The effects of devulcanize microwave radiation time on crosslink density of EPDM waste/natural rubber blend

Abstract

Ethylene Propylene Diene Monomer Rubber (EPDM) waste is a vulcanize rubber waste that content a highly crosslinking molecular structure which makes recycling and waste management of the EPDM waste to be a challenge. Hence, the microwave devulcanization method is one of the most promising method to recycle rubber waste as it gives a uniform heating throughout the rubber waste. The microwave radiation may effectively break the rubber waste crosslink molecular structure. In this study, grind EPDM (G-EPDM) was devulcanize at a different exposure microwave radiation time (3, 5, 7 and 9 minutes) and blended with natural rubber (NR). Then, the blends were characterized for Fourier Transform Infrared (FTIR), cure characteristics, swelling, and crosslink density. The Fourier Transform Infrared (FTIR) spectrum of the microwave devulcanized EPDM shows changes after the radiation. The FTIR spectrum of G-EPDM and microwave devulcanized EPDM was focused at wavenumber of 1659 cm−1 (C=C link), 1532 cm−1 (methyl-assisted conjugated double bond), 1392 cm−1 (CH3) and 856 cm-1 (RC=CH2 group). Observed of spectrum changes after the G- EPDM was exposed to the microwave radiation. Meanwhile, the infrared spectrum of NR/G-EPDM and NR/M (5)–EPDM, were studied at wavenumber of 1272 cm-1, 962.3 cm−1, and 874 cm−1 and 667 cm−1 indicate the C-N aromatic group, S-O bond and C-S bond, respectively. From G-EPDM until 5 minutes exposure times, crosslink density shows an increment pattern of 21.13% conversely swelling of rubber which shows a decrement pattern of 5.14 %.