Dicumyl Peroxide DCP

DCP by far is the most common organic peroxide used by the rubber industry. Approximately 85% of all peroxide curatives used by the rubber industry are DCP. The use of this peroxide curative generates a carbon-carbon crosslink that can withstand higher temperatures without degrading and gives better resistance to compression set and stress relaxation (maintenance of sealing pressure) than sulfur curatives. 

DCP is commonly used by the rubber industry at a 40% concentration on an appropriate mineral carrier such as clay, for safety. 

United Rubber Chemical Corp. (Beijing, China) 

DCP is relatively inexpensive compared to many other peroxides that can also be used to cure rubber. Peroxide cures, in general, impart to a rubber compound advantages over conventional sulfur cures in terms of heat resistance and compression set. 

There are other organic peroxides available to cure rubber compounds however, they are usually more expensive. 

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Figure 1. Effect of dicumyl peroxide (DCP) and processing conditions (excess, OM, and restricted, CM, oxygen amount) on melt stability of PP.

The reaction of EPR with dicumyl peroxide (DCP) at 180°C yielded a fraction insoluble in cyclohexane at 22 C. The presence of maleic anhydride (MAH) in the EPR-DCP reaction mixture increased the amount of cyclohexane-insoluble gel. However, the gel concentration decreased as the DCP concentration increased. The MAH content of the soluble polymer increased when either the MAH or the DCP concentration increased. The molecular weight of the soluble polymer increased with increasing MAH concentration and decreased with increasing DCP concentration in the reaction mixture. The products from the EPR-DCP and EPR-MAH-DCP reactions were soluble in refluxing xylene and were fractionated by precipitation with acetone. The presence of stearamide in the EPR-MAH-DCP reaction increased the amount and the molecular weight of the cyclohexane-soluble polymer. 

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... 

In addition to dicumyl peroxide (DCP), in two different batches zinc oxide (ZnO) or a conventional organic accelerator (ZDMC) were used. Figure 34 depicts the corresponding XRD pattern. In both cases, the peak positions are almost the same as that of the pure peroxide-cured vulcanizates. However, the intensity of the XRD pattern was significantly reduced in the case of ZDMC, and there is only a little effect of ZnO. Obviously, the sulfur-containing zinc salt influences and promotes dispersion and reorientation of the layered... 

Figure 10.10 Correlation between the crystallizability of polycyclooctene and its crosslinking level. A mixture of polycyclooctene and dicumyl peroxide (DCP 3% w/w) was subjected to the temperature program shown in (a). The sample is heated at 130° fort minutes (10 minutes in this example) for crosslinking, (b) The...

The 13C NMR crosslink density results were compared with the crosslink density obtained by the mechanical measurements. In the determination of the crosslink density by mechanical methods, the contributions of the topological constraints on the results were neglected and the density was expressed as G/2RT. The 13C and mechanical-crosslink densities were obtained for both sulfur and dicumyl peroxide (DCP)-cured samples to ensure the effect of wasted crosslinks (pendent or intramolecular type sulfurisations), which are expected in the typical sulfur-vulcanisation of NR. In the major range of crosslink densities, the crosslink densities for those two systems are described by the same linear function with a slope of 1.0. Based on these observations, it is shown that the crosslink density of the sulfur-vulcanised NR as determined by 13C is identical with the true crosslink density, and the influence of the wasted or ineffective crosslinks (pendent and cyclic crosslinks) and chain ends is negligible. However, this conclusion seems to be only valid if the effect of topological constraints or entrapped entanglements on the mechanical modulus is negligible which is rarely the case in real systems. 

Method 1 Poly (ethylene glycol) dimethacrylate (23G), and phenolic resol (PR) were mixed at 50°C for 10 minutes and dicumyl peroxide (DCP) was added. The polymerization and phenolic curing reactions then took place simultaneously at 170°C for 90 minutes in 200mm x 10mm x 1.5mm stainless steel mold. This product was called IPN 1. 

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

Kurian et al. [1993] examined gamma-irradiation of the HDPE/LLDPE blends, at a dose rate of 10 kGy/h (Table 11.9). The blends of HDPE and LLDPE were prepared by melt mixing in an extruder attached to an internal mixer (L/D ratio, 20 screw compression ratio, 3 1 screw speed, 30 rpm extruder heater zones, 140°C die temperature, 150°C). Eor irradiation, the samples were compression-molded at 150°C in a steam-heated laboratory hydraulic press for 5 min. Eor the dicumyl peroxide (DCP) crosslinkable samples, 1 % DCP was added during compound-... 

Gao et al. (158) showed that LDPE-g-PS prepared based on Friedel-Crafts alkylation reaction could increase the impact strength, elongation at break and tensile strength of LDPE/PS blends. Wang et al. (159) reported that adding dicumyl peroxide (DCP) into HDPE/PS/SBS blends can obviously increase their impact and tensile strength. The mixing order affected the blend properties very much. However, DCP did not show such effect with HDPE/PS blends. 

For PE, the relationship between grafting efficiency and cross-linking of chains can be controlled by varying the concentration ratio of the initiator to the monomer (3). For example, no cross-linking was detected when diethylmaleate (DEM) was grafted to PE as initiated by dicumyl peroxide (DCP) if the ratios (DCP) [DEM] < 0.09. A positive effect on grafting is caused by lower molecular weight of PO (lower melt viscosity) (3). 

Ha et al. (24) studied the structure-property relationship of EPDM/PP blend. EPDM was cured with PP with dicumyl peroxide (DCP) at different shear conditions. 

Shujum et al. described compatible TPS/LLDPE blends, produced by one-step reactive extrusion in a single-screw extruder. Maleic anhydride (MAH), and dicumyl peroxide (DCP) were used to graft MA onto the LLDPE chain [88]. 

FIGURE 10.26 Tensile strength of natural rubber crosslinked with dicumyl peroxide (DCP) versus temperature. (From Thomas and Whittle (1970).)... 

Maliger et al. [216] have reported on a compatible blend of starch and polyester through reactive extrusion using maleic anhydride (MA) and dicumyl peroxide (DCP) as compatilizer and initiator, respectively. It was found that distributing diisocyanate in the polyester phase prior to blending resulted in better mechanical properties than distribution in starch phase [194, 196]. 

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