Different rotations in the acrylonitrile-butadiene-styrene extrusion process and their influence on fracture and mechanical properties

Abstract

ABS resins have wide application in the market, mainly in the manufacture of household appliances, telephones, automotive industry and others, and need to be processed by extrusion for the manufacture of products. The variables used in the process of extrusion of polymers have a direct influence on their mechanical properties. The objective of this study was to evaluate the different speeds of the extruder screw (15, 30, 45 and 60 rpm) on the mechanical properties of raw ABS after the extrusion process. Izod impact resistance and tensile tests, were also performed. The fractures of the samples tested by Izod impact were observed via optical microscopy, scanning electronic microscopy (SEM), and roughness was measured. Calorimetric tests (DSC) and thermogravimetry (TGA), as well as melt flow index (MFI), were also performed. The most significant results were observed for the extruder screw speed of 60 rpm. For the impact test, a reduction in impact energy of approximately 3% was observed, with the same result for tensile resistance. However, an increase in the value of the elastic modulus and the MFI was observed due to the increase in the degree of crystallinity, which was caused by the higher shear of the polymer mass in the screw of the extrusion equipment. Additionally, an atypical case occurred for the ABS polymer in the highest rotation, since it was the polymer that suffered the greatest shear in the polymer chains due to the degradation of the butadiene phase.