Zur Anlagerung von Dichlorcarben an niedermolekulare cis‐ und Vinyl‐cis‐Polybutadiene

Konietzny, Alfred; Biethan, U.

doi:10.1002/apmc.1978.050740105

Cited by 8 publications

(1 citation statement)

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“…Dichlorocarbene modification [16][17][18][19][20][21][22][23][24][25][26][27][28] consists of carbene addition and halogenation and has been used to modify several types of polymer, including styrene butadiene rubber, [17][18][19] natural rubber (NR), [20][21][22][23][24][25] olefin, 16,26,27 and butadiene rubber (BR). [28][29][30][31] Among these rubbers, BR is an important synthetic rubber being the second largest, by volume, synthetic rubber produced in the world after styrene butadiene rubber. It has the excellent properties of high abrasion resistance and high resilience and high resistance to heat build-up and has previously been modified by dichlorocarbene using a phenyl(trihalomethyl) mercury compound (Seyferth reagent) as the dichlorocarbene precursor.…”

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confidence: 99%

Dichlorocarbene modified butadiene rubber (DCBR): Preparation, kinetic study, and its properties in natural rubber/DCBR blend vulcanizates

Witinuntakit

Kiatkamjornwong

Poompradub

2017

Polymers for Advanced Techs

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Dichlorocarbene modified butadiene rubber (DCBR) was prepared via the addition of the dichlorocarbene group in the presence of 2 phase transfer agents (cetyltrimethylammonium bromide and tetraethylammonium chloride). The effects of the reaction temperature and time, amount of dichlorocarbene precursor, and the type and amount of phase transfer agent on the chlorine content were investigated. The highest chlorine content (30%) in DCBR was obtained using 0.062 mol chloroform and 0.003 mol cetyltrimethylammonium bromide at room temperature for 19 hours although 27.9% was obtained after 12 hours. The kinetics of this dichlorocarbene modification was best described by the pseudo-first order rate law with 2 rate constants. For practical applications, the DCBR with chlorine contents of 10%, 20%, or 30% were blended with natural rubber (NR) and then vulcanized using the sulfur-curing system. Although the polarity of DCBR was increased, a good compatibility between NR and DCBR still existed, resulting in improved mechanical properties. The oil resistance, flame retardant, and ozone resistance properties of the NR/DCBR blend vulcanizates were enhanced compared to those of a NR/butadiene rubber blend vulcanizate, which was related to the amount of chlorine incorporated into the DCBR. KEYWORDS mechanical properties, oxidation, rubber, thermal properties | INTRODUCTIONRubber products have recently been extensively used in tire production, healthcare supplies, household supplies, interior construction, and transportation. Therefore, there is a demand for flame retardant, ozone, and oil resistance properties of these rubber products. Because rubber molecules contain carbon-carbon double (C═C) bonds, which are reactive to free radicals, ozone, and oxygen, rubber compounds alone have some disadvantages, especially their poor thermal properties and low ozone resistance. modification of rubber is another method of improving the properties of rubber containing C═C bonds. This modification reduces the number of C═C bonds in the rubber structure and introduces the polar dichlorocarbene group into the rubber molecules. Although the increased polarity may cause mixing problems in rubber blends, partially dichlorocarbene modified rubber is less polar than halogenated rubber, which often has a mixing problem. Thus, modification by dichlorocarbene may cause reduced mixing problems compared to halogenated rubber, and so dichlorocarbene modification was chosen for this study. and tetraethylammonium chloride (TEAC) were purchased from AjaxFinechem Pty Ltd (New Zealand) and Sigma-Aldrich Co LLC (USA), respectively. The chemical structures of CTAB and TEAC, the phase transfer agents, are shown in Figure S1. All chemical reagents were used as received. Zinc oxide (ZnO) and stearic acid were used as activators. N-cyclohexyl-2-benzothiazol-sulfenamide (CBS) and sulfur were used as an accelerator and a crosslinking agent, respectively. All vulcanizing agents were purchased from PAN Innovation Industry Ltd (Thailand). | Preparation of DCBRThe DCBR ...

