Maximizing macromonomer content produced by starved-feed high temperature acrylate/methacrylate semi-batch polymerization

2020 ◽  
Vol 11 (12) ◽  
pp. 2137-2146 ◽  
Author(s):  
Nina Heidarzadeh ◽  
Robin A. Hutchinson
Keyword(s):  
High Temperature ◽  
Molar Mass ◽  
Reaction Conditions ◽  
Batch Reaction

Suitable semi-batch reaction conditions are determined to maximize the fraction of acrylate chains with TDBs while also achieved a target polymer molar mass.

Production and Study of Ca/Sn(II) Metastable Fluoride Ion Conductors

1997 ◽  
Vol 481 ◽  
Author(s):  
Michael F. Bell ◽  
Georges Dénès ◽  
Zhimeng Zhu
Keyword(s):  
Solid Solution ◽  
Electrical Conductivity ◽  
High Temperature ◽  
Calcium Nitrate ◽  
Fluoride Ion ◽  
Conductivity Measurements ◽  
Ambient Conditions ◽  
Reaction Conditions ◽  
Density Measurements ◽  
Ion Conductors

ABSTRACTPrecipitation reactions from aqueous solutions of calcium nitrate and tin(II) fluoride result in the formation of two metastable phases, depending on the reaction conditions. Crystalline CaSn2F6 and the microcrystalline Ca1-xSnxF2 solid solution are obtained, the latter crystallizing in the cubic fluorite (CaF2) type with total Ca/Sn disorder. Both phases are fluoride ion conductors. Electrical conductivity measurements versus temperature and bulk density measurements show that both phases are far from thermodynamic equilibrium at ambient conditions, and thus are metastable. Both decompose to a mixture of SnF2 and CaF2 at high temperature. In addition, CaSn2F6 is chemically unstable in an aqueous medium, in which it looses SnF2 to give the microcrystalline Ca1-xSnxF2 solid solution.

scholarly journals The investigations of bioactive copper(II) complexes with reduced low-molar dextran

2008 ◽  
Vol 22 (2-3) ◽  
pp. 177-185 ◽  
Author(s):  
Milorad Cakić ◽  
Žarko Mitić ◽  
Goran S. Nikolić ◽  
Ljubomir Ilić ◽  
Goran M. Nikolić
Keyword(s):  
Fourier Transform ◽  
Complex Formation ◽  
Room Temperature ◽  
Molar Mass ◽  
Reaction Conditions ◽  
Average Molar Mass ◽  
Square Planar ◽  
Physicochemical Methods ◽  
Fourier Transform Ir ◽  
Aqueous Complexes

The optimization of the reaction conditions (pH,T,t) to obtain stable copper(II) ion complexes with dextran derivatives were investigated in this paper. A complete synthesis of stable aqueous complexes can be realized with reduced low-molar polysaccharides, at an average molar mass 5000 g mol–1and pH 7.5–8. Fourier-transform IR spectra of polysaccharide dextran and its compounds with copper(II) ion, recorded at room temperature, were analyzed in order to obtain the information about the structure and the conformation of these polymer compounds. The ESR parameters of the spectra indicate the square-planar coordination of Cu(II) ion with four O atoms. Copper(II) complex formation with dextran and its derivatives were analyzed by physicochemical methods. Synthesized complexes of Cu(II) ion with reduced low-molar dextran in comparison with commercial preparations showed the considerably lower acute toxicity (LD501705).

Preparation and Properties of MgAl2O4-CaAl12O19 High Temperature Composite

2012 ◽  
Vol 512-515 ◽  
pp. 617-620
Author(s):  
Yong Hong Wang ◽  
Yan Gai Liu ◽  
Tao Yang ◽  
Zhao Hui Huang ◽  
Ming Hao Fang
Keyword(s):  
Phase Composition ◽  
High Temperature ◽  
Reaction Temperature ◽  
Bending Strength ◽  
Raw Materials ◽  
Weight Ratio ◽  
Raw Material ◽  
Reaction Conditions ◽  
Optimum Reaction ◽  
Industrial Alumina

