Thermal and rheological properties and processability of thermoplastic lignocellulose

Artikel i vetenskaplig tidskrift, 2024

Fossil-free biobased materials like thermoplastic lignocellulose are gaining attention because of climate issues. However, there is a challenge to make these as thermoplastic as commonly used thermoplastics. Arboform® is one of today's commercially available thermoplastic lignocellulose materials. In this work, the processability of this material was studied in detail and the effects of plasticizers on its processability, rheological, and mechanical properties were determined. Thermal/calorimetry analysis indicated that the processing temperature window was shifted to lower temperature with the use of tributyl citrate (TBC) and poly(ethylene glycol) (PEG 400) plasticizers, thus enabling extrusion at lower temperature. TBC and PEG 400 decreased both the glass transition temperature and melting point of the polylactide component. Surprisingly, they also affected the lignin component, as observed by the decreasing lignin decomposition temperature. It is observed that TBC and PEG400 lowered the stiffness of the compression molded material in the temperature range investigated (−30–180°C), and tensile tests in the presence of TBC revealed a decrease in ductility. Notable is that, in contrast to most thermoplastics, the Arboform® melt increases in viscosity and elastic moduli when the processing temperature was increased (from 180 to 200°C) or when processing time was increased.