Investigation of the thermoformability of bioplastics

Abstract

In an effort to move towards a more sustainable future, bioplastics are being promoted as sustainable alternatives to plastics. Nevertheless, the market transition to bioplastics requires the materials to be incorporated into already existing manufacturing processes with the capability of creating a variety of three-dimensional customized shapes. Thermoforming is a widely used process in the plastics industry to manufacture a wide range of products of different sizes. However, thermoforming of several types of bioplastics has received relatively scant research to date. Therefore, this study examines the feasibility of thermoforming three bioplastics, Polylactic Acid (PLA), Cellulose Acetate Propionate (CAP), and Bio-Polyethylene Terephthalate (Bio PET). Materials were tested using an industrial Form-Fill-Seal (FFS) thermoforming line equipped with a custom-designed sheet-forming chamber. Additionally, the results were compared to a commonly used thermoforming plastic, multilayer polyethylene/polyethylene terephthalate. The aim is to provide insight into the possibilities of this transition from a perspective of energy efficiency, processing speed, and possible shape-making, with an assessment of the optimal forming window for materials and a detailed analysis of the formed products. A further investigation is conducted into factors that may hamper the thermoforming performance of the materials being investigated. Results indicate that the thermoforming performance and processability of the studied materials differ clearly; PLA and BioPET yet face limitations in processability considering their properties and possibilities for their incorporation into existing thermoforming lines, whereas CAP material can compete the commercial materials on the basis of product shape, production speed, and energy requirements in thermoforming.