Polyisoprene peroxide-curing

Oh, S. J. and Koenig, J. L. (1999) Studies of peroxide curing of cis-polyisoprene/diallyl phthalate blends by spectroscopic techniques. Rubber Chem. Technol. 72(2), 334-42. 

Rubbers rely on fillers (both reinforcing and nonreinforcing) to obtain their properties. The curing system also produces a dirty-colored material. To color a rubber is difficult, and only a few basic colors are used. To obtain a transparent rubber, special latex or synthetic cis-polyisoprene must be used, and the use of a peroxide cure is normal. Polyurethanes can be colored any color, but the yellowing of aromatic systems must be taken into account. Aliphatic systems can give transparent nonyellowing systems. 

In a second paper Brown and Tinker [101] examined the effects of a number of parameters, such as the accelerator used in the sulfur curing, peroxide versus sulfur curing, and swelling ratio at constant crosslink density. The results for c/s-polyisoprene show that the value of H% is independent of accelerator. However, lower values of H% were seen for peroxide-cured materials. The results for BR were independent of curant the reasons... 

Funatsu et al. examined the change in free radical concentration of sulfur and peroxide cured cA-l,4-polyisoprene rubber (IR) vulcanizates during tensile deformation. Figure 25.32 shows the first derivative ESR curves determined... 

In two situations in particular MAS NMR has a strong edge over IR or NMR with solubilisation [696]. The first involves highly cured samples or samples where solubilisation of the elastomer component is difficult or impossible. For example, peroxide cured rubber is difficult to devulcanise using ODCB. Here, MAS NMR with or without CP, as appropriate, provides spectra of equal quality as for samples cured to a lesser degree. The problems of incomplete or selective solubilisation of elastomeric components can be avoided. MAS NMR maybe the method of choice for peroxide-cured rubber. The second application for which MAS NMR is well suited is the aforementioned analysis of relatively small amounts of NR or synthetic c -polyisoprene in filled vulcanisates [696]. 

The development of a new generation of peroxide-initiated solid functional coagents is reported along with the results of a study carried out to compare these cure systems with sulphur and peroxide cure systems in polyisoprene formulations. Data are provided on the cure characteristics, compression set, tensile properties, hardness, heat ageing, flexural properties, tan delta, complex modulus and lap shear adhesion of the formulations and the benefits of the new systems are highlighted. 

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EPTMs are suffidently reactive toward firee radicals (see previous Section), even when they contain low amounts of conjugated unsaturation (0.1 M or less). Thus degradation phenomena are practically avoided during their radical curing. We have verified the po ibility of codicumyl peroxide-based formulations. Figure 13 shows that with 0 J—1.5 % peroxide... 

Shawbury, Rapra Technology Ltd., 2001, Paper 9, pp.6. 012 COMPARISON OF RUBBER CURING SYSTEMS - PEROXIDE-COAGENT VS SULFUR-ACCELERATOR EV POLYISOPRENE(IR)... 

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