Reduction of Production Waste in High-Density Polyethylene (HDPE) Water Bottle Manufacturing by Recycling Plastic Scraps

Abstract

This study aimed to reduce waste in the production process of high-density polyethylene (HDPE) water bottles by reusing plastic scraps generated during manufacturing. In the existing production system, plastic waste resulted in an average material loss of more than 110,000 THB per month. To address this issue, a prototype plastic grinder was designed and developed to process HDPE scraps for reuse. The recycled plastic was then mixed with virgin HDPE grade A pellets at different ratios of 1:1, 2:1, and 1:2. The mixtures were subsequently processed using the blow molding technique to produce 20-liter water bottles. Tensile test specimens were prepared according to ASTM D638 Type IV and tested using a Universal Testing Machine (UTM). Five specimens were prepared for each mixing ratio, and each experiment was repeated five times. The results were analyzed using mean values and standard deviations.

The experimental results indicated that the mixing ratios of 1:1 and 2:1 produced tensile strength values within the standard range of HDPE materials (20–31 MPa). Among the tested ratios, the 1:1 ratio was identified as the most suitable, as it maintained the mechanical properties of the product without compromising material strength. The results demonstrate that incorporating recycled HDPE at proportions up to 50% can reduce production waste by approximately 50% and decrease raw material losses from about 110,000 THB to approximately 55,000 THB per month. These findings highlight the potential of recycling plastic scraps to improve resource efficiency and support sustainable plastic manufacturing in industrial applications.