Mohammad Nourmohammadi - Department of Polymer Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
Reza Jahanmardi - Department of Polymer Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
Hamid Moeenfard - Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
Gholamhossein Zohuri - Department of Chemistry, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran
Saeed Bazgir - Department of Polymer Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran

Novel EPDM-based polymer foams were prepared using a combination of nanomaterials, namely nano silica, nano clay, and graphene nanoplatelets. In order to achieve optimal acoustic performance, the Taguchi design (TD) technique was applied to reduce the number of experiments and optimize the formulation. By employing an orthogonal array of L۹(۳۴), four controlled factors, including content of the three nanomaterials and the blowing agent (Unicell D۲۰۰A), were chosen. In practice, the acoustic properties of the nine suggested experiments with TD were examined with an impedance tube, and the signal-to-noise ratio analysis revealed two more optimal formulations for foam composites. Further experiments for the last two formulations compared to the nine Taguchi tests, showed an improvement of ۱۳.۰۴ and ۱۹.۶۸%, respectively, for noise reduction coefficient (NRC) and average transmission loss (ATL). It seemed that the idea of using multiple nanomaterials simultaneously is to be an effective way. Besides, the SEM images of nine samples proved that the smaller cell size of the foam were achieved using the higher concentration of nanoparticles. These findings are in accordance with the acoustic results, as the sample with larger cell size and more open cells (C۳) showed higher NRC and the sample with larger cell size and closed cells (B۲) showed higher ATL values. To complete the study, some blank samples with zero level or only one type of the nanomaterial were also investigated. Interestingly, the obtained results indicated that the formula should contain more than one type of nanoparticle to achieve a better acoustic performance. Comparing the result obtained in this study for EPDM foam with the same EVA foam in our previous work, it can be seen that EPDM showed an increase of ۱۵.۵۶% in NRC and a slight decrease of ۲.۵% in ATL. This behavior could be due to the difference in their morphology, in which the EPDM has probably more open cells and thinner cell walls.

EPDM foam, Nanomaterial, Acoustic, Taguchi design, foam morphology