Extrusion blow molding of environmentally friendly bottles in biodegradable polyesters blends

Abstract

Increasing awareness of the environmental impact of oil-relying plastic materials is prompting Academia and manufacturing industry to develop eco-friendly materials and alternative technological solutions. Blown bottles and containers represent a significant share of the worldwide plastic market and great environmental concern is arising about their disposal. Generally, blown plastic bottles are made of three different materials: (i) a cap manufactured from High Density Polyethylene (HDPE), (ii) a bottle body manufactured from Polyethylene Terephthalate (PET), (iii) a label manufactured from printed Low Density Polyethylene (LDPE). The disposal of blown bottles requires, therefore, the separation of the different materials and, then, their individual recovery. An eco-friendly alternative to multi-material blown bottles is the development of a bottle entirely made from a biodegradable polymeric blend, designed to be suitable for manufacturing both the cap, the bottle body and the label. In this framework, the present manuscript deals with the design and development of novel biodegradable blends based on bio-based polyesters. The blends are herewith specialized for extrusion blow molding of the bottle body, although they could be further customized for both the cap and the label. Twin-screw co-rotating extrusion of the compounds, extrusion blow molding of the compounds for bottle manufacturing and the evaluation of the thermo-physical and mechanical properties of the bottles are hereinafter reported. The novel polymeric blends are found to be suitable for extrusion blow molding of the bottle body, also exhibiting valuable performances in terms of mechanical strength and impact resistance as well as protection against gas permeation and light transmission.