Curing characteristics and mechanical properties of wasted crumb rubber-styrene butadiene rubber binary blends using bio based softener

Abstract

The softener commonly used to produce rubber compounds is paraffin oil, which is non-renewable because it obtained from petroleum processing. It is necessary to look for the alternative natural renewable softener such as bio-based oil that used to produce rubber compounds. This study aimed to investigate the effect of softener types from bio-based oils on rubber compound cure characteristics and its mechanical properties including characterization of functional group structures by using Fourier Transform Infra-Red (FTIR). This study used the variety of softener as follows: paraffin oil (A), wasted vegetable oil (B), palm oil (C) and castor oil (D), with a concentration of 1.5 phr. The parameters chosen were the vulcanization characteristics at 150 °C, mechanical properties and characterization of functions by using Fourier Transform Infra Red (FTIR) method. The results showed that variations of softener oil opposed the characteristics of maximum vulcanization (Smax), minimum torque (Smin), ΔS (Smax -Smin), optimal cure time (t90) and scorch time (ts2). The mechanical properties of rubber compounds for hardness and tensile strength, by using softeners from natural oil were difficult to increase compared to paraffin oil. The best results found in formula C (using palm oil) where the Smax: 22.74 kg/cm, Smin: 0.74 kg/cm, ΔS: 22 kg/cm, t90: 7.48 minutes, sec and ts2: 2.06 minutes, sec. Meanwhile, the results of mechanical testing are hardness 70 Shore A and tensile strength 3.8 MPa. The results of the FTIR, which regulates the functional groups contained in formulas A, B, C and D in this study indicate that the most dominant functional groups are C-H (alkanes) and C-H (alkenes).