scholarly journals A Versatile Equilibrium Method for the Synthesis of High-Strength, Ladder-like Polyphenylsilsesquioxanes with Finely Tunable Molecular Parameters

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4452
Author(s):  
Tatyana O. Ershova ◽  
Anton A. Anisimov ◽  
Maxim N. Temnikov ◽  
Maxim A. Novikov ◽  
Mikhail I. Buzin ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Liquid Ammonia ◽  
Reaction Medium ◽  
Monomer Concentration ◽  
High Strength ◽  
29Si Nmr ◽  
Molecular Weights ◽  
Equilibrium Method ◽  
Molecular Weight Characteristics ◽  
Polycondensation Process

A versatile equilibrium method for synthesizing ladder-like polyphenylsilsesquioxanes (L-PPSQs) with various molecular weights (from 4 to 500 kDa) in liquid ammonia was developed. The effect of diverse parameters, such as temperature, monomer concentration, reaction time, addition or removal of water from the reaction medium, on the polycondensation process was determined. The molecular weight characteristics and structure of the L-PPSQ elements obtained were determined by GPC, 1H, 29Si NMR, IR spectroscopy, viscometry, and PXRD methods. The physicochemical properties of L-PPSQs were determined by TGA and mechanical analyses.

Environmentally Benign Adhesive Synthesized by Dispersion Copolymerization of Styrene and Butyl Acrylate

2006 ◽  
Vol 11-12 ◽  
pp. 757-760
Author(s):  
Jun Ying Zhang ◽  
Peng Dou
Keyword(s):  
Molecular Weight ◽  
Butyl Acrylate ◽  
Monomer Concentration ◽  
Environmentally Benign ◽  
Functional Monomer ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Stabilizer Concentration ◽  
Ethanol Medium ◽  
Weight Distributions

Environmentally benign adhesive was synthesized by dispersion copolymerization of styrene(St) and butyl acrylate (BA) in an ethanol medium with benzoyl peroxide (BPO) as the initiator and poly(vinylpyrrolidone) as the stabilizer in the presence of acrylic acid(AA) as the functional monomer. The effect of the concentration of stabilizer, initiator and functional monomer on the conversions, molecular weights and molecular weight distributions was investigated. The results show that the conversions almost keep invariable with the increasing of stabilizer concentration, but the molecular weights increase and molecular weight distributions decrease. Conversions increase with the increasing of initiator concentration, but the molecular weights and molecular weight distributions decrease. However with the increasing of functional monomer concentration, conversions and molecular weight distributions increase but the molecular weights decrease.

Polymerization of n-butyl methylacrylate using bis(β- ketoamino)nickel(II)/MAO catalytic systems

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Xiaohui He ◽  
Yiwang Chen ◽  
Yongming Liu ◽  
Muqing Chen ◽  
Shuxian Yu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Monomer Concentration ◽  
Polymerization Temperature ◽  
Moderate Activity ◽  
Polymerization Time ◽  
Catalytic Systems ◽  
Molecular Weights ◽  
Molar Ratios ◽  
Broad Molecular Weight Distribution ◽  
C Nmr

AbstractThe polymerizations of n-butyl methylacrylate (nBMA) were carried out using bis(β-ketoamino)nickel(II) complexes (Ni[CH3C(O)CHC(NR)CH3]2: R = phenyl, 1; R = naphthyl, 2) in combination with methylaluminoxane (MAO) in toluene. The effect of parameters such as polymerization temperature, Al/Ni molar ratios, polymerization time, and monomer concentration, on catalytic polymerization activity and polymer molecular weights, were examined in detail. Both of the nickel(II) catalytic systems exhibited moderate activity, and produced P(nBMA) with high molecular weight and relatively broad molecular weight distribution (Mw/Mn=2.0~3.0. The obtained polymer has been characterized by means of FTIR, 1H NMR, 13C NMR, DSC, and WAXD technique and was confirmed to be syndio-rich stereospecific P(nBMA).

scholarly journals Application of Molecular Weight Regulators for the Synthesis of Sodium Polyacrylate Thinners of Mineral Suspensions

