Viability Study of Use of Reprocessed High Density Polyethylene for Manufacturing Products and Multi Response Optimization of Injection Moulding Parameters Using Grey Relational Analysis

Abstract

In landfill, it was found that the majority of the plastic items are not biodegradable and very gradually degrade. With reprocessed consumer plastics, many attempts have been made to reduce the impact on the environment and to avoid the consumption of virgin plastics. The plastic blend of 50% reprocessed high density polyethylene (HDPE) and 50% virgin HDPE has been used purposely for this study. Usability of reprocessed HDPE as alternative for virgin HDPE is investigated. This paper investigates the influence of the process parameters melt temperature, holding pressure, and cooling time on tensile strength and flexural strength through Taguchi methodology and grey relational analysis in Injection moulding machine. Multi response characteristics like tensile and flexural strengths are selected to evaluate the process performance and the corresponding moulding parameters of the melt temperature, holding pressure, and cooling time. Optimal combination of injection moulding parameters is determined using Taguchi and Grey relational analysis. Tensile and flexural strengths of the reprocessed HDPE are found close to that of virgin HDPE. Hence, reprocessed HDPE is found a good alternative for virgin HDPE. The confirmation results reveal that, there is significant progress in tensile strength and flexural strength of reprocessed HDPE and Grey relational grade are improved by 6%, 5% and 74% respectively. Optimal combination of the process parameters for the multi-performance characteristics of the reprocessed HDPE is the set with melting temperature at 235 °C, holding pressure at 250 N/m2 and cooling time at 25 s.