scholarly journals Self-Stable Precipitation Polymerization Molecular Entanglement Effect and Molecular Weight Simulations and Experiments

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2243
Author(s):  
Jiali Qu ◽  
Yi Gao ◽  
Wantai Yang
Keyword(s):  
Molecular Weight ◽  
Maleic Anhydride ◽  
Molecular Conformation ◽  
Average Molecular Weight ◽  
Precipitation Polymerization ◽  
Radius Of Gyration ◽  
Propagation Mechanism ◽  
Reactive Molecular Dynamics ◽  
End Distance ◽  
Good Agreement

In this paper, we developed a reactive molecular dynamics (RMD) scheme to simulate the Self-Stable Precipitation (SP) polymerization of 1-pentene and cyclopentene (C5) with maleic anhydride (MAn) in an all-atom resolution. We studied the chain propagation mechanism by tracking the changes in molecular conformation and analyzing end-to-end distance and radius of gyration. The results show that the main reason of chain termination in the reaction process was due to intramolecular cyclic entanglement, which made the active center wrapped in the center of the globular chain. After conducting the experiment in the same condition with the simulation, we found that the distribution trend and peak value of the molecular-weight-distribution curve in the simulation were consistent with experimental results. The simulated number average molecular weight (Mn) and weight average molecular weight (Mw) were in good agreement with the experiment. Moreover, the simulated molecular polydispersity index (PDI) for cyclopentene reaction with maleic anhydride was accurate, differing by 0.04 from the experimental value. These show that this model is suitable for C5–maleic anhydride self-stable precipitation polymerization and is expected to be used as a molecular weight prediction tool for other maleic anhydride self-stable precipitation polymerization system.

Continuous Ultrasonic Treatment of Uncured and Sulfur Cured SBR: Effect of Styrene Content

2005 ◽  
Vol 78 (4) ◽  
pp. 606-619 ◽  
Author(s):  
A. I. Isayev ◽  
S. H. Kim ◽  
Wenlai Feng
Keyword(s):  
Molecular Weight ◽  
Ultrasonic Treatment ◽  
Crosslink Density ◽  
Main Chain ◽  
Structural Characteristics ◽  
Average Molecular Weight ◽  
Chain Scission ◽  
Gel Fraction ◽  
Styrene Content ◽  
Good Agreement

Abstract Unvulcanized and vulcanized SBR samples with styrene content of 18 and 23.5% were used to investigate the effect of ultrasound treatment on their structural characteristics. Gel fraction and crosslink density of gel are measured. Molecular weight and molecular weight distribution of sol are studied to determine the level of degradation of the macromolecular chain in ultrasonically treated unvulcanized and vulcanized rubbers. It is shown that the weight and number average molecular weight of sol in devulcanized SBR is, respectively, lower and higher in the samples having higher styrene content. Ultrasonic treatment of virgin unvulcanized SBR causes generation of gel along with its main chain modification due to the competition between chain scission and crosslinking. The competitive reactions taking place during this treatment are discussed. It was found that the intermolecular bonds in SBR vulcanizates containing higher styrene content are easier to break. The structural characteristics of devulcanized SBR rubber were simulated using the Dobson-Gordon theory of rubber network statistics. A fairly good agreement between experimental data and theoretical prediction on normalized gel fraction vs. normalized crosslink density was achieved. The simulation of devulcanized SBR rubber indicated that the rate of crosslink rupture is much higher than that of main chain. The styrene content in SBR rubber does not affect kp/kα substantially.

First GPC results of terpyridine based chain extended supramolecular polymers: comparison with viscosity and analytical ultracentrifugation

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
Michael A. R. Meier ◽  
Harald Hofmeier ◽  
Caroline H. Abeln ◽  
Christos Tziatzios ◽  
Mircea Rasa ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Analytical Ultracentrifugation ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Supramolecular Polymers ◽  
Supramolecular Polymer ◽  
Poly Ethylene ◽  
A Chain ◽  
First Time ◽  
Good Agreement

AbstractThe molecular weight of an extended metallo-supramolecular polymer, based on a α,ω-bis-terpyridine-poly(ethylene glycol) polymer linked via ruthenium(II) ions, was determined by gel permeation chromatography, viscosimetry as well as analytical ultracentrifugation. An optimized GPC method was applied for the first time to this kind of chain extended supramolecular polymers and the obtained results showed a good agreement with viscosimetry and analytical ultracentrifugation. A chain extended polymer with an average molecular weight of around 140 000 was found. These results clearly demonstrate that well-soluble high-molecular-weight metal-containing coordination polymers that are based on well-defined telechelics can be synthesized and fully characterized.

scholarly journals Use of a Styrene-Maleic Anhydride Copolymer as an Adjuvant with Testosterone-Serum Albumin Immunogens and its Application to Increasing Ovulation Rate in the Ewe

1986 ◽  
Vol 39 (1) ◽  
pp. 99
Author(s):  
MSF Wong ◽  
RM Hoskinson ◽  
RI COX ◽  
D O Hawthorne ◽  
DH Solomon ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Maleic Anhydride ◽  
Antibody Response ◽  
Serum Albumin ◽  
Average Molecular Weight ◽  
Ovulation Rate ◽  
Binding Antibody ◽  
Styrene Maleic Anhydride ◽  
Maleic Anhydride Copolymer

A synthetic poly(styrene-maleic anhydride) copolymer of average molecular weight 470000 potentiated a testosterone-binding antibody response during immunization of sheep with immunogenic testosterone- 3-carboxymethyloxime-serum albumin conjugates.

