Synthesis and Properties of Uniform Polyisoprene Networks. I. Synthesis and Characterization of α,ω-Dihydroxy-Polyisoprene

1976 ◽  
Vol 49 (2) ◽  
pp. 303-319 ◽  
Author(s):  
M. Morton ◽  
L. J. Fetters ◽  
J. Inomata ◽  
D. C. Rubio ◽  
R. N. Young
Keyword(s):  
Molecular Weight ◽  
Physical Properties ◽  
Soluble Fraction ◽  
Synthesis And Characterization ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
The Subject

Abstract The results of this study are the first to show that high-1,4 linear α,ω-dihydroxypolydienes can be synthesized with (a) predictable molecular weights, (b) narrow molecular weight distributions, and (c) high functionalities. Using the functionalized polyisoprenes prepared in this work, a series of networks was prepared with a purified triisocyanate as the chain linking agent. The soluble fraction in these networks ranged from 4.6 to 1.6 per cent. The characteristics and physical properties of these networks will be the subject of a forthcoming publication.

Mechanical and Viscoelastic Characterization of Hyperbranched Polyisobutylenes

2002 ◽  
Vol 75 (5) ◽  
pp. 853-864 ◽  
Author(s):  
Judit E. Puskas ◽  
Christophe Paulo ◽  
Volker Altstädt
Keyword(s):  
Molecular Weight ◽  
Butyl Rubber ◽  
Structure Property ◽  
Carbocationic Polymerization ◽  
Molecular Weights ◽  
Structure Property Relationships ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Living Carbocationic Polymerization

Abstract Structure-property relationships were investigated in hyperbranched polyisobutylenes, in comparison with commercial linear butyl rubber. The gel-free, soluble hyperbranched polyisobutylenes, synthesized by living carbocationic polymerization, had molecular weights, Mw≈400,000 to 1,000,000 g/mol, molecular weight distributions, MWD ≈1.2 to 2.6, and branching frequencies, BR ≈ 4 to 60. The mechanical and viscoelastic characterization of these polymers revealed interesting properties, including the characteristics of crosslinked rubbers.

Synthesis and characterization of new phenanthrolinetriether copolymers with rotaxane architecture

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
Aurica Farcas ◽  
Valeria Harabagiu
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Ethylene Glycol ◽  
Synthesis And Characterization ◽  
Nmr Analysis ◽  
H Nmr ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Different Content

AbstractThis paper is devoted to the preparation and characterization of new phenanthroline-triether copolymers with rotaxane architecture by reaction of complexes of α- or β- cyclodextrin and tri(ethylene glycol) ditosylate with 2,9-di(4-hydroxyphenyl)-1,10- phenanthroline, which is large enough to prevent dethreading of cyclodextrin molecules. Comparative 1H-NMR analysis of tri(ethylene glycol) ditosylate complexes and of rotaxane copolymers evidenced the lower cyclodextrin content in rotaxane copolymers as compared to the calculated values. The rotaxane copolymers present bimodal molecular weight distributions attributed to the separation of the fractions with different content of cyclodextrin threaded on the copolymer chain. As evidenced by thermogravimetric analysis, the rotaxane copolymers show higher thermal stability than its non-complexed homologue.

Synthesis and Characterization of Polythiophene Derivatives with Different Alkyl Substitution Groups

2015 ◽  
Vol 815 ◽  
pp. 477-482
Author(s):  
Wei Xing Chen ◽  
Yong Qiang Gu ◽  
Chun Yan Luo ◽  
Xiao Long Zhang
Keyword(s):  
Molecular Weight ◽  
Synthesis And Characterization ◽  
H Nmr ◽  
Chemical Structures ◽  
Molecular Weight Distributions ◽  
Alkyl Substitution ◽  
Weight Distributions ◽  
Maximum Absorption Wavelength ◽  
Uv Absorption Spectrum

Three kinds of poly (3-alkylthiophene), such as poly (3-butylthiophene) (P3BT), poly (3-hexylthiophene) (P3HT) and poly (3-dodecylthiophene) (P3DDT) were prepared by the Grignard Metathesis Method (GRIM). Their chemical structures are characterized by FTIR,1H-NMR and GPC.1H-NMR result shows that regioregular structure of these polymers is relatively higher. The GPC results show that the molecular weight of the polymers is 8.42×104, 1.06×105and 1.21×104g/mol with molecular weight distributions of 1.41, 2.18 and 1.18, respectively. The DSC result shows that the glass transition temperature of three kinds of polymers is 120.8, 146, 118 °C, respectively. UV absorption spectrum and fluorescence spectroscopy of three polymers in THF solution show that the maximum absorption wavelength is 448 nm, 470 nm, 390 nm, and the maximum emission wavelength is 531, 535, 527 nm with the band gap of 2.06, 1.86, 2.21 eV, respectively.

Boryl-substituted Zirconocene Dichloride Complexes as Catalyst Precursors for Homogeneous Ethylene Polymerization

2007 ◽  
Vol 62 (3) ◽  
pp. 314-322 ◽  
Author(s):  
Alexandra Kestel-Jakob ◽  
Helmut G. Alt
Keyword(s):  
Molecular Weight ◽  
Ethylene Polymerization ◽  
Nickel Catalysts ◽  
Synthesis And Characterization ◽  
Zirconocene Dichloride ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Methyl Aluminoxane

The synthesis and characterization of 16 new boryl-substituted zirconocene dichloride complexes are reported. After activation with methyl aluminoxane (MAO) these complexes are catalysts for homogeneous ethylene polymerization. The combination of these complexes with nickel catalysts containing Lewis basic substituents produces polymers with bimodal molecular weight distributions.

