Vulcanization degree influence on the mechanical properties of Fiber Reinforced Elastomeric Isolators made with reactivated EPDM. (April 2022)

• Record Type: Journal Article
• Authors: Habieb, A.B.; Milani, F.; Milani, G.; Pianese, G.; Torrini, D.
• Is Part Of: Polymer testing. Volume 108(2022)
• Publication Date: 2022-04
• Subjects: Fiber reinforced elastomeric isolator (FREI) -- Recycled rubber -- Regenerated EPDM -- Crosslinking -- Vulcanization -- Experimental tests and numerical computations; Polymers -- Testing -- Periodicals; Polymères -- Tests -- Périodiques; 620.1920287
• DOI: 10.1016/j.polymertesting.2022.107496
• Languages: English
• ISSNs: 0142-9418

Abstract

Abstract: Rubber is well known as the basic material for some structural devices, such as seaport fenders and seismic isolators. In practice, to seismically isolate a structure it is necessary to interpose between the foundation and the superstructure a rubber device that increases the period of the superstructure, a feature that allows the structure to be "transparent" to the seismic excitation. A seismic isolator is constituted typically by a package of several rubber pads 1–2 cm thick vertically interspersed with either steel laminas or FRP dry textiles suitably treated. In this latter case the isolator is called FREI (Fiber Reinforced Elastomeric Isolator). FREIs exhibit light weight, easy installation and low cost. In this study, recycled rubber in the form of reactivated EPDM has been used to produce very low cost FREIs, combined with glass fiber reinforcement. To be ready for structural application, the rubber used must be vulcanized correctly to properly create the polymer crosslinking. However, all rubber mechanical properties are strongly affected by curing temperature and curing time. Here, the mechanical properties of a typology of FREI conceived and produced by the authors in prototypes are evaluated through a series of experimental tests and numerical computations, taking into account the different levels of vulcanization degree. Shore A hardness test, uniaxial tensile test, and relaxation test have been conducted and verified through Finite Element (FE) modeling. All collected data allow to precisely determine the curing time and temperature to use in the industrial production to obtain optimal output mechanical properties for FREIs. Highlights: Fibre Reinforced Elastomeric Isolators FREIs, experimental vs numerical analyses. Utilization of full 3D FE and FD method to evaluate degree of vulcanization. Stress-strain and relaxion behavior of undervulcanized pads made by regenerated rubber. Numerical hardness vs experimental one, full 3D viscoelastic simulation. Utilization of Yeoh model and Prony series to characterize rubber pads.