Isoprene peroxide, polymeric

Dimethyl peroxide Diethyl peroxide Di-t-butyl-di-peroxyphthalate Difuroyl peroxide Dibenzoyl peroxide Dimeric ethylidene peroxide Dimeric acetone peroxide Dimeric cyclohexanone peroxide Diozonide of phorone Dimethyl ketone peroxide Ethyl hydroperoxide Ethylene ozonide Hydroxymethyl methyl peroxide Hydroxymethyl hydroperoxide 1-Hydroxyethyl ethyl peroxide 1 -Hydroperoxy-1 -acetoxycyclodecan-6-one Isopropyl percarbonate Isopropyl hydroperoxide Methyl ethyl ketone peroxide Methyl hydroperoxide Methyl ethyl peroxide Monoperoxy succinic acid Nonanoyl peroxide (75% hydrocarbon solution) 1-Naphthoyl peroxide Oxalic acid ester of t-butyl hydroperoxide Ozonide of maleic anhydride Phenylhydrazone hydroperoxide Polymeric butadiene peroxide Polymeric isoprene peroxide Polymeric dimethylbutadiene peroxide Polymeric peroxides of methacrylic acid esters and styrene... 

Isoprene (2-Methy 1-1,3-butadiene) Peroxide, Polymeric. (No formula given). Resinous substance decomp slightly above 0°. Reported in Ref 2 as a highly explosive substance. May be prepd by the reaction of isoprene with molecular oxygen... 

In 1838 Regnault [15] reported that vinylidene chloride could be polymerized. In 1839 Simon [16] and then Blyth and Hofmann (1845) [17] reported the preparation of polystyrene. These were followed by the polymerization of vinyl chloride (1872) [18], isoprene (1879) [19], methacrylic acid (1880) [20], methylacrylate (1880) [21], butadiene (1911) [22], vinyl acetate (1917) [23], vinyl chloroacetate [23], and ethylene (1933) [24]. Klatte and Rollett [23] reported that benzoyl peroxide is a catalyst for the polymerization of vinyl acetate and vinyl chloroacetate. 

Butadiene is available commercially as a liquefied gas underpressure. The polymerization grade has a minimum purity of 99%, with acetylene as an impurity in the parts-per-million (ppm) range. Isobutene, 1-butene, butane and cis-l- and Zrc//7.s-2-butcnc have been detected in pure-grade butadiene (Miller, 1978). Typical specifications for butadiene are purity, > 99.5% inhibitor (/c/V-butylcatecliol). 50-150 ppm impurities (ppm max.) 1,2-butadiene, 20 propadiene, 10 total acetylenes, 20 dimers, 500 isoprene, 10 other C5 compounds, 500 sulfur, 5 peroxides (as H2O2), 5 ammonia, 5 water, 300 carbonyls, 10 nonvolatile residues, 0.05 wt% max. and oxygen in the gas phase, 0.10 vol% max. (Sun Wristers, 1992). Butadiene has been stabilized with hydroquinone, catechol and aliphatic mercaptans (lARC, 1986, 1992). 

Phenanthroline in the presence of heavy metals acts as an activator of the polymerization of vinyl compounds558,559 and other olefins.560-564 It also assists the dimerization of olefins in the presence of titanium catalysts.565,566 It enhances the metal catalyzed oxidation of ascorbic acid567 and dimethyl sulfoxide.568 On the other hand, on its own it can inhibit several polymerization processes.545,569 It also stabilizes butadiene and isoprene and prevents their dimerization.570 It prevents peroxide formation in ether,571 inhibits the vinylation of alcohol572 and stabilizes cumyl chloride.573 It accelerates the vulcanization of diene rubbers574 and copolymers.575 1,10-Phenanthroline catalyzes the autooxidation of linoleic and ascorbic acids in the absence of metals.567... 

The catalytic or initiated reaction involves heating the poly(diene) in an aromatic solvent to temperatures between 120-150 °C in the presence of free radical initiators such as peroxides, hydroperoxides and azo compounds. The ensuing reaction involves addition of maleic anhydride to a polymeric radical which was formed by abstraction of an allylic hydrogen by initiator radicals. Four modes of addition are possible leading to partial structures such as (175)-(178) illustrated with poly(isoprene). It can readily be seen that some crosslinking is an inherent problem because of structures (177) and (178). The amount of gel formed, however, is found to be largely dependent on the initiator employed and can be minimized, especially with hydroperoxide initiators. 

