PLA-based composite material with a flax husk filler

The use of environmentally friendly biodegradable materials allows to reduce the environmental impact. It is possible to use composite materials based on biodegradable plastics with plant fillers, which should be pre-treated to increase their adhesion to the polymer matrix.

The initial flax husk was ground. After milled flax husk powder was acetylated with acetic anhydride, which leads to improved adhesion of filler and polymer matrix. To create the composite, modified flax husk powder in the amount of 30, 40 and 50 wt. % was mixed with the PLA powder and then then obtained mixture was pressed at a pressure of 18.5 MPa and a temperature of 185°C.

With the addition of the filler to the polymer matrix, a decrease in tensile strength was observed for the 20 wt. % filler content (5.29 MPa), while the maximum decrease in strength was observed for the 50 wt. % filler content sample (4.87 MPa) compared to 14 MPa for the unfilled PLA. This decrease in strength is explained by the appearance of the interface between the matrix polymer and the filler. All samples are biodegradable, with the maximum degree of biodegradation observed after 90 days of testing at a temperature of 29°C and humidity of 75% for the sample containing 50 wt. %. The testing simulated a natural environment based on the assessment of the impact of resident biocenoses according to the ISO 846:2019 methodology. It should be noted that increasing the filler loading from 30 wt. % to 50 wt. % does not lead to a significant decrease in strength, while increasing biodegradability and reducing production costs.

The composite material obtained in this study can be used in products that do not require significant strength properties, while reducing the environmental impact.

This work was supported by grant FZWN-2024-0001