The utilization of lightweight refractories plays an important role in reducing the energy consumption of industrial furnaces. In this paper, MgAl2O4-CaA112O19 high temperature composite was synthesized via solid state reaction using magnesite, dolomite and industrial alumina as raw materials. The influences of raw materials and reaction temperature on phase compositions and microstructure of the composite were investigated by XRD and SEM，respectively. The parameters to prepare MgAl2O4-CaA112O19 high temperature composite were optimized. The results show that the optimum reaction conditions for synthesizing MgAl2O4-CaA112O19 composite is the CA6/MA weight ratio of 2:3, and the reaction temperature of 1500°C for 4h. The CaA112O19 crystals showed laminated or plate-like structure, and the MgAl2O4 showed spherical morphology. The reaction temperature had little effect on the phase compositions of MA-CA6 composite in this experiment. The content of Al2O3 in the raw material affected the phase composition of MA-CA6 composite.With the increase of the CaA112O19 amount, the bending strength of the composite decreased.

High-temperature gradient HPLC and LC-NMR for the analysis of complex polyolefins

2008 ◽  
Vol 80 (8) ◽  
pp. 1747-1762 ◽  
Author(s):  
Harald Pasch ◽  
Lars-Christian Heinz ◽  
Tibor Macko ◽  
Wolf Hiller
Keyword(s):  
High Temperature ◽  
Chemical Composition ◽  
Temperature Gradient ◽  
Molar Mass ◽  
Size Exclusion ◽  
Copolymer Composition ◽  
Composition Distribution ◽  
High Temperature Gradient ◽  
Chemical Composition Distribution ◽  
On Line

The synthesis and characterization of polyolefins continues to be one of the most important areas for academic and industrial polymer research. One consequence of the development of new "tailor-made" polyolefins is the need for new and improved analytical techniques for the analysis of polyolefins with respect to molar mass and chemical composition distribution. The present article briefly reviews different new and relevant techniques for polyolefin analysis. Crystallization analysis fractionation is a powerful new technique for the analysis of short-chain branching in linear low-density polyethylene (LLDPE) and the analysis of polyolefin blends and copolymers regarding chemical composition. For the fast analysis of the chemical composition distribution, a new high-temperature gradient high-performance liquid chromatography (HPLC) system has been developed. The efficiency of this system for the separation of various olefin copolymers is demonstrated. The correlation between molar mass and chemical composition can be accessed by on-line coupling of high-temperature size exclusion chromatography (HT-SEC) and 1H NMR spectroscopy. It is shown that the on-line NMR analysis of chromatographic fractions yields information on microstructure and tacticity in addition to molar mass and copolymer composition.

Improve the Temperature Resistance of Guar Gum by Silanization

2011 ◽  
Vol 415-417 ◽  
pp. 652-655
Author(s):  
Jie Zhang ◽  
Gang Chen
Keyword(s):  
High Temperature ◽  
Reaction Time ◽  
Hydraulic Fracturing ◽  
Reaction Temperature ◽  
Guar Gum ◽  
Molar Ratio ◽  
Fracturing Fluid ◽  
Reaction Conditions ◽  
Temperature Resistance ◽  
Optimized Conditions

For gelating agent in hydraulic fracturing fluid, the temperature resistance is required. To improve the temperature resistance of Guar gum (GG), it was modified by silanization. The reaction conditions were investigated, and the optimized conditions were as following: the reaction temperature of 85°C, 5: 1 molar ratio of guar gum to TMS-Cl and 4-6 h of reaction time. The viscosity of silanized guar gum (SGG) aqueous gel was greatly improved even high temperature at 80°C.

scholarly journals A Greener Enzymatic Oligoesterification of Biobased Renewable Synthons

2021 ◽  
Author(s):  
Juan Villavicencio ◽  
Ferley Orozco ◽  
Ricardo Benitez ◽  
Jaime Martin ◽  
Giovanni Rojas
Keyword(s):  
Molecular Weight ◽  
Molar Mass ◽  
Gel Permeation Chromatography ◽  
Scanning Calorimetry ◽  
Reaction Conditions ◽  
Step Process ◽  
Gel Permeation ◽  
One Step ◽  
First Time ◽  
Temperature Time

