Polymerization oxygen

Decomposes violently on heating. Forms explosive peroxides with air or oxygen. Polymerizes under pressure and heat. 

If the inhibitor is not removed, dissolved oxygen reacting with the inhibitor TCB will prevent polymerization. In the absence of dissolved oxygen, polymerization will proceed at essentially the same rate as that of the uninhibited monomer. A nitrogen blanket can be used to remove the oxygen from the mixture prior to polymerization. 

At the conclusion of the induction period due to oxygen, polymerization sets in at a rate exceeding that for pure monomer under the same conditions. The polymeric peroxides apparently furnish a source of free radicals. Oxygen therefore combines the roles of inhibitor, comonomer, and (indirectly) of initiator. 

Poly(4-vinylpyridine) was used also as a template for polymerization of maleic anhydride. Maleic anhydride is very difficult to polymerize by conventional radical polymerization, but in the presence of poly(4-vinylpyridine) in chloroform or in nitromethane, polymerization proceeds at room temperature just after mixing 0.5% solution of poly(4-vinylpyridine) with 1% solution of maleic anhydride. A yellow precipitate is obtained. The precipitate is a mixture of poly(maleic anhydride), poly(4-vinylpyridine), and unreacted maleic anhydride. In the absence of oxygen, polymerization is much slower. The reaction stops on the stage of donor-acceptor complex formation. 

Figure 7.2-5. Influence of oxygen. Dashed line, excess of oxygen 20 wt. ppm solid line, without excess of oxygen , polymerization , decomposition during polymerization.

Formerly the basis of paints, reacting with oxygen, polymerizing, and drying to a hard film... 

Pvapor pressure = exp [Cl + (C2/T) -H C3 x In (T) -H C4 x Decomposes violently on heating. Forms explosive peroxides with air or oxygen. Polymerizes under pressure and heat. 

The optical spectra of the oxygen-polymerized samples exhibited a blueshift (A ,ax = 570 nm) in comparison with electrochemically produced PITN, while the samples prepared using the dibenzoyl peroxide exhibited lower energy transitions at 670 nm [41]. It was concluded that the difference in the... 

Scheme of radical polymerization and oxygen polymerization anti-inhibition by thiol RSH. 

As suggested in Figure 31-7, DTA peaks result from both physical changes and chemical reactions induced by temperature changes in the sample. Physical processes that are endothermic include fusion, vaporization, sublimation, absorption, and desorption. Adsorption and crystallization are generally exothermic. Chemical reactions may also be exothermic or endothermic. Endothermic reactions include dehydration, reduction in a gaseous atmosphere, and decomposition. Exothermic reactions include oxidation in air or oxygen, polymerization, and catalytic reactions. 

In another experiment. Ford and Hanfordt l replaced benzoyl peroxide with borax, ammonium persulfate and oxygen. Polymerization of vinylidene fluoride was carried out in water at elevated temperature and pressure. Table 5.36 shows a summary of a variety of polymerization conditions and characteristics of the polymer. The optimum pressure and temperature depend, to a large extent, on the type and activity of the initiator(s). The reaction temperature must be selected so that the reaction rate remains controllable to avoid excessive heat generation, which cannot be removed. 

In the presence of oxygen polymeric hydroperoxides (POOH) are formed, which are further photolysed to polymer oxy radicals (PO ) ... 

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