Investigating the effects of recycling number and injection parameters on the mechanical properties of glass-fibre reinforced nylon 6 using Taguchi method

Highlights: ► The glass-fibre reinforced nylon 6 was processed until the five processing cycles. ► Samples were analyzed by chemical structures as a function of processing cycles. ► Effects of injection molding parameters on mechanical properties were investigated. ► The length of the fibres was shortened after each injection molding process. ► Decrement in mechanical properties after each reprocessing cycle was observed. - Abstract: In this study, the glass-fibre reinforced nylon 6 (PA6-GF) was reprocessed in the five processing cycles. The recycled PA6-GF samples were characterized by its chemical, thermal, and mechanical properties as a function of the number of processing cycles. It was also investigated how the controlled factors affect the output factors and what the optimal injection settings of the controlled factors can be employed to obtain the best mechanical properties. To achieve these aims Taguchi's mixed level parameter design (L18) was employed for the experimental design. Number of recycling, melt temperature, mold temperature, injection pressure, and holding pressure were considered as the control factors. Regression analyses were applied to predict tensile strength, yield strength, impact energy and impact strength. Analysis of variance (ANOVA) was used to determine the effects of the control parameters on tensile strength, yield strength, impact energy, and impact strength. In the plastic injection of PA6-GF, the number of recycling was found to be the most effective factor on mechanical properties. From the experimental results it was concluded that there was a decrement in mechanical properties after each reprocessing cycle