Polymerization of vinyl chloride in the presence

Strohmeier and Griibel [21] have reported that some vanadyl carbonyls of CpV(CO)4 (Cp = cyclopentadie-nyl) can photochemically induce the polymerization of vinyl chloride in the presence of CCI4. 

In previous work (13) we outlined the preparation of the crude reaction products by the polymerization of vinyl chloride in the presence of ethylene-propylene saturated elastomers, the mechanical properties of the products obtained, and some elastomer-PVC mechanical mixtures. 

Table IV. Polymerization of Vinyl Chloride in the Presence of EPR EPR Graft EPR Grafted Copolymer VC ...

Another popular class of heat stabilizers for PVC consists of the alkali earth metal salts of carboxylic acids. An Italian patent issued in 1940 suggested conducting the polymerization of vinyl chloride in the presence... 

Some peculiarities of the thermal and thermooxidative decomposition of polyvinyl chloride depend on the conditions of its production. Thus, it is known that samples of the polymer produced by initiating the polymerization of vinyl chloride with ultraviolet irradiation possess higher stability in comparison with samples produced in polymerization under the action of chemical agents [26, 27]. Reversibility of the process of dehydrochlorination in the decomposition of samples of polyvinyl chloride produced by the latex method is noted, while in the process of decomposition of suspension polymer, the phenomenon of reversibilily is not observed [21]. It has been shown that the rate of dehydrochlorination of the latex polymer is significantly higher than that of the suspension polymer under the same conditions [21]. It has been established that the polymerization of vinyl chloride in the presence of oxygen leads to the formation of unstable peroxide groups, which can initiate decomposition of the polymer [28, 29]. It is noted that an extremely substantial influence on the stability of polyvinyl chloride is exerted by the purity of the monomer, as well as the presence of impurities of metals of variable valence [28]. 

The same group [76] carried out polymerizations of vinyl chloride in the presence of anionic emulsifiers (Aerosol AY and Aerosol MA at concentrations below CMC) varying peroxodisulfate concentrations. The reaction orders with... 

Neelson et al. [138] investigated the emulsion polymerization of vinyl chloride in the presence of inhibitors. The used p-benzoquinone and a stable radical 2,2, 6,6 -tetramethylpyperidine-JV-oxide at concentrations 1 x 10 mol dm After the consumption of inhibitor, the conversion vs. time curve was the same shape as that without inhibitor. In some experiments the inhibition period varies with the emulsifier and initiator concentration. The inhibitor efficiency decreased with increasing concentration of emulsifier. The solubilization of inhibitor is expected to decrease the amount of inhibitor available for reactions with radicals. For this reason, the inhibitor acts more efficiently at the low emulsifier concentration as it was reported in Ref. [139]. 

Neelsen et al. [140] investigated the effect of NaCl on the emulsion polymerization of vinyl chloride in the presence and absence of emulsifier (SDS) or inhibitor (p-benzoquinone (BQ) or chloranile (CA)). Under reaction conditions 2 [BQ] = [CA], the same induction periods and the conversion curves were obtained. The addition of NaCI (a coagulating agent) caused the decrease of the rate of polymerization and the increase of the particle size. The addition of NaCl led to an increase in the induction period. Here, the same induction period and the same shape of the conversion curves were obtained and [BQ] = [CA]. The different behavior of BQ in the presence of NaCl was explained by the reaction of O with BQ which leads to the chlorination of BQ. O radicals are generated by the reaction of peroxodisulfate with NaO (a labelled salt). The addition of NaO increased flocculation of particles which led to the formation of larger particles and lower rates of prflymerization. The dependence of the rate rtf polymerization on the NaO concentration was expressed by the following equation. 

There is some evidence of the free-radical mechanism of polymerization using a peroxygen compound and Sn halides. The effective polymerization of vinyl chloride in the presence of the peroxyester—SnCl2 catalyst system confirms the generation of free radicals [23]. This contrasts with the reported rapid decomposition of diacyl peroxides in solution at... 

A process for the bulk or suspension polymerization of vinyl chloride in the presence of a redox catalyst system consisting of a peroxyester and a monosaccharide or carboxylic acid esters of monosaccharide was described by Gaylord [230]. The monosaccharides which were used as reductants include pentoses and hexoses wherein the carbonyl group is either an aldehyde or ketone that is, polyhydroxy aldehydes commonly referred to as aldoses and polyhydroxy ketones commonly referred to as ketoses. 

Ascorbic acid has been used extensively as a sole reducing agent or in combination with cupric, ferrous, or ferric salts for the polymerization of vinyl chloride in the presence of water-soluble catalysts including hydrogen peroxide [232-235], potassium persulfate [236], cumene hydroperoxide [237], acetyl cyclohexanesulfonyl peroxide [238], and a mixture of hydrogen peroxide and acetyl cyclohexanesulfonyl peroxide [239]. 

Ascorbic acid has also been used as a complexing agent in the polymerization of vinyl chloride [240] in the presence of a diacyl peroxide and various water-soluble metal salte. Similarly 6-O-polmitoyl-L-ascorbic acid has been used as a reducing agent in the polymerization of vinyl chloride in the presence of hydrogen peroxide [241] and methyl ethyl ketone peroxide [242]. 

In another German patent, Mazzolini et al. [253] reported the low-temperature bulk polymerization of vinyl chloride in the presence of a catalyst system consisting of an organic hydroperoxide, SO2, and at least one alkali metal alcoholate at a [R0X]-[S02]/[R 00H] mole ratio of 0-0.5 and 0.005-1% mercapto compound which gave a degree of conversion >18% and a polymer with outstanding physical and chemical properties. The typical recipe for the polymerization is presented in Table 23. 

Obloj-Muzaj, M., Zielecka, M., Kozakiewicz, J., Abramowicz, A., Szulc, A. Domanowski, W., Polymerization of Vinyl Chloride in the Presence of... 

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