Radiation-Induced Graft Polymerization of Maleic Anhydride onto Poly-β-Hydroxybutyrate

2005 ◽  
Vol 288-289 ◽  
pp. 477-480 ◽  
Author(s):  
Herong Ye ◽  
Dongzhi Yang ◽  
Ping Hu ◽  
Feng Bo Zhang ◽  
Qinglei Qi
Keyword(s):  
Molecular Weight ◽  
Maleic Anhydride ◽  
Graft Polymerization ◽  
Average Molecular Weight ◽  
Commercial Application ◽  
Radiation Induced

This paper focuses on an effective way to improve the thermostability of poly-β-hydroxybutyrate (PHB). Maleic anhydride (MA) is grafted onto PHB by 60Co γ of radiation. The spectra of both 1HNMR and 13CNMR were investigated following the radiation-induced polymerization. The results are consistent with successful grafting of the MA monomer onto the PHB, with a low graft degree. The graft degree and viscosity-average molecular weight Mηof the radiated samples were also investigated. The results observed through TGA demonstrate that thermostability has been measurably improved with the introduction of MA groups. These significant results suggest that wide commercial application of PHB may be possible.

THE FRACTIONATION OF POLYTHENE

1961 ◽  
Vol 39 (10) ◽  
pp. 1888-1891 ◽  
Author(s):  
W. R. Blackmore ◽  
W. Alexander
Keyword(s):  
Molecular Weight ◽  
Distribution Function ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Negative Binomial ◽  
Average Molecular Weight ◽  
Weight Average Molecular Weight ◽  
Log Normal ◽  
Molecular Weight Fractions ◽  
Good Agreement

An apparatus is described for fractionating large quantities (400 g) of polythene into five roughly equal fractions using a fractional precipitation technique. Application of this method of fractionation to a linear polythene has shown that the width of the molecular-weight distribution of the successive fractions decreases as the fractionation proceeds. Consequently, the initial high-molecular-weight fractions require refractionation to produce equally narrow distributions in them as are found in later fractions. Good agreement is obtained with the experimentally determined values of the number-average and weight-average molecular weight for the parent polymer when the measured values of Mn and Mw for each fraction are used to calculate the values for the parent. The differential molecular-weight distribution function of the parent polymer was calculated on a Bendix G-15 computer from the data for the fractions by using the weight, number-average and weight-average molecular weight, measured for each fraction in conjunction with an assumed log-normal or negative binomial molecular-weight distribution function in each fraction.

scholarly journals MOLECULAR SIZE AND CONFIGURATION OF CELLULOSE TRINITRATE IN SOLUTION

1958 ◽  
Vol 36 (6) ◽  
pp. 952-969 ◽  
Author(s):  
M. M. Huque ◽  
D. A. I. Goring ◽  
S. G. Mason
Keyword(s):  
Molecular Weight ◽  
Light Scattering ◽  
Ethyl Acetate ◽  
Average Molecular Weight ◽  
Molecular Size ◽  
Random Coil ◽  
Radius Of Gyration ◽  
Molecular Weight Range ◽  
Scattering Measurements ◽  
The Relationship

Viscosity and light-scattering measurements were made on several fractions and two unfractionated samples of cellulose trinitrate. The samples were prepared from bleached ramie, unbleached ramie, and cotton linters. The solvents were acetone and ethyl acetate. Viscosity was measured in a multishear viscometer designed for the purpose. Light-scattering measurements were made in a Brice-Phoenix Light-scattering Photometer modified to accommodate a cell which could be ultracentrifuged.The range of molecular weight investigated was from 6.5 × 105 to 25.0 × 105 The relationship between the z-average mean-square radius of gyration, [Formula: see text] and the z-average molecular weight was approximately linear in both solvents. The ratio of [Formula: see text] (where [Formula: see text] is the value of [Formula: see text] in the unperturbed state) was found constant in acetone but to increase with [Formula: see text] in ethyl acetate. This indicated that, whereas in acetone random coil configuration was attained, a configurational transition occurred in ethyl acetate in the molecular weight range investigated.The value of the exponent a in the relationship between intrinsic viscosity and molecular weight was found to be lower than unity but approximately equal in both solvents.The significance of the experimental data is discussed.

