Chloroprene rubber formation

The iodometrical analysis of active oxygen in the ozonized Denka M40 solutions shows that the amount of 0-0 groups is ca. 43%. It is of interest to note that the HI reaction with ozonized polychloroprene solutions occurs quantitatively for 3—4 h, while in SKD the same proceeds only to 20% after 24 h. The above data, however, provide insufficient information for the preferable route of the zwitterions deactivation via dimerization, polymerization of zwitterions or secondary processes). The DSC analysis of the products of Denka M40 ozonolyis reveals that the chloroprene rubber ozonolyis yields polyperoxide as the enthalpy of its decomposition is found to be very elose to that of dicumeneperoxide (DCP), The higher value of (ca. two times of that of DCP) testifies the possible formation of polymer peroxides [4],... 

Table 15.5 shows the results of Mochel [22] for the effect of conversion upon the gel content of polychloroprene rubbers prepared by emulsion polymerization at 40 °C. In section (a) of this table are shown results for polymers produced in the absence of added sulfur section (b) shows results for polymers produced with the addition of 0.6 parts of sulfur per 100 parts by mass of chloroprene, before chemical peptization of the polymer. In both types of reaction system, polymer gel begins to form quite early in the reaction. However, these results indicate that sulfur has a slight tendency to act as a modifier during the polymerization, in that the onset of gel-formation is delayed when sulfur is present. Also delayed is the pdnt at which the polymer is virtually entirely gel. Mochel et al. [23] have reported results for the molar mass distribution of a thiuiam-modified polychloroprene rubber produced by emulsion polymerization at 40 °C,... 

Rubber can also be made in the laboratory from polymerizing isoprene in the presence of suitable catalysts that favor formation of the c/s polymer. Rubber produced in this way is virtually indistinguishable from natural rubber. Other substituted dienes can also be polymerized in the laboratory to produce a wide variety of rubberlike, synthetic polymers. In the early 1930s, chemists at the Du Pont chemical company produced a commercially important polymer via the free-radical polymerization of chloroprene. The resulting polymer is sold under the trade name Neoprene. 

Coextrusion of chloroprene and EPDM rubbers has given graft copolymers containing 7% chloroprene units [141a]. Mastication of extracted natural rubber with methyl methacrylate in an extruder gives a relatively high conversion of monomers, more than 60%, and the formation of a modified rubber [141]. 

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