2020 ◽  
Author(s):  
Dmitry Belov
Keyword(s):  
Molecular Weight ◽  
Sodium Acrylate ◽  
Sodium Polyacrylate ◽  
Molecular Weights ◽  
Ceramic Slurry ◽  
Molecular Weight Characteristics ◽  
Acrylate Polymers ◽  
Molecular Weight Regulator ◽  
Mineral Suspensions ◽  
Polymeric Samples

The synthesis of additives for thinning mineral suspensions based on sodium polyacrylate was carried out. The effect of molecular weight regulators on the molecular weight characteristics of the polymer and the effect of such polymers on the rheological properties of suspensions was studied. Sodium acrylate polymers are synthesized by free radical polymerization in aqueous solution using molecular weight regulators. The molecular weight characteristics of the polymeric samples were estimated by viscometry using Mark-Houwink-Kuhn-Sakurada (MHKS) equation. Synthesized polymers were used as thinners ceramic slurries, prepared according to the recipe of the enterprises producing ceramic products. The thinning ability of polymer samples with different molecular weights was estimated using an Engler viscometer from the time of the ceramic slurry flow. The influence of the type and amount molecular weight regulator on polyacryates was revealed. It was found that molecular weight synthesized samples was in the range of 21000 - 91000. It was determined that samples with a molecular weight of 28000 - 35000 synthesized using mercaptoethanol (at a dosage of 0.5-1.5% by weight of the monomer) provide optimal fluidity to the ceramic slurry.

Change in molecular weight characteristics of an aromatic copolyamide during the polycondensation process

1989 ◽  
Vol 21 (2) ◽  
pp. 133-135
Author(s):  
O. I. Manina ◽  
L. M. Braginskaya ◽  
V. I. Komissarov ◽  
S. V. Shorin ◽  
I. F. Kuyantseva ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Characteristics ◽  
Polycondensation Process

Assoziationsverhalten von T2-Lysozym

1964 ◽  
Vol 19 (3) ◽  
pp. 230-234 ◽  
Author(s):  
K. Wagner ◽  
W. Katz
Keyword(s):  
Molecular Weight ◽  
Diffusion Coefficients ◽  
Egg White ◽  
Molecular Weights ◽  
Egg White Lysozyme ◽  
Equilibrium Method ◽  
Ph Dependent ◽  
Reversible Association ◽  
And Diffusion

Particle-bound T 2 phage lysozyme and lysozyme from T 2 phage lysates are compared with each other by ultracentrifugation. The molecular weights determined by an equilibrium method and by sedimentation and diffusion coefficients are identical within the error of estimation.Similar to egg-white lysozyme, T 2 phage lysozyme shows a pH-dependent, reversible association.The value of the molecular weight obtained at pH 5.1 is 13 900.

scholarly journals Synthesis of Disentangled Ultra-High Molecular Weight Polyethylene: Influence of Reaction Medium on Material Properties

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Giuseppe Forte ◽  
Sara Ronca
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Catalyst Activity ◽  
Reaction Medium ◽  
High Strength ◽  
Catalytic Performance ◽  
Lower Amount ◽  
Processing Route ◽  
Molecular Characteristics ◽  
Ultra High Molecular Weight

The polymerization of ethylene to Ultra-High Molecular Weight Polyethylene (UHMWPE) in certain reaction conditions allows synthesis of nascent powders with a considerably lower amount of entanglements: the material obtained is of great interest from both academic and industrial viewpoints. From an academic point of view, it is interesting to follow the evolution of the metastable melt state with the progressive entanglements formation. Industrially, it is valuable to have a solvent-free processing route for the production of high modulus, high strength tapes. Since the polymer synthesis is performed in the presence of a solvent, it is interesting to investigate the influence that the reaction medium can have on the catalyst activity, resultant molecular characteristics, and polymer morphology at the macroscopic as wells as microscopic level. In this paper, we present the effect that two typical polymerization solvents, toluene and heptane, and mixtures of them, have on the catalytic performance and on the polymer properties. The observations are that an unexpected increase of catalyst activity, accompanied by a significant improvement in mechanical properties, is found when using a carefully chosen mixture of solvents. A tentative explanation is given on the basis of the presented results.