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Section: Funding Informationmentioning

confidence: 99%

Dichlorocarbene modified butadiene rubber (DCBR): Preparation, kinetic study, and its properties in natural rubber/DCBR blend vulcanizates

Witinuntakit

Kiatkamjornwong

Poompradub

2017

Polymers for Advanced Techs

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Kinetics and mechanism for the phase transfer catalyzed cycloaddition of dichlorocarbene to cis‐1,4‐polybutadiene

Huvard¹,

Nicholas²,

Horne³

1985

J. Polym. Sci. Polym. Chem. Ed.

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The kinetics for the cycloaddition of dichlorocarbene to cis‐1,4‐polybutadiene (BR) have been examined for aqueous and solid sodium hydroxide–chloroform mixtures containing 350 molecular weight α‐methyl‐ω‐hydroxy‐poly(oxy‐1,2‐ethanediyl) (Carbowax 350) as a phase transfer catalyst. This study describes the influence of reaction variables on rate and the partitioning of dichlorocarbene between dichlorocyclopropanation and hydrolysis. The results are consistent with a kinetic model derived for the case where mass transfer is not rate limiting. However, this does not apply at high conversions where mass transfer control occurs due to large increases in viscosity. Higher BR concentrations can be achieved by replacing chloroform with methylene chloride containing stoichiometric amounts of chloroform. This mass action effect causes more favorable partitioning toward cyclopropanation; otherwise, chloroform and methylene chloride behave similarly as solvents. Water is an essential component in this reaction because it greatly increases the ability of the catalyst to extract sodium hydroxide into the organic phase.

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Reactions of Polymers

Ravve¹

1995

Principles of Polymer Chemistry

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In consideration of various chemical reactions of macromolecules, the reactivity of their functional groups must be compared to those of small molecules. The comparisons have stimulated many investigations and led to conclusions that functional groups exhibit equal reactivity in both large and small molecules, if the conditions are identical. These conclusions are supported by theoretical evidence. i ,2 Specifically, they apply to the following situations i :1. Reactions that take place in homogeneous fluid media with all reactants, intermediates, and end products fully soluble. These conditions exits from the start to the end of the reactions. 2. All elementary steps involve only individual functional groups. The other reacting species are small and mobile. 3. The steric factors in the low molecular weight compounds selected for comparison must be similar to those of the large molecules.The above can be illustrated by a few examples. For instance, the rates of photochemical cis-trans isomerization of azobenzene residues on the backbones of flexible polymeric chains are analogous to those of small molecules? Another example is the activation energy for cis-trans isomerization of azoaromatic polyuria. It is the same for low molecular weight analogs. 4 A third example is an experiment in comparing conformational transitions of some eximers in large and small molecules. A sandwich complex forms between an excited aromatic chromophore, Ar, and a similar chromophore in the ground state when irradiated with light of an appropriate wavelength. The conformation required by such an excimer can correspond to a prohibitive energy requirement for the unexcited molecule. All conformational transitions must take place during the lifetime of the excited state of the chromophore that is of the types:The ratio of the fluorescence intensity of an excimer and a normal molecule is a measure of the probability that the conformational transition takes place during the excited lifetime. A polyamide with only a small proportion of the following units was used for comparison: 403A. Ravve, Principles of Polymer Chemistry © Springer Science+Business Media New York 1995 Diffusion-Controlled ReactionsReactions that are bimolecular can be affected by the viscosity of the medium. 9 The translational motions of flexible polymeric chains are accompanied by concomitant segmental rearrangements. Whether this applies to a particular reaction, however, is hard to tell. For instance, two dynamic processes affect reactions, like termination rates, in chain-growth polymerizations. !fthe termination processes are controlled by translational motion, the rates of the reactions might be expected to vary with the translational diffusion coefficients of the polymers. Termination reactions, however, are not controlled by diffusions of entire molecules, but only by segmental diffusions within the coiled chains. IO The reactive ends assume positions where they are exposed to mutual interaction and not affected by the viscosity of the medium. Paired Group and Ne...

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Zur Anlagerung von Dichlorcarben an niedermolekulare cis‐ und Vinyl‐cis‐Polybutadiene

Cited by 8 publications

References 6 publications

Dichlorocarbene modified butadiene rubber (DCBR): Preparation, kinetic study, and its properties in natural rubber/DCBR blend vulcanizates

Dichlorocarbene modified butadiene rubber (DCBR): Preparation, kinetic study, and its properties in natural rubber/DCBR blend vulcanizates

Kinetics and mechanism for the phase transfer catalyzed cycloaddition of dichlorocarbene to cis‐1,4‐polybutadiene

Reactions of Polymers

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