The effects of epoxidized natural rubber (ENR-50) and processing parameters on the properties of natural rubber/ethylene-propylene-diene rubber (NR/EPDM; 70 : 30 phr) blends were studied. The compounds were prepared by melt compounding method. Using response surface methodology of two-level full factorial, the effects of ENR-50 contents (21 : 5 phr; 11 : 10 phr), mixing temperature (21 : 50 C; 11 : 110 C), rotor speed (21 : 40 rpm; 11 : 80 rpm), and mixing time (21 : 5 min; 11 : 9 min) in NR/EPDM blends were evaluated. Cure characteristics and tensile properties were selected as the responses. The significance of factors and its interaction was analyzed using ANOVA and the model's ability to represent the system was confirmed using the constant of determination, R 2 with values above 0.90. It was found that the presence of ENR-50 has the predominant role on the properties of NR/EPDM blends. The addition of ENR-50 significantly improved cure characteristics and tensile strength up to 5.12% and 6.48% compared to neat NR/EPDM blends, respectively. These findings were further supported by swell measurement, differential scanning calorimetry, and scanning electron microscopy.

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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 12.303% 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.

Epoxidized natural rubber-alumina nanoparticle composites were prepared by melt compounding with an internal mixer for a constant filler loading of 10 phr. Mixer parameters such as the mixing temperature, mixing time, and rotor speed were screened and optimized with response surface methodology to maximize the impact strength. The parameters were selected as three independent variables and the impact strength (J/m) was selected as the response in a screening factor study. The mixing temperature and its interaction terms were identified as insignificant factors with a P value greater than 0.0500. The optimum calculated values of the tested variables (rotor speed and mixing time) for the maximum impact strength were found to be a rotor speed of 60 rpm and a mixing time of 6 min with a predicted impact strength of 208.88 J/m. These predicted optimum parameters were tested in real experiments. The final impact strength was found to be close to the predicted value of 215.84 J/m, with only a 3.33% deviation.