Unsaturation of Polyisobutylenes and Butyl Rubber. Reactions with Nitrosobenzene, Thiocyanogen, Iodine Monochloride, and Ozone

1944 ◽  
Vol 17 (3) ◽  
pp. 679-692 ◽  
Author(s):  
John Rehner
Keyword(s):  
Molecular Weight ◽  
Small Molecules ◽  
Extreme Values ◽  
Average Molecular Weight ◽  
The Other ◽  
Iodine Monochloride ◽  
Incomplete Reaction ◽  
A Current ◽  
End Group ◽  
Good Agreement

Abstract Table III summarizes unsaturation values obtained for the various polymers. The ranges indicated are, in most cases, extreme values of determinations made with two or more different samples of a given polymer type. Taking into consideration the small amounts of unsaturation involved, the values based on end-group determinations are in reasonably good agreement with one another and with the values based on the viscosity of the degraded polymer. Higher values are observed for the nitrosobenzene determinations, but these are considered to be less reliable because of the ease with which oxidation phenomena can occur with this reagent. The thiocyanogen values are the lowest of all; on the basis of values obtained by the other methods as well as of experimental evidence not included in this paper, these values are believed to result from incomplete reaction. As a class the iodine monochloride methods give considerably higher values than those obtained with the other reagents. This may be attributed to the substitution reaction that readily occurs with that reagent. The effect is perhaps most marked in the data obtained for polyisobutylene sample 2 with 0.1 N Wijs reagent; the upper value (0.4) is far greater than can be explained on the basis of the knowa molecular weight of this polymer and the corresponding terminal double bond contribution. Furthermore, since this polymer sample was fractionated in such a way as to remove all species of viscosity-average molecular weight less than about 50,000, the high value cannot be ascribed to the presence of dimers, trimers, or other small molecules formed during polymerization. In view of the data and the above considerations, it is believed that the unsaturation values based on ozone degradation are correct within the limits of experimental error, and that this reagent makes possible a relatively good estimation of the number of double bonds in polymers such as have been described. A modified procedure more suitable for rapid evaluations is the object of a current investigation.

Simulation of size exclusion chromatography for branched polymers formed by simultaneous long-chain branching and random scission

e-Polymers ◽  
2002 ◽  
Vol 2 (1) ◽  
Author(s):  
Hidetaka Tobita ◽  
Hideki Kawai
Keyword(s):  
Molecular Weight ◽  
Size Exclusion Chromatography ◽  
Average Molecular Weight ◽  
Branched Polymers ◽  
Size Exclusion ◽  
Radius Of Gyration ◽  
Simple Relationship ◽  
Weight Average Molecular Weight ◽  
Exclusion Chromatography ◽  
Long Chain

AbstractIn free-radical olefin polymerization, polymer transfer reactions can lead to chain scission as well as to the formation of long-chain branches. The dimensions of branched polymers so formed are investigated theoretically, by focusing our attention on the effects of scission frequency that is often difficult to determine. Scission reactions decrease the weight-average molecular weight significantly. When the polymer molecules are fractionated by the degree of polymerization (DP), however, the averages of branching density P ρ ̅and the mean-square radius of gyration of polymers with DP = P, <s2>P, are essentially unchanged, as long as the scission frequency is not very large. In a simple relationship between the ratios g and g’ of radii of gyration and hydrodynamic radii, g’ = gb, the value of b may change as a function of DP, and a simplified model function b = A log P + B was used to investigate the elution curve of size exclusion chromatography (SEC). It is shown that, although the molecular weight distribution (MWD) calibrated relative to standard linear polymers in SEC is much narrower than the true MWD, the use of a light scattering photometer to determine the absolute weight-average molecular weight within the elution volume makes the obtained MWD very close to the true one. On the basis of the <s2>P vs. P relationship, the calibrated MWD can be converted reasonably well to the true MWD. This simplified transformation method can be applied without knowing the scission frequency or the DP dependence of b. Once the true MWD is successfully estimated, a reliable parameter for the scission reaction can be determined.

The Structure of Radiation Cross-Linked Poly (ethylene oxide) Gels

1971 ◽  
Vol 29 ◽  
pp. 76-77
Author(s):  
C. E. Cluthe ◽  
G. G. Cocks
Keyword(s):  
Molecular Weight ◽  
Ethylene Oxide ◽  
Parallel Plate ◽  
Average Molecular Weight ◽  
Radical Reaction ◽  
Free Radical Reaction ◽  
Nitrogen Gas ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Initial Viscosity

Aqueous solutions of a 1 weight-per cent poly (ethylene oxide) (PEO) were degassed under vacuum, transferred to a parallel plate viscometer under a nitrogen gas blanket, and exposed to Co60 gamma radiation. The Co60 source was rated at 4000 curies, and the dose ratewas 3.8x105 rads/hr. The poly (ethylene oxide) employed in the irradiations had an initial viscosity average molecular weight of 2.1 x 106.The solutions were gelled by a free radical reaction with dosages ranging from 5x104 rads to 4.8x106 rads.

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