Estimation of the inherent friction factor per main-chain friction unit of liquid low-molecular-weight unsaturated polyesters

1986 ◽  
Vol 31 (6) ◽  
pp. 1567-1574
Author(s):  
Alois Kaštánek ◽  
Miroslav Balcr ◽  
Miloslav Bohdanecký ◽  
František Lešek ◽  
Jaroslav Kitzler
Keyword(s):  
Molecular Weight ◽  
Friction Factor ◽  
Main Chain ◽  
Friction Unit ◽  
Low Molecular Weight ◽  
Unsaturated Polyesters

Polymerization of Nitrophenyl and 3-Diethylaminophenyl Prop-2-yn-1-yl Ethers with PdCl2. Polymers and Copolymers Characterization

1998 ◽  
Vol 63 (11) ◽  
pp. 1803-1814 ◽  
Author(s):  
Hynek Balcar ◽  
Petr Holler ◽  
Jan Sedláček ◽  
Vratislav Blechta
Keyword(s):  
Molecular Weight ◽  
Dimethyl Sulfoxide ◽  
Size Exclusion Chromatography ◽  
Main Chain ◽  
Size Exclusion ◽  
Low Molecular Weight ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Exclusion Chromatography

2-, 3- and 4-Nitrophenyl prop-2-yn-1-yl ethers were polymerized with PdCl2 in N,N-dimethylformamide (DMF) giving brown polymers soluble in DMF, dimethyl sulfoxide and N-methylpyrrolidone. Broad (mostly bimodal) molecular weight distributions were observed by size-exclusion chromatography (SEC) with maxima at molecular weight of about 4 . 103 and 1 . 105. With the same catalyst, 3-diethylaminophenyl prop-2-yn-1-yl ether gave predominantly low molecular weight homopolymer (Mn = 4 200) soluble in DMF, N-methylpyrrolidone, CHCl3 and tetrahydrofuran-soluble copolymers with 4-nitrophenyl prop-2-yn-1-yl ether (Mn about 3 000). IR, NMR and UV-VIS spectra of prepared polymers and copolymers proved the structure to consist of the polyene-type main chain with phenoxymethyl pendant groups bearing nitro or diethylamino substituents.

Zinc Oxide Crosslinking Reaction of Polychloroprene Rubber

1989 ◽  
Vol 62 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Yoshiaki Miyata ◽  
Masao Atsumi
Keyword(s):  
Molecular Weight ◽  
Zinc Oxide ◽  
Main Chain ◽  
Reaction Pathway ◽  
Main Reaction ◽  
Low Molecular Weight ◽  
Crosslinking Reaction ◽  
Chain Component ◽  
Carbonium Ion ◽  
Intermolecular Reaction

Abstract There was some ambiguity on the reality of the formation of ether crosslinks in the ZnO crosslinking of CR. This report clearly indicates the absence of the ether crosslinks. The main reaction pathway of the ZnO crosslinking of CR is the addition of the carbonium ion formed from the isomerized 1,2 unit to the double bond in the neighboring 1,4 unit, catalyzed by ZnCl2. The isomerized 1,2 unit is formed by the rearrangement of allylic chlorine in the 1,2 unit. The crosslinking reaction takes place between one curing site and one main chain component, not between two curing sites. The intramolecular cyclization predominantly occurs as compared with the intermolecular reaction (crosslinking) in Scheme 2. Therefore, the efficiency of the ZnO crosslinking of CR is quite small as expected from the concentration of the curing sites (1,2 units). Model polymer of low molecular weight and NMR spectroscopy have led to a better understanding of the chemistry of this process.

scholarly journals Synthesis and Properties of Poly(ferrocenylsilane)s Containing Si-Vinylene Units in the Main Chain

2016 ◽  
Vol 8 (2) ◽  
pp. 86
Author(s):  
Naofumi Naga ◽  
Yoshie Saito
Keyword(s):  
Molecular Weight ◽  
Electron Transfer ◽  
Cyclic Voltammetry ◽  
Redox Potential ◽  
Diffusion Coefficients ◽  
Heck Reaction ◽  
Main Chain ◽  
Low Molecular Weight ◽  
Alternating Copolymers

<p>Poly(ferrocenylsilane)s containing Si-vinylene unit in the main chain have been synthesized by Mizoroki-Heck reaction of 1,1’-bis(dimethylvinylsilyl)ferrocene (MVFS) and dibromo aryl compounds using palladium diacetate as a catalyst. The alternating copolymers with relatively low molecular weight were obtained in good yields. Cyclic voltammetry of the copolymers in CH<sub>2</sub>Cl<sub>2</sub> solutions showed redox potential derived from the ferrocene units in the copolymers. The voltammograms the copolymers indicated that almost no difference in numbers of electron transfer compared with MVFS. By contrast, diffusion coefficients of the ferrocene units in the copolymers were smaller than that of MVSF. The copolymers showed reversible electrochromism from yellow to blue-green due to the redox of ferrocene units in the main chain by 3V of application.</p>

Unusually high values of the quotient d ln η/d ln M of some low-molecular-weight liquid polymers

1985 ◽  
Vol 50 (11) ◽  
pp. 2570-2578
Author(s):  
Miloslav Bohdanecký ◽  
Alois Kaštánek ◽  
František Lešek
Keyword(s):  
Molecular Weight ◽  
Main Chain ◽  
Low Molecular Weight ◽  
Atomic Group ◽  
Polymeric Liquids ◽  
Random Coils ◽  
Chain Atom ◽  
Flow Processes ◽  
Liquid Polymers ◽  
Main Chain Atom

Unusually high values of the quotient d ln η/d ln M ≡ a (where η is viscosity and M is molecular weight) found for some low-molecular-weight liquid polymers (4 ⪬ a ⪬ 8) are discussed in terms of the theory of flow processes of polymeric liquids. The effect is assigned mainly to the dependence on the chain length of the friction factor per main chain atom or atomic group but deviations of short chains from the conformation of random coils can also contribute significantly. The variation of the quotient a with temperature, however, is due to the former factor only.

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