Polyesters of xylitol and succinic acid were prepared yielding from 70 to 75% by enzymecatalyzed esterification using a molar mass from 1:1 to 2:5 at 120 and 140 °C employing from 1 to 10% m/m of enzyme. Control over branching degree was achieved by tuning the reaction conditions (temperature, time, comonomer ratio, enzyme content). This one-step process from renewable starting materials avoids protection-deprotection techniques, as well as the use of toxic solvents by introducing limonene as solvent for polyesterification for the first time. All materials were structurally characterized by infrared (IR) and nuclear magnetic resonance (NMR)spectroscopy, their thermal properties were studied by differential scanning calorimetry (DSC)and thermogravimetric analysis (TGA), and the molecular weight of samples were obtained by gel-permeation chromatography (GPC).

scholarly journals A transient initiator for polypeptoids post-polymerization α-functionalization via activation of thioester group

2021 ◽  
Author(s):  
Solomiia Borova ◽  
Christine Schlutt ◽  
Joachim Nickel ◽  
Robert Luxenhofer
Keyword(s):  
Small Molecules ◽  
Ring Opening ◽  
Molar Mass ◽  
Fluorescent Dyes ◽  
Gel Permeation Chromatography ◽  
Laser Desorption Ionization ◽  
Reaction Conditions ◽  
Ionization Time ◽  
Modification Method ◽  
End Group

Here we introduce a post-polymerization modification method of an α-terminal functionalized poly-(N-methyl-glycine), also known as polysarcosine. We utilized 4-(methylthio)phenyl piperidine-4-carboxylate as an initiator for the ring-opening polymerization of N-methyl-glycine-N-carboxyanhydride followed by oxidation of the thioester group to yield an α-terminal reactive 4-(methylsulfonyl)phenyl piperidine-4-carboxylate polymer. This represents an activated carboxylic acid terminus, allowing straightforward modification with nucleophiles under mild reaction conditions and provides the possibility to introduce a wide variety of nucleophiles as exemplified using small molecules, fluorescent dyes and model proteins. The new initiator yielded polymers with well-defined molar mass, low dispersity and high end-group fidelity, as observed by gel permeation chromatography (GPC), nuclear magnetic resonance (NMR) spectroscopy and matrix-assisted laser desorption/ionization time-of-flight (MALDI-ToF) mass spectroscopy. The introduced method could be of great interest for bioconjugation, but requires optimization, especially for protein conjugation.

scholarly journals Identification of β scission products from free radical polymerizations of butyl acrylate at high temperature

2019 ◽  
Vol 10 (15) ◽  
pp. 1956-1967 ◽  
Author(s):  
Marco Drache ◽  
Maria Stehle ◽  
Jonas Mätzig ◽  
Katrin Brandl ◽  
Marcel Jungbluth ◽  
...  
Keyword(s):  
High Temperature ◽  
Free Radical ◽  
Radical Polymerization ◽  
Butyl Acrylate ◽  
Molar Mass ◽  
Esi Ms ◽  
Radical Polymerizations

Unsaturated low molar mass species were identified via ESI-MS after fractionation of poly(butyl acrylate) from high temperature radical polymerization.

Study on a High-Temperature Delayed Cross-Linked Acid

2012 ◽  
Vol 624 ◽  
pp. 252-255 ◽  
Author(s):  
Xiao Zhao ◽  
Qi Song ◽  
Hai Lin ◽  
Yan Ling Wang ◽  
Zeng Bao Wang ◽  
...  
Keyword(s):  
Lactic Acid ◽  
High Temperature ◽  
Reaction Time ◽  
Influencing Factors ◽  
Reaction Temperature ◽  
Zirconium Oxychloride ◽  
Cross Linking ◽  
Acid System ◽  
Mass Ratio ◽  
Reaction Conditions

A retarded zirconium cross-linking agent ECA-1 was prepared by using zirconium oxychloride, lactic acid， xylitol, and so on, then we got a high-temperature delayed cross-linking acid with cross-linking agent ECA-1 added to EVA-180 gelling acid, cross-linked acid performance and its influencing factors were discussed in details, such as reaction conditions of crosslinker, concentrations of crosslinker and thickener, and so on. The results showed that the obtained cross-linked acid had good temperature-tolerate and shear-tolerate properties when the mass ratio of zirconium oxychloride, lactic acid and xylitol is 1:1.25:0.0208 , the reaction temperature is 50~55°C, the reaction time is 4 hours, the delayed cross-linking time of acid system can be adjusted by changing the dosage of crosslinker and thickener.

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