Dados do Trabalho

Título

Biodegradable materials of citrus pulp pellets (CPP), polybutylene succinate (PBS), and thermoplastic starch (TPS) produced by thermoplastic injection molding

Introdução

Plastics from fossil sources have emerged as a significant concern at present. Biodegradable materials from renewable sources are an alternative to fossil ones and have the potential for several uses. This study explores a novel approach to producing low-cost, biodegradable materials with citrus pulp pellets (CPP), polybutylene succinate (PBS), and thermoplastic starch (TPS) by extrusion and thermoplastic injection.

Material e Métodos

Five formulations were produced: P20 (20 PBS/44.8 TPS/24 Glycerol/11.2 CPP % w/w); P40 (20 PBS/33.6 TPS/24 Glycerol/22.4 CPP % w/w); P60 (20 PBS/ 22.4 TPS/24 Glycerol/ 33.6 CPP % w/w); P80 (20 PBS/11.2 TPS/24 Glycerol/44.8 CPP % w/w); F100 (20 PBS/24 Glycerol/56 CPP % w/w). The microstructure analyses of the biodegradable materials were performed using a scanning electron microscope (SEM). Mechanical tensile tests (tensile strength – TS and elongation at break - EB) were performed using a Universal Testing Machine. Five specimens of each formulation were placed in a desiccator for one week at 53% relative humidity, then weighed and measured thickness, length, and width with a digital caliper to calculate the volume.

Resultados e Discussão

The SEM images of all the formulations showed the non-homogeneity of the polymer matrix. This lack of interactions occurred due to CPP's high cellulose, hemicellulose, and lignin contents, which are incompatible with PBS. P20 had the highest TS (1.31 MPa) and EB (11.7 %). There was a tendency for decreasing TS and EB with CPP concentration increasing. This occurred due to the non-homogeneity of the blend matrix. Still, they are adequate for several uses. There was no statistical difference between the densities of P20, P40, P60, and P80 (1.34~1.36 g cm-3). P100 formulation had the lowest density (1.32 g cm-3), probably due to the absence of TPS. This can lead to applications where the material needs to be light and resistant, such as single-use trays, packaging cups, spoons, and straws.

Conclusão

Producing CPP, PBS, and TPS blends showed excellent processability. They presented adequate mechanical properties for several uses and low cost once both CPP and TPS are cheaper than PBS and even other conventional polymers like PE or PP.