Dados do Trabalho

Título

Biodegradable materials containing oat hulls, thermoplastic starch (TPS), and polybutylene succinate (PBS) by thermoplastic injection.

Introdução

The production of fossil-origin materials (350 million tons annually) has sparked growing concerns. Biodegradable polymers like polybutylene succinate (PBS) have emerged as an alternative to fossil-origin materials. However, their high cost is a disadvantage. Developing blends using oat hulls and thermoplastic starch (TPS) can reduce PBS costs and ensure biodegradability. This study aimed to develop low-cost biodegradable materials by extrusion and thermoplastic injection using oat hulls, PBS, and starch.

Material e Métodos

Four formulations were produced: F0 (20 PBS/56.0 TPS/24.0 Glycerol % w/w); F20 20 PBS/44.8 TPS/24 Glycerol/11.2 Oat hulls % w/w); F60 (20 PBS/ 22.4 TPS/24 Glycerol/ 33.6 Oat hulls % w/w); F100 (20 PBS/24 Glycerol/56 Oat hulls % w/w). They were extruded in a single-screw extruder, and then the materials were produced by thermoplastic injection. The microstructure images of the samples were captured using a scanning electron microscope. Density was calculated by weighing the mass and measuring the volume using a digital caliper. Linear contraction index (LCI) was determined by measuring the specimens from each formulation with a digital caliper.

Resultados e Discussão

The images of the F0 material showed starch granules (circular shape) and a plasticized superficial area, characteristic of blends containing thermoplastic starch. Cracks were also observed due to the poor compatibility between PBS and TPS. The F20, F60, and F100 surface and fractured images show aligned oat hull fibers (cylindrical shape), possibly due to extrusion orientation. F100 (1.28 g cm-3) had the lowest density. The high oat hull content in the F100 formulation contributed to decreased material density, as fibers have lower densities than TPS. F60 (0.75%) and F100 (0.70%) had the lowest LCI values. Increasing the fiber concentration resulted in a lower LCI because the fibers can act as fillers, occupying spaces in the blend structure and making it less capable of shrinking or expanding. This provides good dimensional stability and avoids deformation.

Conclusão

Biodegradable materials produced with oat hulls, TPS, and PBS presented excellent processability; the extrusion aligned the oat hull fibers, making the material dimensionally stable and reducing material density. Their compatibility with existing equipment highlights their potential for large-scale manufacturing.