A study of rheological properties in sulfur-vulcanized CPE/NR blends

The use of natural rubber (NR) for partly substituting elastomeric chlorinated polyethylene (CPE) was investigated. Sulfur curing was used to vulcanize NR phase in the blends. Rheological properties of CPE/NR blends were determined from two rheometers with different shear modes; the rate-controlled capillary rheometer and the oscillating die rheometer (Rubber Process Analyser, RPA2000). Results obtained reveal that the viscoelastic behavior of neat CPE and the blends with CPE as a major component is governed by the viscous response, which could be observed from the time-dependent properties. By contrast, the viscoelasticity of neat NR and blends with NR as a matrix is influenced strongly by vulcanization of the NR phase in the blends. The time-dependent properties become time-independent after the NR phase is cured by sulfur. Furthermore, results measured with these two rheometers could successfully be superimposed.