Characteristics of Carrageenan/Corn Starch Biodegradable Plastic Films Produced by Extrusion Blending

This research investigated the production of biodegradable plastic films made from a blend of carrageenan and corn starch biopolymers. The procedure included producing bioplastic resin pellets using a single screw extrusion at a 110 °C temperature, followed by hot compression at a temperature of 160 °C to form a biodegradable plastic film. The project aimed to develop a continuous biodegradable plastic production method, particularly made from carrageenan, which is more adaptable for commercial-scale production. The carrageenan/corn starch films were prepared with various compositions, ranging from formulations dominated by carrageenan (56:14% w/w) to those dominated by corn starch (14:56% w/w), with the addition of a constant amount of glycerol (30% w/w) as a plasticizer. After the films were obtained, each of the samples was evaluated for their physico-mechanical properties, chemical structure, water sensitivity, and soil biodegradability. In general, an increase in corn starch content within the film matrix led to an enhancement of the overall properties of the resulting film. The film with the highest corn starch content exhibited tensile strength and elongation at break values that were 49% and 163% higher, respectively, compared to the film with the lowest corn starch content. Additionally, these samples demonstrated improved thermal stability, with a 12% increase in the thermal decomposition temperature, and enhanced barrier properties, as evidenced by a 6% reduction in water vapor permeability and a 72% decrease in water uptake. This is mainly due to the inherent molecular structure of corn starch, particularly due to its long straight-glucose chains. On the other hand, carrageenan increased the biodegradability rate of the films. These findings demonstrate the potential of carrageenan/corn starch blends as promising candidates for future packaging materials.