Dicumyl peroxide cross-linked

A = anionic R = radical E = emulsion polymerization, ° 3-C denotes hex-3-ene, etc. W(=CHCMe2Ph)(=NAr)[OCMe(CF3)2]2- Partially aralkylated by reaction with 4-chlorotoluene/dicumyl peroxide. Cross-linked by partial bromination with NBS/AIBN followed by reaction with BrMg(CH2) MgBr (n = 4, 6). 1,10-di(9-borabicyclononane)-dec-5-ene. Cross-linked by heating with dicumyl peroxide. 

ATH Dicumyl peroxide cross-linked LDPE, LLDPE Isostearoyl titanate, isopro-poxy tris (dioctyl pyropho-sphoryl) titanate Increased mechanical properties through synergism of titanate and a vinyltriethoxysilane [37-39]... 

Ethylene-propylene and silicone rubbers are crosslinked by compounding with a peroxide such as dicumyl peroxide or di-t-butyl peroxide and then heating the mixture. Peroxide cross-linking involves the formation of polymer radicals via hydrogen abstraction by the peroxy radicals formed from the decomposition of the peroxide. Crosslinks are formed by coupling of the polymer radicals... 

The most common compound for peroxide cross-linking of PE in the wire and cable industry is dicumyl peroxide (DCP), which decomposes at 120-125°C (248-257°F), generating free radicals needed for the process plus by-products (carbinol, acetophenone, and methane). The production line for continuous vulcanization of wire and cables by peroxide must be about 200 m (61 ft) long. 2 The plant space required for radiation cross-linking using... 

For peroxide cross-linking, organic peroxides, such as dicumyl, di-t-butyl, and benzoyl peroxides, are used in amounts 1 to 3 phr (parts per hundred parts of rubber). Typical cure cycles are 5 to 10 min at temperatures 115 to 170°C (239 to 338°F), depending on the type of peroxide used. Each peroxide has a specific use. A postcure is recommended to complete the cross-linking reaction and to remove the residues from the decomposition of peroxide. This improves the long-term heat aging properties.62... 

Few monomeric radicals are lost by coupling with polymeric radicals when diaUcyl peroxides are used as the curative. Also, if the elastomer is properly chosen, the scission reaction is not excessive. For dicumyl peroxide in natural rubber, the cross-linking efficiency has been estimated at about 1.0. One mole of cross-links is formed for each mole of peroxide cross-linking is mainly by the coupling of two polymeric radicals. One peroxide moiety gives two monomeric free radicals that react with rubber to give two polymeric radicals, which couple to form one cross-hnk. 

Cross-linking of polyethylene can be accomphshed either chemically or by high energy radiation. Radiation cross-linking is usually accomphshed by x-rays (44) or electrons (45,46). Chemical cross-linking of polyethylene is accomphshed with dicumyl peroxide (47), d4-tert-huty peroxide (48), or other peroxides. Radiation cross-linking (49) is preferred for thin foams, and chemical cross-linking for the thicker foams. 

Vulcanised (cross-linked) polyethylene is being used for cable application where service temperatures up to 90°C are encountered. Typical cross-linking agents for this purpose are peroxides such as dicumyl peroxide. The use of such agents is significantly cheaper than irradiation processes for the cross-linking of the polymer. An alternative process involves the use of vinyl silanes (see Section 10.9). 

Similar blends have been made by cross-linking the E-plastomer with peroxides. This process suffers from an inherent degradation of the iPP by peroxide. In a representative formulation, a mixture of 60 parts of E-plastomer (octene commoner), 15 parts maleated (0.6%) iPP, 25 parts of EPDM, 10 parts of paraffinic plasticizer, 5 parts of dicumyl peroxide, and 1 part of stabilizer was treated at 170°C for 5 min to give a cross-linked blend with Shore A hardness 66, tensile strength 5.5 MPa, and elongation 190%. Similar blends have been made with the incorporation of a limited amount of a SEES polymer to act as a compatibilizer between the E-plastomer and the iPP. 

Cross-Linking of Ethylene-Propylene Copolymer Rubber with Dicumyl Peroxide-Maleic Anhydride... 

The two component FID (and corresponding superposed broad line spectra), for some polydimethylsiloxanes (PDMS) arises from crystalline and amorphous components. Polymers highly crosslinked with dicumyl peroxide exhibit quite similar data, but after the removal of all unlinked material, the FID consists only of a single component, indicating an almost complete reduction in crystallinity due to the cross-linking 84). 

Poly(vinyl ethyl ether) is soluble in ethanol, acetone and benzene. It is a rubbery product which may be cross-linked by heating with dicumyl peroxide. Polyfvinyl isobutyl ether), has a glass transition temperature of —5°C. It has been used as an adhesive for upholstery, cellophane and adhesive tape. 

Table 11. Cross-linking density of some EPTMs, EPDMs and EPM cured with dicumyl peroxide (DCP)... 

The results obtained, when dicumyl peroxide is used as curing agent (Table 19), indicate that 13,5-hexatriene (HTl) and 2,4,6-octatriene (OTI)-based copolymers can be easily cross-linked. 

Figure 8.29 plotted against Gg for three rubbers [polybutadiene (PB), styrene-butadiene copolymer (SBR), and natural rubber (NR)] at different stages of cross-linking by (O) dicumyl peroxide and ( ) sulfur. (From Ref. 44.)... 

The reactivity of EPTMs in radical curing, predicted by these calculations, has been confirmed directly by cross-linking density measurements (Table 11) also carried out on EPM and some EPDMs vulcanized with dicumyl peroxide at 145 °C. 

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