The Influence of a Low‐Molecular Plasticizer on the Physical and Mechanical Properties and Electrical Conductivity of a Composite Material Based on Polylactide Modified With a Carbon Filler

ABSTRACT Polylactide (PLA) is a widely used biodegradable polymer for 3D printing, but its brittleness and stiffness limit applications, especially when reinforced with high‐modulus fillers like carbon black (CB). This study investigates the effect of propylene carbonate (PC) plasticizer on PLA‐CB composite properties. Composites containing 10 wt.% CB were prepared with varying PC content (5–35 wt.%). Mechanical testing revealed that PC up to 10 wt.% slightly increased tensile strength, while higher PC contents (20–30 wt.%) significantly improved elongation at break (up to 59%) but decreased elastic modulus to 290 MPa. Electrical resistivity decreased from 0.049 to 0.022 Ω m with increasing PC up to 30 wt.%. A three‐stage mechanism of PC influence was established: at low PC levels (< 10 wt.%), adsorption on CB improves interfacial interaction; at intermediate levels (10–30 wt.%), PC diffuses into the matrix, enhancing CB dispersion; at high levels (> 30 wt.%), excessive plasticization reduces viscosity and causes CB agglomeration. Key findings include: PC content of 10–15 wt.% provides optimal balance between mechanical properties and conductivity. The composites exhibit semiconducting behavior, suitable for sensors, electronic components, EMI shielding, and heating elements. Results demonstrate that PC plasticization effectively modifies PLA‐CB composites, enabling tailored properties for specific applications.