Linoleum waste as PLA filler for components cost reduction: Effects on the thermal and mechanical behavior

Polylactic acid (PLA) is a biodegradable polymer from renewable resources with mechanical properties comparable to traditional polymers, but with a higher cost. A solution to this issue is the production of bio-based composites to partially replace the PLA matrix with industrial wastes characterized by a zero-cost, e.g., linoleum, to also valorize them in a circular economy perspective. Linoleum heterogeneous nature deriving from the simultaneous presence of lignocellulosic and inorganic fillers and oil/rosin binders, made the evaluation of matrix/filler compatibilization strategies necessary. Two approaches were considered, one from the filler perspective with NaOH and silane treatments, and the other one from the matrix perspective by adding a chain extender (C.E.). The first approach marginally improved tensile stiffness (by 1.6 %) compared to neat PLA but caused a significant decrease of 32.8 % in strength. Considering this, the costs and disposal of the chemicals and the increased environmental impact of the process, this approach was discarded. One the contrary, the introduction of C.E. does not modify the manufacturing process and increases tensile stiffness and elongation at break of 7.2 % and 415.5 % compared to neat PLA with a tolerable reduction in strength, i.e., 16.6 %, thus being a suitable way to exploit linoleum as zero-cost filler.