Peroxides polymerization agents

Polymer immobilization. Mo-peroxide, 427 Polymerization agents, 621, 622 peroxide value, 661, 662 peroxycarboxyUc acids, 698 radical polymerization, 697, 707 styrene, 697, 720 sulfonyl peroxides, 1005 thermochemistry, 155 Polymers aging, 685 autoxidation, 623 hydroperoxide determination, 685 Poly(methacrylonitrile peroxide)... 

Dynamic viscoelastic and stress-optical measurements are reported for blends of crosslinked random copolymers of butadiene and styrene prepared by anionic polymerization. Binary blends in which the components differ in composition by at least 20 percentage units give 2 resolvable loss maxima, indicative of a two-phase domain structure. Multiple transitions are also observed in multicomponent blends. AU blends display an elevation of the stress-optical coefficient relative to simple copolymers of equivalent over-all composition. This elevation is shown to be consistent with a multiphase structure in which the domains have different elastic moduli. The different moduli arise from increased reactivity of the peroxide crosslinking agent used toward components of higher butadiene content. 

Redox initiation was discovered by Kern [38] in 1937. Today a great number of pairs are known, producing radicals at very much higher rates than the peroxides themselves. They enable vinyl and diene monomers to be polymerized at low temperatures without the use of spontaneously rapidly decomposing (and therefore dangerous) peroxides. On the other hand, the use of the peroxide-reducing agent pair introduces some complications. A non-stationary polymerization process may result. 

Di-cup [Aqualon], TM for a series of vulcanizing and polymerization agents containing dicumyl peroxide. 

Di-Cup. [Hercules Hercules Europe] Dicumyl peroxides vulcanizing agent, polymerization catalyst for robbo and plastics. 

Thermacure . [Cook Composites ft Polymers] Dicumyl peroxide vulcanizing agent (X polymerizing catalyst in rubber or plastte. 

Another variable which we have examined is the compatibility of the polymeric peroxide crosslinking agent with the triblock copolymer. For... 

Fiberglass panels can be made from glass fibers, a liquid polyester syrup, and styrene plus a peroxide curing agent. Polymerization of the styrene and the resin occurs but secondary reactions can be carried out on the unreacted hydroxyl ends of the polymer. The extent of these reactions depends upon the number of unreacted ends remaining. How much hydroxyl is there in the resin We need it in a hurry,... 

Benzoyl peroxide Direct sunlight, sparks and open flames, shock and friction, acids, alcohols, amines, ethers, reducing agents, polymerization catalysts, metallic naph-thenates... 

Water-soluble peroxide salts, such as ammonium or sodium persulfate, are the usual initiators. The initiating species is the sulfate radical anion generated from either the thermal or redox cleavage of the persulfate anion. The thermal dissociation of the persulfate anion, which is a first-order process at constant temperature (106), can be greatly accelerated by the addition of certain reducing agents or small amounts of polyvalent metal salts, or both (87). By using redox initiator systems, rapid polymerizations are possible at much lower temperatures (25—60°C) than are practical with a thermally initiated system (75—90°C). 

Derivative Formation. Hydrogen peroxide is an important reagent in the manufacture of organic peroxides, including tert-huty hydroperoxide, benzoyl peroxide, peroxyacetic acid, esters such as tert-huty peroxyacetate, and ketone derivatives such as methyl ethyl ketone peroxide. These are used as polymerization catalysts, cross-linking agents, and oxidants (see Peroxides and peroxide compounds). 

R = alkyl, R = H) can be condensed, using acid, dehydrating agents (eg, phosphoms pentoxide), or vacuum to form polymeric peroxides (3). Most such polymeric peroxides decompose explosively. 

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