Mona Taheri and Somayyeh Mohammadian Gezaz* Payame Noor University, Iran *Corresponding author: Somayyeh Mohammadian-Gezaz, Payame Noor University, Tehran, PO Box: 19395-3697, Iran. Submission: September 17, 2018; Published: September 21, 2018 Curing Characterization of EPDM Rubber Compounds using RPA: Effects of Cure Conditions Research Article 262 Copyright © All rights are reserved by Somayyeh Mohammadian Gezaz. Volume - 2 Issue - 5 Progress in Petrochemical Science C CRIMSON PUBLISHERS Wings to the Research ISSN 2637-8035 Abstract The cure characteristics of EPDM compounds were investigated using of an oscillatory cure meter, namely, the rubber process analyzer (RPA 2000). Cure tests were conducted at different cure conditions and the effects of temperature, frequency and strain on the elastic (S’) and viscous (S”) cure torque curves were studied. The results showed that the cure process was affected strongly by the changes in the test conditions. Increasing temperature assisted the vulcanization which was indicated by the greater rate of cure and shorter cure time. It was found that with increasing cure temperature, t max S” were approximately is the same them as real scorch time (tC10). As the cure frequency increased, scorch and cure time and the slope of the elastic torque are not changed significantly and the percentage of cure at t max S” decreases. With increasing strain, the elastic and viscous torques increase and the nonlinearity effect was observed at the higher strain. Keywords: EPDM (Ethylene propylene diene monomer rubber); Rubber process analyzer (RPA); Cure characteristics; Cure conditions Introduction Rheometers are the instruments which can determine the cure characteristics of the rubber compounds [1,2]. Generally, in these equipments, a certain shear strain is applied, and the torque response of the material is measured. Conventional rheometers include two-parallel-plate and cone-and-plate types which are utilized to study the rheological and the cure properties of the rubber compounds [1-7]. But in these instruments wall slip may occur and the sample loading in the gap is not easy, affecting the repeatability of the tests. In addition, the high viscosities of rubber compounds may raise a number of difficulties. For these reasons, it is necessary to develop specific measuring equipments. RPA (rubber process analyzer) is a strain-controlled shear cone-and- cone rheometer specifically designed for raw elastomers and their compounds. It can be operated in rotation dynamic and relaxation modes. Rheological characterizations of gum and rubber compounds [8-10] and the cure behavior of compounds [11-13] can be investigated using RPA. Figure 1: Schematic of the RPA gap. The reciprocal cone geometry of RPA can be seen in Figure 1 schematically. The values of α and R are equal to 0.125rad and 20.6mm respectively. The lower cone is moved with the rotational angular of θ which induces the shear strain (γ) equal to. A torque transducer at the upper cone measures the torque transmitted through the sample from the lower cone. The rheological properties