Optimization the Mechanical Properties of PVC/n-NBR Blends Using Taguchi Experimental Design Method

The aim of this paper is to study the morphology and mechanical properties of poly(vinyl chloride) (PVC) blends containing acrylonitrile butadiene rubber (NBR) nanoparticles prepared in a counter rotating twin- screw extruder. The effect of nanoparticle’s percent, mixing temperature and time and rotor speed on the properties were studied using the experimental design method. Considering toughness increase of the blends as an optimal state, the process conditions and NBR percent were determined. Scanning electron microscopy (SEM) images showed dispersed matrix-droplet morphology. Uniform distribution of NBR rubber particles was observed within the PVC matrix due to the good compatibility between the rubber particles and the matrix. It was also observed that scattered droplets are present in the spherical form as well as elongated particles within the PVC matrix. Obtained results along with experimental design data showed that the optimal state of break strain and toughness is related to the state with a mixing temperature of about 180 °C, mixing time of 6 minutes, mixing speed of about 70 rpm and a nanoparticle percentage of 2%. The analysis of variance showed that the greatest effect on the modulus was related to the percentage of NBR, while the lowest was related to the mixing time. After that, mixing temperature has the highest share. Interactions between different factors and their effects on tensile modulus showed that the highest intensity of the interaction index is related to the interaction of mixing temperature with mixing time and the lowest is the time and percentage of NBR.