Preparation and Properties of Thermoplastic Polyurethane Composites Filled with Powdered Buckwheat Husks

Bio-based fillers for the polymer composites are still interesting from the scientific and industrial point of view, due to their low cost and renewable nature. In this work partially green composites were obtained by the mixing of thermoplastic poly(ester-urethane) with the unmodified and modified (by acetylation) grinded buckwheat husks. Obtained biocomposites were characterized in the terms of their chemical structure (FTIR), microstructure (SEM), thermal stability (TGA), thermomechanical properties (DMTA), and selected mechanical properties. The results showed that introduction of grinded buckwheat husks (even if the amount is 60 wt%) permit retaining high values of tensile strength (around 8-10 MPa), but the increasing amount of applied filler is connected with the decreasing of elongation at break. It can result from good interaction between the polymer matrix and the bio-based filler (confirmed by high values of polymer matrix-filler interaction parameter determined from Pukanszky's model for the tensile strength of composites). The applied chemical treatment results in changing of mechanical properties of filler and composites. Obtained results confirmed the possibility of using powdered buckwheat husks as filler for thermoplastic polyurethane.

Automated summary

Bio-based fillers for polymer composites are still of interest due to their low cost and renewable nature. In this study, partially green composites were prepared using thermoplastic poly(ester-urethane) mixed with unmodified and modified grinded buckwheat husks. The results showed that the introduction of buckwheat husks retained high tensile strength but decreased elongation at break. The chemical treatment altered the mechanical properties of the filler and composites.