Atomistic Simulation of the Polymerization Reaction by a (Pyridylamido)hafnium(IV) Catalyst: Counteranion Influence on the Reaction Rate and the Living Character of the Catalytic System

2021 ◽  
Vol 125 (5) ◽  
pp. 1453-1467
Author(s):  
Nana Misawa ◽  
Yuichi Suzuki ◽  
Kentaro Matsumoto ◽  
Soumen Saha ◽  
Nobuaki Koga ◽  
...  
Keyword(s):  
Catalytic System ◽  
Atomistic Simulation ◽  
Reaction Rate ◽  
Polymerization Reaction

scholarly journals Effects of Various Mixed Metal Chlorides- AlCl3 in TiCl4/MgCl2/THF Catalytic System on Ethylene Polymerization

2015 ◽  
Vol 14 (2) ◽  
pp. 12
Author(s):  
Nittaya Sudsong ◽  
Wanna Phiwkliang ◽  
Bunjerd Jongsomjit ◽  
Piyasan Praserthdam
Keyword(s):  
Catalytic System ◽  
Ethylene Polymerization ◽  
Catalyst System ◽  
Polymerization Reaction ◽  
Molar Ratio ◽  
Metal Chlorides ◽  
Mixed Metal ◽  
Icp Analysis ◽  
Co Addition

In this research, the modification of TiCl4/MgCl2/THF catalyst system with various metal chlorides was investigated on ethylene polymerization. Experimentally, metal chlorides (CaCl2, FeCl2 and ZnCl2) were simultaneously introduced different with TiCl4/MgCl2/THF catalyst. ICP analysis was used to determine the total amount of each metal in the catalyst. For polymerization reaction, TEA was used as cocatalyst and hexane was used as a medium solvent. The Al/Ti molar ratio was 140. The activity result of Ca-Al, Zn-Al and Fe-Al was 979, 1009 and 1476 kgPE/molTi.h, respectively. The coaddition of AlCl3 and FeCl2 in TiCl4/MgCl2/THF catalyst system exhibited the highest activity. It suggested that the co-addition of AlCl3 and FeCl2 has higher electronegativity (EN) and the radius of Fe2+ is closer to Mg2+ resulting in an increased efficiency of the THF removal. This result led to improve the catalyst performance.

Application of a Novel Initiator on Acrylic Emulsion Polymerization

2011 ◽  
Vol 233-235 ◽  
pp. 1415-1418
Author(s):  
Shao Guo Wen ◽  
Shi Gao Song ◽  
Hong Bo Liu ◽  
Ji Hu Wang ◽  
Qian Xu ◽  
...  
Keyword(s):  
Emulsion Polymerization ◽  
Reaction Rate ◽  
The Other ◽  
Polymerization Reaction ◽  
Polymerization Temperature ◽  
Acrylic Emulsion ◽  
Polymerization Mechanism ◽  
Lower Temperature ◽  
Classical Mechanism ◽  
Mechanism Of The Reaction

New initiator of FFM6 is used to initiate the acrylic emulsion polymerization. The influences of concentration of FFM6 (c[I]) and polymerization temperature (T) on polymerization reaction rate (Rp) were discussed. Rp is proportional to (c[I])1.4 which is different with classical emulsion polymerization whose Rp is proportion to (c[I])0.4, that indicate polymerization mechanism of the reaction in the study is different with classical mechanism. The value of Ea, 56.4 kJ/mol, is lower than the value of general radical polymerization’s Ea (80.0-96.0 kJ/mol), which indicates the FFM6 can initiate acrylic emulsion polymerization at a lower temperature compared with the other kinds of initiator.

Study on the Cure Kinetic Behavior of Thermosetting Polyurethane Solids and Foams: Effect of Temperature, Density, and Carbon Nanofiber

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Mrinal C. Saha ◽  
Bipul Barua ◽  
Sriram Mohan
Keyword(s):  
Reaction Rate ◽  
Carbon Nanofiber ◽  
Polymerization Reaction ◽  
Shear Mode ◽  
Kinetic Behavior ◽  
Cure Reaction ◽  
Cure Behavior ◽  
Pu Foam ◽  
Cure Kinetic ◽  
Reaction Orders

