Thermomechanical Assessment of Novel Composites Intended for Fused Deposition Modeling

Abstract

New types of filaments were formed by adding various fillers into polymers during the fabrication. We designed two new composites in cooperation with a filament producer. Biodegradable thermoplastic polyester polylactic acid (PLA) was filled with carbon black. Carbon black (CB) formed 30 wt.% of in the final mixture. The second composite was made by compounding the polyethylene terephthalate glycol-modified (PET-G) with titanium dioxide. Two different contents of TiO2, namely 10 and 20 wt.%, were selected for filament preparation. The goal of the testing was to evaluate the change of mechanical and thermomechanical properties in contrast to pure filaments. The testing specimens were prepared by Fused Deposition Modeling (FDM), which belongs to 3D printings techniques. The printed samples were subjected to mechanical tensile testing and to microhardness measurement by the Vickers method. Thermomechanical analysis (TMA) and dynamic mechanical analysis (DMA) were performed too. In particular, glass transition temperature, coefficient of thermal expansion (CTE), and storage modulus were analyzed. All composites showed a lower ultimate tensile strength than the neat polymer. Notable changes in thermomechanical behavior were also detected. The most significant difference was the drop in CTE above the glass transition in the case of filled PLA samples.