Effects of EPDM-g-MAH compatibilizer and internal mixer processing parameters on the properties of NR/EPDM blends: An analysis using response surface methodology

This study evaluates the effects of ethylene-propylene-diene-monomer grafted maleic anhydride (EPDM-g-MAH) and internal mixer melt compounding processing parameters on the properties of natural rubber/ethylene-propylene-diene rubber (NR/EPDM) blends. Using Response Surface Methodology (RSM) of 2(5) two-level fractional factorial, we studied the effects of NR/EPDM ratio, mixing temperature, Banbury rotor speed, mixing period, and EPDM-g-MAH contents in NR/EPDM blends. The study found that the presence of EPDM-g-MAH in NR/EPDM blends had a predominant role as a compatibilizing agent, which affected the processability and properties of the final material. We also determined the model fitting with constant determination, R-2 of 99.60% for tensile strength (TS) response with a suggested combination of mixing process input parameters. The reproducibility of the proposed mixing strategy was then confirmed through model validation with a minor deviation at +2.303% and higher desirability of 0.960. This study is essential in providing a process design reference for NR/EPDM blends preparation by melt-blending and the role of a compatibilizer from the systematic Design of Experiment (DOE) approach. The experimental findings were further supported with swelling and cross-link density measurements, differential scanning calorimetry analysis, and observation of fracture morphology using a scanning electron microscope. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42199.