Combined Numerical, Finite Element and Experimental-Optimization Approach in the Production Process of Medium-Voltage, Rubber-Insulated Electric Cables Vulcanized With Steam Water. Part 1: DSC and Rheometer Experimental Results

Abstract

The standard industrial process to produce medium-voltage electric cables based on EPDM consists of cross-linking by peroxides with high-temperature steam (pressurized water vapor). Suboptimal material cross-linking is usually due to a decrease of the temperature along the vulcanization pipe. Temperature variations are connected to variations in steam pressure into pipe system. A combined numerical and experimental approach to optimize the production process of medium-voltage, rubber-insulated electric cables vulcanized with steam water is presented. The numerical part of this process is based on the use of finite elements and an optimization genetic algorithm (GA) and will be presented in Part 2. In Part 1, attention focuses on the experimental investigation. In particular, the final cross-linking degree is experimentally obtained by means of differential scanning calorimetry (DSC) determination of nondecomposed peroxide from the external layer to the core of the cable insulation. The final task is to minimize the difference between numerically predicted and experimentally determined cross-linking degree using a steam-temperature profile along the pipe to explain the variations. A preliminary evaluation of kinetic-reaction constants of rubber cured with peroxides is provided with the support of a comprehensive experimental investigation of the curing process by means of standard rheometer characterizations done at different curing temperatures. An existing mathematical, kinetic model is applied to the experimentally determined rheometer curves, allowing the determination of partial-reaction kinetic constants used in the finite-element computations

Development of an intermediate layer for multilayer hoses used in turbo lines of motor vehicles

“…While designing the relating multilayer hose (Figure ), E100U (Table ) was formulated as the outer layer. It contains 100 phr of EPDM and peroxide curatives . One of the biggest advantage of this formulation is its superior stability in weathering conditions.…”

Modeliranje procesa umreženja izolacije izoliranih vodiča energijskih kabela

“…Na kraju treba reći da prikazana istraživanja (model vulkanizacijske cijevi, simulacije) predstavljaju manji dio opisa cjelovitog procesa proizvodnje energijskih kabela u tvornici Elka d. o. o. Jednako važna su i prethodna ispitivanja ulaznih materijala, vodiča i izolacije, 10 nanošenje izolacije na vodič (izvedba ekstrudera, kapacitet), hlađenje, otplinjavanje kabela u komorama (nužno kod visokonaponskih kabela zbog zaostajanja plinova u izolaciji) te ostala standardizirana tipska ispitivanja proizvoda. Isto tako, s obzirom na to da se radi o kontinuiranoj proizvodnji, potrebno je riješiti problem pregrijavanja uslijed smanjenja brzine linije (u nekim slučajevima s 20 m min −1 na 8 m min −1 pri spajanju vodiča) za nesmetani nastavak rada.…”

Effect of Mixing Method on Properties of Ethylene Vinyl Acetate Copolymer/Natural Rubber Thermoplastic Vulcanizates

“…This morphology allows this material to be reprocessed at temperature higher than the melting temperature of the thermoplastic phase. There are several types of crosslinking agents used for the DV process such as sulfur, peroxide, and phenolic resin [ 16 , 17 , 18 ], which have been used in typical crosslinked elastomers [ 19 , 20 , 21 , 22 , 23 , 24 ]. Moreover, the curing behavior of the elastomer can be predicted using mathematical techniques such as finite element technique [ 25 ], effective close form [ 26 ], and forward-backward numerical calculation [ 27 ].…”