motion, and it has been used over a half century. Meanwhile, there is a continuous demand for better particle solvers. In this contribution, we introduce a family of Boris-type schemes for integrating the motion of charged particles. We call the new solvers the multiple Boris solvers. The new solvers essentially repeat the standard two-step procedure multiple times in the Lorentz-force part, and we derive a single-step form for arbitrary subcycle number <em>n</em>. The new solvers give <em>n<sup>2</sup></em> times smaller errors, allow larger timesteps, but they are computationally affordable for moderate <em>n</em>. The multiple Boris solvers also reduce a numerical error in long-term plasma motion in a relativistic magnetized flow.</p> </div> </div> </div><p>Reference:</p><ul><li>S. Zenitani & T. N. Kato, <em>Multiple Boris integrators for particle-in-cell simulation</em>, Comput. Phys. Commun. <strong>247</strong>, 106954, doi:10.1016/j.cpc.2019.106954 (2020)</li> </ul>

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Partition of tert-dodecyl mercaptan in systems containing styrene, polystyrene, and polybutadiene. Its effect on the macromolecular characteristics of high-impact poly styrene

e-Polymers ◽

10.1515/epoly.2007.7.1.980 ◽

2007 ◽

Vol 7 (1) ◽

Cited By ~ 1

Author(s):

Natalia Casís ◽

Carla Vanesa Luciani ◽

Diana Alejandra Estenoz ◽

Marisa Martinelli ◽

Miriam Strumia ◽

...

Keyword(s):

Total Concentration ◽

Strong Dependence ◽

Monomer Conversion ◽

Theoretical Work ◽

High Impact ◽

Proton Nuclear Magnetic Resonance ◽

Molecular Weights ◽

H Nmr ◽

Dodecyl Mercaptan ◽

Good Agreement

AbstractThis work investigates the distribution between phases of tert-dodecyl mercaptan (t-DDM) in systems containing styrene (St), polystyrene (PS), and polybutadiene (PB) with the aim of studying its effect on the molecular macrostructure of High-Impact Polystyrene (HIPS) produced via the bulk process. Experimental work involved the study of several St/PS/PB/t-DDM blends, and of 2 polymerizations of St in presence of PB (with and without t-DDM). Blends were prepared with increasing PS/St ratios to emulate monomer conversions of 7, 9, 11, 13, and 15%, employing 2 base PSs of different molar masses, and several total concentrations of t-DDM. Measurements by Proton Nuclear Magnetic Resonance (1H NMR) indicate that t-DDM is almost evenly distributed between the phases at room temperature. In addition, for samples taken along the 2 investigated polymerizations, monomer conversion, grafting efficiency, and free PS molecular weights were measured. Theoretical work involved first to model the species partitions through the Flory-Huggins theory [1]; and then, to combine such partition model with a polymerization model extended from that by Casís et al. [2]. Theoretical estimations were in good agreement with experimental determinations. Simulations suggest that t-DDM partition coefficients exhibit a weak dependence with temperature, but a strong dependence with its total concentration. Also, the combined partition/polymerization model indicates that the free PS contained in the occlusion regions exhibits lower molecular weights than that in the continuous matrix.

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Safety of Single Stage Revision Laparoscopic Sleeve Gastrectomy Compared to Laparoscopic Roux-Y Gastric Bypass after Failed Gastric Banding

Obesity Surgery ◽

10.1007/s11695-020-04975-6 ◽

2020 ◽

Author(s):

Michał Janik ◽

Christopher Ibikunle ◽

Ahad Khan ◽

Amir H. Aryaie

Keyword(s):

Gastric Bypass ◽

Sleeve Gastrectomy ◽

Gastric Banding ◽

Laparoscopic Sleeve Gastrectomy ◽

Revisional Surgery ◽

Perioperative Complications ◽

Single Step ◽

Single Stage ◽

Step Procedure ◽

User File

Abstract Background Reoperation, after failed gastric banding, is a controversial topic. A common approach is band removal with conversion to laparoscopic Roux-Y gastric bypass (LRYGB) or laparoscopic sleeve gastrectomy (LSG) in a single-step procedure. Objective This study aimed to assess the safety of revisional surgery to LSG compared to LRYGB after failed laparoscopic adjustable gastric banding (LAGB) based on MBSAQIP Participant User File from 2015 to 2018. Methods Patients who underwent a one-stage conversion of LAGB to LSG (Conv-LSG) or LRYGB (Conv-LRYGB) were identified in the MBSAQIP PUF from 2015 to 2017. Conv-LRYGB cases were matched (1:1) with Conv-LSG patients using propensity scoring to control for potential confounding. The primary outcome was all-cause mortality. Results A total of 9974 patients (4987 matched pairs) were included in the study. Conv-LRYGB, as compared with conv-SG, was associated with a similar risk of mortality (0.02% vs. 0.06%; relative risk [RR], 0.33; 95% confidence interval [CI], 0.03 to 3.20, p = 0.32). Conversion to LRYGB increased the risk for readmission (6.16% vs. 3.77%; RR, 1.63; 95%CI, 1.37 to 1.94, p < 0.01); reoperation (2.15% vs. 1.36%; RR, 1.57; 95%CI, 1.17 to 2.12, p = <0.01); leak (1.76% vs. 1.02%; RR, 1.57; 95%CI, 1.72 to 2.42, p < 0.01); and bleeding (1.66% vs. 1.00%; RR, 1.66; 95%CI, 1.7 to 2.34, p < 0.01). Conclusions The study shows that single-stage LRYGB and LSG as revisional surgery after gastric banding, are safe in the 30-day observation with an acceptable complication rate and low mortality. However, conversion to LRYGB increased the risk of perioperative complications.

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Tailor-made high porosity VOC oxidation catalysts prepared by a single-step procedure

Applied Catalysis B Environmental ◽

10.1016/j.apcatb.2006.06.017 ◽

2007 ◽

Vol 73 (1-2) ◽

pp. 128-134 ◽

Cited By ~ 15

Author(s):

J. Blanco ◽

A.L. Petre ◽

M. Yates ◽

M.P. Martin ◽

J.A. Martin ◽

...

Keyword(s):

Single Step ◽

High Porosity ◽

Oxidation Catalysts ◽

Voc Oxidation ◽

Step Procedure

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Response of green roof performance to multiple hydrologic and design variables: a laboratory investigation

Water Science & Technology ◽

10.2166/wst.2018.275 ◽

2018 ◽

Vol 77 (12) ◽

pp. 2834-2840 ◽

Cited By ~ 3

Author(s):

Musa Akther ◽

Jianxun He ◽

Angus Chu ◽

Caterina Valeo ◽

Usman T. Khan ◽

...

Keyword(s):

Early Stage ◽

Green Roof ◽

Influential Factor ◽

Moisture Condition ◽

Antecedent Moisture ◽

Design Variables ◽

Multiple Dimensions ◽

Growing Medium ◽

Roof Design ◽

Main Effects

Abstract Multiple factors affect green roof performance and their effects might vary at different stages of operation. This paper aimed to link green roof performance to hydrologic variables (antecedent moisture condition (AMC) and rainfall intensity) and design variables (growing medium (GM) type and depth) under multiple dimensions at the early stage of operation using laboratory experiment data. The results showed that the AMC is the most influential factor of hydrologic performance, whereas the GM type appeared to primarily affect the nutrient levels of the outflow. The significant main effects of other variables and interaction effects between two variables point to challenges in green roof design.

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