scholarly journals A Novel Ziegler–Natta-Type Catalytic System—TiCl4/2,2′-Dimethoxy-1,1′-Binaphthalene/Et3Al2Cl3/Bu2Mg for Production of Ultrahigh Molecular Weight Polyethylene Nascent Reactor Powders, Suitable for Solvent-Free Processing

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1281 ◽  
Author(s):  
Olga Serenko ◽  
Mikhail Buzin ◽  
Vladislav Tuskaev ◽  
Svetlana Gagieva ◽  
Nikolay Kolosov ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Catalytic System ◽  
High Strength ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Melting Behavior ◽  
Solvent Free ◽  
X Ray Diffraction ◽  
Molecular Weights ◽  
Ultrahigh Molecular Weight ◽  
Different Temperatures

A series of ultrahigh molecular weight polyethylenes with viscosity-average molecular weights in the range of 1.6–5.6 × 106 have been prepared by using a novel Ziegler–Natta-type catalytic system—TiCl4/2,2′-dimethoxy-1,1′-binaphthalene/Et3Al2Cl3/Bu2Mg at different temperatures (Tpoly) in the range between 10 and 70 °C in toluene. The morphology of the nascent reactor powders has been studied by scanning electron microscopy, wide-angle X-ray diffraction, and the DSC melting behavior. Polymers are suitable for the modern processing methods—the solvent-free solid-state formation of super high-strength (tensile strength over 1.8–2.5 GPa) and high-modulus (elastic modulus up to 136 GPa) oriented film tapes. With decrease of Tpoly, the drawability of the reactor powders increased significantly.

Polymerization of styrene using 1,1,2,2-tetraphenyl-1,2- ethanediol as initiator in the presence of 2,2,6,6-tetramethyl- 1-piperidinyloxy

e-Polymers ◽  
2004 ◽  
Vol 4 (1) ◽  
Author(s):  
Gang Wang ◽  
Xiulin Zhu ◽  
Dijun Hu ◽  
Zhengping Cheng ◽  
Jian Zhu
Keyword(s):  
Molecular Weight ◽  
Monomer Concentration ◽  
Bulk Polymerization ◽  
Polymerization Rate ◽  
First Order ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
End Groups

Abstract The bulk polymerization of styrene using 1,1,2,2-tetraphenyl-1,2-ethanediol as initiator in the presence of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) was investigated. The results show that polymerization proceeded in a controlled/ ’living’ way, i.e., polymerization rate is first order with respect to monomer concentration. Molecular weights increase linearly with conversion and molecular weight distributions are relatively low (Mw/Mn = 1.10 - 1.35). Well-defined polystyrenes with α-hydrogen and TEMPO end groups were obtained.

Effects of Polymerization Parameters on Aqueous Deposited Copolymerization of Acrylonitrile and Itaconic Acid

2013 ◽  
Vol 774-776 ◽  
pp. 508-511
Author(s):  
Ya Qi Zhao ◽  
Qiao Feng ◽  
Ling Zhi Du
Keyword(s):  
Molecular Weight ◽  
Reaction Time ◽  
High Molecular Weight ◽  
Reaction Temperature ◽  
Itaconic Acid ◽  
Temperature Region ◽  
Monomer Concentration ◽  
Initiator Concentration ◽  
Molecular Weights ◽  
Total Monomer Concentration

Pure powdery high molecular weight polyacrylonitrile (HMW-PAN) copolymers were firstly synthesized by aqueous deposited polymerization (ADP) technique employing 2,2'-Azobis (isobutyramidine) dihydrochloride (AIBA) as initiator and itaconic acid (IA) as comonomer. Various PAN polymers were obtained through changing different polymerization parameters. It is indicated that with the increase of total monomer concentration, initiator concentration, reaction temperature and reaction time, polymerization conversions of PAN copolymers all increased. While the molecular weights become greater with the increase of total monomer concentration. With the increase of initiator concentration and reaction temperature (under higher reaction temperature region), the molecular weights decreased. However, the molecular weights only had very little decrease at the end of long extension of reaction time.

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