Cure kinetic behavior was studied for both thermosetting polyurethane (PU) solids and foams. The effects of cure temperature, foam density, and carbon nanofiber (CNF) contents were examined. Cure studies were performed experimentally by measuring the evolution of complex shear modulus as a function of time using an advanced polymer analyzer operating in dynamic shear mode. Isothermal cure behavior of PU solid and foams was investigated at four different temperatures, namely, 25°C, 45°C, 60°C, and 80°C and at three different amounts of CNF, namely, 0.01%, 0.05%, and 0.1% by weight. The cure data were analyzed by using an autocatalytic cure kinetic model. The cure behavior of both solid and foam was found to be temperature dependent. Addition of CNF was also found to affect the cure behavior of the PU foam. It was observed that the PU foam with 0.1% CNF shows the highest polymerization reaction compared with the neat foam. It was also observed that the reaction rate constants follow an Arrhenius dependence on temperature, whereas the reaction orders remain fairly constant. A simple predictive model using the reaction orders indicated that the maximum cure reaction rate was occurred at 37.5% conversion.

scholarly journals Surface chromium single sites: open problems and recent advances

2012 ◽  
Vol 468 (2143) ◽  
pp. 2087-2098 ◽  
Author(s):  
Adriano Zecchina ◽  
Elena Groppo
Keyword(s):  
Ethylene Polymerization ◽  
Reaction Rate ◽  
Single Site ◽  
Polymerization Reaction ◽  
Detailed Knowledge ◽  
Open Problems ◽  
Initiation Mechanism ◽  
Characterization Methods ◽  
Polymerization Catalyst ◽  
Recent Advances

The results of decades of studies on the Phillips chromium (Cr)/silica polymerization catalyst are briefly summarized. The application of several characterization methods has allowed a detailed knowledge of the structure and reactivity of Cr centres to be obtained. In particular, many aspects of this apparently simple single-site catalyst, including the heterogeneity, the modification of the ligand sphere upon interaction with many molecules and the initiation mechanism of the ethylene polymerization reaction, have been clarified. It is shown that based on the acquired knowledge, it is now possible to proceed further towards the intelligent modification of the ligand sphere with the scope to increase the reaction rate and selectivity. It is also illustrated that, besides polymerization/oligomerization reactions, it is possible to extend the study of Cr II reactivity towards new reactions.

scholarly journals Chemical Modification of ED-24 Epoxy Resin Peroxy Derivative by C9H4F16O Fluorine-Containing Alcohol-Telomer

2010 ◽  
Vol 4 (2) ◽  
pp. 125-130 ◽  
Author(s):  
Michael Bratychak ◽  
◽  
Taras Chervinskyy ◽  
Olena Shust ◽  
Olena Shyshchak ◽  
...  
Keyword(s):  
Ir Spectroscopy ◽  
Chemical Modification ◽  
Epoxy Resin ◽  
Catalytic System ◽  
Reaction Rate ◽  
Process Time ◽  
Catalyst Amount ◽  
Active Additive

The possibility of chemical modification of ED-24 epoxy resin peroxy derivative (PDER) by C9H4F16O fluorine-containing alcohol-telomer (FAT-C9) has been shown using 18-Crown and ZnCl2 catalytic system. The effect of catalyst amount, temperature and process time on the reaction rate has been studied. New peroxy oligomer containing fluorine atoms (FPO) has been synthesized and characterized. The FPO structure has been confirmed by IR-spectroscopy. It has been proposed to use FPO as an active additive to the polymeric mixes based on ED-20 industrial epoxy resin and TGM-3 oligoesteracrylate.

Microwave Technology Based Polymer Process

2014 ◽  
Vol 484-485 ◽  
pp. 132-136
Author(s):  
Shi Hong ◽  
Zhu Qing
Keyword(s):  
Green Chemistry ◽  
Emulsion Polymerization ◽  
Reaction Rate ◽  
Bulk Polymerization ◽  
Polymerization Reaction ◽  
Solution Polymerization ◽  
Microwave Technology ◽  
Energy Consumptions ◽  
Microwave Techniques ◽  
Time And Energy

In this paper the author summarizes the application of microwave techniques in the bulk polymerization, solution polymerization, emulsion polymerization and functional polymer. It is pointed out that the microwave technology can reduce the time and energy consumptions of the polymerization reaction, and improve the properties of polymeric reaction rate, yield and selectivity, which will play an important role in the green chemistry synthesis of polymers.

