Peroxide Cross-link of EPM/EPDM Rubber Compound for Medium Voltage Cable Application: Experimental Insight

The vulcanization of Medium and High Voltage (M-H V) cables is an important industrial application where manufacturers use principally EPM/EPDM, cross-linked polyethylene (XLPE) and now also thermoplastic rubbers. In the present paper, an EPDM compound for medium voltage cables –normally distributed to producers in pellets and ready to be cured– is considered and several experimental tests (rheometer curves and mechanical characterizations) are conducted changing controlled curing temperature, peroxide type and peroxide concentration. In particular, tests are replicated in a temperature range between 160°C and 200°C, with data provided every 20°C, using 2 different peroxides, a mixture of three commercial peroxides at 5 different concentrations. A huge amount of experimental data (cure curves) is obtained (one for each temperature, peroxide used and concentration) and results are critically compared one each other, to have a quantitative insight into the most effective temperature and peroxide to be used during this kind of vulcanization, with the aim of maximizing vulcanization velocity, final torque reached and mechanical properties of cured rubber. The comprehensive study proposed, assessed from a numerical point of view, is part of a more general research (1) aimed to set up the most suitable production parameters (e.g. curing time and temperature) to guarantee improved mechanical properties and a good aging resistance and (2) to find the most suitable recipe, also in presence of mixtures of peroxides, able to provide items with a uniform vulcanization level.