Additives are costly and can have negative environmental effects. Thus, searching for other alternatives to improve recycling plastics without using additives is necessary. This study aims to improve the hoop tensile strength, elongation at break, and shrinkage of the ring stopper made from an acrylonitrile butadiene styrene blend comprising 40% recyclates through the optimization of processing parameters using the Taguchi method. By adopting the Taguchi orthogonal array, four controllable factors each at three levels are tested to determine the optimal combination of factors and levels in the injection moulding process. Considering the multiple quality characteristics involved in this study, we investigate the effects of processing parameters on hoop tensile strength, elongation at break, and shrinkage of the ring stopper both separately and simultaneously because changing a parameter can result in the improvement or deterioration of each quality response and of the overall product performance. The results revealed that the performance of an injection-moulded ring stopper under the optimal process conditions is equivalent or slightly better than that of the part produced from virgin resin. The performance of recycled plastics can be effectively enhanced to levels comparable with virgin resins using the Taguchi optimization approach. 1. Introduction Plastics have entrenched themselves within the spectrum of modern materials as approximately 16% of applications are designed with plastics, which cannot be feasibly substituted. A world without plastics is difficult to imagine as plastic products have infiltrated every corner of human life, from the morning toothbrush to the garbage bag that is carried out at the end of the day. However, high plastic consumption inexorably causes an increasing amount of plastic to end up in the waste stream. Relative to population growth and along with the significant influx of foreign workforce to cities, the problem of plastic waste tends to be more severe in developing countries, such as Malaysia. Given their nonbiodegradability and high visibility in the waste stream, plastic waste can persist for at least decades and probably for centuries, resulting in serious pollution problems. Therefore, a sustainable plastic waste management strategy must be established to manage the large amount of generated plastic waste. The large-scale practice of plastic recycling can be conducted on a multitude of products, ranging from consumer commodities, such as soft drink bottles [1], to industry applications, such as automobile
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