Factors Affecting Photopolymerization Stress in Dental Composites

2008 ◽  
Vol 87 (11) ◽  
pp. 1043-1047 ◽  
Author(s):  
C.S. Pfeifer ◽  
J.L. Ferracane ◽  
R.L. Sakaguchi ◽  
R.R. Braga
Keyword(s):  
Reaction Rate ◽  
Radiant Energy ◽  
Degree Of Conversion ◽  
Volumetric Shrinkage ◽  
Polymerization Reaction ◽  
Dental Composites ◽  
Scanning Calorimetry ◽  
Factors Affecting ◽  
Stress Development ◽  
Rate Of Polymerization

Polymerization stress development results from the complex interplay of volumetric shrinkage, reaction kinetics, and viscoelastic properties. The objective of this study was to examine the relationships among volumetric shrinkage, degree of conversion, rate of polymerization (RPmax), and stress development for 2 model bis-GMA-based composites. Three irradiances were used—220, 400, or 600 mW/cm2—with exposure times adjusted to deliver the same radiant energy. Volumetric shrinkage was determined with a mercury dilatometer, degree of conversion and RPmax by differential scanning calorimetry (DSC), and polymerization stress with a low-compliance device ( Sakaguchi et al., 2004b ). Results indicated that polymerization reaction rate and shrinkage were not correlated. Irradiance was directly related to polymerization reaction rate and to stress development. The group with the highest stress/degree of conversion exhibited the lowest RPmax, so it can be assumed, within the limitations of this study, that the conversion was most closely related to stress development.

A pH-switched Pickering emulsion catalytic system: high reaction efficiency and facile catalyst recycling

2015 ◽  
Vol 51 (34) ◽  
pp. 7333-7336 ◽  
Author(s):  
Jianping Huang ◽  
Hengquan Yang
Keyword(s):  
Catalytic System ◽  
Reaction Rate ◽  
Pickering Emulsion ◽  
Catalyst Recycling ◽  
Rate Enhancement ◽  
Reaction Efficiency ◽  
Nanoparticle Catalysts ◽  
High Reaction

A smart Pickering emulsion catalytic system is first constructed, which not only exhibits fivefold reaction rate enhancement effects in comparison to the conventional biphasic reactions but also can be demulsified by tuning pH at the end of reaction, allowing for in situ recycling nanoparticle catalysts.

Locating Al in the DABCO catalyst before and after Al extraction

1990 ◽  
Vol 48 (4) ◽  
pp. 265-267
Author(s):  
Kathleen B. Reuter
Keyword(s):  
Active Site ◽  
Inverse Relationship ◽  
Transverse Direction ◽  
Reaction Rate ◽  
Acid Phosphate ◽  
Fracture Surfaces ◽  
Al Content ◽  
Before And After ◽  
Relationship Of

The reaction rate and efficiency of piperazine to 1,4-diazabicyclo-octane (DABCO) depends on the Si/Al ratio of the MFI topology catalysts. The Al was shown to be the active site, however, in the Si/Al range of 30-200 the reaction rate increases as the Si/Al ratio increases. The objective of this work was to determine the location and concentration of Al to explain this inverse relationship of Al content with reaction rate.Two silicalite catalysts in the form of 1/16 inch SiO2/Al2O3 bonded extrudates were examined: catalyst A with a Si/Al of 83; and catalyst B, the acid/phosphate Al extracted form of catalyst A, with a Si/Al of 175. Five extrudates from each catalyst were fractured in the transverse direction and particles were obtained from the fracture surfaces near the center of the extrudate diameter. Particles were also obtained from the outside surfaces of five extrudates.

Direct observation of Fe-Al-Zn ternary intermetallic compound and its transformation during the early stage of hot-dip galvanizing

1993 ◽  
Vol 51 ◽  
pp. 1116-1117
Author(s):  
C. S. Lin ◽  
W. A. Chiou ◽  
M. Meshii
Keyword(s):  
Intermetallic Compound ◽  
Reaction Rate ◽  
Diffusion Rate ◽  
Early Stage ◽  
Zinc Bath ◽  
Steel Sheets ◽  
Direct Observations ◽  
Solid Iron ◽  
Iron And Zinc ◽  
Ternary Intermetallic Compound

The galvannealed steel sheets have received ever increased attention because of their excellent post-painting corrosion resistance and good weldability. However, its powdering and flaking tendency during press forming processes strongly impairs its performance. In order to optimize the properties of galvanneal coatings, it is critical to control the reaction rate between solid iron and molten zinc.In commercial galvannealing line, aluminum is added to zinc bath to retard the diffusion rate between iron and zinc by the formation of a thin layer of Al intermetallic compound on the surface of steel at initial hot-dip galvanizing. However, the form of this compound and its transformation are still speculated. In this paper, we report the direct observations of this compound and its transformation.The specimens were prepared in a hot-dip simulator in which the steel was galvanized in the zinc bath containing 0.14 wt% of Al at a temperature of 480 °C for 5 seconds and was quenched by liquid nitrogen.

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