This group covers polymeric peroxides of indeterminate structure rather than polyfunctional macromolecules of known structure. These usually arise from autoxidation of susceptible monomers and are of very limited stability or explosive. Polymeric peroxide species described as hazardous include those derived from butadiene (highly explosive) isoprene, dimethylbutadiene (both strongly explosive) 1,5-p-menthadiene, 1,3-cyclohexadiene (both explode at 110°C) methyl methacrylate, vinyl acetate, styrene (all explode above 40°C) diethyl ether (extremely explosive even below 100°C ) and 1,1-diphenylethylene, cyclo-pentadiene (both explode on heating). 

An other interesting example of copolymer is given by Georges et al. [52,59] who first demonstrated the living character of the polymerization of styrene initiated by dibenzoyl peroxide in the presence of Tempo or Proxyl (2,2,5,5-tetramethyl-l-pyrrolydinyloxy). Polystyrene with a narrow polydispersity (Mw/Mn = 1.2) is obtained and block copolymers with butadiene, isoprene, acrylate and methacrylate sequences are prepared ... 

Acrylamide, 2-methyl-5-vinylpyridine and /V-vinylpyrrolidone can be polymerized under similar conditions, and also after decomposition of a monomer-peroxide complex. On the other hand, styrene, methyl methacrylate, isoprene, methyl acrylate, vinyl acetate and ascorbic acid do not polymerize under these conditions. Complex formation between persulphate and these monomer donors is more favourable energetically [165]. The complex is more stable, it is not decomposed into initiating radicals and polymerization does not occur. 

The transfer reactions to the solvent and the initiator have been described for butadiene, isoprene, or vinyl acetate polymerizations using thermally decomposed hydrogen peroxide in methanol or rm-pentanol (Table 3.5)l55). The Mayo-Lewis equation has been applied... 

Potentially hazardous reactants. Spontaneons polymerizations with exothermic heat generation inclnde styrene, snbstitnted styrene, vinyl chloride, vinyl pyridine, acrylonitrile, bntadience, isoprene cyclopentadience, and methyl isocyanate reactions involving peroxides as illnstrated in Table 16.17, azides, perchlorates, or nitro componnds and decompositions, nitrations, oxidations, alkylations, aminations, combnstions, condensations, diazotizations, halogenations, or hydrogenations. 

Cross-linking by addition polymerization is also used to a considerable extent. Unsaturated polyesters are cross-linked by copolymerization with styrene or methyl methacrylate. Cross-linking soft, natural rubber with sulfur gives the normally used hard, vulcanized rubber. Ethylene-propylene rubbers can be cross-linked with peroxides. The cross-linking of elastomers is also called vulcanization, since the classic cross-linking of natural rubber, cis-l,4-poly(isoprene), uses heat and sulfur, which were the elements assigned to the god Vulcan (see also Chapter 37). 

It is therefore not surprising that the early investigators saw no promise in this mechanism of polymerization of butadiene, isoprene, etc., either by pure thermal initiation or by the use of free radical initiators, such as the peroxides. Instead they turned to sodium polymerization, which, although also rather slow and difficult to reproduce, at least yielded high-molecular-weight rubbery polymers from the dienes. Later, in the 1930s, when emulsion polymerization was introduced, it was found that this system, even though it involves the free... 

Peroxide Vulcanization of Unsaturated Hydrocarbon Elastomers. The initiation step in peroxide-induced vulcanization is the decomposition of the peroxide to give free radicals. If the elastomer is derived from butadiene or isoprene, the next step is either the abstraction of a hydrogen atom from an allyUc position on the polymer molecule or the addition of the peroxide-derived radical to a double bond of the polymer molecule. In either case, polymeric free radicals are the result (Scheme 17). 

Cross-linking can be done by various techniques depending on the chemical composition of the polymer. Thus, if the polymer contains C=C unsaturation, e.g. in polydienes, natural rubber, polyisobutylenes (from copolymerized isoprene), then reaction with sulphur forms —S—S— links. With polysiloxanes or EP rubbers (no C=C) then peroxides are used. With fluorocarbon elastomers, e.g. Viton (a copolymer of vinylidene difluoride and hexafluoropropylene), diamines are used which form H-bonded cross-links. With polyurethanes (formed from diols and di-isocyanates) a controlled number (low) of cross-links are formed during the polymerization by the addition of triols. 

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