Effect of Molecular-Weight Distribution on Physical Properties of Natural and Synthetic Polymers

1948 ◽  
Vol 21 (3) ◽  
pp. 654-666 ◽  
Author(s):  
B. L. Johnson
Keyword(s):  
Molecular Weight ◽  
Physical Properties ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Synthetic Polymers ◽  
Natural Polymers ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Styrene Copolymers ◽  
Weight Distributions

Abstract The molecular weights of rubberlike polymers are average values for mixtures of macromolecules which differ greatly in size. The heterogeneity of natural rubber was recognized as early as 1929 by Whitby. The fact that solutions of higher quality crude rubbers are more viscous than lower quality rubbers was observed by Axelrod in 1905. Other workers have separated rubber solutions into fractions of differing molecular weight and have studied the properties of the fractions. In the case of synthetic polymers, these heterogeneous mixtures of molecules have been characterized by fractional precipitation and construction of molecular-weight distribution curves. The particular type of distribution determined in this investigation is that obtained from weight average properties based on viscosity measurements of fractions of the polymers. Application of these methods to the characterization of natural polymers confirmed observations that a variety of molecular-weight distributions existed in the case of the natural polymers. The physical properties of the natural polymers having these diverse molecular-weight distributions were well known. Therefore a correlation of their physical properties and weight distributions seemed pertinent to an evaluation of the fractionation technique. Such a correlation had not been possible on early butadiene-styrene copolymers because of the similarity of the distributions then obtained, even under different polymerization conditions.

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.

scholarly journals Naturally-Derived Amphiphilic Polystyrenes Prepared by Aqueous Controlled/Living Cationic Polymerization and Copolymerization of Vinylguaiacol with R–OH/BF3·OEt2

Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1404 ◽  
Author(s):  
Hisaaki Takeshima ◽  
Kotaro Satoh ◽  
Masami Kamigaito
Keyword(s):  
Molecular Weight ◽  
Ferulic Acid ◽  
Cationic Polymerization ◽  
Living Polymerization ◽  
Block Copolymerization ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Living Cationic Polymerization ◽  
Naturally Occurring ◽  
Weight Distributions

In this study, we investigated direct-controlled/living cationic polymerization and copolymerization of 4-vinylguaiacol (4VG), i.e., 4-hydroxy-3-methoxystyrene, which can be derived from naturally-occurring ferulic acid, to develop novel bio-based amphiphilic polystyrenes with phenol functions. The controlled/living cationic polymerization of 4VG was achieved using the R–OH/BF3·OEt2 initiating system, which is effective for the controlled/living polymerization of petroleum-derived 4-vinylphenol in the presence of a large amount of water via reversible activation of terminal C–OH bond catalyzed by BF3·OEt2, to result in the polymers with controlled molecular weights and narrow molecular weight distributions. The random or block copolymerization of 4VG was also examined using p-methoxystyrene (pMOS) as a comonomer with an aqueous initiating system to tune the amphiphilic nature of the 4VG-derived phenolic polymers. The obtained polymer can be expected not only to be used as a novel styrenic bio-based polymer but also as a material with amphiphilic nature for some applications.

Relationships between Molecular Weights and Rheological Properties of Asphalts

1996 ◽  
Vol 1535 (1) ◽  
pp. 10-14 ◽  
Author(s):  
Jan F. B ranthaver ◽  
Raymond E. Robertson ◽  
John J. Duvall
Keyword(s):  
Molecular Weight ◽  
Rheological Properties ◽  
Size Exclusion Chromatography ◽  
Size Exclusion ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Molecular Associations ◽  
Weight Distributions ◽  
Exclusion Chromatography ◽  
Microstructural Model

It is known that the rheological properties of mixtures of organic compounds are functions of molecular weight distributions. However, with respect to asphalts, which are composed of many different compounds and compound types, molecular weights are difficult to measure. This difficulty occurs because the molecular associations that form are held together by forces of varying strengths and are partly broken up by heat and solvents. In theory, the strongest molecular associations in asphalts should have the greatest influence on the rheological properties of asphalts. These associations would be expected to be the major contributors to the asphalt's behaving as if it were a relatively high molecular weight material. Asphalt molecular associations should be isolatable by means of size exclusion chromatography. Several fractions of varying molecular weights (measured by membrane osmometry and vapor phase osmometry) were isolated from Strategic Highway Research Program (SHRP) asphalt AAD-1 by preparative size exclusion chromatography. Molecular weights of these fractions ranged from approximately 2,000 daltons to over 40,000 daltons. When these fractions were independently mixed with asphalt AAD-1 solvent moiety, mixtures were obtained whose rheological properties were a function of the molecular weights and concentrations of the associated materials. These results support the microstructural model of asphalt proposed during SHRP. The results also suggest that the unusual rheological properties of some asphalts may be explained by measuring molecular weight distributions. This type of information may be useful for modification of asphalts to achieve desirable rheological properties.

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